Ch-16_Human Health and Disease

Chapter 16
Human Health and Disease

Chapter Contents
z Common Diseases in Humans Health
z Immunity Health does not simply mean ‘absence of disease’ or ‘physical fitness’.
z AIDS It is defined as a state of complete physical, mental and social well being.
Health can be affected by
z Cancer
(i) Genetic disorders : Deficiencies with which a child is born or
z Drugs and Alcohol Abuse deficiencies/defects which the child inherits from parents birth.
(ii) Infections,
(iii) Life style including food and water (balanced diet) we take, rest and
exercise (yoga) we give to our bodies or habits that we have or lack.
Note :
z Hippocrates is called father of medicine.
z William Harvey disproved the ‘good humor’ hypothesis.
Disease
When the functioning of one or more organs or systems of the body
is adversely affected, characterised by various signs and symptoms,
we say, that we are not healthy, i.e., we have a disease. Disease can
be broadly classified into two categories:
(A) Congenital Diseases : These diseases occur at birth and may
result from metabolic disorders or defects in development.
(B) Acquired diseases : These diseases develop after birth and can
be divided into two main categories :
(i) Infectious diseases/Communicable diseases : Diseases
which are easily transmitted from one person to another are
called infectious diseases. Infectious diseases are very
common and some of the infectious diseases like AIDS are
fatal.
(ii) Non-infectious diseases/Non-communicable diseases :
These diseases are not spread to other persons. Among
non-infectious diseases, cancer is the major cause of death.
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2 Human Health and Disease NEET
Pathogen
A wide range of organisms could cause diseases in man. Such disease causing organisms are called
pathogens e.g., bacteria, viruses, fungi, protozoans, helminths etc.
Most parasites are therefore pathogens as they cause harm to the host body by living in or on them. The
pathogens can enter our body by various means, multiply and interfere with normal vital activities, resulting
in morphological and functional damage. Pathogens have to adapt to life within the environment of the host.
For example, the pathogens that enter the gut must know a way of surviving in the stomach at low pH and
resisting the various digestive enzymes.
COMMON DISEASES IN HUMANS

A. Bacterial Diseases
(i) Typhoid: (Enteric fever)
Pathogen: Salmonella typhi (A Gram negative bacterium)
Mode of transmission: These pathogens generally enter the small intestine through contaminated food
& water and migrate to other organs through blood.
Symptoms: Sustained high fever (39° to 40°C), weakness, stomach pain, constipation, headache, and
loss of appetite are some of the common symptoms of this disease. Intestinal perforation and death may
occur in severe cases.
Test: Typhoid fever could be confirmed by Widal test.
Note :
z Mary Mallon was carrier of typhoid who spread the disease through the food she prepared. Hence
was nicknamed, Typhoid Mary.
(ii) Pneumonia:
Pathogen: Bacteria like Streptococcus pneumoniae and Haemophilus influenzae.
Mode of transmission: A healthy person acquires the infection by inhaling the droplets / aerosols
released by an infected person or even by sharing glasses and utensils with an infected person.
Symptoms: In pneumonia, infection occurs in alveoli of the lungs. As a result of the infection, the alveoli
gets filled with fluid leading to severe problems in respiration. The symptoms of pneumonia are fever,
chills, cough and headache. In severe cases, the lips and finger nails may turn gray to bluish in colour.
(iii) Plague/Bubonic plague: (Black death)
Pathogen: Yersinia pestis
Mode of infection: It is primarily a disease of rodents but can accidently affect man. It spreads from rat
to rat through rat flea (Xenopsylla). But when the infected rats die, the fleas leave their body and could
bite man injecting plague pathogens into his blood.
Symptoms: It is characterised by high fever and a bubo (lump) in the groin or the armpit. Red patches
appear on skin which turn black and ultimately lead to death (black death). Wayson–stain test helps
to detect plague.
(iv) Tuberculosis (TB) : It is also called Koch’s disease. It is caused by Mycobacterium tuberculosis. The
bacteria damages the tissues and releases a toxin named tuberculin which produces the disease.
It affects the lungs, lymph nodes, bones and joints. Incubation period is quite variable. Symptoms of
pulmonary (lungs) tuberculosis are fever, cough, sputum containing blood, pain in the chest and loss
of weight, excessive fatigue, loss of appetite, rise of temperature in the evening, hoarseness of throat,
night sweating and rapid pulse. BCG vaccine gives considerable protection against tuberculosis. TB can
be detected using Mantoux test.
NEET Human Health and Disease 3
(v) Leprosy (Hansen’s Disease) : This disease is caused by Mycobacterium leprae, which was discovered
by Hansen. Symptoms of leprosy include appearance of light coloured patches on the skin, thickening
of the nerves, partial or total loss of sensation in the affected parts of the body. These are accompanied
by fever, pain, ulcers and skin eruptions. Deformities of toes and fingers may also develop. The bacilli
leave the body in nasal discharge, from the throat during coughing, sneezing or speaking and through
broken skin lesions. The patient is treated with DDS (diamino diphenyl sulphone).
(vi) Cholera : This is an acute infectious disease caused by Vibrio cholerae. These may get into a healthy
person with contaminated food and water. The patient starts passing stools frequently, which are white
like rice-water and vomits repeatedly.
Since, a large quantity of fluid and salts are rapidly lost through stools and vomit, therefore, the most
important treatment is to replace the lost fluid and salts equally by oral rehydration therapy.
(vii) Diphtheria : This disease is caused by Corynebacterium diphtheriae usually affecting children upto five
years of age. It may start with sore throat, chills with mild fever, sometimes vomiting and headache.
Throat or tonsils show a grey membrane which may spread down and cause hoarseness and difficulty
in breathing. The most important preventive measure-against this disease is that all babies should be
immunised within the first six weeks of birth using DPT vaccine.
(viii) Tetanus (Lock Jaw) : It is caused by Clostridium tetani which produces a neurotoxin tetanospasmin
which acts at neuromuscular junction. The first indications of this disease are irritability and restlessness,
stiffness of neck and difficulty in chewing and swallowing. Subsequently, spasms of muscles of the jaw
and face take place and thus “Lock Jaw” occurs. There is severe pain. It is often a fatal disease. The
toxin mainly affects ‘voluntary muscles’. Tetanus organisms live in the intestine of horses and other
animals without doing any harm. Anti tetanus serum (ATS) injection should be administered in case
of an injury.
B. Viral Diseases
(i) Common cold/Rhinitis :
Pathogen: Rhino virus.
Mode of infection: It is one of the most infectious human diseases, transmitted through inhalation of
droplets resulting from cough or sneeze of an infected person, either inhaled directly or transmitted through
contaminated objects such as pens, books, cups, door knobs, computer keyboard etc. (fomite borne).
Symptoms: Rhino virus infects the nose and respiratory passage but not the lungs. (Upper Respiratory
tract infection) It is characterised by nasal congestion and discharge, sore throat, hoarseness, cough,
headache, fatigue, etc., which usually lasts for 3-7 days.
(ii) Influenza : It is commonly known as “Flu” and is highly infectious. The disease is caused by various
types of influenza viruses (e.g., Myxovirus influenzae). It causes fever and pain all over the body and
affects the nose, throat and air passages as in common cold. It starts with fever, headache, sore throat,
cold with sneezing and pain all over the body with restlessness. In neglected cases, complications like
pneumonia, bronchitis and ear infections may develop.
(iii) Small Pox : This disease is caused by a small pox virus named Variola virus (ds DNA virus). The virus
is present in the oral and nasal discharges of the patients and is ejected during the acts of coughing,
sneezing, fomites etc., and infects the healthy people. It is highly infectious disease starting with high
fever, chill, backache and headache, followed by appearance of rash on the third day of illness. The rash
appears first on the face followed by rest of the body. It is more on the face and limbs and less on the
trunk. The rash starts as a small reddish spot which change into papules. These in turn change into
small vesicles containing clear fluid. Vesicles change into pustules. Finally, a scab is formed and it falls
off by the third week. These scabs leave deep pits or scars known as pock marks. Many children may
become blind and develop discharge from the ear. Vaccination against small pox is one of the best
preventive remedies available today. This was discovered by Edward Jenner in 1798. Small-pox has
been eradicated from the world.
(iv) Chicken Pox : This disease is caused by a virus of chicken-pox named

Varicella zoster (dsDNA virus) which is passed out in the discharges of the
respiratory tract of an infected person directly as droplets or through
contaminated articles used by the patient. It is a mild but highly infectious
disease causing slight fever and a rash which undergoes changes into
vesicles, pustules and finally a dark brown scab which falls off leaving no scar
unlike smallpox. The rash comes out in crops and with each fresh crop, there
may be slight fever again. The rash first appears on the trunk and there
are more lesions on the trunk than on the face and limbs. Vaccination
against chicken-pox is now available. The most common late complication Chicken-pox
of chicken-pox is shingles caused by reactivation of Varicella zoster.
(v) Measles (Rubeola Disease) : It is caused by Rubeola virus (RNA virus) which is passed out in the
secretions of nose and throat of the infected persons as droplets or in articles soiled by these secretions.
The disease starts with catarrh of the nose and throat, and fever. It is a highly infectious disease causing,
inflammation of the air passages and a rash all over the body. The rash which is slightly pinkish in colour
first appears on the back of the ear and face, and spreads downwards on the body. It attacks
especially the children below the age of 5 years and those who have escaped may be attacked in the
later years of life. The eyes are red and watery, and the face is flushed.
(vi) Mumps (Infectious Parotitis) : It is an infectious disease causing fever,

difficulty in opening the mouth and painful swelling of the parotid glands
which lie just below the lobe of the ears. It is caused by Paramyxovirus
(RNA virus), which comes out in the saliva of the infected person. The
patient should take complete bed rest till the swelling subsides in order to
avoid complications. Usually, there are no complications, but in some
cases there may be pain and swelling of the testes (orchitis) or pain in the
A boy with mumps
abdomen.
(vii) Rabies (Hydrophobia) : It is caused by a virus called Rhabdo virus. It is mostly introduced in humans
by the bite of rabid (mad) dogs. It can also be injected by the bite of jackals, wolves, cats etc., Incubation
period is from 10 days to one year. Fear of water is the most important characteristic symptom of this
disease. Other symptoms are excess salivation, severe headache, high fever, alternating periods of
excitement and depression, inability to swallow food and even fluids due to choked throat. The virus
destroys the brain and spinal cord. Rabies is 100% fatal. There should be compulsory immunisation
of dog and cat population.
(viii) Poliomyelitis : This disease was called infantile paralysis. But it is now known that the disease may
occur at any age. This disease spreads mainly through intestinal discharges. It may also spread
through contaminated food or drink and by flies or other insects that may contaminate food or drink. Polio
virus (ss RNA) usually enters the body via alimentary canal where it multiplies and reaches the nervous
system (spinal cord) through the blood stream. Its incubation period is 7-14 days. It produces
inflammation of the nervous system. The earliest sign of this disease is involvement of the central nervous
system causing inability to bend the head forward. Stiffness of the neck is an important sign. Paralysis
starts following the weakness of particular skeletal muscles. The attack of paralysis begins with high
fever, headache, chills, pain all over the body. If muscles of larynx and pharynx are involved it proves
fatal. Within two to three days the paralysis reaches its maximum. There is no sure cure for polio. The
patient should be kept isolated. He should be given complete rest. An adequate arrangement for proper
disposal of urine and faeces of the patient must be provided because they contain polio virus.
Overcrowding of children in schools, playgrounds and cinema should be avoided. Polio is preventable.
Polio vaccine is safe and effective. Now-a-days multiple vaccines are used against polio, diphtheria,
whooping cough and tetanus simultaneously.
(ix) Dengue fever : Dengue fever is caused by a RNA containing Arbovirus (Arthropod borne virus) of
flavivirus group which also causes yellow fever (not found in India). Thus, the virus which causes dengue
fever is a mosquito borne flavi-ribo virus. The virus of dengue fever is transmitted by the bite of female
Aedes aegypti (tiger mosquito). Incubation period is 38 days. Two types : classical dengue fever and
dengue haemorrhagic fever are known to occur.
Symptoms of Classical Dengue Fever are (i) Abrupt onset of high fever. (ii) Severe frontal headache.
(iii) Pain behind the eyes which worsens with eye movement. (iv) Muscles and joint pain. (v) Loss of
sense of taste and appetite. (vi) Measles like rash over chest and upper limbs. (vii) Nausea and vomiting.
Symptoms of Dengue Haemorrhagic Fever are symptoms similar to classical dengue fever except
the following (i) Bleeding from the nose, mouth, gums and skin bruising. (ii) Severe and continuous
stomach pains. (iii) Frequent vomiting with or without blood. (iv) Pale cold or clammy skin. (v) Excessive
thirst (dry mouth). (vi) Rapid weak pulse. (vii) Difficulty in breathing. (viii) Restlessness and constant
crying.
If there is fever doctor should be consulted at once, paracetamol tablets should be taken on the advice
of doctor. Aspirin and Dispirin should be avoided. Cold sponging is required if fever is high. Plenty of
liquids must be given to the patient. Dengue can be detected using diagnostic Tourniquet test.
No vaccine for Dengue fever is available. Mosquito breeding places are to be eliminated by covering small
water containers, water tanks, changing the water of cooler every week, and also eliminating areas where
Aedes mosquitoes breed. Do not allow children to play in shorts and half sleeved clothes. Use mosquito
repellents, repellent cream and sleep in mosquito-nets.
(x) Chikungunya : It is caused by Chikungunya virus. This virus was first isolated from human patients and
Aedes aegypti mosquitoes from Tanzania in 1952. The name ‘Chikungunya’ is derived from the native
word for the disease in which patient walks “doubled up” due to severe joint pain. Its symptoms include
sudden onset of fever, crippling joint pain, lymphadenopathy and conjuctivitis. Some show haemorrhagic
manifestations. No vaccine is available.
(xi) Hepatitis :
(1) Hepatitis refers to inflammation of the liver and can be caused by viruses, drugs, and chemicals,
including alcohol. Clinically, several viral types are recognized. Hepatitis A (infectious hepatitis)
is caused by hepatitis A virus and is spread by faecal contamination of food, clothing, toys,
or utensils (faeco-oral route). It is generally a mild disease of children and young adults
characterized by anorexia (loss of appetite), malaise, nausea, diarrhoea, fever, and chills. Eventually,
jaundice appears. Most people recover in 4-6 weeks. Hepatitis A virus has single-stranded
RNA genome and non-enveloped capsid.
(2) Hepatitis B (serum hepatitis) is caused by hepatitis B virus. HBV is a 42 nm enveloped
virion, containing partially double-stranded circular DNA genome. Within the core there is
DNA-dependent DNA polymerase. It is spread primarily by sexual contact and contaminated
syringes or transfusion equipment. It can also be spread by saliva and tears. Hepatitis B
virus can be present for years or even a lifetime. It can produce cirrhosis and possibly cancer of
the liver. Persons who harbor the active hepatitis B virus are at a risk for cirrhosis and also become
carriers. Vaccines produced through recombinant DNA technology (for example,
Recombivax HB) are available to prevent hepatitis B infection. This vaccine is second
generation vaccine.
(3) Hepatitis C (non-A, non-B hepatitis) is caused by hepatitis C virus. It is clinically similar to
hepatitis B and is often spread by blood transfusions. Hepatitis C can cause cirrhosis and possibly
liver cancer. It has enveloped virion with ss-RNA.
(4) Hepatitis D (delta hepatitis) is caused by hepatitis D virus which has ss-RNA. It is transmitted
like hepatitis B. In fact, a person must be coinfected with hepatitis B before contracting hepatitis
D. Hepatitis D results in severe liver damage and has a fatality rate higher than that of people
infected with hepatitis B virus alone. HDV is a defective virus for which HBV acts as a helper.
(5) Hepatitis E (infectious NANB hepatitis) is caused by hepatitis E virus and is spread like hepatitis
A. Although it does not cause chronic liver disease, hepatitis E virus is responsible for a very high
mortality rate in pregnant women. HEV has ss-RNA.
Important properties of Hepatitis Virus
Virus Genome Mode of Transmission

HAV ssRNA Faeco-oral
HBV dsDNA Blood, sexual contact
HCV ssRNA Blood, sexual contact
HDV ssRNA Blood, sexual contact
HEV ssRNA Faeco-oral
C. Diseases Caused by Protozoans

