Com Science Biology Section Notes

COMBINED SCIENCE STUDY PACK
5/23/2019 BIOLOGY SECTION O’LEVEL

for ZIMSEC syllabus code 4002
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COMBINED SCIENCE STUDY PACK

(ZIMSEC COMBINED SCIENCE SYLLABUS CODE 4002)
MR MOYO DUMISANI (2019)
CONTENTS
1.0 LABORATORY RULES AND SAFETY……………………………………… 02
2.0 CELLS AND LEVELS OF ORGANISATION……………………………….. 04
3.0 NUTRITION IN PLANTS……………………………………………………… 07
5.0 ECOSYSTEMS………………………………………………………………….. 12
4.0 NUTRITION IN ANIMALS……………………………………………………. 16
6.0 RESPIRATORY SYSTEM…………………………………………………….. 23
7.0 TRANSPORT SYSTEMS IN PLANTS……………………………………...... 26
8.0 TRANSPORT SYSTEMS IN ANIMALS………………………………....…… 29
9.0 REPRODUCTION IN PLANTS………………………………………………... 35
10.0 REPRODUCTION IN ANIMALS……………………………………………… 39
11.0 HUMAN HEALTH AND DISEASES…………………………………………... 44
12.0 IMMUNITY……………………………………………………………………… 50
13.0 DEFINITION OF NEW TERMS………………………………………………. 58
14.0 REVISION QUESTIONS…………………………………………………..…... 60
COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

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This section on laboratory rules and safety is not part of the main syllabus ordinary level
section, but it has been added to remind the learners of the importance of order and safety
in the laboratory
1.0 LABORATORY RULES AND SAFETY
 Natural sciences are generally practical fields of study; of which they require
specialized rooms for the sake of their study.
 These are called Science Laboratories
 The kind instruments and materials found inside the laboratories vary as per subject
specification of which that room is built for.
 These laboratories are usually associated with storerooms that have chemicals, and gas
cylinders are usually attached to them of which they contain gases.
 Therefore, there are rules and regulations that govern the use of these rooms, i.e.
laboratory rules
1.1 LABORATORY RULES
1. Report all accidents, injuries, and breakage of glass or equipment to instructor
immediately.
2. Keep pathways clear by placing extra items (books, bags, etc.) on the shelves or under
the work tables. If under the tables, make sure that these items cannot be stepped on.
3. Long hair (chin-length or longer) must be tied back to avoid catching fire.
4. Wear sensible clothing including footwear. Loose clothing should be secured so they
do not get caught in a flame or chemicals.
5. Work quietly — know what you are doing by reading the assigned
experiment before you start to work. Pay close attention to any cautions described in
the laboratory exercises
6. Do not taste or smell chemicals.
7. Wear safety goggles to protect your eyes when heating substances, dissecting, etc.
8. Do not attempt to change the position of glass tubing in a stopper.
9. Never point a test tube being heated at another student or yourself. Never look into a
test tube while you are heating it.
10. Unauthorized experiments or procedures must not be attempted.
11. Keep solids out of the sink.
12. Leave your work station clean and in good order before leaving the laboratory.
13. Do not lean, hang over or sit on the laboratory tables.
14. Do not leave your assigned laboratory station without permission of the teacher.
15. Learn the location of the fire extinguisher, eye wash station, first aid kit and safety
shower.
16. Do not lift any solutions, glassware or other types of apparatus above eye level.
17. Follow all instructions given by your teacher.
18. Learn how to transport all materials and equipment safely.
19. No eating or drinking in the lab at any time

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1.2 LABORATORY EQUIPMENT

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2.0 CELLS AND LEVELS OF ORGANISATION

2.1.1 MICROSCOPY
 A microscope is a laboratory instrument used to view objects that cannot be seen by the
naked eye
2.1.2 FUNCTIONS OF THE PARTS OF A MICROSCOPE

Part function
Eyepiece or ocular lens Eyepiece is the lens, present at the top and is used to see the objects under
study. Eyepiece lens contains a magnification of 10X or 15X
Tube Tube or the body tube, connects the eyepiece to the objective lenses
Resolving nosepiece also known as the Turret. Resolving nosepiece has holders for the different
objective lenses. It allows the rotation of the lenses while viewing
Objective lenses Generally, three or four objective lenses are found on a microscope, with
ranges of 10X, 40X, 100X powers. Lenses are colour coded, the shortest lens
is of the lowest power, and the longest lens is high power lenses
Diaphragm Control the amount of light that is passing through the opening of the stage
Coarse adjustment knob Used for focus on scanning.
Fine adjustment knob Moves the body tube for focusing the high power lens
Arm supports the tube of the microscope and connects to the base of the microscope
Stage Flat platform for placing the slides under observation
Stage clip Stage clips hold the slides in proper place
Condenser focuses the light on the specimen under observation. Presence of condenser
lens gives a sharper image as compared to the microscope with no condenser
lens.
Base Provides basal support for the microscope
Power switch The main power switch that turns the illumination on or off.

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2.2 ANIMAL AND PLANT CELL STRUCTURES

 Cells are the basic structural and functional units of living organisms
 They group together to form tissues, with tissues forming organs, and organs forming
the body as a whole
2.2.1 BASIC ANIMAL CELL AND PLANT CELLS
2.3
2.3 STRUCTURE OF THE PLANT AND ANIMAL CELLS
structure function Animal cell Plant cell
Nucleus -contains hereditary information Present Present
-controls the activities of the cell
cytoplasm -liquid part were cell organelles are suspended Present Present
-Site for chemical reactions
cell membrane -partially permeable Present present
-allows certain substances in, and others out
mitochondria -site for respiration in the cell Present Present
-responsible for energy production
cell wall -permeable Absent Present
-made of cellulose
-maintains the rigid structure
vacuole -contains salts and other dissolved minerals Small Large
-responsible for maintenance of the osmotic temporary permanent
potential of the cell
-responsible for thee vacuolar pathway
chloroplasts -contains chlorophyll which is stored in the Absent Present
grana