(i) Malaria :
Pathogen: Malaria is caused by Plasmodium, a tiny protozoan. Different species of Plasmodium which
attack humans are P.vivax, P. malariae, P. ovale and P. falciparum.
Mode of transmission: Malarial parasite (Plasmodium) requires two hosts to complete its life cycle:
(i) Human, (ii) Mosquito (female Anopheles) which is the vector/transmitting agent too. Plasmodium enters
the human body as sporozoites (infectious form) through the bite of infected female Anopheles.
Life-history : When an infected female Anopheles bites a human to suck blood, it also injects the
malarial parasites into the human blood with its saliva. This infective stage of Plasmodium is a minute
sickle-shaped sporozoite. Sporozoites are inoculated in thousands into the human blood. In about half
an hour the sporozoites disappear from the blood stream and enter the parenchymatous cells of the liver
to escape from phagocytic white blood corpuscles and multiply their own number.
Schizogony : Each sporozoite grows in the liver cell to form a large and rounded schizont, which divides
to form about 1,000 small spindle-shaped merozoites. The multiple fission is called schizogony. The
schizont ruptures and merozoites are liberated into liver venous passages (sinusoids). This phase of
reproduction is termed as the pre-erythrocytic phase and in this stage the merozoites are also called
cryptozoites; they are immune to medicines and also to the resistance of the host.
The cryptozoites (merozoites) enter new liver cells, grow into schizonts which again divide to
form merozoites. These merozoites of the second generation are termed metacryptozoites and their
formation is called the exo-erythrocytic phase. The exo-erythrocytic cycle may continue in more liver
cells to form a reservoir of parasites, or some merozoites after two or more cycles in the liver may re-
enter the blood stream. Those merozoites which reach the blood stream attack healthy erythrocytes,
these are called phanerozoites or metacryptomerozoites. Pre-patent period is the duration between
the initial sporozoite infection and the first appearance of the parasites in blood. It is 8 days in
Plasmodium vivax. Incubation period is the duration between the initial sporozoite infection and the
first appearance of malarial symptoms. It is about 14 days in P. vivax, 30 days in P. malariae, 14 days
in P. ovale and 12 days in P. falciparum.
Erythrocytic Schizogony:
Inside the erythrocyte, another multiplication phase of schizogony follows, which is known as erythrocytic
phase (also called cycle of Golgi). On entering the red blood corpuscles the merozoites begin to feed
on the corpuscles. Soon a vacuole appears in the merozoite pushing its nucleus to one side, this stage
is called a ring-shaped trophozoite which is 1/3 to 1/2 the size of an erythrocyte. The trophozoite grows
further at the expense of the corpuscle to become somewhat rounded and amoeboid. This full grown
trophozoite is called a schizont and it has yellowish-brown pigment granules of haemozoin derived from
the iron of haemoglobin of the corpuscle. The corpuscle becomes much enlarged and acquires
granules called Schuffner’s dots.
The schizont undergoes repeated divisions to form about 12 to 24 merozoites. A certain amount of residual
cytoplasm along with the haemozoin granules is left unshared. This phase of asexual multiplication is called
erythrocytic schizogony. The merozoites so produced burst the weakened corpuscle and are liberated
into the blood plasma. These merozoites or schizozoites are short thick spindles and they enter new
erythrocytes and repeat the cycle of erythrocytic schizogony once every 48 hours, and this may go on
for many generations. They may also go to the liver cells to undergo a post-erythrocytic schizogony.
Along with the merozoites, toxins are liberated into the blood when corpuscles rupture, the toxins are
carried to all parts of the body and are deposited in the spleen, liver and under the skin. Accumulation
of toxins causes benign tertiary malaria fever, skin becomes sallow coloured, there is high temperature
after every 48 hours with chill and shivering, followed by profuse sweating.
Sexual cycle or Gamogony : After several generations of schizogony some of the merozoites grow
into large cells inside blood corpuscles. They become large slowly and produce much pigment. These
merozoites form two types of cells called gamonts or gametocytes; these are male and female
gametocytes. The female gametocytes or megagametocytes are round with food-laden cytoplasm and
a small eccentric nucleus. Male gametocytes of microgametocytes have clear cytoplasm and a large
central nucleus. Both contain large amounts of haemozoin.
Note :
Gametocytes remain in the blood for several weeks but are unable to develop further in the human
host, because of the high body temperature of man. It is therefore necessary for them to be taken
into the body of an Anopheles, where suitable temperature is available. Mosquito is a cold-blooded
animal. If this does not happen, gametocytes degenerate and die.
If gametocytes are sucked up by an Anopheles mosquito along with blood, they reach its stomach, the
corpuscles are dissolved but gametocytes are not digested. When removed from the warm human blood
into the mosquito, the microgametocytes undergo a striking change called exflagellation. The nucleus
divides into 6 to 8 nuclei around which cytoplasm collects to form long flagellated structures called
microgametes, which break from the pigmented residual cytoplasm. They grow and begin to swim in
the gut of the mosquito.
The megagametocytes undergoes little change, nucleus divides into two, one of which moves out along
with some cytoplasm and projects outward as a polar body; this changes it into a mature megagamete.
Soon the mature megagamete puts out a small conical projection, the cone of fertilization. The
gametes, being dissimilar, are called anisogametes.
One microgamete attaches itself to the cone of fertilization of the megagamete and the two fuse to form
a round zygote. (Anisogamous syngamy)
The sexual cycle is completed in any kind of mosquito which may feed on human blood, but further
development of malarial parasite will occur only if the parasite is sucked along with blood by an
appropriate species and variety of mosquito, i.e., only in certain species of Anopheles.
Sporogony : The round zygote may come to lie between the cells of the stomach of the mosquito.
Ookinete: The zygote elongates and becomes a worm like motile organism called Ookinete.
Penetration and Encystment :

The ookinete moves and bores through the wall of the stomach of female Anopheles mosquito. Here the
ookinete becomes immobile, reassumes spherical shape and begins to encyst. The encysted zygote
is called oocyst. Just one or two days after fertilization, several oocysts appear upon the surface of the
stomach of an infected female Anopheles bulging as tiny nodules. The cyst wall of the oocyst is partly
secreted by the zygote and partly secreted by the stomach of the mosquito. The encysted zygote in
each oocyst is now called a sporont.
The nucleus of oocyst (sporont) divides first by meiosis and subsequently by mitosis, forming large
number of small haploid nuclei. At the same time, the cytoplasm develops large vacuoles. The tiny nuclei
and cytoplasmic masses form enlongated and spindle shaped bodies called sporozoites.
When mature oocysts rupture, the sporozoites are liberated into the haemocoel (body cavity filled with
hemolymph) of the mosquito. Being motile, the sporozoites move towards different organs in the body
cavity of mosquitoes, but many of them penetrate the salivary glands. The mosquito now becomes
infective. When such a female Anopheles mosquito bites a healthy person, the sporozoites are injected
into his/her blood along with saliva. These sporozoites start the cycle again in human body.
Species of Plasmodium :
Plasmodium is found in man, birds reptiles and rats. Plasmodium berghei is found in rats and P.
gallinacum is found in rats and chicken. Four species of Plasmodium cause malaria in man and their
life histories are very much alike with minor differences in the structure of stages and the time required
for schizogony. These species are :
(1) Plasmodium ovale is found in humans of West Africa and South America. In it, new generations
of merozoites are formed every 48 hours causing mild tertian malaria. Its incubation period is
14 days. Schizonts and gametocytes enlarge the infected erythrocytes. The other three species
are common and have a wide distribution.
(2) Plasmodium vivax causes benign tertian malaria in which fever comes every 48 hours due to
formation of new generations of merozoites. It is the most widespread in both tropical and temperate
zones and relapses occur in it. Incubation period is 14 days. Schizonts and gametocytes make
erythrocytes very large. Its haemozoin granules are light brown and the gametocytes are round in
shape and larger than the blood corpuscles.
(3) Plasmodium malariae causes quartan malaria, in which fever comes after every 72 hours, and
relapses occur. Incubation period varies from 27 to 30 days. Erythrocytes are not enlarged. It is
found in both tropical and temperate zones but is not very widespread. It has dark brown haemozoin
granules, and its gametocytes are round but smaller than the blood corpuscles.
Two forms of fever are modifications of tertian malaria : Tertiana duplex in which two generations
of P. vivax mature on two successive days; and Quartana triplex in which three generations of
P. malariae mature on three successive days.
(4) Plasmodium falciparum is very common in tropics and it causes malignant deadly cerebral
malaria or sub-tertian malaria fever. Cerebral malaria is quite common in north-eastern states of
India. If not treated, it causes death in three days. Its schizogony cycle is irregular taking 24 to
48 hours. Incubation period is 12 days. It is the most dangerous type with almost continuous fever,
but its course is shorter and without relapses. Death-rate of falciparum malaria is the highest as
in it the RBCs clump together into masses causing blockage of blood capillaries particularly of the
brain. Ring-shaped trophozoites are small and often two in one erythrocyte. It has dark brown or
black haemozoin granules, its gametocytes are crescent-shaped. P.falciparum infection also causes
black water fever (pernicious malaria) in which there is mass destruction of RBCs and breakdown
products of haemoglobin pass into the urine giving the latter a blackish colour.
Duration of erythrocytic cycle is 48 hours in P. vivax, P. ovale and P. falciparum. Duration of
erythrocytic cycle is 72 hours in P. malariae.
When the mosquito

bites another human,
sporozoites are
injected with bite
Mature infective stages
(sporozoites) escape from
intestine and migrate
to the mosquito
salivary glands
Sporozoites
Parasites (sporozoites)
Salivary glands reach the liver through blood
Mosquito
Host
Fertilisation and
development take place
in the mosquito's
stomach The parasite reproduces
asexually in liver cells,
bursting the cell and
Human releasing into
Host the blood
Female
mosquito
takes up
gametocytes
Gametocytes
with blood
meal Female
Parasites reproduce asexually in

Male red blood cells, bursting the red
blood cells and causing cycles of
fever and other symptoms.
Sexual stages (gametocytes) Released parasites infect new
develop in red blood cells red blood cells
Fig. : Stages in the life cycle of Plasmodium

Treatment: Quinine the oldest drug for malaria is extracted from the bark of the cinchona tree.
(ii) Amoebiasis/Amoebic dysentery :

Pathogen: It is caused by a protozoan
parasite, Entamoeba histolytica in the large
intestine of human.
Mode of transmission: Housefly acts as a
mechanical carrier and serves to transmit the
parasite from faeces of infected person to food
and food products, thereby contaminating them.
So intake of contaminated food and water are
the main source of infection. Adult Entamoeba
is called trophozoite (pathogenic form) and is
monopodial. It has two forms, magna or
pathogenic form found in the mucosa and sub-
mucosa of intestine forming ulcers and
minuta, nonpathogenic form found in the
lumen of intestine. Entamoeba has no
contractile vacuole. Trophozoite of Entamoeba
reproduces by binary fission. Minuta form
encysts. A mature cyst is called
quadrinucleate cyst. It has four nuclei and
two chromatoid bodies. The reserve food
material in cyst of E. histolytica is glycogen.
Quadri (tetra) nucleate cyst is the infective
stage.
Symptoms: This disease is characterised by constipation, abdominal pain, cramps and stools with
excess mucus and blood clots.
D. Diseases Caused by Helminthes
(i) Ascariasis :
Pathogen: It is caused by the common round worm, Ascaris lumbricoides, an intestinal parasite of small
intestine of human beings.
Mode of transmission: A healthy person acquires this infection through contaminated water, vegetables,
fruits, etc.
Symptoms: This disease is characterised by internal bleeding, muscular pain, fever, anaemia and
blockage of intestinal passage. The eggs of the parasite come out along with the faeces of infected
persons which contaminate soil, water, plants, etc.
(ii) Filariasis :
Pathogen: This disease is caused by Wuchereria (W. bancrofti and W. malayi), filarial worm.
Mode of transmission: The pathogens are transmitted to a healthy person through the bite of infected
female Culex (mosquito).
Symptoms: The filarial worms cause a slowly developing chronic infection / inflammation of the organs
in which they live for many years. They usually affect the lymphatic vessels. This disease is characterised
by the swelling of the legs, scrotum and other parts of the body. This is commonly called Elephantiasis
due to its resemblance to the leg of an elephant. The genital organs are also often affected, resulting
in gross deformities.
E. Fungal Diseases
Ringworm:
Pathogen: Many fungi belonging to genera Microsporum, Trichophyton and Epidermophyton are responsible
for ringworms, one of the most common infectious diseases in man.
Mode of transmission: Ringworms are generally transmitted from soil or by using infected towels, clothes
and combs of infected individuals.
Symptoms: Appearance of dry, scaly lesions on various parts of the body such as skin, nails and scalp are
the main symptoms of the disease. These lesions are accompanied by intense itching. Heat and moisture
help these fungi to grow, which makes them thrive in skin folds such as those in the groins or between the
toes (athletes foot). In Tinea cruris, the groin and perineum are involved. In Tinea barbae, the beard areas
of the face and neck are involved. Tinea pedis or athletes’s foot affects foot.
Fig. : Diagram showing ringworm affected area of the skin
Preventive Measures and Control of Diseases

Maintenance of personal and public hygiene is very important for prevention and control of many infectious
diseases.
(i) Personal hygiene includes keeping the body clean, consumption of clean drinking water, food,
vegetables, fruits etc.
(ii) Public hygiene includes proper disposal of waste and excreta, periodic cleaning and disinfection of water
reservoirs, pools and tanks. These measures are particularly essential where the infectious agents are
transmitted through food and water such as typhoid, amoebiasis and ascariasis.
(iii) For air borne diseases such as pneumonia and common cold, close contact with the infected persons
or their belongings should be avoided.
(iv) For diseases such as malaria and filariasis transmission occurs through insect vectors, the most
important measure is to control or eliminate the vectors and their breeding places. This can be achieved
by avoiding stagnation of water in and around residential areas, regular cleaning of household coolers,
use of mosquito nets, introducing larvivorous fish like Gambusia in pond that feed on mosquito larvae,
spraying of insecticides like DDT in ditches, drainage area and swamps etc., doors and windows should
be provided with wire mesh to prevent the entry of mosquitoes. Such precautions have become all the
more important especially in the light of recent widespread incidences of vector-borne (Aedes mosquito)
diseases like Dengue and Chikungunya in many parts of India.
(v) The use of vaccines and immunisation programmes have enabled us to completely eradicate a deadly
disease like small pox. Large number of other infectious diseases like polio, diphtheria, pneumonia,
tetanus have been controlled to a large extent by the use of vaccines. Many newer and safer vaccine
are available and are synthesised by using biotechnology.
(vi) Discovery of antibiotics and various other drugs has also enabled us to effectively treat infectious
diseases.
IMMUNITY
Everyday we are exposed to a large number of infectious agents. However, only few of these exposures result
in disease, as body is able to defend itself from most of these foreign agents. This overall ability of the host
to fight the disease causing organisms, provided by, immune system is called immunity.
Immunity is of two types:
1. Innate immunity
2. Acquired immunity
1. Innate Immunity
Innate immunity is accomplished by providing different types of barrier to the entry of foreign agents or any
pathogen into our body. It is present at the time of birth and is also called inborn immunity. It is a non-
specific type of defence.
Innate immunity consists of four types of barriers. These are :
(i) Physical barriers : It includes skin that is the main barrier which prevents entry of micro-organisms into
the body. It also includes mucus coating of epithelium lining the respiratory, gastrointestinal and
urinogenital tracts which help in trapping microbes entering our body.
(ii) Physiological barriers : It includes acid in stomach, saliva in mouth, tears from eyes. Tears and saliva
contain lysozymes which can destroy bacterial pathogens.
(iii) Cellular barriers : It includes WBC like PMNL-neutrophils (polymorpho-nuclear leukocytes), monocytes
and natural killer cells. Natural killer cells are types of lymphocytes which will produce proteins called
perforins that create pores on the plasma membrane of tumor cells and virally infected cells through which
water enters and causes lysis of cells. Later on macrophages in the tissues and body fluids phagocytose
and destroy microbes.
(iv) Cytokine barriers : It includes interferons, a type of protein secreted by virus infected cells which
protects non-infected cells from further viral infection. Interferons will act by inhibiting the viral replication
as they stimulate synthesis of enzyme which inhibits the synthesis of proteins required for replication
of virus. So they are used to control viral diseases but they do not kill the virus.
2. Acquired Immunity
Acquired immunity is gained after birth and is pathogen specific. When our body encounters the pathogen
for the first time, it initiates a response called primary response. It is of low intensity and the person will
feel sick. When a specific antigen enters into the body of a person, specific B and T cells start dividing to
produce effector B and T cells for controlling disease and also produce memory B and T cell. These are stored
in the spleen and lymph nodes throughout life. If the same pathogen enters our body again, memory B and
T cells will immediately start dividing to produce effector B and T cells. This is called secondary or
anamnestic response, which is highly intensified or is of high intensity. This is due to the fact that our body
has memory of its first encounter.
The primary and secondary immune responses are carried out with the help of two types of lymphocytes, present
in our blood i.e., B-lymphocytes and T-lymphocytes and provide two types of acquired immunity in body:
(i) Humoral immunity or antibody mediated immunity (AMI)
(ii) Cell mediated immunity (CMI)
(i) Humoral immunity : The B-lymphocytes produce an army of proteins in response to the pathogen.
As any pathogen enters the blood, B-lymphocytes get activated and differentiated into plasma cells that
secretes a large number of antibodies in response to pathogens in order to fight them. Undifferentiated
B-lymphocytes remain as memory cells.
Antigens : The antigens are ‘molecules’ which when introduced into the body, stimulate the production
of antibodies. The word ‘antigen’ is a shortened form of ‘antibody generating’ because they stimulate the
production of antibodies in response to infection. Antigens are generally large molecules. The majority
of them are made of proteins or polysaccharides found on the cell walls of bacteria and other cells or
on the coats of viruses. All antigens are not a part of microorganisms. Other structures like pollen grains,
white of an egg, shell fish, certain fruits and vegetables, chicken, feathers of birds, blood cells from other
individuals or animals, drugs, chemicals, etc. can also induce the immune system to produce antibodies.
Haptens: are small organic molecules that are antigenic but are themselves incapable of inducing a
specific immune response.
Antigen which is present on the body’s own cell is a self antigen (Antigen related to blood group). Note
that, self antigens do not trigger immune response within one’s own body normally.
Antibody: Antibodies are immunoglobulins (Ig) which are produced in response to antigenic stimulation.
Each antibody molecule has four peptide chains, two long chains called heavy or H chain (each of
molecular weight 50,000 Da) and two short chains called light or L chains (each of molecular weight
25000 Da). Hence, an antibody is represented as H2L2. The heavy and light chains consist of amino
acid sequences. In the regions concerned with antigen binding, these regions are extremely variable,
whereas in other regions of the molecule, they are relatively constant. Thus, each heavy and each light
chain possesses a variable and a constant region. The isotype of an Ig is determined by the constant
region. Both chains are linked by disulphide links
One end of the antibody binds to an antigen (the Fab portion, so called because it is the fragment of
the molecule which is antigen binding or paratope), and the other end which is crystallisable and
therefore called Fc, is responsible for effector function.
Antigen binding site Antigen binding site
Variable region
N of the heavy chain N
N N
Antigen
Antigenic
Light chain determinant
C C
Variable region of the Antigen-
Disulfide bonds light chain binding
site
Heavy chain Heavy