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2.4 SPECIALIZED CELLS

Specialized cell General Basic structure Function
description function
Red blood cell General Transport of no nucleus To accommodate the
animal cell oxygen and hemoglobin
Made in the hemoglobin elastic To pass through
red bone capillary lumen
marrow biconcave To increase surface area
Old ones for absorption of
are broken oxygen and carbon
down in the dioxide
liver, the has Binds with the oxygen
iron(haem) hemoglobin and carbon dioxide in
make new gaseous
Palisade Normal Photosynthesis located in the To absorb as much light
plant cell upper side of as possible
the leaf
has Which has chlorophyll
chloroplasts
has To absorb sunlight
chlorophyll
Root hair cells Normal Absorption of Large surface To absorb as much

plant cell water and area water and mineral ions
mineral ions as possible
Large Storage and

permanent transportation of water
central
vacuole
Muscle cell General -Contraction Lot of Maximum production
animal cell and relaxation, mitochondria of mitochondria
enabling
locomotion of
the skeleton Striated For easier and efficient
packing
Allows contraction and
relaxation enabling
locomotion of the
skeleton

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3.0 NUTRITION IN PLANTS

3.1 PHOTOSYNTHESIS
 Process whereby green plants produce glucose for energy production using carbon
dioxide and water
 Equation for photosynthesis
sunlight
Carbon dioxide + water glucose + oxygen
Chlorophyll
 After photosynthesis, the products are transported from the source to the sink
 Source; this is where photosynthesis takes place, (usually, the leaves)
 Sink; this is where the products are stored or used.
3.2 FATE OF THE END PRODUCTS OF PHOTOSYNTHESIS
Substance Fate
Glucose -used for respiration by the plant
-aminated to produce essential amino acids
-used to produce cellulose which is a structural sugar in plants (form cell walls
of the plant cell)
-converted to starch for storage in different organs of the plant (roots, fruits,
stems)
NB glucose is stored in the form of starch because starch is insoluble in water
Oxygen -used for oxidation of glucose to produce energy
-Can diffuse out of the leaf to be taken-in by animals for their respiration
process
3.3 CROSS SECTION OF A LEAF

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3.4 ADAPTATIONS OF A LEAF TO PHOTOSYNTHESIS

STRUCTURE FUNCTION
Waxy cuticle Reduce direct transpiration
Upper and lower epidermal cells Protects the leaf from bacterial infection
Palisade cells Has chloroplasts which are a site for photosynthesis
Spongy mesophyll cells Facilitates gaseous exchange
Has chloroplasts which are a site for photosynthesis
Guard cells Open and close the stomata regulating amount of water
loss through stomata
Air spaces Provides a moist environment for maximum gaseous
exchange
Phloem Transport of dissolved of products of photosynthesis
from the leaf to the rest of the plant
Xylem Transport of water and dissolved mineral ions from the
roots to the rest of the plant
Green pigment; chlorophyll Absorb chlorophyll for photolysis of water during
photosynthesis
Thin To allow sunlight to reach all parts of the leaf
Hairs on the lower part of the leaf Trap moisture to reduce water loss by the leaf
Stomata Allows gases in and out of the leaf
3.4 FACTORS AFFECTING RATE OF PHOTOSYNTHESIS

3.4.1 CHLOROPHYLL
 In ordinary level combined science, a plant that does not have the green chlorophyll is
assumed to not be photosynthesizing.
 So for light to be absorbed, there is need for the chlorophyll to absorb light so as for
photosynthesis to take place, thus it cannot be considered as affecting the rate
3.4.2 LIGHT INTENSITY
 With increase of amount of sunlight, there is increase in the rate of photosynthesis

 This happens until we reach an optimum, of which there is much sunlight that the
stomata close to avoid further loss of water
 The closing of the stomata closes out carbon dioxide which is needed for photosynthesis

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3.4.3 CARBON DIOXIDE CONCENTRATION
 With increase of carbon dioxide, the rate of photosynthesis increases

 This happens until an optimum is reached, at which, the rate is now being limited by
other factors that limit the rate of photosynthesis
3.5 EXPERIMENTS ON FACTORS NECESSARY FOR PHOTOSYNTHESIS

3.5.0 TEST FOR STARCH (PRE-REQUISITE)
AIM
 To test a leaf for starch
APPARATUS AND CHEMICALS
 General lab apparatus
 White tile
 Water bath
 Ethanol
 leaf
 Iodine solution
METHOD IN STEPS
1. Boil the leaf in water to stop chemical reactions
photosynthesis is a series of enzyme controlled reactions, there enzyme can be
denatured by high temperatures
2. Boil the leaf in alcohol to dissolve chlorophyll so that results are easy to see
heat alcohol using a water bath because it is flammable
The leaf is now white/off-white in colour
3. Dip the leaf in warm water to soften it
it would have become brittle as it would have been boiled in alcohol
4. Put the leaf on a white tile so as to observe colour changes clearly
5. Add 2 drops of iodine solution using a dropper and observe any colour changes, if
available

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RESULTS/OBSERVATIONS
 Positive test, colour changes from brown to blue-black
At times, the final colour is not blue-black, but a bit off from the expected, except if you
use the leaf from a geranium (Pelargonium) plant
 Negative test, colour remains brown
it might be distorted by of the food sample
CONCLUSION
 Positive test, starch was present
 Negative test, starch was absent
3.5.1 CHLOROPHYLL
AIM
 To test whether chlorophyll is necessary for photosynthesis or not
1. Lab apparatus
2. Potted plant with variegated leaves
These are leaves that have two sections, the other green and the other off-white
METHOD IN STEPS
1. De-starch the plant
Place it in a dark cabinet for about 24-48hours for the plant to use all the starch
2. Place the plant back in sunlight for 6-12 hours
This induces starting of photosynthesis, producing starch again
3. Test the leaf for starch
 The green region turns blue black
 The off-whitish region is colour brown
CONCLUSION
 Chlorophyll is needed for photosynthesis
A conclusion is actually a re-phrasing of the aim, or rather, an answer of the aim
3.5.2 SUNLIGHT
AIM
 To test whether sunlight is needed for photosynthesis
1. Lab apparatus
2. Aluminum
3. Potted plant
This is basically a planted plant

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METHOD IN STEPS
2. Fasten the aluminum foil on half part of the plant
The aluminum foil with prevent sunlight from reaching the covered region
3. Expose the plant to sunlight for 6-12 hours
4. Pluck the leaf and test for starch
 The region with the aluminum foil, iodine remains brown
 The region exposed to sunlight, iodine turns from brown to blue-black
CONCLUSION
 Sunlight is needed for photosynthesis
3.5.3 CARBON DIOXIDE
AIM
 To test whether carbon dioxide is necessary for photosynthesis
1. Lab apparatus
2. Polythene bag
3. Calcium hydroxide/lime water
4. Potted plant
METHOD IN STEPS
2. Tie one plant into a polythene bag which has lime water (calcium hydroxide)
Polythene bag keeps inside gases in, calcium hydroxide will absorb the carbon dioxide
Calcium hydroxide + carbon dioxide  calcium carbonate
3. Expose the plant to sunlight for 6-12 hours
4. Pluck one leaf from inside the polythene bag, and the other from outside (control) and
test for starch
 Positive test (iodine turns from brown to blue-black) on the leaf from outside the
polythene bag
 Negative test (iodine remains brown) from the leaf inside the bag
CONCLUSION
 Carbon dioxide is necessary for photosynthesis

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4.0 ECOSYSTEMS
 An ecosystem is the interaction of organisms and their physical environment
4.1 COMPONENTS OF AN ECOSYSTEM
Components of an ecosystem
Biotic (living components) Abiotic (non-living components)
Plants Rocks, soil and stones
Animals Water
Air
4.2 NATURAL AND ARTIFICIAL ECOSYSTEMS

ASPECT NATURAL ECOSYSTEM ARTIFICIAL ECOSYSTEM
Management Naturally, by weather elements Man is the custodian
Biodiversity -Unlimited variation of species -Limited biodiversity
-the weather elements exert -man chooses which organisms to
limiting factors that initiate natural tend and keep
selection
Examples of the National parks, ocean, dams and Gardens, ponds
ecosystems rivers
Differences Many species of organisms Monoculture
Genetic diversity is high Genetic diversity is low
Sunlight is the source of energy Sunlight is the ultimate source of
light, but artificial fertilizer and
manure are supplied to the soil
Food chains are long and complex Simple, incomplete food chains as
other species are killed as pests or
weeds
Ecological succession over a No ecological succession
period of time
Natural nutrient cycling ensures Incomplete nutrient cycling.
maximum and efficient cycling of Harvesting of the crops removes
nutrients large amount of nutrients from the
soil
Productivity is variable depending Designed for high productivity
on the environment
High naturally sustainable Un-sustainable as most of the
fertilizers are from non-renewable
resources

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4.3 FOOD CHAINS, WEBS AND PYRAMIDS OF BIOMASS

Type of organism subclass Description examples
Producers plants -Autotrophic Trees
-harness sun’s energy Scrubs
through photosynthesis Grass
Consumers Primary grazers Feed on grass Cow
consumers Browsers Feed on tree leaves and Giraffe
scrubs
Secondary Carnivores Feed on meat Lions
consumers
Tertiary Omnivores Feed on both meat and Humans
consumers plants
decomposers Feed on everything Maggots
Examples of a
a. Food chain
 Interconnection of organisms per their feeding
 It always starts with a producer and ends with a decomposer
 For example
Producer primary consumer secondary consumer decomposer
Grass  cow  man  maggots
b. Food web
 Interconnection of food chains, one stage of feeding can have many organisms
contained within
Grass human
Cow maize
Lion maggots

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c. Pyramid of biomass
 Biomass is the dry mass of an organism #
 Its arranged in a pyramid of trophic levels, with the lowest level having the
producers, and the highest having the last consumer
4.4 ENERGY FLOW IN AN ECOSYSTEM

 Energy in an ecosystem comes from the sun
 It is taken up by plants through the process of photosynthesis
 Then during nutrition of the different classes of organisms, it is passed through the
trophic levels right up to the decomposers
Not all the energy is passed on to the next trophic level
Trophic Examples How energy is lost

level
Plants (grass, schrubs) Respiration, Development of new tissues
Primary Grazers (cow, antelope) Growth and development of new tissues Respiration
consumers Browsers (goat,) Growth and development of new tissues, Respiration
Secondary Carnivores (lion, dog) Growth and development of new tissues, Respiration
consumers
Tertiary Omnivores (humans,) Growth and development of new tissues, Respiration
consumers Decomposers (maggots) Growth and development of new tissues Respiration

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4.4.1 CARBON CYCLE
4.4.2 NITROGEN CYCLE
4.5.1 BIODIVERSITY
 Collection of different species of organisms per given environment
4.5.2 EFFECTS OF LIMITED BIODIVERSITY
 Limited food provisions for other organisms in the ecosystem
 Less species of organisms means less productivity
 Less pressure on the land for resources, if populations can be controlled

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5.0 NUTRITION IN ANIMALS

5.1 BALANCED DIET
 It is a meal that contains all food nutrients in their correct proportions
Component examples Food sources
Carbohydrates glucose, starch Cereals
Proteins Protein Meat, Leguminous plants
Vitamins A, B, C Vegetables
Fats and oils lipids, cholesterol Meat, vegetables
Mineral ions Iron Dairy products, cocktail of vegetables,
Iodine, calcium iodised salt
Fiber Fiber Vegetables
Water Water Water
5.2 SEDENTARY, MANUAL, ADOLESCENT, BABY, PREGNANT WOMAN

Type of person Type of nutrients mostly needed reasons
Sedentary worker Balanced diet Minimal energy is used
Manual worker Carbohydrates Maximum energy is
needed
adolescent Protein, carbohydrates Development of tissues
Energy production as the
adolescent is highly active
Baby/toddler Protein, mineral ions Development of tissues and
maintenance of the osmotic
potential of the baby’s
body
Pregnant woman more proteins → growth of fetus Support the developing
slightly more fat → to produce new cell membranes fetus
more vitamin C and D → for proper development of blood
vessel walls and bones
iron → to produce hemoglobin
calcium → for the growth of bones and teeth
5.3 CARE OF TEETH

5.3.1 CROSS SECTION OF A TOOTH

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5.3.2 ROTTING OF TEETH

1. Food/sugars is left over on the teeth
2. Bacteria acts on the sugar producing acids
3. Acids dissolve/corrode the enamel
4. Rot reaches the dentine and a sharp pain is felt as it has reached the nerves
5.3.3 HOW CAN ONE TAKE CARE OF TEETH
 Flocking
 Brushing of teeth
 Eating healthy food rich in calcium
 Visiting the dentist
 Avoid opening bottle lids with teeth
5.4 ALIMENTARY CANAL