Constant regions of the chain Light chain
heavy and light chains
C C
(a) (b)
Fig. : Immunoglobulin : (a) Structure, (b) Antigen binding site
Different types of antibodies are produced in our body such as IgA, IgM, IgE, IgG based on the type of heavy
chain in them.
Five classes (Isotypes) of Antibodies:

(a) IgA forms 15% of total antibody count. It is found in mucous secretions of the respiratory tract
and the upper part of the digestive tract and the vagina. It is also found in colostrum. Colostrum is
a golden liquid substance that a nursing mother expels from her breasts within 24-48 hours after
delivery. This substance is produced before the milk and is very important in the transfer of antibodies
to a newborn infant. IgA given by the mother in the colostrum will protect the baby for about six
months. Dimeric IgA has four paratopes. The link between monomers are made by a J-chain of
polypeptide.
IgA
(b) IgD forms less than 1% of the total antibodies. It appears to have a role in activating and suppressing
lymphocyte activity and is found in large quantities in the cell membrane of many B-cells. IgD has two
paratopes.
(c) IgE is less than 1% of total antibodies. It is a mediator in allergic responses and activates histamine
secreting cells. IgE also appears to play a role in parasitic infections. IgE has two paratopes.
IgE
(d) IgG-composes 75% of our immunoglobulin pool. IgG stimulates phagocytic cells, activates the
complement system, binds neutrophils, opsonizes and neutralises toxins. Most importantly, it is
the only antibody that can cross the placenta and confer immunity to the foetus. IgG also has
two paratopes. It is the most abundant antibody.
(e) IgM-makes up 7-10% of our total antibodies. It is the predominant early antibody and is first
activated in an initial attack of antigen. It exists as a pentamer where five molecules are linked by
a J-chain. Because of its high number of antigen binding sites (10), it is an effective agglutinator
of antigen. This is important in the initial activation of B-cells, macrophages, and the complement
system. It is the largest antibody.
Note :
z First antibody to be produced during primary immune response is lgM.
z lgG is produced maximally during secondary immune response.
IgM
Because all these antibodies are found in the blood, the response is called humoral (fluid) immune
response.
Antigen-Antibody Interaction :
(a) Agglutination : Clumping of micro-organisms typically due to an antigen antibody reaction.
(b) Opsonisation or Adherence : Antibodies (especially IgG) called opsonins get attached over the
surface of antigen containing pathogen. This enhances recognition of microbes by phagocytes.
(c) Precipitation : A soluble antigen is picked up by an antibody making the complex heavier and
insoluble so that phagocytic cells ingest it more readily.
(d) Neutralisation : Antibodies cover the toxic sites of an antigen. This converts the virulent form into
a nonvirulent form. Some antibodies neutralise toxins by acting as antitoxin.
(e) Lysis : Some powerful antibodies attack plasma membrane of the cell and cause rupture of plasma
membrane called lysis.
Antibodies are synthesised by B lymphocytes and exist in 2 forms- either membrane bound or secreted.
B lymphocytes use membrane bound antibodies to interact with antigens. B cells make antibodies all
of the same specificity i.e. they are able to react with the same antigenic determinants, and their progeny
(as a consequence of mitotic division) is referred to as a clone. The clone will continue making antibodies
of the same specificity. Simultaneously, there will be lots of other clones of different specificity. This is
known as a polyclonal response. Antigens have determinants called epitopes. Epitopes are molecular
shapes recognized by antibodies, which recognise one epitope rather than the whole antigen. Antigens
may be proteins, lipids or carbohydrates. An antigen may consist of many different epitopes, and/or may
have many repeated epitopes. B-lymphocytes evolve into plasma cells under the influence of T cell
released cytokines. Plasma cells secrete antibodies in greater amounts, but do not divide. They exist
in lymphoid tissues, not blood. Other B cells circulate as memory cells. B cells divide, forming plasma
cells and B memory cells. Plasma cells make and release between 2000 to 20,000 antibody molecules
per second into the blood for the next four or five days. B memory cells live for months or years, and
are part of the immune memory system.
(ii) Cell mediated immunity (CMI) : It is T-lymphocyte mediated or CMI. T-cells themselves do not secrete
antibodies but help B cells to produce them. Bone marrow gives rise to immature lymphocytes which
migrate to thymus via blood. In the thymus these cells mature as T-lymphocytes / T-cells and migrate
to lymphoid tissue through the body and get differentiated into the following types:
(a) Helper T cell : These cells stimulate B-cells to produce antibodies and killer T cells to destroy
the non-self cells.
(b) Cytotoxic / Killer T cell : These cells secrete perforins which create pores on the invader’s cell
membrane for water to enter into it. The cell then swells up and finally lyses.
(c) Suppressor T cell : These cells suppress the functions of cytotoxic and helper T cell so that
immune system does not attack the body’s own cells.
(d) Memory T cell: These cells are formed by activated T cells and remain in the lymphatic tissue
and recognise original invading antigens or pathogens, even after many years of the first encounter.
When some human organs like heart, eyes, liver, kidneys fail to function satisfactorily, then transplantation
is the only remedy that enables the patient to live a normal life. The organ or tissue used for transplantation
are commonly called grafts which are not just from any source (an animal, another primate, or any human
being) because graft would be rejected sooner or later. Tissue matching, blood group matching are essential
before undertaking any graft/transplant. Transplantation may result in the rejection of transplanted organs.
The immune system recognizes the protein in the transplanted tissue or organs as foreign and initiates
cellular immunity. To suppress the immune response during transplantation, histocompatibility antigen and
immunosuppresants play an important role.
(i) Histocompatibility is the property of having the same or mostly the same alleles of a set of genes called
the major histocompatibility complex. The major histocompatibility complex (MHC) is a set of
molecules displayed on cell surfaces that are responsible for lymphocyte recognition and antigen
presentation. It is encoded by several genes located on human chromosome 6. Major histocomptability
complex (MHC) is also referred as the HLA (or Human Leucocyte Antigen) system in humans.
(ii) Immunosuppressive drugs are used to prevent rejection. A kidney transplant from an identical twin, is
always successful. If a kidney is transplanted from a person other than a twin, it may also be successful
with the use of an immunosuppressants. The drug, called cyclosporin is a good immunosuppressant.
It destroys T-Cell mediated immune responses, but spares humoral antibody responses. This drug prevents
rejection of kidney, heart and liver transplants. Cell mediated immune response is responsible for graft
rejection.
Note :
z Antigen presenting cells (APCs) are special class of cells that process and present exogenous
antigens. These cells include macrophages, B cells, dendritic cells in skin etc.
Active and Passive Immunity

Acquired immunity can also be classified into
(i) Active immunity: When a host is exposed to antigens (in the form of living or dead microbes or other
proteins), antibodies are produced in the host body. This type of immunity is called active immunity.
Active immunity is slow and may be natural or artificial.
(a) Natural active immunity : It is acquired when antigens gain access into the body during natural
infection. So a person who has recovered from an attack of small pox, measles or mumps develops
natural active immunity.
(b) Artificial active immunity : It is the resistance induced by vaccines.
(ii) Passive immunity : When ready made antibodies are directly given to protect the body against foreign
agents it is called passive immunity.
(a) Natural passive immunity : The yellowish fluid colostrum secreted by mother during initial days
of lactation has abundant antibodies (IgA) to protect the infant. The foetus also receives some
antibodies IgG from their mother, through the placenta during pregnancy.
(b) Artificial passive immunity : When preformed antibodies are directly injected into the body. e.g.,
Anti-venom after snake bite or Anti-tetanus serum (ATS), it confers artificial passive immunity.
Vaccination and Immunisation

The principle of immunisation or vaccination is based on the property of memory of the immune system.
Vaccination
In the preparation of the vaccine, inactivated / weakened pathogens or antigenic proteins of pathogens are
introduced in the body. The antibodies produced in the body against these antigens would neutralise the
pathogenic agents during actual infection. The vaccines also generate memory B and T-cells that recognise
the pathogen quickly on subsequent exposure and overwhelm the invaders with a massive production of
antibodies.
Vaccines are classified as follows:

(a) First generation vaccines : These are whole organism vaccines, either live and weakened (attenuated)
or killed forms. e.g. Small pox, oral polio vaccine (OPV), BCG (Bacillus, Calmette, Guerin), Influenza
vaccines are attenuated.
Vaccines against typhoid, rabies, cholera and Salk’s polio vaccines are killed types.
(b) Second generation vaccines: These are subunit vaccines, consisting of defined protein antigens (such
as tetanus or diphtheria toxoid) or recombinant protein components (such as hepatitis B surface antigen
produced from yeast, Herpes vaccine).
(c) Third generation vaccines: These are DNA vaccines, made up of a plasmid that has been genetically
engineered to produce one or two specific proteins (antigens) from a pathogen. The vaccine DNA is
injected into the cells of the body, where the host cell reads the DNA and synthesizes the pathogen’s
protein. Because these proteins are recognized as foreign, the immune system is alerted and a range
of immune responses are triggered. e.g. third generation hepatitis B vaccine has been developed.
Passive Immunisation
When preformed antibodies are injected to provide quick immune response it is called as passive
immunisation. e.g. if a person is injected with some deadly microbe like tetanus, to which quick immune
response is required we need to directly inject the preformed antibodies or antitoxins (a preparation containing
antibodies to the toxin). Even in case of snake bites, the injection which is given to the patients contains
preformed antibodies against snake venom. This type of immunisation is passive immunisation.
In 1891, a daring step was taken which added to the growing understanding of immunology. A little girl lay
dying of diphtheria. Her physician, Emil von Behring, infected a sheep with diphtheria bacteria and waited
for some time. He then withdrew some blood from sheep and separated the serum by allowing it to clot.
He injected the serum-into the patient. Within a few hours she began to recover dramatically. A new
method of treatment had been discovered i.e., passive immunity. Von Behring was awarded the Nobel prize
for this work.
Disorders of Immune System
(a) Allergy or Hypersensitivity
It is the hypersensitiveness of a person to some foreign substances called allergens coming in contact with
or entering the body. It is the exaggerated response of the immune system to certain antigens present in
the environment. The substances to which such an immune response is produced are called allergens. It may
be mites, dust, pollens, animal danders fabrics, feather, mould, heat, cold, sunlight, etc.
Cause: The antibodies produced against these allergens are of IgE type. Allergic reaction is due to the release
of chemicals like histamine and serotonin from the mast cells. During allergic reaction there is an increased
release of histamine from mast cells. It causes marked dilation of all the peripheral blood vessels and the
capillaries become highly permeable so that large amounts of fluid leak out from the blood into the tissues.
The blood pressure decreases drastically often resulting in the death of the individual within a short time. The
exact nature of the substance to which a person is hypersensitive must be known before he can be properly
treated.
Types of allergy :
(i) Hay fever : In this allergic form, there is swollen, reddened, runny eyes and nose. The drugs called
antihistamines are of major importance in the treatment of this allergic disorder.
(ii) Asthma : It is the sudden spasm of tissue surrounding respiratory tract causing narrowing of respiratory
tract. The tissue surrounding the respiratory tubes in the lungs swell up and compress the tubes. Hence
there is difficulty in breathing.
(iii) Anaphylactic shock : It is an allergic reaction involving all the tissues of the body and occurs within a
few minutes after the injection of an antigen such as penicillin. Such a reaction is very serious. Histamine
released from ruptured mast cells causes marked dilation of all the arteries so that a large amount of fluid
is passed from the blood to the tissues and there is a drastic fall in blood pressure. The affected person
may become unconscious and the individual may die within a short time.
(iv) In eczema the skin becomes red, followed by the appearance of minute blisters.
Symptoms: Symptoms of allergic reaction includes sneezing, watery eyes, running nose and difficulty in
breathing.
Treatment: For determining the cause of allergy, patient is exposed to or injected with a very small doses
of possible allergen and after that the reactions on the body are studied. The use of drugs like antihistamines,
adrenaline and steroids quickly reduce the symptoms of allergy.
(b) Autoimmunity
Higher vertebrates have memory-based acquired immunity. The uniqueness of the immune system is that it
always destroys the foreign particles/proteins but never attacks the body’s own protein as it has the ability
to differentiate foreign organisms (e.g. pathogens) from self cells. But sometimes, due to genetic and other
unknown reasons, the body attacks self cells. This results in damage to the body and is called as Autoimmune
Disease.
So autoimmune diseases occur if the body’s immune system fails to recognize ‘self’ from ‘non-self’ and starts
destroying the body’s own cells.
For example, If the autoantigens are RBCs then the body destroys its own RBCs resulting in chronic
anaemia, if the autoantigens are muscle cells then it results in destruction of its own muscles resulting is
severe weakness : (Myasthenia gravis); if the autoantigens are liver cells, then it results in chronic hepatitis.
Other autoimmune diseases are insulin-dependent diabetes, Addison’s disease, ulcerative colitis and
rheumatoid arthritis.
Immune System in the Body