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5.5 DIGESTION
Point of Description Mechanical Chemical digestion
digestion of the digestion Enzyme/chemical Process catalysed
structure
mouth -teeth -teeth grinds food Salivary amylase Starch to maltose
-tongue from big insoluble
-salivary molecules to small
glands that soluble molecules
secrete -tongue mixes food
saliva with saliva an rolls
food into a bolus
Oesophagus longitudinal -peristalsis Salivary amylase Starch  maltose
and smooth
muscle
Stomach -glandular -churning mixing with Hydrochloric acid Pepsinogen to pepsin
lining being stomach juices, -produced by the Hydrolyses of
protected by producing chime glandular lining of sucrose to glucose
an epithelial which is sent into the the stomach and fructose
lining duodenum -it destroys
-produces bacteria
enzymes Renin Coagulation of milk
and the HCl Pepsin Proteins  peptones
Duodenum Epithelial Bile (produced by -Emulsify fats
lining liver stored in the -neutralises stomach
gall bladder) acid
Maltase Maltose  glucose
(pancreatic juice)
proteases Peptones  amino
(pancreatic juice) acids
Lipase (pancreatic Fat  fatty acids and
juice) oils
5.5 ABSORPTION
 It begins in the ileum and ends at the large intestines
NB a little absorption happens in the jejunum, but usually it is considered to begin in
the ileum
5.5.1 ROLE OF THE ILEUM
Structure Function
Long Affords a large surface area for absorption
One cell thick Allow faster diffusion of ions and nutrients into the blood
system
Has villi Increase surface area for absorption of nutrients
Associated with many To transport the diffused nutrients and ions
capillaries

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 The blood with the absorbed nutrients are carried by the hepatic portal vein from the
gut to the liver
 The liver will regulate the amount of substances and nutrients in the blood
5.5.2 ASSIMILATION
Component Product Uses in animals If in excess
after
digestion
Carbohydrates Glucose -substrate for cellular 1st converted to glycogen (stored in
respiration the liver 250g)
-formation of chitin, an 2nd converted to fat and stored in the
exoskeleton for some adipose tissue (under the skin)
organisms 3rd if adipose tissue if full, it then
accumulates around the vital organs
Proteins Amino -used for protein synthesis Amino acids are de-aminated to
acids Formation of non-amino acids form urea and carbohydrate
Urea forms urine and the
carbohydrate is used for respiration
Vitamins Vitamin A Eye sight and respiratory Excreted
tissues
Vitamin C Blood vessel development
Vitamin D -aids in absorption of calcium
in bones
Fats, oils and Fatty acids Used in formation of cell Stored in the form of fats
lipids membranes
Glycerol Can be used as a respiratory
substrate
Mineral ions Calcium Strengthening of bones and Excreted
teeth
Iron Formation of the haem group
in the hemoglobin
Iodine Formation of thee growth
hormone
Fiber cellulose Prevents constipation Excreted
Water water Aqueous medium for chemical Excreted
reactions in the body
5.6 MALNUTRITION AND DEFICIENCY DISEASES

Disease Lack Of Signs And Symptoms Treatment And Cure
Kwashiorkor Protein Muscle wasting; Bloated stomach because of Seek medical attention
the enlargement of the liver; Thin limbs;
Sparse hair
Goiter Iodine Swelling on the neck as a results of Seek medical attention
swelling of the thyroid gland
Rickets Vitamin D Softening of bones Seek medical attention
Scurvy Vitamin C Flacking of skin Seek medical attention
Anaemia Iron Muscle fatigue; shortness of breath; fainting Seek medical attention
Night Vitamin A Poor eye sight Seek medical attention
blindness

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5.7 Food tests for starch, simple sugars, protein and fats
5.7.1 Starch
AIM
 To test for the presence of starch in a food sample
 Lab apparatus
 Food sample
 Iodine solution
METHOD IN STEPS
1. Place the food sample on a white tile
if the food sample is a solid, crush, if it’s a solution, pour it in a beaker and place the
beaker of a white tile
2. Add drops of iodine
use a dropper for this process
3. Observe colour changes if any
At times, colour changes are not clear, you must be observant
 Positive test, colour changes from brown to blue-black
At times, the final colour is not blue-black, but a bit off from the expected, except if you
use the leaf from a ________________ tree
 Negative test, colour remains brown
it might be distorted by of the food sample
CONCLUSION
 Positive test, starch was present
 Negative test, starch was absent
5.7.2 REDUCING SUGARS
AIM
 To test for the presence of reducing sugars in a food sample
 Lab apparatus
 Benedict’s solutions
 Water bath
METHOD IN STEPS
 Dissolve the food sample in water
If the food sample does not dissolve in water, first dissolve in ethanol, then add to water
 Add benedict’s solution
 Warm gently in a water bath

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 Positive test, blue  yellow  orange  brick-red
This test can be used to test for the difference in concentrations of the reducing sugars
Different colour transitions will give you different colour changes
 Negative test, solution remains blue
Colour of thee food sample must be clear so as to observe colour changes well
CONCLUSION
 Reducing sugars were present
Testing for glucose using a clinistix
 A clinistix is a strip of paper that is pink in colour.
 It is dipped into the food solution and if glucose is present, the clinistix will
change colour from pink to purple. The purple colour shows a positive test for
glucose.
 If glucose is not present, the clinistix remains pink. This is a negative test to
glucose.
5.7.3 PROTEIN
AIM
 to test a food sample for
1. laboratory apparatus
2. copper sulphate
3. sodium hydroxide
4. food sample
METHOD IN STEPS
1. dissolve food sample into 10ml of water
2. add 5ml of sodium hydroxide, then 5ml of copper sulphate
 positive test, colour change from blue to purple colour.
 Negative test, the solution remains blue.
CONCLUSION
Test for proteins using an albustix
 An albustix is a strip of paper which is yellow in colour.
 A solution of the food to be tested is prepared and an albustix is dipped into the
food solution.
 If the food contains proteins, the albustix will change colour from yellow to green.
Green shows a positive colour for proteins.
 If the albustix remains yellow, then there is no protein in the food.

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5.7.4 FATS
Testing for fats
 Fats can be tested using either the spot test or the emulsion test.
Using the spot test to test fats

 The food sample to be tested is rubbed onto a white clean paper and the paper is
allowed to dry.
 If fats are present, a translucent spot remains on the paper after drying. The spot will
allow more light to pass through it than any other part of the paper.
 If there are no fats in the food, the paper dries to its original colour.
Using the emulsion test to test for fats

 A solution of the food sample to be tested is prepared and an equal volume of ethanol
is added to the food solution.
 The mixture is allowed to settle and an equal volume of water is added. On adding
water, the mixture turns milky if fats are present. The milky colour shows a positive
test for fats.
 If there are no fats, then the solution remains clear.

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6.0 RESPIRATORY SYSTEMS

6.1 COMPOSITION OF AIR
Component Inhaled air Exhaled air
Nitrogen 78% 78%
Rare gases <1% <1%
Oxygen 21% 16%
Carbon dioxide 0.03% 4%
Water vapour Less moist More moist
Temperature cool Warm
Dust particles present absent
pathogens present Present at times
6.2 TESTS FOR OXYGEN AND CARBON DIOXIDE

 Oxygen relights a glowing splint
 Carbon dioxide turns colorless lime water milky, and bicarbonate indicator red
6.3 STRUCTURE OF THE RESPIRATORY SYSTEM
Structure Function
Nose Allow air in, ciliated with mucus to trap dust and micro
organisms, warm the air
Voice box Allow passage of air
Trachea Cartilage structure, ciliated to trap dust and micro organisms
Bronchus and bronchioles Channel air into the lungs, mucus and cilia to trap dust and
micro organisms
Alveoli Gaseous exchange
ribs protect lungs from puncture
6.4 GASEOUS EXCHANGE

 Air is taken by the nose, cleaned of dust particles and micro-organisms, then passed
through the system into the alveolus
 In the alveolus, the capillaries come with de oxygenated blood, the red blood cell would
be having carbon dioxide (carboxy-hemoglobin)

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 When the blood reaches the alveolus, the carboxyhemoglin breaks down giving out
carbon dioxide.
 The carbon dioxide diffuses into the alveolus, then the oxygen diffuses into the blood
stream, into the red blood cell, forming oxy-hemoglobin
 Then the blood is transported back to the heart by the pulmonary vein
6.5 ADAPTATION OF THE ALVEOLI
Structure Function
Many Increase surface area for absorption
Surrounded by capillaries Easier diffusion of gases to and fro the blood system
Moist Easier diffusions
Thin walled (one cell thick) Partially permeable for diffusion of air only to take place
6.6 AEROBIC AND ANAEROBIC RESPIRATION

6.6.1 AEROBIC RESPIRATION
 Oxidation of glucose in the presence of excess oxygen
Glucose + oxygen  carbon dioxide + water
 This process takes place in the mitochondria
 There are four stages to the process
a. Glycolysis
 Breakdown of glucose to form 2 molecules of pyruvate
 Happens in the cytoplasm
b. Link reaction
 This is when the pyruvate molecule is converted to Acetyl-Co-
Enzyme-A
c. Krebs cycle
 This is when the acetyl Co-A is broken down to give energy carrier
molecules NADH+, FADH+
d. Oxidative phosphorylation
 Breakdown of the energy carrier molecules to give 38 molecules of
the energy carrier molecule, or ‘currency’ ATP

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6.6.2 ANAEROBIC RESPIRATION

 When exercising at high intensity, the cells’ energy demands will exceed what the
available levels of O2 can supply aerobically
 Hence the body will begin breaking down glucose anaerobically to maximise ATP
production
 This will result in an increase in the production of lactic acid, which leads to muscle
fatigue
 When the individual stops exercising, oxygen levels will increase and lactate will
be converted back to pyruvate
 Although carbohydrates, lipids and proteins can all be consumed as energy sources,
only carbohydrates will typically undergo anaerobic respiration

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7.0 TRANSPORT SYSTEMS IN PLANTS

7.1 TRANSPIRATION
 It is loss of water by plants through leaves
7.2 POTOMER
 Used to measure the rate of photosynthesis
 This is done by recording the amount of water in the calibrated pipette against time,
then drawing a graph
NB The set-up must be done under water to avoid formation of bubbles in the water
column
7.3 FACTORS AFFECTING RATE OF TRANSPIRATION
7.3.1 LIGHT INTENSITY
 An increase in light intensity results in the increase of rate of transpiration due to
an increase in stomata opening.
 As light intensity increase, more water is lost, guard cells become flaccid and close
the stomata

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7.3.2 TEMPERATURE
 Plants transpire faster at higher temperatures; this is because the rate of evaporation
increases with temperature.
 Same effect as light intensity
 Temperature also reduces air humidity, so transpiration increases
7.3.3 HUMIDITY
 Inversely proportional to transpiration
7.3.4 WIND
 Directly proportional to rate of transpiration
7.4 ADAPTATION OF LEAVES TO REDUCE THE RATE OF TRANSPIRATION

Structure Adaptation
Hairy leaves Trap moisture as it leaves the leaf
Stoma Close under high temperatures to avoid water loss
Waxy cuticle Avoid direct transpiration
Less leaves on trees Reduce surface area for loss of water

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7.5 IMPORTANCE OF TRANSPIRATION

 Induces transpiration pull of water and mineral ions dissolved to maintain turgor
pressure of the cells
 If this turgor pressure is lost, the plant will wilt
 Cools the plant
7.6 PLASMOLYSIS AND TURGIDITY
Plasmolysed cell Turgid cell
-when you put a cell in a hypertonic solution, -when you put a cell in a hypotonic solution,
it loses water, the vacuole shrinks, and the it will gain maximum water, the vacuole
cell seems to collapse enlarges pushing against the cell membraned
-The cell wall maintains its shape which is kept in shape by the cell
-the cell wall will prevent the cell from
bursting

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8.0 TRANSPORT SYSTEMS IN ANIMALS

8.1 COMPONENTS OF BLOOD
 When blood is centrifuged, four sections of blood can be clearly observed
Component structure Function

Red blood cell Refer to section 2.4 -transport of oxygen and
Erythrocyte carbon dioxide refer to
section 6.4
White blood cell -Lymphocytes -Production of pathogen
-normal large nucleus specific antibodies
-Important in immunity
-Phagocytes Engulfing of bacteria and
-lobed nucleus digest them
-granular cytoplasm
Plasma 55% Has Plasma proteins, Contains dissolved nutrients,

Liquid part of the blood, known as serum nutrients, antibodies, hormones, aqueous medium
when its devoid of blood cells hormones, urea etc for chemical reactions
Forms tissue fluids Also seeps out of the blood
vessels forming tissue fluid
Platelets Blood clotting to reduce
further loss of precious fluid

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8.2 USES OF BLOOD

 Blood is important because
a. Promotes even distribution of body temperature
b. Transportation of nutrients, oxygen carbon dioxide and waste products to all
parts of the body
c. Collects waste products for excretion by the lungs, liver and kidneys
d. Acts as an aqueous medium for dissolved substances to be transported
e. Transport hormones to target organs
8.3 NECESSITY FOR BLOOD CLOTTING
 When an injury occurs, fibrinogen in the blood interacts with platelets to form
insoluble fibrin.
 This forms a net over the wound which traps blood cells plugging the wound and
stopping the bleeding.
 Clotting is important because

a. Prevent excessive blood loss from the body when there is a damage of the
blood vessel.
b. Maintain the blood pressure.
c. Prevent the entry of microorganism and foreign particles into the body.
d. Promote wound healing.