The human immune system consists of lymphoid organs, tissues, cells and soluble molecules like antibodies.
Immune system recognises, respond to foreign antigens and remembers them (memory). Human immune
system also plays an important role in allergic reactions, auto immune diseases and organ transplantation.
Lymphoid Organs
These are the organs where origin, maturation and proliferation of lymphocytes occur. There are two types
of lymphoid organs
(i) Primary lymphoid organs
(ii) Secondary lymphoid organs
(i) Primary lymphoid organs: Primary lymphoid organs are those where immature lymphocytes differentiate
into antigen specific lymphocytes, e.g., bone marrow and thymus.
Bone marrow is the main lymphoid organ where all blood cells including lymphocytes are produced and
is considered equivalent to Avian Bursa of Fabricius. It is the site where B-lymphocytes mature.
Thymus is a lobed organ located near the heart and beneath the breast bone (sternum). It is quite large
at the time of birth but keeps on reducing in size with age and by the time puberty is attained it reduces
to a very small size. It is the site where T-lymphocytes mature.
Primary lymphoid organs (bone marrow, thymus) provide micro environment for the development and
maturation of lymphocytes.
(ii) Secondary lymphoid organs: After maturation, B-lymphocytes and T-lymphocytes migrate through blood
vascular and lymphatic system to secondary lymphoid organs which provide the site for interaction of
lymphocytes with the antigens, here they proliferate and differentiate to become effector cells e.g.,
spleen, lymph nodes, tonsils, Peyer’s patches of small intestine and appendix.
Spleen : It is a large bean shaped organ which mainly contains lymphocytes, phagocytes and large
number of erythrocytes. It acts as a filter of blood by trapping blood borne micro-organisms. Spleen also
has a large reservoir of RBCs and is commonly called as “Graveyard of RBCs”.
Lymph nodes : These are the small solid structures located at different points along the lymphatic
system. Lymph nodes serve to trap the micro-organisms or other antigens which are present in lymph
and tissue fluid. Antigens trapped in lymph nodes are responsible for the activation of lymphocytes
present there and cause the immune response.
MALT : Mucosa associated lymphoid tissue constitutes about 50% of lymphoid tissue in human body.
Lymph
nodes
Thymus
Lymphatic
vessels
Fig. : Diagrammatic representation of lymph nodes
EXERCISE
1. Which of the following disease does not spread through droplet infection?
(1) Tuberculosis (2) Diphtheria
(3) Pertussis (4) Gonorrhoea
2. Entamoeba histolytica is transmitted through
(1) Insect bite
(2) Sweat
(3) Food and water contamination
(4) Bird droppings
3. Malarial parasite can be obtained in RBCs of patient
(1) When temperature reaches normal
(2) An hour before rise in temperature
(3) When temperature rises with rigor
(4) A few hours after temperature reaches normal
4. Recurrent high fever in malaria is due to completion of
(1) Erythrocytic schizogony (2) Sporogony
(3) Gamogony (4) Exoerythrocytic schizogony
5. Which of the following disease has been eradicated from world by the use of vaccine?
(1) Plague (2) Poliomyelitis
(3) Small pox (4) Kala-azar
6. A person without thymus would not be able to
(1) Reject a tissue transplant (2) Receive a tissue transplant
(3) Develop an inflammatory response (4) Produce antibodies
7. Passive immunity is provided through
(1) Exogenous supply of antigens (2) Exogenous supply of antibodies
(3) Endogenous supply of antigens (4) Endogenous supply of antibodies
8. DPT vaccination provides
(1) Active immunity (2) Passive immunity
(3) Natural immunity (4) Both (1) & (2)
9. Which of the following antibody is chiefly related to allergic response?
(1) IgA (2) IgE
(3) IgM (4) IgG
10. Which of the following is not an autoimmune disorder?
(1) Myasthenia gravis (2) Rheumatoid arthritis
(3) Hashimoto's disease (4) Adam’s-Stoke syndrome
AIDS
AIDS stands for Acquired Immuno Deficiency Syndrome. It is a deficiency of immune system, acquired during
the life time of an individual indicating that it is not a congenital disease. AIDS was first reported in USA
amongst homosexuals in 1981.
Pathogen
AIDS is caused by Human Immuno deficiency Virus (HIV), a name given in 1986 by the International
committee on viral Nomenclature. This virus belongs to a group of viruses called Retrovirus which has an
envelope consisting of a lipid bilayer derived from host cell membrane and projecting knob like glycoprotein
spikes with pedicels formed of virus coded glycoprotein. This envelope encloses the RNA genome (single
stranded RNA filament is segmented into two identical filaments and is associated with a reverse transcriptase
enzyme). HIV consists of a core RNA with Reverse Transcriptase surrounded by a protein coat. The protein
coat around the core consists of a protein called P24. Outside this protein coat is a layer composed of
another protein called P17.
The outermost envelope consists of a phospholipid bilayer studded with glycoproteins (GP120 and GP41). HIV
is a retrovirus; using the enzyme reverse transcriptase, it can synthesize DNA from RNA. Once HIV produces
DNA from its RNA, the DNA is integrated into the host cell’s DNA. There it can remain dormant, giving no
sign of its presence, or it can take over the host cell’s genetic machinery to produce more viruses. The major
cell infected by HIV is the Helper T-lymphocyte that bears the CD4 receptors site. The attachment of
virus to CD4 receptor site is by the help of GP120 on the protein coat of the virus.
Glycoprotein spikes (GP 120)
Two single stranded

RNA filaments
Lipid membrane
P17 Protein coats
P24
(capsid)
Reverse
transcriptase
Enzyme (Transcribes
DNA from RNA)
Glycoprotein pedicel (GP41)
Fig. : Diagrammatic representation of HIV
Mode of Transmission
Transmission of HIV infection generally occurs by
(a) Sexual contact with infected person.
(b) By transfusion of contaminated blood and blood products.
(c) By sharing infected needles as in the case of intravenous drug abusers.
(d) From infected mother to her child through placenta.
So, people who are at high risk of getting AIDS infection include
(a) Individuals who have multiple sexual partners.
(b) Drug addicts, who take drugs intravenously.
(c) Individuals who require repeated blood transfusions.
(d) Children born to an HIV infected mother.
Mode of Action of AIDS Virus

After the entry of virus into the body through body fluids or blood, the virus enters into the macrophages where
RNA genome of the virus replicates to form viral DNA with the help of enzyme reverse transcriptase. This viral
DNA gets incorporated into host cells DNA and directs the infected cells to produce virus particles. The
macrophages continue to produce virus and in this way ‘Macrophage acts like an HIV Factory’.
Simultaneously, HIV enters into Helper T-lymphocytes below 200/mm3 (Having CD4 receptors), replicates and
produces progeny viruses which destruct the helper T-cell. The progeny virus released in the blood attacks
the other helper T cells. This is repeated leading to progressive decrease in the number of helper T-lymphocytes
in the body of the infected person. During this period, the infected person suffers from fever, diarrhoea and
weight loss.
Due to decrease in the number of helper T-lymphocytes below 200/mm3 , the person starts suffering from
opportunistic infections of bacteria especially Mycobacterium, viruses, fungi and even parasites like Toxoplasma.
The patient becomes so immunodeficient that he/she is unable to protect himself/herself against these
infections. Besides Pneumocystis carinii (Pneumonia), AIDS victims have persistent diarrhoea and are
especially susceptible to Toxoplasma infections (tuberculosis), Candidiasis (whitish patches on mucus
membranes primarily due to fungal infections), Cytomegalovirus (leading to blindness and dementia). Herpes
simplex, many other opportunistic infections, and Kaposi’s sarcoma.
Retrovirus
Viral RNA core
Virus infects
normal cell
Viral protein
coat
Plasma
membrane
Animal cell
Viral RNA is introduced into cell
Cytoplasm
Viral DNA is
produced
by reverse Viral DNA incorporates
transcriptase into host genome
New viral RNA

is produced by
the infected cell
New viruses
are produced
Nucleus DNA
New viruses
can infect other cells
Note: Infected cell can survive while viruses are being replicated and released
Fig. : Replication of retrovirus

Note :
z Reverse Transcriptase (RT) has the ability to convert ssRNA of virus into ssDNA.
z The ssDNA then gets converted into dsDNA by DNA dependent DNA polymerase activity.
Diagnosis
A widely used diagnostic test for AIDS is Enzyme Linked Immuno-Sorbent Assay (ELISA). Western blotting
test is employed for confirmation of ELISA positive cases.
Treatment
Treatment of AIDS with antiretroviral drugs is only partially effective because it can only prolong the life of
the patient but cannot prevent death. Zidovudin or AZT (Azidothymidine) was first and still continues to
be the drug of choice for the treatment of AIDS. Drugs with similar action are used to inhibit HIV replication
and slow the progression of AIDS. Four drugs with similar action are used to inhibit HIV replication
and slow the progression of AIDS. All are nucleoside analogs, substances that are similar to the
naturally occurring nucleosides in RNA and DNA. They block conversion of retroviral RNA into DNA.
The first and still most commonly used drug to treat AIDS is AZT (azidothymidine) or Retrovir. Among
patients taking AZT, there is a slowing in the progression of symptoms. The main side effects are red bone
marrow damage and anemia. Eventually, the virus develops resistance to the drug. Other drugs are DDI
(dideoxyinosine), DDC (dideoxycytidine), and D4T (stavudine), which may be used in patients who do
not respond to AZT or have become resistant to it. Doctors generally give Zidovudine and Nevirapine to
HIV positive pregnant woman to ensure that their babies do not carry the infection.
Prevention of AIDS:
As AIDS has no cure, prevention is the best option. No vaccine has been prepared so far against AIDS virus.
WHO (World Health Organisation) has started number of programmes to prevent the spreading of HIV
infections. The following steps may help in preventing the AIDS.
(i) Proper blood testing to make blood safe from HIV.

(ii) Ensuring the use of only disposable needles and syringes in public/private hospitals and clinics.
(iii) Free distribution of condoms and advocating safe sex.
(iv) Controlling drug abuse.
(v) Promoting regular check up for HIV in susceptible population.
(vi) People should be educated about AIDS.
Every year 1st December is commemorated as World AIDS Day. NACO (National AIDS Control Organisation)
and NGOs (Non-governmental Organisations) are doing a lot of work to educate people about AIDS.
AIDS can only be tackled by the society and medical fraternity working together by preventing its spread and
finding new ways to cure the disease.
CANCER
It is one of the most dreaded diseases of human beings and is a major cause of death all over the world.
More than a million Indians suffer from cancer and a large number of them die annually.
In our body, cell growth and differentiation is a highly controlled and regulated process. But in cancer cells,
there is an abnormal and uncontrolled division of cells due to breakdown of these regulatory mechanisms.
Normal cells show a property called contact inhibition, in which, the dividing cells when in contact with other
cells, inhibit their uncontrolled growth but cancer cells do not have this property. Therefore, cancerous cells
continue to divide giving rise to mass of cells called neoplasm or tumors.
Types of Tumors:
(i) Benign Tumors : It remains confined to their original location and do not spread to other parts of the
body and hence cause little damage.
(ii) Malignant Tumors : It is a tumor where neoplastic or tumor cells divide and grow very rapidly, invading
and damaging surrounding normal tissues, starving the normal cells by competing for vital nutrients. Cells
sloughed from such tumors reach distant site through blood and whenever they get lodged in the body,
they start a new tumor formation. This property is called metastasis and is the most feared property
of malignant tumors.
Causes of Cancer/Carcinogenic agents

Transformation of normal cells into cancerous, neoplastic cells may be induced by physical, chemical and
biological agents.
(i) Physical agents
Ionising radiations like X-rays and gamma rays and non-ionizing radiations like UV rays cause DNA
damage which leads to neoplastic transformation.
(ii) Chemical agents
Chemical carcinogens are present in tobacco smoke which have been identified as a major cause of
lung cancer. For instance, asbestos exposure can lead to cancer of lungs while carcinogen like cadmium
oxide is associated with prostate cancer.
(iii) Biological agents

Cancer causing viruses called oncogenic viruses have genes called viral oncogenes which can cause
cancer. Several genes called cellular oncogenes (c-onc) or protooncogenes have been identified in normal
cells. Activation of these genes under certain conditions could lead to oncogenic/carcinogenic
transformation of the cells.
Types of cancer :
(a) Carcinomas are malignant growths of the epithelial (ectodermal) tissues that cover or line the body
organs. e.g., skin cancer, breast cancer, lung cancer, cancer of the stomach and pancreas
(about 85 percent of all tumors are carcinomas).
(b) Sarcomas are malignant growths arising in tissues derived from primitive mesoderm. e.g., bone tumors,
cancer of lymph nodes.
(c) Leukaemias result from unchecked proliferation of cell types present in blood and their precursors in
the bone marrow.
Other types of cancers are :
Melanoma : Cancer of pigment cells of the skin
Adenocarcinoma : Cancer of glands
Lymphoma : Cancer of lymphatic tissue
Glioma : Cancer of glial cells of CNS
Detection and Diagnosis

An early detection of cancer is life saving, but if it spreads to various parts and organs, the treatment becomes
ineffective. The diagnosis of cancer is usually done by
(a) Biopsy and histopathological studies of the suspected tissue. In this a piece of suspected tissue is
cut into thin sections, stained and examined under a microscope by a pathologist for detection of cancerous
cells.
(b) Blood and bone marrow tests for increased cell counts in the case of leukaemia.
(c) Techniques like radiography (use of X-rays).
CT (Computed tomography) and MRI (Magnetic Resonance Imaging) are useful to detect cancers of the
internal organs. CT scan uses X-rays to generate a three dimensional image of internal organs while MRI
uses strong magnetic fields and non-ionising radiations to accurately detect pathological and physiological
changes in the living tissue.
(d) Antibody against cancer specific antigens are also used for detection of certain cancers. e.g., Herceptin
(e) Techniques of molecular biology can be used to detect genes in individuals with inherited susceptibility
for certain cancers. After detection or identification of these genes in any individual, they may be advised
to avoid exposure to particular carcinogens to which they are susceptible (e.g. Tobacco smoke in case
of lung cancer)
Treatment of Cancer
Common treatment prescribed for different types of cancers are :
(i) Surgery
Generally a tumor is surgically removed wherever possible.
(ii) Radiotherapy/Radiation therapy
Tumor cells are irradiated lethally by gamma radiations taking proper care of the normal tissues
surrounding the tumor mass or neoplasm. e.g., use of I131 for thyroid cancer.
(iii) Chemotherapy
Several chemotherapeutic drugs are used to kill cancerous cell. Some of these are specific for
particular tumor e.g. two anticancer drugs, vincristine and vinblastine, used in the treatment of
leukaemia are obtained from common weed Catharanthus roseus. Majority of drugs have side effects
like hair loss, anemia etc.
(iv) Immunotherapy
Sometimes tumor cells are seen to avoid detection and destruction by immune system. So the patients
are given substances called biological response modifiers such as -interferons which activate their
immune system and help in destroying the tumor.
EXERCISE
11. AIDS was first reported in

(1) USA (2) France
(3) Russia (4) India
12. Which one of the following statements is correct w.r.t. AIDS?
(1) Drug addicts are least susceptible to HIV infection
(2) AIDS patients are being fully cured with proper care and nutrition
(3) HIV can be transmitted through eating food together with an infected person
(4) Causative HIV retrovirus attacks helper T-lymphocytes thus reducing their numbers
13. Enzyme responsible for replication of HIV in macrophages is
(1) RNA polymerase (2) DNA ligase
(3) DNA polymerase (4) Reverse transcriptase
14. After entering T-cell, HIV first forms
(1) mRNA (2) Single stranded DNA
(3) Double stranded DNA (4) Double stranded RNA
15. Which of the following cancer is opportunistic disease associated with HIV?
(1) Cancer of cervix (2) Liver cancer
(3) Pancreatic cancer (4) Kaposi’s sarcoma
16. Which one of the following is a sarcoma?
(1) Adenoma (2) Breast cancer
(3) Skin cancer (4) Cancer of lymph nodes
17. Cancer cells are characterised by
(1) Uncontrolled growth (2) Spreading to the other body parts
(3) Invasion of local tissue (4) All of these
18. Metastasis is connected with
(1) Benign tumour (2) Malignant tumour
(3) Both benign and malignant tumours (4) Crowngall tumour
19. Asbestos causes cancer of
(1) Liver (2) Lungs
(3) Lungs and urinary bladder (4) Urinary bladder
20. Bone cancer belongs to the category of
(1) Carcinoma (2) Sarcoma
(3) Malignant lymphoma (4) Leukemia
DRUGS AND ALCOHOL ABUSE
It has been observed that the use of drugs has increased especially among youth. This is a matter of concern,
as it could cause many harmful effects. Proper education and guidance would enable youth to safeguard
themselves against dangerous behavioural patterns and follow healthy life styles.
Major Categories of Psychoactive Drugs, their Effects and Clinical Uses
Type of Drug Examples Effects Clinical Uses

Sedatives and Barbiturates Depress brain activity and produce Hypnotic, antianxiety
tranquillisers Benzodiazepines feelings of calmness, relaxation,
(depressants) (e.g., Valium) drowsiness and deep sleep (high
doses)
Opiate narcotics Opium, morphine, heroin, Suppress brain function, relieve Analgesic
pethidine, methadone intense pain (physical and mental),
produce temporary euphoria
Stimulants Caffeine (very mild), Stimulate the nervous system; Attention deficit,
amphetamines (including make a person more wakeful, Narcolepsy, weight
dexamphetamine), cocaine increase alertness and activity, control
and its derivative produce excitement
Novacaine
Hallucinogens LSD, mescaline, psilocybin, Alter thoughts, feelings and None

(charas, hashish, marijuana perceptions; hallucinations
bhang) Cannabinoids
Commonly abused drugs are opioids, cannabinoids and coca alkaloids.