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8.4 STRUCTURE OF THE HEART
 The heart is made of a special type of muscle called cardiac muscle which
contracts and relaxes regularly, throughout life.
 The heart’s muscle is constantly active, so it needs its own blood supply, through
the coronary artery, to provide it with oxygen and glucose.
 Valves in the heart prevent blood from being pushed backwards up into the atria
when the heart ‘beats’.
 Semi lunar valves at the bottom of the aorta and pulmonary artery prevent the
back flow of blood into the ventricles when the muscles of the heart relax.
1. Blood in the right ventricle (RV) is pumped to the lungs

2. Blood from the lungs flows back into the left atrium (LA)(through the
pulmonary vein) and then is pumped into the left ventricle (LV).
3. Blood in the LV is pumped to the rest of the body (except for the lungs)
through the aorta.
4. Blood returns to the heart where it enters the right atrium (RA) through the
Vena cava.
5. The right atrium pumps blood to the right ventricle

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8.5 STRUCTURE OF BLOOD VESSELS
Type Function Structure
Artery Carry blood away Outer layer It is composed of connective tissue as

from the heart well as collagen and elastic fibers
Carry oxygenated Middle layer Smooth muscle cells and elastic
blood except fibers predominate
pulmonary and Inner layer simple squamous endothelium cells,
umbilical arteries elastic
Narrow lumen For high pressure
Vein Carry blood to the Outer layer, It is composed of connective tissue as
heart tunica well as collagen and elastic fibers
Carry de-oxygenated adventitia or
blood except tunica externa
pulmonary and Middle layer, Smooth muscle cells and collagenous
umbilical/ maternal tunica media fibers predominate
veins Inner layer, Endothelial cells, elastic
tunica intima
large lumen Less resistance to blood flow
Valves Prevent backflow of blood
Capillary Carry blood from the One cell thick Allow diffusion of substances in and
arteries to the veins, Narrow lumen out of the blood vessel
thus supplying all the
cells with blood

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8.6 DOUBLE CIRCULATION

 Beginning at the lungs, blood flows into the left-hand side of the heart, and then out to
the rest of the body.
 It is brought back to the right-side of the heart, before going back to the lungs again.
 This is called a double circulation system, because the blood travels through the heart
twice in one complete journey around the body:
1. one circuit links the heart and lungs (low pressure circulation)
2. the other circuit links the heart with the rest of the body (high pressure circulation).
 leaves the left side of the heart, goes into the aorta
 in the aorta, it has the maximum pressure, rich in oxygen and nutrients needed by the
body cells for their metabolism
 the aorta branches into target arteries which will transport the blood to specific organs
 for example, the hepatic artery will carry blood to the gut
 upon reaching the target organs, the target arteries branch into finer capillaries which
will manage to reach the individual cells
 when blood reaches the cells, blood plasma seeps out bathing the cells forming tissue
fluid, the nutrients diffuse into the cells, and the oxy-hemoglobin complex breaks
down releasing oxygen
 waste products diffuse into the blood, and carbon dioxide forms the carboxy-
hemoglobin with hemoglobin in the red blood cells
 capillaries rejoin forming the target veins, target veins join to form the vena cava
 the vena cava will transport the blood into the right atrium
 when the right ventricle relaxes, blood flows into it
 when the right ventricle contracts, blood is pushed out of the ventricle, but it cannot
go back into the atrium, because the atrioventricular valve has closed, so the blood is
forced into the pulmonary artery,
it is the only artery that carries de-oxygenated blood
 pulmonary artery carries blood into the lungs, there in the lungs, carboxy-hemoglobin
breaks down releasing carbon dioxide, and oxyhemoglobin is formed

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 blood leaves the lungs via the pulmonary vein, going to the left side of the heart
it is the only vein that carries oxygenated blood
 the oxygenated blood goes into the left atrium, pushed into the left ventricle when the
atrium contracts
 it is pushed into the aorta when the ventricles contracts, thus the cycle continues
NB: All arteries carry oxygenated blood except the Pulmonary Artery which has de
oxygenated blood. All veins carry de oxygenated blood except the Pulmonary Vein
which carries Oxygenated Blood.

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9.0 REPRODUCTION IN PLANTS

 Both sexual and asexual
9.1 STRUCTURE OF A FLOWER
STRUCTURE FUNCTION
Stigma Receives pollen grains during the process of pollination
Produces a sticky substance to ensure pollen grains get stuck
Style Supports the stigma
Provides pathway for pollen tube to the ovules
Ovary Produces ovules, develops into fruit after fertilisation
Ovule female sex cells
Develops into a seed after the process of fertilisation
Petals Attract insects for pollination by their bright colour and nice scent
Their shape promotes pollination as they direct insects towards the
nectaries
Sepals Protects the flower bud
Anther Produces pollen grains
Pollen grains These are the male sex cells
9.2 DIFFERENCE BETWEEN IINSECT AND WIND POLLINATED FLOWERS

component Insect pollinated Flowers Wind Pollinated Flowers
Petals Petals are bright and produce a Dull coloured, usually green or brown
nice scent to attract insects and produce no scent as there is no need
to attract insects
Size of pollen Produce large sticky pollen Produce small smooth pollen grains
grains grains which are light enough to be carried by
the wind

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Quantity of Relatively small number of Produces a large quantity of pollen

pollen grains pollen grains as chances of grains to increase the chances of
produced pollination are high pollination
Position of Inside the flower Are hanging outside the flower

stigma and
anthers
Nectaries They have nectarines which No need for nectaries
produce nectar to attract
insects
9.3 AGENTS AND MECHANISM OF POLLINATION UP-TO REPRODUCTION

 Agents of pollination are ways in which pollen grains are transported from the anther
to the stigma
 Organisms like bees, and wind can be used as a means of transfer of pollination
 When pollen grains are added to the stigma, it bursts producing the male sex cell.
 The pollen tube develops down to the ovary, reaching the ovules
 The male sex cells travel down the pollen tube, reaching the ovules,
 The male and female sex cells fuse together, thus fertilisation
 The fertilised ovules develop into seeds and the ovary into fruits
9.4 STRUCTURE OF SEEDS
9.4.1 MONOCOTYLEDONOUS AND DICOTYLEDONOUS SEEDS
9.4.2 FUNCTIONS OF PARTS OF SEEDS

STRUCTURE FUNCTION
Cotyledon Food store for respiration during germination
radicle Grows into a root
Plumule Grows into leaves
Testa Protects the seed
Endosperm Food store for respiration during germination

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9.5 GERMINATION
 This is the process when seeds mature to produce plants
 The plumule develops into leaves, and the radicle into leaves
 The starch in the seed is used for respiration, producing the energy needed to germinate
the seed
 Moisture softens the testa, thus allowing oxygen and to enter and help in respiration
9.6 CONDITIONS NECESSARY FOR GERMINATION
 Moisture and oxygen are needed for germination
9.7 PERCENTAGE GERMINATION
9.8 ASEXUAL REPRODUCTION

 Occurs when a piece of the parent plant is taken and used to grow a new plant.
 No sex cells are used during this type of reproduction.
 Plants which use this type develop modified parts such as roots, stems and leaves which
can develop into new plants.
9.9 RHIZOMES, CUTTINGS, TUBERS
Component Description
Rhizomes Rhizome e.g. strawberry plants, couch grass
Is an underground stem that grows
horizontally underground and have nodes
from which new stems will develop towards
the surface to produce new plants.
Cuttings Cuttings e.g. sweet potatoes, sugar cane,

cassava
Small parts of the plant are used to produce
other plants.
These portions of the parent plant are put into
the ground in wet soil and will eventually
grow into a new plant.
tubers Stem Tubers e.g. potatoes

These are swollen parts at the end of an
underground stem and they store food during
photosynthesis.
They have buds which can develop into new
plants
Root tubers e.g. sweet potatoes
These are swollen parts of roots which store
food during photosynthesis.
They also have buds from which will develop
new plants if the right conditions exist.

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9.10 ADVANTAGES AND DISADVANTAGES OF ASEXUAL REPRODUCTION

advantages Disadvantages
New plants have the good features of the parent No genetic variation and therefore no
plant as there is no variation. improvement to meet changes in the
environment or diseases. This can lead to
extinction of species.
There is a higher chance of survival for the new Overcrowding leads to competition for
plant as it has a larger store of food. nutrients, water, and light. This affects the
growth of plants.
Plants mature much more quickly as there is no Pests and disease spread quickly because of
time wasted during germination. overcrowding.
No need to find a mating partner and therefore it Not possible to obtain large number of plants
is quicker. The methods do not need pollination, in a short time compared with seeds
fertilisation, and seed dispersal.
Asexual reproduction is beneficial in an
unchanging environment where the parent
organism is well adapted to survive

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7.0 REPRODUCTION IN ANIMALS

10.1 REPRODUCTIVE SYSTEMS
Male reproductive system female reproductive system
Male reproductive system Female reproductive system

Structure Function Structure Function
Testes produce sperms and Ovary Production of oestrogen
testosterone Keeping of the unmatured ova
Maturation of grafian follicle
Scrotum Hold the testicles away Funnel of Receives the ovum from the
from the body oviduct ovary
epididymis Long coiled tube storing Oviduct Pathway for the ovum
sperms
Sperm duct Carries sperms from the Uterus Support the fetus with
epididymis to the urethra nutrition
Prostate gland Produce seminal fluid Cervix Close the womb
seminal vesicles
Urethra Passage for semen and vagina Receives the semen
urine
Penis Expelling urine and Uterus wall Implantation
semen onto the vagina,
10.2 SEX CELLS
Sex cells Description
Sperms -haploid nucleus
-Tail for mobility
Ovum -haploid nucleus
10.3 FERTILIZATION
 Fusion of the male and sex cell’s nucleus
 Sperms are made in the testes then stored in the epididymis, 2oC below body temperature
 When the glans penis has been sensitized, spasm are induced to release the sperms
 They move from the epididymis into the sperm duct where seminal fluid is added from the
seminal vesicles, thus forming semen
 From there, semen passes into the urethra, out onto the acidic vagina
The vagina is acidic so as to destroy bacteria that might accumulate in there
 Sperms survive this acidic condition because of the alkaline condition of the semen

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 The sperms swim from the vagina, through the cervix, right into the womb, until they
reach the ovum
 One sperm fertilizes one ovum, resulting in formation of a zygote
There is no multiple fertilization
Identical twins are a result of cell division, whereas fraternal twins and multiple births
are a result of multiple ovulation
 When the zygote divides forming a ball of cells, then implants onto the uterus wall, it
becomes and embryo
Ectopic pregnancy is when the zygote implants onto the fallopian tubes
10.4 PREGNANCY,
 When all the limbs have formed, it is now a fetus
 Growth is increase in number of cells
Phase Period of time Description
embryo Implantation - -no distinct limbs
-Placenta is formed
-The heart is the first to be formed
-formation of the amniotic sack containing amniotic
fluid protecting the fetus against mechanical stress from
outside
Fetus -birth -Sex of the fetus is evident
-Libs are now distinct
-Other organs form
10.5 PLACENTA
 Connects the fetus to the mother
 Nutrients are transported across the placenta
 Produces progesterone during pregnancy, this hormone is meant to maintain the uterine
wall throughout pregnancy
 Blood from the mother does not mix with that of the fetus, to avoid coagulation and
infection, also to protect the under-developed fetal blood system from the high pressure
of the mother’s system
There is no HIV infection whilst in womb, except during birth
10.6 ANTENATAL CARE

 This period is called pregnancy or gestation period; the fetus is developing in the womb
for an average of 36weeks
10.6.1 DIET
Check section 5.2 on diet of a pregnant woman
10.7 BIRTH
 Towards the end of the gestation period, the fetus turns down with the head facing the
cervix
 ‘breaking of the water’ denotes the breaking of the amniotic sack
 Production of the hormone oxytocin will induce rhythmic uterine contractions pushing
the fetus down
 The cervix opens and the fetus comes out through the canal opening
 The umbilical cord is tied and cut, thus having the fetus exposed to the outside
conditions
 Crying induces a breathing reflex, thus we have a baby