(i) Opioids :
These drugs bind to specific receptors present in our central nervous system and gastrointestinal tract
and relieve pain, so they are also called as analgesic (pain killers).
Morphine is extracted from the latex of poppy plant Papaver somniferum. It is a very effective sedative
and painkiller and is very useful for patients who have undergone surgery.
Heroin is obtained by acetylation of morphine (diacetyl morphine) commonly called as smack which
is white, odourless and bitter crystalline compound. Generally, it is taken by snorting or injection. It is
a depressant and slows down body functions.
HO
O
H
N—CH3
HO
Fig. : Chemical structure of Morphine Fig. : Opium poppy

(ii) Cannabinoids:
These are a group of chemicals which interact with cannabinoid receptors present principally in brain.
z Natural cannabinoids are obtained from the inflorescences of the plant Cannabis sativa.
z The flower tops, leaves and the resin of Cannabis plant are used in various combinations to produce
marijuana, hashish, charas and ganja.
z Generally taken by inhalation and oral ingestion and are known for their effects on cardiovascular
system of body.
z These days cannabinoids are also being abused by some sports persons.
OH
OH
Fig. : Skeletal structure of cannabinoid molecule Fig. : Leaves of Cannabis sativa

(iii) Cocaine :
Coca alkaloid or cocaine is obtained from coca plant, Erythroxylum coca, a native to South America.
z Cocaine, commonly called coke or crack is usually snorted.
z It interferes with the transport of the neuro-transmitter dopamine.
z It has a potent stimulating action on central nervous system, producing a sense of euphoria (feeling
of well being) and increased energy.
z Excessive dosage of cocaine causes hallucinations.
(iv) Seeds of Datura and aerial parts of Atropa belladona are misused for their hallucinogenic properties.
Fig. : Flowering branch of Datura
(v) Tobacco addiction:

Tobacco has been used by humans for more than 400 years
z It is smoked, chewed or snuffed.
z Tobacco contains large number of chemical substances including nicotine (an alkaloid).
z Nicotine stimulates adrenal gland to release adrenaline and nor-adrenaline into blood circulation,
both of which increase blood pressure and heart rate.
z Tobacco chewing is associated with increased risk of oral cavity cancer.
z Smoking increases carbon monoxide (CO) content in blood and reduces the concentration of
haembound oxygen so it causes oxygen deficiency in body and is associated with increased
incidence of cancer of lungs, urinary bladder and throat, bronchitis, emphysema, coronary heart
diseases, gastric ulcer etc.
Smoking is very prevalent in society, both among youth and the old. There is a need to spread
awareness about its addictive nature and addicts must be given proper medical help and
counselling. The cigarette packing also carriers a warning “Smoking is injurious to health”.
Adolescence and Drug/Alcohol Abuse
Adolescence is the period of rapid growth (physical, mental and psychological development) and is a bridge
linking childhood with adulthood (the period between 12-18 years). It is also marked by several biological and
behavioural changes.
Curiosity, excitement, need for adventure and experimentation are common causes which motivate youngsters
towards drug and alcohol. The first use of drugs or alcohol may be due to curiosity or experimentation but
later on child starts using it to escape facing problems such as academics, examinations etc. The thought
amongst youngsters that it is ‘cool’ or progressive to smoke, use drugs or alcohol is also a major cause for
youth to start these habits. Television, movies, newspapers, internet etc. also promote this perception. Unstable
or unsupportive family structures have been seen to be associated with drug and alcohol abuse among
adolescents.
Alcohol Abuse
The use of alcohol during adolescence may also have long term effects. It could lead to heavy drinking in
adulthood. The chronic use of alcohol damages the nervous system and liver (Liver cirrhosis).
Effects of Alcohol on an Individual

1. Effect on liver : Absorbed alcohol is carried directly to the liver, where it becomes the preferred fuel.
Use of moderate amounts of alcohol does not cause liver damage, provided adequate nutrition is
maintained. However, chronic alcoholism causes the following diseases. (i) Alcoholic fatty liver. The
liver becomes enlarged, yellow, greasy and firm. Hepatocytes (cells of liver) are distended by large fat
globules which push the hepatocyte nucleus against the cell membrane. There is increase in the fat
synthesis in the liver (ii) Alcoholic hepatitis. It is characterised by degeneration of hepatocytes. The
damaged (degenerated) hepatocytes are surrounded by polymorphonuclear leucocytes. These
hepatocytes may be pale and swollen and some contain dense eosinophilic masses called Mallory’s
hyaline. (iii) Alcoholic cirrhosis. With continued alcohol intake, there is destruction of hepatocytes
and fibroblasts (cells which form fibres) and stimulation of collagen protein formation. (iv) Cholestasis
(Gr. Chole - bile, stasis - a standing still). It is stoppage in the flow of bile. It is characterised by
jaundice, abdominal pain and hepatomegaly (enlargement of liver).
2. Effect on nervous system : These are characterised as :
(i) Will power, judgement power and self control become reduced.
(ii) Control on emotion becomes reduced.
(iii) Moral sense becomes reduced.
(iv) Cerebellum becomes affected which results the loss of muscle co-ordination so affected person
shows staggering gait and incoherent speech.
(v) Inflammation of axons of neurons leads to neuritis.
3. Effects on stomach : High doses of alcohol cause ill effect on gastric glands of stomach, these glands
secrete gastric juices in excess which causes the inflammation of gastric mucosa. This condition is
known as gastritis. It may also result in gastric carcinoma, peptic ulcer. Dilute alcohol (optimum 10%)
stimulates gastric secretion (specially acid). Acute alcoholic intake can result in inflammation of the
oesophagus (oesophagitis) and stomach (gastritis).
4. Effect on heart : Due to deposition of alcoholic fat in the wall of blood vessels, the lumen of blood
vessels becomes reduced, this increases the blood pressure and hence, the activity of heart.
Size of RBCs increases but the number of RBCs, WBCs and platelets is reduced.
5. Effect on kidneys : Alcohol reduces the release of hormone ADH (Antidiuretic hormone) due to which
the excess amount of water is released from the body. So, alcoholism greatly causes dehydration
condition.
6. Heavy drinking can cause acute alcoholic myopathy characterized by painful and swollen muscles
and high levels of serum creatine phosphokinase (CK).
7. Alcohol increases RBC size causing mild anaemia. Chronic heavy drinking can also decrease production
of white blood cells (WBCs). Alcohol may decrease platelet aggregation.
8. Effects on the skeletal system include alterations in calcium metabolism with an increased risk for
fracture and osteonecrosis (death of bone mass) of the head of femur.
9. Hormonal changes include an increase in cortisol levels, inhibition of vasopressin, reversible decrease
in serum thyroxine and a more marked decrease in serum triiodothyronine (T3).
10. Heavy drinking during pregnancy results in serious consequences for foetal development. The foetal
alcohol syndrome (FAS) includes facial changes, poorly formed concha (cavity of pinna), small teeth
with faulty enamel, defects in atria and ventricles of heart.
Interaction of Alcohol and other Substances of Abuse with some Common Drugs
Drugs Effects
Alcohol and other depressants, Dramatically increased depressant effect
e.g., Barbiturates
Alcohol + Antihistamines Marked drowsiness
(normally little or no sedative effect)
Alcohol + Benzodiazepines Rapid increase in sedative effect; often dramatic
Alcohol + Marijuana or Hashish Decreased coordination, increased
reaction time, impaired judgement
Alcohol + Aspirin Increased risk of damage to gastric mucosa
Benzodiazopines + Barbiturates Increased sedation
Amphetamine + Insulin Decreased insulin effect
Nicotine + Cocaine Increased cardiovascular effects
Cocaine + Antidepressants Hypertension
Addiction and Dependence

The drugs are normally used as medicines to help the patients cope with illnesses. But when these drugs
are taken for purposes other than their normal clinical use, it is called drug abuse / addiction. Addiction is
a habitual, physiological and psychological dependence on a substance or practice which is beyond voluntary
control. A person who is habituated to a substance/drug is called an addict. Repeated use of drugs increases
the tolerance level of the receptors present in our body, consequently the receptors respond only to higher
doses of drugs or alcohol leading to greater intake. So addiction is a psychological attachment to certain
effects such as euphoria and a temporary feeling of well being associated with drugs and alcohol.
In the absence of any guidance or counselling, the person gets addicted and becomes dependent on drug use.
WHO (1964) has introduced the term drug dependence in place of drug addiction.
Dependence is the tendency of the drug addict’s body to manifest a characteristic and unpleasant withdrawal
syndrome symptoms, if regular dose of drugs/alcohol is discontinued. This is characterised by anxiety,
shakiness, nausea and sweating, which may be relieved when drug use is resumed.
In some cases, withdrawal symptoms can be severe or even life threatening and the person may need medical
supervision.
Effects of Drug/Alcohol Abuse
(i) Behavioural and psychological changes: The most common warning signs of drug and alcohol abuse
among youth include drop in academic performance, unexplained absence from school/college, lack of
interest, withdrawal, isolation, depression, fatigue, aggressive and deteriorating relationship with family
and friends.
(ii) Social problems: If an abuser is unable to get money to buy drugs/alcohol, he/she may turn to stealing.
Adverse effects are just not restricted to the addicts only but also cause mental and financial agony
to their entire family and friends.
(iii) AIDS and Hepatitis: Those who take drugs intravenously (direct injection into the veins using a needle
or syringe) are much more likely to acquire serious infections like AIDS and hepatitis B because the
viruses which are responsible for these diseases are transferred from one person to another by sharing
of infected needles and syringes.
(iv) Misuse of drugs by certain sports persons:Some drugs like narcotic/analgesics, anabolic steroids,
diuretics and certain hormones are misused by certain sports persons to enhance their performance
because these drugs stimulate or increase muscle strength / bulk and promote aggressiveness thereby
increasing the athletic performance.
The side effects of the use of anabolic steroids in females include masculinisation (features like males),
increased aggresiveness, mood swings, depression, abnormal menstrual cycle, excessive hair growth
on the face and body, enlargement of clitoris and deepening of voice etc. In males, it includes acne,
increased aggresiveness, mood swings, depression, reduction of size of testicles, decreased sperm
production, potential for kidney and liver dysfunction, breast enlargement, premature baldness,
enlargement of prostate gland etc. In adolescent male or female, premature closure of the growth
centres of the long bones occur which may result in stunted growth.
(v) The use of drugs and alcohol during pregnancy adversely affects the foetus.
(vi) The chronic use of drugs and alcohol damages the nervous system and liver (Cirrhosis).
Prevention and Control
‘Prevention is better than cure’. Tobacco, drug/alcohol abuse are more during young adolescent age. Thus
remedial measures should be taken well in time. In this regard, parents and teachers have a special
responsibility. The following measures would be particularly useful for prevention and control of alcohol and
drug abuse in adolescents.
(i) Avoid pressure: Every child has his/her own choice and personality, which should be kept in mind. So
a child should not be pressurized unduly to achieve beyond his/her capacities be it in studies, sports
etc.
(ii) Education and counselling: Education and counselling are very important to face problems, stresses
disappointments and failures in life. These should be taken as a part of life. One should utilize child’s
energy in some positive activities like sports, music, reading, yoga and other extracurricular activities.
(iii) Seeking help from parents and peers: Whenever there is any problem, one should seek help and
guidance from parents and peers. Help should be taken from close and trusted friends. This would help
young to share their feelings of anxiety and inner thoughts.
(iv) Looking for danger signs: If friends find some one using drugs or alcohol, they should bring this to
the notice of parents or teachers so that appropriate measures are taken to diagnose the illness and
the causes.
This would help in taking proper remedial steps or treatment.
(v) Seeking professional and medical helps: Highly qualified psychologists, psychiatrists, de-addiction
and rehabilitation programmes can help individuals who are suffering from drug/alcohol abuse. If such help
is provided to the affected persons and with sufficient efforts and will power, the patient can be completely
cured thereby leading a normal and healthy life.
EXERCISE
21. A useful drug that damages gastric mucosa if taken along with alcohol is
(1) Valium (2) Antihistamine
(3) Aspirin (4) Morphine
22. Fatty liver syndrome is due to excessive intake of
(1) Morphine (2) Tobacco
(3) Alcohol (4) Both (1) & (2)
23. Drug addict shows symptoms of depressed brain activity, feeling of calmness, relaxation, drowsiness. Possibly
the addiction is of
(1) Valium (2) Amphetamine
(3) Mescaline (4) Marijuana
24. Alcoholism induces fat deposition in
(1) Fat bodies (2) Dermis of skin
(3) Around heart (4) Liver
25. The drug which does not have sedative effect but along with alcohol produces marked drowsiness is
(1) Barbiturates (2) Valium
(3) Antihistamines (4) Marijuana

t
en
nm nment
sig ssig
As A Assignment
Assignment
SECTION - A Column I Column II
NCERT Based MCQs a. (A) (i) Viral RNA is introduced

into host cell
1. Read the following statements.
b. (B) (ii) Viral DNA is produced
a. Chewing tobacco increases blood pressure and
heart rate. from RNA by reverse
b. Morphine is given to a person as a painkiller transcriptase

after surgery c. (C) (iii) Viral DNA incorporates
c. Patients are advised to take cocaine which into host genome
accelerates recovery after surgery
d. (D) (iv) New viral RNA is
d. Cannabinoids are known for their effect on produced by the infected
cardiovascular system of the body
cell
Choose the option which contains the correct
Choose the correct option. [NCERT Pg. 155]
statements. [NCERT Pg. 160]
(1) a(i), b(ii), c(iii), d(iv)
(1) a, b, c
(2) a(ii), b(iii), c(iv), d(i)
(2) a, b, d
(3) a(iii), b(iv), c(i), d(ii)
(3) b, c & d
(4) a, c & d (4) a(iv), b(i), c(ii), d(iii)
2. Identify the steps A, B, C and D in given figure 3. Choose the correct option which supports physical
representing the mode of action of AIDS virus. barriers of innate immunity.
Match the labelling in column I with column II.
[NCERT Pg. 151]
(1) B lymphocytes produce immunoglobulins in
response to pathogen attack
(2) PMNL, macrophages, lymphocytes in tissue can
phagocytose and destroy microbes
(3) Saliva in the mouth prevents microbial growth
(4) Mucous in urogenital tracts helps in trapping
microbes entering our body
4. The antibody present in colostrum is
[NCERT Pg. 152]
(1) IgA
(2) IgG
(3) IgM
(4) IgD
5. Identify A, B, C and D from the given diagram. Select 9. Fertilisation during the life cycle of Plasmodium
the correct match between the labelling in column I occurs in [NCERT Pg. 147]
with column II.
(1) Stomach of female Anopheles
C D
(2) Salivary gland of female Anopheles
(3) Liver of female Anopheles
(4) RBC of humans
10. Dry, scaly lesions on various parts of the body can
B be seen in [NCERT Pg. 149]
(1) Amoebiasis
(2) Ringworm infection
A (3) Filariasis
(4) Polio
Column I Column II 11. Chills and high fever in case of malaria, is due to
a. (A) (i) Heavy chain of antibody [NCERT Pg. 147]
b. (B) (ii) Light chain of antibody (1) Release of haemozoin particles in the blood
c. (C) (iii) Antigen binding site of (2) Gametocyte infection

antibody (3) Sporozoite infection
Choose the correct option. [NCERT Pg. 151] (4) Destruction of WBCs
(1) a(i), b(ii), c(iii) 12. Which of the following options describes the term
(2) a(ii), b(iii), c(i) ‘health’ most correctly? [NCERT Pg. 145]
(3) a(iii), b(ii), c(i) (1) Absence of disease
(4) a(iii), b(i), c(ii) (2) Physical fitness
6. The phenomenon of movement of tumor cells from (3) Absence of disease alongwith physical fitness
source to other parts of body, showing proliferation (4) A state of complete physical, mental and social
and rapid secondary growth is called well being
[NCERT Pg. 157] 13. Choose the correct option w.r.t. Plasmodium.
(1) Teratogenesis (2) Metastasis
[NCERT Pg. 148]
(3) Metagenesis (4) Mitosis
Man Mosquito
7. Extracts of A and B primarily have (1) Infective stage Gametocyte Sporozoite
hallucinogenic properties.
of Plasmodium
Choose the correct option which fills the blanks.
(2) Type of Asexual Asexual
[NCERT Pg. 159]
reproduction
A B
(3) Infective stage Sporozoite Gametocyte
(1) Canabis sativa Papaver somniferum
of Plasmodium
(2) Papaver somniferum Canabis sativa
(4) Type of Sexual Asexual
(3) Erythroxylum coca Atropa belladona
reproduction
(4) Atropa belladona Datura
14. Mucus coating of epithelium lining the respiratory
8. Select the component in tobacco smoke which
and gastro intestinal tract is an example of
stimulates secretion of adrenaline and
noradrenaline. [NCERT Pg. 160] [NCERT Pg. 150]
(1) Caffeine (2) Curcumin (1) Cellular barrier (2) Physiological barrier
(3) Cocaine (4) Nicotine (3) Cytokine barrier (4) Physical barrier
15. The exaggerated response of the immune system
SECTION - B
to certain foreign antigens is called _________.
Objective Type Questions
Choose the option that fills the blank correctly.
1. Which of the following pairs of innate immunity
[NCERT Pg. 153]
barriers belong to the same category?
(1) Autoimmunity (2) Allergy
(1) Skin and lysozyme of saliva
(3) Innate immunity (4) Passive immunity
(2) Acid in stomach and lysozyme in saliva
16. Mucosa associated lymphoid tissue (MALT)
(3) Mucus coating of respiratory tract and
constitutes about ______ percent of the total
cytokines
lymphoid tissue in the human body.
Choose the option that fills the blank correctly. (4) Inflammation and vaginal acidity
[NCERT Pg. 154] 2. An acquired disease whose entry in the body

occurs through deep skin cuts which are exposed
(1) 25 to dormant pathogenic spores present in the soil is
(2) 50 (1) Tuberculosis (2) Schistosomiasis
(3) 75
(3) Tetanus (4) Ascariasis
(4) 90
3. Virus infected cells secrete anti-viral glycoproteins
17. The correct expansion of abbreviation NACO is which move into nearby non infected cells and
[NCERT Pg. 156] prevent viral replication in them called
(1) National Anti Cancer Organisation (1) Interferons (2) Interleukins
(2) National Alcoholism Control Organisation (3) Complement proteins (4) Cytokinins
(3) National AIDS Control Organisation 4. The dimeric structure of antibody present in
(4) National Anthrax Control Organisation immunoglobulin A (IgA) consists of
(1) 2 heavy polypeptide chains and 2 light
18. Treatment of cancer involving use of biological
polypeptide chains
response modifiers which activate the immune
system and help in destroying the tumor is (2) 4 heavy polypeptide chains and 4 light
polypeptide chains
[NCERT Pg. 158]
(1) Radiation therapy
polypeptide chains
(2) Use of -interferon
(3) Surgery polypeptide chains
(4) Use of mitotic inhibitors 5. Which of the following does not act as an antigen
19. For diagnosis of AIDS which technique is used? presenting cell during specific immune response
[NCERT Pg. 156] against a pathogen?
(1) ELISA (1) B cell (2) Dendritic cell
(2) Northern blotting (3) Macrophage (4) CD-8 ‘T’ cell

(3) Widal test 6. Antivenin injected in a person suffering from snake
bite is
(4) Mantoux test
(1) A second generation vaccine produced by
20. The RNA genome of the HIV replicates in the host
recombinant DNA technology
cell to form viral DNA with the help of
(2) A collection of synthetic anti snake venom
[NCERT Pg. 156]
chemicals which destroy the poison
(1) RNA polymerase
(3) Collection of pre-formed antibodies produced in
(2) Reverse transcriptase a heterologous host
(3) DNA polymerase (4) Collection of antibodies taken from the serum
(4) Polynucleotidase of another snake.
7. A mature quadrinucleate cyst is an infective stage 15. Select the incorrect statement w.r.t the largest
for human host during completion of life cycle of sized antibody.
_____ parasite. Choose the option that fills the
(1) Its structure has J-chains
blank correctly.
(2) It is pentameric with ten paratopes
(1) Ascaris
(3) It is the first antibody to be produced in
(2) Enterobius
primary immune response
(3) Entamoeba histolytica
(4) It is the predominant antibody in the secondary
(4) Ringworm immune response
8. Which of the following set of structures is not a 16. Interferons are
part of an immunoglobulin molecule?
(1) Antibacterial cytokines
(1) Paratopes
(2) Antiviral glycolipids
(2) Antigen binding site
(3) Glycoproteins which make uninfected cells less
(3) Heavy and light polypeptide chains susceptible to viral attacks
(4) Epitope and antigenicity determinant region (4) Phospholipids which act as antifungal agents
9. ‘T’ and ‘B’ lymphocytes involved in cell and humoral 17. 'A healthy person acquires the infection by using
mediated immune responses of the body are towels, clothes or comb of the infected individual
produced from and the infection occurs easily in moist and warm
(1) Thymus and bone marrow respectively conditions'.
(2) Bone marrow Above statement is applicable to
(3) Thymus only (1) Viral infections
(4) Lymph nodes and bone marrow respectively (2) Bacterial infections
10. Ringworm of scalp i.e. Tinea capitis is caused by (3) Fungal infections
(1) Tinea solium (2) Tinea saginata (4) Helminthic infections
(3) Round worms (4) Trichophyton 18. Which of the following event during malaria is
11. Choose the odd one amongst the following responsible for chills and high fever recurring after
every 3 to 4 days?
(1) Histocytes (2) Clasmatocytes
(1) Entry of sporozoites in human blood
(3) Kupffer cells (4) Cytotoxic Tcell
12. Female mosquitoes of any type are not involved as (2) Release of metacryptozoites from hepatocytes
secondary hosts or vectors in the life cycle of (3) Release of haemozoin particles along with
(1) Wuchereria malayi rupture of RBCs
(2) Dengue and chikungunya viruses (4) Formation of gametes in the blood of humans.
(3) Plasmodium malariae 19. Along with lymphoid organs, WBCs are also
present within the mucosa of digestive, respiratory
(4) Leishmania donovani
and excretory tracts as MALT which constitutes
13. Site of formation of gametes and fertilisation in the about _____ of total lymphoid tissue of the body.
life cycle of Plasmodium is
(1) 50%
(1) Human blood and liver
(2) 75%
(2) Stomach of the mosquito
(3) 15%
(3) Salivary glands of the mosquito
(4) 30%
(4) RBCs of humans
20. Which of the following is an 'odd one out' w.r.t.
14. The only disease which does not spread through
types of lymphoid organs of animals?
droplet infection among the given options is
(1) Bone marrow (2) Thymus
(1) Measles (2) Tuberculosis
(3) Diphtheria (4) Plague (3) Bursa of Fabricius (4) Lymph nodes
21. Tinea barbae is 27. Opsonization action of antibodies refers to
(1) Fungal infection of groin (1) Precipitation of antigens on their surface
(2) Ringworm of scalp (2) Neutralization of pathogens bound to surface of
(3) Fungal infection of bearded area of face antibodies
(4) Ringworm of toes (3) Coating of pathogens with antibodies by their

paratope parts making them susceptible to
22. HCl of stomach belongs to the same barriers of phagocytosis as macrophages can recognise
immunity as tail of antibodies
(1) Skin and mucous membranes (4) Clumping of many micro-organisms together on
(2) Lysozyme in saliva and tears the antibody
(3) Macrophages and neutrophils 28. Choose the correct option w.r.t. the disease and
its diagnostic test.
(4) Cytokines and interferons
(1) Dengue - Wayson stain test
23. Small molecule that is antigenic but not
immunogenic is called (2) Syphilis - Western blot test
(1) Epitopes (3) Tuberculosis - Mantoux test
(2) Paratopes (4) Plague - Tourniquet test
(3) Hapten 29. The correct set of diseases which spread through
faeco-oral route are
(4) Proteins
(1) Cholera, hepatitis A and typhoid
24. The set of diseases for which antibiotics can be
used for treatment are (2) Elephantiasis, hepatitis B and enteric fever
(1) Chicken pox and polio (3) Enteric fever, hepatitis B and Ascariasis
(2) Rabies and dengue (4) Hepatitis A, hepatitis B and elephantiasis
(3) Diphtheria and tuberculosis 30. An allergic response to pollen characterised by
swollen running nose and redness with excess
(4) Whooping cough and common cold
tear production from eyes is
25. Consider the following statements about Antigen
(1) Eczema
Presenting Cells (APCs) and select the option with
incorrect statements. (2) Hay fever
(a) Macrophages, dendritic cells and B- (3) Urticaria
lymphocytes can act as APCs (4) Anaphylactic shock
(b) They engulf the pathogens and present their 31. Secondary immune response is
fragments secondary lymphoid organs
(1) Subsequent and vigorous immune response
(c) B and T-lymphocytes act as antigen presenting against a pathogen
cells
(2) Slow and short lived response against two
(1) (a) & (b) pathogens entering at the same time in the
(2) (b) & (c) body
(3) Only (c) (3) Immune response triggered by memory cells
(4) (a), (b) & (c) (4) Both (1) & (3)
26. Which of the following is an example of auto- 32. Longest incubation period is characteristic of which
immune disease? species of Plasmodium?
(1) SCID (1) Plasmodium falciparum
(2) AIDS (2) Plasmodium vivax
(3) Myasthenia gravis (3) Plasmodium ovale
(4) Graft rejection (4) Plasmodium malariae
33. Providing passive immunity to a person will include 40. During amoebic dysentery caused by Entamoeba
all strategies, except histolytica, the pathogenic stage for a human host
(1) Administration of ATS (anti tetanus serum) is
(2) Providing IgA antibodies to the new born (1) Magna form (2) Minuta form
through colostrum (3) Octanucleate cyst (4) Tetranucleate cyst
(3) Poliomyelitis vaccine administered to a child
SECTION - C
(4) Administration of Antisera against viper toxin
Previous Years Questions
34. Select the incorrect match w.r.t disease and the
1. Coca alkaloid or cocaine is obtained from :
causative agent.
[NEET-2019 (Odisha)]
(1) Diphtheria - Corynebacterium
(1) Datura
(2) Small pox - Varicella zoster
(2) Papaver somniferum
(3) Plague - Yersinia pestis
(3) Atropa belladonna
(4) Pertussis - Bordetella
(4) Erythroxylum coca
35. Anamnestic immune response is
2. Humans have acquired immune system that
(1) Primary immune response leading to activation
produces antibodies to neutralize pathogens but
of new plasma cells
innate immune system is present at the time of
(2) Secondary immune response initiated by birth because it [NEET-2019 (Odisha)]
memory cells
(1) Provides passive immunity
(3) Slow and short lived
(2) Is very specific and uses different
(4) Both (1) and (3) macrophages.
36. Which of the following is not a phagocytic cell of (3) Produces memory cells for mounting fast
non-specific immunity? secondary response.
(1) Histiocyte (2) Neutrophil (4) Has natural killer cells which can phagocytose
(3) Microglial cell (4) Basophil and destroy microbes
37. Which of the following is not a symptom of allergic 3. Drug called ‘Heroin’ is synthesized by [NEET-2019]
reaction to dust particles? (1) Methylation of morphine
(1) Difficult breathing/wheezing due to (2) Acetylation of morphine
bronchioconstriction
(3) Glycosylation of morphine
(2) Release of histamine by mastocytes
(4) Nitration of morphine
(3) Nails appearing bluish due to decreased
oxygenation of blood as pus fills up the alveoli 4. Which of the following immune responses is
responsible for rejection of kidney graft?
(4) Rashes on the skin
[NEET-2019]
38. Vaccine which is synthesised by genetic
engineering containing only surface antigens of the (1) Auto-immune response
pathogen is (2) Humoral immune response
(1) DPT (2) Recombivax-HB (3) Inflammatory immune response
(3) TT (4) OPV (4) Cell-mediated immune response
39. Organ transplant rejection can be prevented by 5. Identify the correct pair representing the causative
administration of 'Cyclosporin-A' which primarily agent of typhoid fever and the confirmatory test for
suppresses typhoid. [NEET-2019]
(1) Cell mediated immunity (1) Plasmodium vivax / UTI test
(2) Humoral mediated immunity (2) Streptococcus pneumoniae / Widal test
(3) Antibody mediated immunity (3) Salmonella typhi / Anthrone test
(4) All of these (4) Salmonella typhi / Widal test
6. Which of the following is not an autoimmune 12. MALT constitutes about ___________ percent of
disease? [NEET-2018] the lymphoid tissue in human body [NEET-2017]
(1) Psoriasis (2) Rheumatoid arthritis (1) 50% (2) 20%
(3) Vitiligo (4) Alzheimer's disease (3) 70% (4) 10%
7. In which disease does mosquito transmitted 13. Which of the following sets of diseases is caused
pathogen cause chronic inflammation of lymphatic by bacteria? [NEET(Phase-2)-2016]
vessels? [NEET-2018]
(1) Cholera and tetanus (2) Typhoid and smallpox
(1) Elephantiasis (2) Ascariasis
(3) Tetanus and mumps (4) Herpes and influenza
(3) Amoebiasis (4) Ringworm disease
14. Which of the following is correct regarding AIDS
8. Which part of poppy plant is used to obtain the causative agent HIV? [NEET(Phase-2)-2016]
drug “Smack”? [NEET-2018]
(1) HIV is enveloped virus containing one molecule
(1) Flowers (2) Latex of single-stranded RNA and one molecule of
(3) Leaves (4) Roots reverse transcriptase
9. Match the items given in Column I with those in (2) HIV is enveloped virus that contains two
Column II and select the correct option given identical molecules of single-stranded RNA and
below: [NEET-2018] two molecules of reverse transcriptase
Column I Column II (3) HIV is unenveloped retrovirus
a. Fibrinogen (i) Osmotic balance (4) HIV does not escape but attacks the acquired
immune response
b. Globulin (ii) Blood clotting
15. Which of the following statements is not true for
c. Albumin (iii) Defence mechanism
cancer cells in relation to mutations? [NEET-2016]
a b c
(1) Mutations inhibit production of telomerase
(1) (iii) (ii) (i)
(2) Mutations in proto-oncogenes accelerate the cell
(2) (i) (ii) (iii) cycle
(3) (ii) (iii) (i) (3) Mutations destroy telomerase inhibitor
(4) (i) (iii) (ii) (4) Mutations inactivate the cell control
10. Transplantation of tissues/organs fails often due to 16. Antivenom injection contains preformed antibodies
non-acceptance by the patient's body. Which type while polio drops that are administered into the body
of immune-response is responsible for such contain [NEET-2016]
rejections? [NEET-2017]
(1) Attenuated pathogens
(1) Autoimmune response
(2) Activated pathogens
(2) Cell-mediated immune response
(3) Harvested antibodies
(3) Hormonal immune response
(4) Gamma globulin
(4) Physiological immune response
17. In higher vertebrates, the immune system can
11. Match the following sexually transmitted diseases distinguish self-cells and non-self. If this property is
(Column - I) with their causative agent (Column - II) lost due to genetic abnormality and it attacks self-
and select the correct option. [NEET-2017] cells, then it leads to [NEET-2016]
Column - I Column- II (1) Active immunity (2) Allergic response
(a) Gonorrhea (i) HIV (3) Graft rejection (4) Auto-immune disease
(b) Syphilis (ii) Neisseria 18. Depletion of which gas in the atmosphere can lead
(c) Genital Warts (iii) Treponema to an increased incidence of skin cancers
(d) AIDS (iv) Human Papilloma virus [NEET-2016]
(1) a(ii), b(iii), c(iv), d(i) (2) a(iii), b(iv), c(i), d(ii) (1) Methane (2) Nitrous oxide
(3) a(iv), b(ii), c(iii), d(i) (4) a(iv), b(iii), c(ii), d(i) (3) Ozone (4) Ammonia
19. Grafted kidney may be rejected in a patient due to 26. The active form of Entamoeba histolytica feeds
[Re-AIPMT-2015] upon [AIPMT-2015]
(1) Innate immune response (1) Blood only
(2) Humoral immune response (2) Erythrocytes; mucosa and submucosa of colon
(3) Cell-mediated immune response (3) Mucosa and submucosa of colon only
(4) Passive immune response (4) Food in intestine

20. If you suspect major deficiency of antibodies in a 27. Which one of the following fungi contains
person, to which of the following would you look for hallucinogens? [AIPMT-2014]
confirmatory evidence? [Re-AIPMT-2015] (1) Morchella esculenta
(1) Serum globulins (2) Fibrinogen in plasma (2) Amanita muscaria
(3) Serum albumins (4) Haemocytes (3) Neurospora sp.
21. Which of the following immunoglobulins constitutes (4) Ustilago sp.
the largest percentage in human milk?
28. Which is the particular type of drug that is obtained
[Re-AIPMT-2015] from the plant whose one flowering branch is
(1) IgG (2) IgD shown below? [AIPMT-2014]
(3) IgM (4) IgA
22. Match each disease with its correct type of
vaccine [AIPMT-2015]
Column-I Column-II
a. Tuberculosis (i) Harmless virus
b. Whooping cough (ii) Inactivated toxin
c. Diphtheria (iii) Killed bacteria (1) Hallucinogen (2) Depressant
d. Polio (iv) Harmless bacteria (3) Stimulant (4) Pain killer

(1) a(i), b(ii), c(iv), d(iii) (2) a(ii), b(i), c(iii), d(iv) 29. At which stage of HIV infection does one usually
show symptoms of AIDS? [AIPMT-2014]
(3) a(iii), b(ii), c(iv), d(i) (4) a(iv), b(iii), c(ii), d(i)
(1) Within 15 days of sexual contact with an
23. Which of the following viruses is not transferred
infected person
through semen of an infected male? [AIPMT-2015]
(2) When the infected retro virus enters host cells
(1) Ebola virus
(3) When HIV damages large number of helper
(2) Hepatitis B virus
T lymphocytes
(3) Human immunodeficiency virus
(4) When the viral DNA is produced by reverse
(4) Chikungunya virus transcriptase
24. HIV that causes AIDS, first starts destroying 30. Infection of Ascaris usually occurs by [NEET-2013]
[AIPMT-2015]
(1) Eating imperfectly cooked pork
(1) Thrombocytes (2) B lymphocytes
(2) Tse-tse fly
(3) Leucocytes (4) Helper T lymphocytes
(3) Mosquito bite
25. Which of the following is not one of the prime
health risks associated with greater UV radiation (4) Drinking water containing eggs of Ascaris
through the atmosphere due to depletion of 31. The cell-mediated immunity inside the human body
stratospheric ozone? [AIPMT-2015] is carried out by [NEET-2013]
(1) Increased liver cancer (1) B lymphocytes
(2) Increased skin cancer (2) Thrombocytes
(3) Reduced Immune System (3) Eythrocytes
(4) Damage to eyes (4) T lymphocytes
32. Common cold differs from pneumonia in, that (2) Polymorphonuclear – Cellular barriers
[AIPMT (Prelims)-2012] leukocytes and
monocytes
(1) Pneumonia pathogen infects alveoli whereas
(3) Anti-tetanus – Active immunity
the common cold affects nose and respiratory
and anti-snake
passage but not the lungs
bite injections
(2) Pneumonia is a communicable disease
(4) Saliva in mouth – Physical barriers
whereas the common cold is a nutritional
and tears in eyes
deficiency disease
38. Which one of the following sets of items in the
(3) Pneumonia can be prevented by a live
options 1-4 are correctly categorised with one
attenuated bacterial vaccine whereas the
exception in it? [AIPMT (Mains)-2012]
common cold has no effective vaccine
Items Category Exception
(4) Pneumonia is caused by a virus while the
(1) UAA, UAG, UGA Stop codons UAG
common cold is caused by the bacterium
Haemophilus influenzae (2) Kangaroo, Koala, Australian Wombat
Wombat marsupials
33. Widal Test is carried out to test
(3) Plasmodium, Protozoan Cuscuta
[AIPMT (Prelims)-2012] Cuscuta, parasites
Trypanosoma
(1) Typhoid fever (2) Malaria
(4) Typhoid, Bacterial Diphtheria
(3) Diabetes mellitus (4) HIV/AIDS Pneumonia, diseases
Diphtheria
34. Cirrhosis of liver is caused by the chronic intake of
39. Identify the molecules (a) and (b) shown below and
[AIPMT (Prelims)-2012] select the right option giving their source and use
(1) Cocaine (2) Opium HO
(3) Alcohol (4) Tobacco (Chewing)
35. Which one of the following is not a property of
cancerous cells whereas the remaining three are ?
(a) O
[AIPMT (Prelims)-2012]
H
(1) They show contact inhibition N—CH3
(2) They compete with normal cells for vital nutrients
HO
(3) They do not remain confined in the area of
formation OH
(4) They divide in an uncontrolled manner

36. Motile zygote of Plasmodium occurs in (b)
OH
(1) Human liver
(2) Gut of female Anopheles [AIPMT (Mains)-2012]
(3) Salivary glands of Anopheles Options :
(4) Human RBCs Molecule Source Use
37. In which one of the following options the two (1) (a) Cocaine Erythroxylum Accelerates
examples are correctly matched with their coca the transport
of dopamine
particular type of immunity?
(2) (b) Heroin Cannabis Depressant
[AIPMT (Prelims)-2012] sativa and slows
down body
Examples Type of immunity functions
(1) Mucus coating of – Physiological (3) (b) Cannabinoid Atropa Produces
epithelium lining barriers belladona halluci-
nations
the urinogenital
tract and the (4) (a) Morphine Papaver Sedative and
somniferum pain killer
HCl in stomach
40. Which one of the following statements is correct 45. Select the correct statement with respect to
with respect to immunity? [AIPMT (Mains)-2012] diseases and immunisation
(1) Rejection of a kidney graft is the function of [AIPMT (Mains)-2011]
B lymphocytes
(1) Certain protozoans have been used to mass
(2) Preformed antibodies need to be injected to produce hepatitis B vaccine
treat the bite by a viper snake
(2) Injection of snake antivenom against snake
(3) The antibodies against small pox pathogen bite is an example of active immunisation
are produced by T lymphocytes
(3) If due to some reason B and T lymphocytes
(4) Antibodies are protein molecules, each of are damaged, the body will not produce
which has four light chains antibodies against a pathogen
41. Read the following statements (A-D) (4) Injection of dead/inactivated pathogens causes
(A) Colostrum is recommended for the new born passive immunity
because it is rich in antigens. 46. Read the following statement having two blanks
(B) Chikungunya is caused by a Gram negative (A and B).
bacterium.
“A drug used for (A) patients is obtained from
(C) Tissue (Meristem) culture has proved useful a species of the organism (B) .”
in obtaining virus-free plants.
The one correct option for the two blanks is
(D) Beer is manufactured by distillation of
[AIPMT (Mains)-2011]
fermented grape juice.
How many of the above statement is/are wrong? Blank-A Blank-B
[AIPMT (Mains)-2012] (1) Swine flu Monascus
(1) Two (2) Three (2) AIDS Pseudomonas

(3) Four (4) One (3) Heart Penicillium
42. Which one of the following acts as a physiological (4) Organ transplant Trichoderma
barrier to the entry of microorganisms in human body?
47. Common cold is not cured by antibiotics because
[AIPMT (Prelims)-2011] it is [AIPMT (Mains)-2011]
(1) Skin (1) Caused by a Gram-negative bacterium
(2) Epithelium of urogenital tract (2) Not an infectious disease
(3) Tears (3) Caused by a virus
(4) Monocytes (4) Caused by a Gram-positive bacterium
43. Where will you look for the sporozoites of the
48. Which one of the following options gives the correct
malarial parasite? [AIPMT (Prelims)-2011]
matching of a disease with its causative organism
(1) Salivary glands of freshly moulted female and mode of infection [AIPMT (Mains)-2011]
Anopheles mosquito
Disease Causative Mode of
(2) Saliva of infected female Anopheles mosquito Organisms Infection
(3) Red blood corpuscles of humans suffering form (1) Elephantiasis Wuchereria With infected
malaria bancrofti water and food
(4) Spleen of infected humans (2) Malaria Plasmodium Bite of male
44. A certain patient is suspected to be suffering form vivax Anopheles
Acquired Immuno Deficiency Syndrome. Which mosquito
diagnostic technique will you recommend for its
(3) Typhoid Salmonella With inspired
detection? [AIPMT (Prelims)-2011]
typhi air
(1) WIDAL (2) ELISA
(4) Pneumonia Streptococcus Droplet
(3) MRI (4) Ultrasound pneumoniae infection
49. The pathogen Microsporum responsible for 55. A person suffering from a disease caused by
ringworm disease in humans belongs to the same Plasmodium, experiences recurring chill and fever
Kingdom of organisms as that of at the time when? [AIPMT (Mains)-2010]
[AIPMT(Mains)-2011] (1) The sporozoites released from RBCs are being
(1) Rhizopus, a mould rapidly killed and broken down inside spleen
(2) Ascaris, a round worm (2) The trophozoites reach maximum growth and
give out certain toxins
(3) Taenia, a tapeworm
(3) The parasite after its rapid multiplication inside
(4) Wuchereria, a filarial worm RBCs ruptures them, releasing the stage to
50. Select the correct statement from the ones given enter fresh RBCs
below: [AIPMT (Prelims)-2010] (4) The microgametocytes and megagametocytes
(1) Barbiturates when given to criminals make are being destroyed by the WBCs
them tell the truth
56. Which one of the following cannot be used for
(2) Morphine is often given to persons who have preparation of vaccines against plague?
undergone surgery as a pain killer.
[AIPMT (Mains)-2010]
(3) Chewing tobacco lowers blood pressure and
(1) Formalin-inactivated suspensions of virulent
heart rate
bacteria
(4) Cocaine is given to patients after surgery as
(2) Avirulent live bacteria
it stimulates recovery
(3) Synthetic capsular polysaccharide material
51. Ringworm in humans is caused by
(4) Heat-killed suspensions of virulent bacteria
(1) Viruses (2) Bacteria 57. Consider the following four statements (a–d)
regarding kidney transplant and select the two
(3) Fungi (4) Nematodes correct ones out of these.
52. Which one of the following statements is correct a. Even if a kidney transplant is proper the
with respect to AIDS? [AIPMT (Prelims)-2010] recipient may need to take immuno-
(1) The causative HIV retrovirus enters helper suppresants for a long time.
T lymphocytes thus reducing their numbers b. The cell-mediated immune response is
(2) The HIV can be transmitted through eating responsible for the graft rejection.
food together with an infected person c. The B lymphocytes are responsible for
(3) Drug addicts are least susceptible to HIV rejection of the graft.
infection d. The acceptance or rejection of a kidney
(4) AIDS patients are being fully cured cent per transplant depends on specific interferons.
cent with proper care and nutrition
The two correct statements are
53. Fastest distribution of some injectible material/
medicine and with no risk of any kind can be
achieved by injecting it into the (1) a & b
[AIPMT (Mains)-2010] (2) b & c
(1) Muscles (2) Arteries (3) c & d
(3) Veins (4) Lymph vessels (4) a & c
54. Which one of the following techniques is safest for 58. A person likely to develop tetanus is immunised by
the detection of cancers? [AIPMT (Mains)-2010] administering [AIPMT (Prelims)-2009]
(1) Magnetic resonance imaging (MRI) (1) Preformed antibodies
(2) Radiography (X-ray) (2) Wide spectrum antibiotics
(3) Computed tomography (CT) (3) Weakened germs
(4) Histopathological studies (4) Dead germs
59. Alzheimer disease in humans is associated with 64. Which one of the following is the correct
the deficiency of [AIPMT (Prelims)-2009] statement regarding the particular psychotropic
(1) Glutamic acid drug specified? [AIPMT (Prelims)-2008]
(1) Barbiturates cause relaxation and temporary
(2) Acetylcholine
euphoria
(3) Gamma aminobutyric acid (GABA)
(2) Hashish causes after thought perceptions and
(4) Dopamine hallucinations
60. Which one of the following statements is correct ? (3) Opium stimulates nervous system and causes
hallucinations
(4) Morphine leads to delusions and disturbed
(1) Benign tumours show the property of
emotions
metastasis.
65. Cornea transplant in humans is almost never
(2) Heroin accelerates body functions.
rejected. This is because [AIPMT (Prelims)-2008]
(3) Malignant tumours may exhibit metastasis. (1) It is a non-living layer
(4) Patients who have undergone surgery are (2) Its cells are least penetrable by bacteria
given cannabinoids to relieve pain.
(3) It has no blood supply
61. Use of anti-histamines and steroids give a quick
(4) It is composed of enucleated cells
relief from [AIPMT (Prelims)-2009]
66. Consider the following statements about
(1) Nausea
biomedical technologies
(2) Cough a. During open heart surgery blood is circulated
(3) Headache in the heart-lung machine.
(4) Allergy b. Blockage in coronary arteries is removed by
angiography.
62. To which type of barriers under innate immunity, do
the saliva in the mouth and the tears from the c. Computerised Axial Tomography (CAT) shows
eyes, belong? [AIPMT (Prelims)-2008] detailed internal structure as seen in a section
of body.
(1) Physical barriers
d. X-ray provides clear and detailed images of
(2) Cytokine barriers organs like prostate glands and lungs.
(3) Cellular barriers Which two of the above statements are correct?
(4) Physiological barriers [AIPMT (Prelims)-2008]
63. Match the disease in Column I with the (1) a and b (2) b and d
appropriate items (pathogen/prevention/treatment)
(3) c and d (4) a and c
in Column II
67. Ultrasound of how much frequency is beamed into
Column I Column II human body for sonography?
a. Amoebiasis (i) Treponema palladium [AIPMT (Prelims)-2007]
b. Diphtheria (ii) Use only sterilized food (1) 45–70 MHz
and water
(2) 30–45 MHz
c. Cholera (iii) DPT Vaccine
(3) 15–30 MHz
d. Syphilis (iv) Use oral rehydration (4) 1–15 MHz
therapy
68. Lysozyme that is present in perspiration, saliva and
[AIPMT (Prelims)-2008] tears, destroys [AIPMT (Prelims)-2007]
(1) a(ii), b(iii), c(iv), d(i) (1) Most virus-infected cells
(2) a(i), b(ii), c(iii), d(iv) (2) Certain fungi
(3) a(ii), b(iv), c(i), d(iii) (3) Certain types of bacteria
(4) a(ii), b(i), c(iii), d(iv) (4) All viruses
69. A person showing upredictable moods, outbursts of 77. Which one of the following is important as one of
emotion, quarrelsome behaviour and conflicts with the first line of defence against inhaled and
others is suffering from [AIPMT (Prelims)-2006] ingested pathogen?
(1) Schizophrenia (1) IgA (2) IgG
(2) Borderline personality disorder (BPD) (3) IgM (4) IgD
(3) Mood disorders 78. Saline solution is given to patients of cholera
(4) Addictive disorders because
70. Antibodies in our body are complex (1) Na+ prevent water loss from body
[AIPMT (Prelims)-2006] (2) NaCl function as regulatory material
(1) Lipoproteins (2) Steroids (3) NaCl produces energy
(3) Prostaglandins (4) Glycoproteins (4) NaCl is antibacterial
71. Both sickle cell anaemia and Huntington’s chorea 79. Interferons are synthesized in response to
are [AIPMT (Prelims)-2006]
(1) Mycoplasma (2) Bacteria
(1) Bacteria-related diseases
(3) Viruses (4) Fungi
(2) Congenital disorders
80. The main reason why antibiotics could not solve all
(3) Pollutant-induced disorders the problems of bacteria mediated disease is
(4) Virus-related diseases (1) Decreased efficiency of the immune system
72. AIDS is caused by HIV that principally infects (2) Insensitivity of the individual following prolonged
[AIPMT (Prelims)-2005] exposure to antibiotics
(1) All lymphocytes (2) Activator B cells (3) Development of mutant strains resistant to
(3) T4 lymphocytes (4) Cytotoxic T cells antibiotics
73. Which one of the following depresses brain activity (4) Activation of antibiotics by bacterial enzymes
and produces feelings of calmness, relaxation and 81. Carcinoma refers to
drowsiness? [AIPMT (Prelims)-2005]
(1) Malignant tumours of the connective tissue
(1) Valium (2) Morphine
(2) Malignant tumours of the skin or mucous
(3) Hashish (4) Amphetamines membrane
Questions asked Prior to Medical Ent. Exams. 2005 (3) Malignant tumours of the bone
74. Which of the following pair of diseases is caused
(4) Benign tumours of the connective tissue
by virus?
82. A metastatic cancerous tumour is termed
(1) Rabies, mumps (2) Cholera, tuberculosis
‘sarcoma’ if the disorder is in
(3) Typhoid, tetanus (4) AIDS, syphilis
(1) Fibroblasts (2) Circulatory system
75. Aggregates of lymphoid tissue present in the distal
portion of the small intestine are known as (3) Immune system (4) Epithelial cells
(1) Villi 83. Human immuno deficiency virus (HIV) has a protein
coat and a genetic material which is
(2) Peyer's patches
(1) Double stranded RNA(2) Double stranded DNA
(3) Rugae
(3) Single stranded DNA (4) Single stranded RNA
(4) Choroid plexus
84. Which of the following is a viral glycoprotein that plays
76. Which of the following is not the main function of
a role in the infection of human cells by HIV?
lymph glands?
(1) gp 120
(1) Forming RBC
(2) Destroying bacteria (2) CD4
(3) Forming WBC (3) CCR5
(4) Forming antibodies (4) Both (1) & (3)
85. Which of the following statement is incorrect? 90. Short-lived immunity acquired from mother to
(1) The antigen binding site of the antibody foetus across placenta or through mother’s milk to
molecule is called ‘paratope’ the infant is categorised as
(2) Toxoids provide passive immunity (1) Active immunity
(3) ‘ATS’ anti-tetanus serum provides us with (2) Passive immunity

artificially induced passive immunity (3) Cellular immunity
(4) The first gene therapy was done for SCID in (4) Innate non-specific immunity
which the gene for the enzyme adenosine
91. What is true about T lymphocytes in mammals ?
deaminase was introduced
(1) There are three main types - cytotoxic T cells,
86. The modern idea about ageing is that our body
helper T cells and suppressor T cells
slowly loses the power of defence against the
invasion of germs and pathogens. This process (2) These originate in secondary lymphoid tissues
starts by the disappearance of which organ? (3) They scavenge damaged cells and cellular
(1) Pituitary gland debris
(2) Spleen (4) These are produced in thyroid
(3) Thymus gland 92. Which of the following pairs of diseases is viral as
(4) Parathyroid gland well as transmitted by mosquitoes?
87. Select the incorrect statement (1) Elephantiasis and dengue
(1) Opioids are the drugs which bind to opioid (2) Yellow fever and sleeping sickness
receptors present in our central nervous (3) Encephalitis and sleeping sickness
system and gastrointestinal tract
(4) Yellow fever and dengue
(2) Cocaine is obtained from coca plant
93. Identify the incorrectly matched pair
Erythroxylum coca
(3) Natural cannabinoids are obtained from the (1) Plague – Viral diseases
inflorescence of the plant Cannabis sativa (2) Malignant malaria – Plasmodium falciparum
(4) LSD (Lysergic Acid Diethylamide) is most (3) Common cold – Rhino virus
powerful hallucinogen extracted from Papaver (4) Trichophyton – Ring worm
somniferum
88. Which one of the following sets of items in the SECTION - D
options (1) - (4) are incorrectly categorised with NEET Booster Questions
one exception in it?
1. Black water fever is caused by
Items Category Exception
(1) Salmonella typhi
(1) PMNL, Cellular barrier Interferons (2) Giardia lamblia
Interferons
(3) Plasmodium falciparum
NK cells
(2) Rheumatoid Auto-immune AIDS (4) Bacillus pestis
arthritis disorders 2. Select the correct set of viral diseases in humans.
Myasthenia
gravis, AIDS (1) Rabies, Common cold, Tetanus
(3) Plasmodium, Protozoan Entamoeba (2) Plague, Dengue, Chicken pox
Trypanosoma parasites
Entamoeba (3) Small pox, Measles, Diphtheria
(4) Typhoid, Bacterial Dengue
Pneumonia, diseases (4) Mumps, Polio, Chikungunya
Dengue 3. Which of the following statements is incorrect w.r.t
89. Which of the following organisation is mainly interferons?
related with AIDS? (1) Interferons are lipoproteins released by virus
(1) NACO (2) DOTS infected cells.
(3) RCH (4) WHO (2) Interferons do not kill virus
(3) Interferons make unattacked cells less 10. Match the following
susceptible from the attack of virus
Column I Column II
(4) Interferons are included in cytokine barrier of
a. Killed vaccine (i) Tetanus
innate immunity.
b. Attenuated vaccine (ii) Tuberculosis
4. Which of the following is a component of
physiological barrier of innate immunity? c. Toxoid (iii) OPV
(1) Skin and mucous membrane (iv) Typhoid
(2) Histamine and serotonin (1) a(iii), b(i), c(iv) (2) a(iv), b(iii), c(i)
(3) Sebum and bile (3) a(iii), b(ii), c(i) (4) a(i), b(iv), c(ii)
(4) Perforins and pyrogens 11. Hay fever is an allergy of
5. Functionally, Bursa of Fabricius in birds can be (1) Lower respiratory tract
considered similar to
(2) Skin with minute blisters
(1) Bone marrow in mammals
(3) Urinary and reproductive tract
(2) Kidney in mammals
(4) Upper respiratory tract
(3) Liver in mammals
(4) Thyroid in mammals 12. Which of the following antibody is present in
mother’s milk and provides natural passive
6. Which of the following is not an antigen presenting immunity to new born?
cell (APC)?
(1) IgD (2) IgM
(a) Histiocytes (b) Clasmatocytes
(3) IgE (4) IgA
(c) B Cells (d) T helper cells
13. Select the correct set of bacterial diseases
(e) T Killer cells
caused by exotoxins.
(1) (a), (b), (c), (d) & (e)
(1) Diphtheria and typhoid
(2) (a), (b) & (c)
(2) Plague and tetanus
(3) (d) & (e)
(3) Dysentery and cholera
(4) (a), (b), (d) & (e)
(4) Diphtheria and tetanus
7. Find out the incorrect match w.r.t disease and its
diagnostic test. 14. Which of the following is incorrect statement w.r.t
rabies?
(1) Tuberculosis – Mantoux test
(2) Plague – Wassermann test (1) Rabies is caused when flavi-ribo virus is
introduced in human body by bite of rabid
(3) Diphtheria – Schick test (mad) dogs usually
(4) Dengue – Tourniquet test
(2) Hydrophobia is most important characteristic
8. The second most abundant antibody in human body symptom
is
(3) Rabies virus destroys brain and spinal cord
(1) IgA (2) IgG
(4) Rabies is 100% fatal
(3) IgM (4) IgE
15. Japanese encephalitis is transmitted by
9. Koch’s postulates are not applicable to
(1) Housefly (2) Sand fly
(a) Mycobacterium leprae
(3) Tsetse fly (4) Culex
(b) Viruses
16. Cirrhosis of liver is caused by chronic intake of
(c) Treponema pallidium
(1) LSD
(1) (a) & (b)
(2) (b) & (c) (2) Tobacco
(3) (a) & (c) (3) Cocaine

(4) (a), (b) & (c) (4) Alcohol
17. Find out the incorrect match w.r.t type of 23. Opsonization is
ringworm.
(1) Coating of bacteria by antibodies and further
(1) Tinea pedis – Athlete’s foot its phagocytosis by macrophages
(2) Tinea capitis – Ringworm of scalp (2) Representation of antigen by macrophage to T
helper cells
(3) Tinea barbae – Ringworm of bearded areas of
face and neck (3) Development of pores in microbe by
complement system proteins
(4) Tinea cruris – Ringworm of hands
(4) Agglutination of bacteria & viruses by
18. Which of the following is not an example of
antibodies
passive immunity?
24. A thymectomized individual will
(1) Colostrum rich in IgA antibodies
(1) Strongly reject an allograft
(2) A person recovering from chicken pox infection
(2) Show proper development/maturation of T cells
(3) IgG antibodies crossing placental barrier to
reach foetus (3) Show reduced ability to reject on allograft
(4) Anti-tetanus serum (4) Show reduced B cell maturation
19. Which of the following is not an autoimmune 25. Which of the following statement is incorrect w.r.t.
disorder? MALT?
(1) Rheumatoid arthritis (1) It is the primary lymphoid organ
(2) Myasthenia gravis (2) It constitutes about 50% of the lymphoid
tissue in human body
(3) Severe combined immunodeficiency (SCID)
(3) It is the site of proliferation and differentiation
(4) Grave’s disease (Exopthalmic goitre)
of B-lymphocytes and T-lymphocytes
20. The cells which secrete antibodies
(4) It is located within the lining of digestive,
(1) Secrete histamine which causes inflammation respiratory and urinogenital tracts
(2) Are major cells of cell mediated immunity 26. Consider the following four statements and select
system whether they are true (T) or false (F).
(3) Are produced in thymus (A) The person suffering from SCID lacks both B-
cells and T-cells
(4) Are a part of humoral mediated immunity
system. (B) Multiple sclerosis is an autoimmune disease
21. Which of the following is not a phagocytic cellular (C) Gamma globulins are synthesised in lymph
barrier? nodes
(a) Histiocytes (b) Kupffer cells (D) Tetanus toxoid provides artificial passive
immunity
(c) Clasmatocytes (d) Mast cells
(A) (B (C) (D)
(1) a & b (2) b & d
(1) T F F F
(3) c & d (4) d only
(2) F T T F
22. Which of the following statement is incorrect w.r.t.
natural killer cells? (3) T T T F
(1) NK cells lack antigen receptors unlike B cells (4) F F F T
and T cells 27. Which of the following disease is correctly
(2) NK cells are formed in bone marrow and matched with its symptoms/description?
mature in thymus (1) Amoebiasis – Abscesses in small
(3) NK cells release chemicals called perforins intestine; high fever bouts
which cause cytolysis of microbe repeating every 3-4 days
(4) NK cells release tumour necrosis factors which (2) Leprosy – Painful urination, pelvic
kills target cells inflammation
(3) Pertussis – Repeated bouts of violent 33. Wuchereria bancrofti, the filarial worm that causes
cough which end in a elephantiasis belongs to phylum
whoop; vomiting (1) Platyhelminthes (2) Aschelminthes
(4) Rabies – Joint pain, muscle pain, (3) Coelenterate (4) Arthropoda
fever and skin rash
34. Recently chikungunya and dengue cases were
28. Mark the incorrect match w.r.t. diseases and reported from various parts of the country. Choose
diagnostic test. the correct vector responsible for these diseases
(1) Hepatitis B – Australian antigen (1) Anopheles mosquito (2) Xenopsylla (Rat flea)
(2) Dengue – Tourniquet (3) Culex mosquito (4) Aedes mosquito
(3) Diphtheria – Mantoux test 35. Which of the following causes plague?
(4) Leprosy – Lepromin test (1) Trichinella spiralis
29. Which of the following is an incorrect match w.r.t. (2) Salmonella typhimurium
lifecycle of Plasmodium vivax? (3) Yersinia pestis
(1) Infective stage for man – Sporozoite in saliva (4) Xenopsylla
of Anopheles 36. A person who met with road accident is likely to
(2) Onset of fever – Liberation of develop tetanus, he is immunised by administering
erythrocytic (1) Weakened germs
merozoites from RBC
(2) Dead germs
(3) Fertilisation – Intestine of (3) Preformed antibodies
Anopheles
(4) Wide spectrum antibiotics
(4) Schizogony – Stomach wall of
37. Antigen binding site in an antibody is formed by
Anopheles
(1) Two light chains
30. Which of the following class of proteins is
represented by antigen presenting cells to express (2) Two heavy chains
antigenic peptide to T helper cells? (3) One heavy and one light chain
(1) MHC I (2) HLA I (4) Either between two light chains or between one
heavy and one light chain depending upon the
(3) MHC II (4) Both (1) & (2)
nature of antigen
31. Choose the incorrect statement w.r.t. common
38. Mark the correct statement
cold
(1) The anamnestic response against a pathogen
(1) Rhinovirus causes common cold
is highly intensified
(2) Rhinovirus infects the nose, respiratory (2) The T lymphocytes produce antibodies
passage and lungs
(3) The B lymphocytes produce cell mediated
(3) Common cold is characterised by nasal response
congestion and discharge, sore throat,
hoarseness, cough, headache, tiredness etc. (4) An antibody is represented by H2L4
39. Which of the following will be included under innate
(4) Droplets resulting from cough or sneezes of an
immunity?
infected person are inhaled directly or
transmitted through contaminated objects and (1) Mucus membranes (2) Interferons
can cause infection in a healthy person (3) Natural killer cells (4) All of these
32. Intestinal perforation is the characteristic symptom of 40. Artificial active immunity can be acquired from
(1) Pneumonia (1) Serious illness
(2) Plague (2) Vaccination
(3) Typhoid (3) Repeated exposure to the some microbes
(4) Pertussis (4) Treatment with penicillin
41. One of the inflammatory reaction induced by 47. Blood cancer is also known as
histamine is (1) Haemolysis (2) Haemophilia
(1) Vasoconstriction (3) Leukaemia (4) Thrombosis
(2) Vasodilation 48. Read the following statements
(3) Decreased vascular permeability a. Heroin, commonly called smack, is obtained
(4) Accelerated blood clotting by acetylation of morphine.
42. Blood cells involved in inflammatory reactions are b. Cocaine is obtained from the latex of Papaver
somniferum.
(1) Basophils (2) Neutrophils
c. Dopamine is always excitatory
(3) Eosinophils (4) Monocytes
neurotransmitter.
43. The letter T in T lymphocyte refers to
d. Morphine is an effective sedative and pain killer.
(1) Thymus (2) Thyroid
Mark the option which includes both correct
(3) Thalamus (4) Tonsil statement
44. The causative organism of AIDS spreads by (1) a & b (2) b & c
(1) Sharing infected needles and syringes (3) c & d (4) a & d
(2) Transfusion of infected blood 49. L.S.D. is
(3) Unsafe sexual relationships (1) Hallucinogenic (2) Sedative
(4) All of these (3) Stimulant (4) Tranquiliser
45. Cancer refers to 50. Tick mark the incorrect match with respect to the
drug, source and its action.
(1) Rupturing of cells
(2) Uncontrolled meiosis Drug Source Action
(3) Uncontrolled mitosis (1) Smack Latex of poppy Depressant slows
plant Papaver down body functions
(4) Loss of immunity of the cells somniferum
46. Oncogene is another name for (2) Cocaine Sense of euphoria
and increased
(1) Inducer gene energy
(2) Jumping gene (3) Coke Atropa Hallucinations
belladona
(3) Structural gene
(4) Hashish Cannabis Hallucinations, affects
(4) Cancer causing gene sativa cardiovascular system


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Chapter 16

Human Health and Disease

COMMON DISEASES IN HUMANS

(iv) Chicken Pox : This disease is caused by a virus of chicken-pox named

(vi) Mumps (Infectious Parotitis) : It is an infectious disease causing fever,

Virus Genome Mode of Transmission

C. Diseases Caused by Protozoans

Penetration and Encystment :

When the mosquito

Parasites reproduce asexually in

Fig. : Stages in the life cycle of Plasmodium

(ii) Amoebiasis/Amoebic dysentery :

Fig. : Diagram showing ringworm affected area of the skin

Preventive Measures and Control of Diseases

Heavy chain Heavy

Five classes (Isotypes) of Antibodies:

Active and Passive Immunity

Vaccination and Immunisation

Vaccines are classified as follows:

Immune System in the Body

Fig. : Diagrammatic representation of lymph nodes

Glycoprotein spikes (GP 120)

Two single stranded

Glycoprotein pedicel (GP41)

Fig. : Diagrammatic representation of HIV

Mode of Action of AIDS Virus

New viral RNA

Fig. : Replication of retrovirus

(i) Proper blood testing to make blood safe from HIV.

Causes of Cancer/Carcinogenic agents

(iii) Biological agents

Detection and Diagnosis

11. AIDS was first reported in

Type of Drug Examples Effects Clinical Uses

Hallucinogens LSD, mescaline, psilocybin, Alter thoughts, feelings and None

Commonly abused drugs are opioids, cannabinoids and coca alkaloids.

Fig. : Chemical structure of Morphine Fig. : Opium poppy

Fig. : Skeletal structure of cannabinoid molecule Fig. : Leaves of Cannabis sativa

Fig. : Flowering branch of Datura

(v) Tobacco addiction:

Effects of Alcohol on an Individual

Addiction and Dependence

NCERT Based MCQs a. (A) (i) Viral RNA is introduced

b. Morphine is given to a person as a painkiller transcriptase

a. (A) (i) Heavy chain of antibody [NCERT Pg. 147]

c. (C) (iii) Antigen binding site of (2) Gametocyte infection

[NCERT Pg. 154] 2. An acquired disease whose entry in the body

(1) ELISA (1) B cell (2) Dendritic cell

(2) Northern blotting (3) Macrophage (4) CD-8 ‘T’ cell

(4) Ringworm of toes (3) Coating of pathogens with antibodies by their

(1) Innate immune response (1) Blood only

(4) Passive immune response (4) Food in intestine

d. Polio (iv) Harmless bacteria (3) Stimulant (4) Pain killer

(4) They divide in an uncontrolled manner

(3) Salivary glands of Anopheles Options :

(4) Human RBCs Molecule Source Use

[AIPMT (Mains)-2012] (1) Swine flu Monascus

(1) Two (2) Three (2) AIDS Pseudomonas