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 For positive expecting mothers, nevirapine or PEP drugs is given to prevent mother to
child transmission
10.8 CHILD CARE
10.8.1 BREASTFEEDING
10.8.1.1 WHAT IS BREASTFEEDING
 Use of mammary glands that produce milk suckled by the baby/infant
10.8.1.2 ADVANTAGES OF BREASTFEEDING
 Breastmilk contains colostrum, which is a cocktail of antibodies to act as passive
immunity for the developing baby
 Breast milk contains balanced nutrients for the baby.
1. The milk contains antibodies which help to protect the baby against diseases. (breast
milk gives the baby natural passive immunity against diseases)
2. Breast feeding creates a close bond between the mother and the child.
3. The mother’s milk is clean and hygienic (it is free from pathogens except HI Virus for
positive mothers)
4. The milk is always at the correct temperature required by the baby.
5. It is cheap and is always available.
6. Breast feeding increases child spacing by mothers and is good for family planning.
10.9 CONTRACEPTION
 Ways to prevent pregnancy
Type examples description advantages Disadvantages Side effects
Barrie Condoms Female (femidom)-Prevents both -reduce sensation -non
r Male pregnancy and -can burst
Thin rubber STIs
-no need for
prescription
Can be used with
other methods
Diaphrag Rubber cap covering -Can be re-used -Trained -induce
m Dutch the cervix, used with for 2 years personnel to discomfort
cap spermicide -no health administer it Irritation of
concerns yet -Inserted before spermicide
sex
-Less effective
with wrong size
Loop Small plastic coated It has a string to Can be painful Discomfort
(IUD) copper coil preventing remove Induce bleeding Bleeding of the
implantation Long lasting and cervical uterine
97-98% effective cancer
Horm Contracep mini pill having -99% effective -Daily intake -Weight gain
onal tive pill progesterone preventing -reversible -Suppress -mood swings
implantation
Combined pill with
-easy to use breast milk -breast
ostrogen and progesterone Menstrual -Increase risk of tenderness
prevents ovulation bleeding is normal heart attack >35 -causing
-Blood clots spotting
levonogest Prevents implantation Self-administered Must be taken -can develop
rel 99% effective as early as resistance over
possible time

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Injection Prevents ovulation 99% effective Medical advise Headaches

(depo Causes thickening of Private and Delay to return Weight gain
vera) cervical mucus reversible to fertility Mood swings
Does not interfere Disturbs Bloated feeling
with sex and other menstrual cycle Decrease of
medication Others are sexual desire
Improves breast scared of
feeding injections
Spermicid Gel which kills No prescription Used with other Can cause
e sperms Private barrier methods irritation of the
Easy to use 60% effective penis or vagina
Improves Apply as least 3
effectiveness of minutes before
other methods sexual
encounter
Natura Abstinenc Avoid sexual activity 100% effective -No sexual Non
l e activity
Rhythm Sex during safe days -Free -60% effective Sexual
method using the menstrual -Accepted by -Unreliable for frustration
cycle religious and those with
cultural groups irregular period
-both partners -Needs
participates discipline
Withdraw Withdrawing before -free High failure Sexual
al method ejaculation -Accepted by rate frustration
religious groups Some sperm
might alredy
have been
deposited
Surgic Vasectom Cutting and tying of 100% reliable Permanent
al y the sperm ducts infertility
Tubal Cutting and tying of
ligation the fallopian tubes
10.10 MENSTRUAL CYCLE

 The 28-day cycle is regulated by hormones.
1. Day 1~5:
 FSH stimulate maturation of the grafian follicle
2. Day 5~12:
 Grafian follicle matures
 Oestrogen is produced by the maturing grafian follicle
 Oestrogen is to repair the uterine wall
3. Day 13/14/15:
 The luteinising hormone is released by the pituitary gland, triggering the release of the
female sex cell
4. Day 15~28:

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 The follicle hardens and then produces progesterone which keeps the uterus lining
thick for possible embryo implantation.
5. Day 28
a. Scenario 1: ovum is not fertilized:
 the hardened follicle degenerates, causing a fall in the levels of progesterone
and the uterus lining collapses
 Menstruation is the removal of the unfertilised egg and uterus lining from the
body and last for 3 – 5 days.
 At this point we go back to day 1, the process starts all over again.
b. Scenario 2: Egg is fertilized:
 If ovum is fertilised, then implantation occurs.
 The hardened follicle remains intact and continues producing progesterone
thus maintaining the uterine wall
10.11 INFERTILITY
10.11.1 CAUSES OF INFERTILITY
1. Low sperm count
 Less sperms produced, in a normal ejaculation, an average of 3 million might
be produced
2. Poor sperm and semen quality
 Deformed sperms, insufficient seminal fluid to neutralise the acidic vagina
3. Physical conditions
 Cancerous growth in the fallopian tube or cervix
 Prostate cancer
4. STIs
 For example, gonorrhea can block the oviduct and sperm ducts
5. Hormonal imbalances in females
 These induce menstrual disorders
10.11.2 WAYS TO CONCEIVE WHILST INFERTILE
1. Artificial insemination
 The sperms are administered artificial through injection into the uterus
2. In-vitro fertilisation
 Multiple ovulation is induced, the ova are collected and fertilised in a test-tube
 Then the fertilized ovum is injected back into the womb
3. Fertility drugs
 Drugs to enhance fertility, especially for women, those containing follicle
stimulating hormone and luteinising hormone

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10.0 HUMAN HEALTH AND DISEASES

10.1 CHANCROID, GONORRHEA, SYPHILIS AND GENITAL HERPES
Disease Pathogen Affected Signs and symptoms Testing/ Prevent
areas In men In women Treat /cure
Chancroid Hemophilus Genitalia -small red -small red -surgery Safe sex
ducrei Lymph bump on bump on the draining of abstinence
-it is a nodes genitalia labia, lymph nodes
bacterium painful -use of
-bumps ulcerate and bleed antibiotics to
-pain during urination for treat e.g
women ceftriaxone
-pain during sex azithromycin
-swollen lymph nodes doxycycline
-pain during sex
Gonorrhea Neisseria Eyes,-2-14days -vaginal -fluids can be Safe sex
gonorrheae throat,
after discharge taken from abstinence
-it is a vagina,
infection -pain during symptomatic
bacterium anus,-Painful urination areas
fallopian
urination -periods of -result in
tubes-Pus-like spotting 24hrs, ready
discharge -pain in in 3days
from the lower -use
penis abdomen antibiotics to
-Swelling or -Fever treat e.g
redness on -pain during ceftriaxone
the head of sex azithromycin
the penis doxycycline
-Persistent
sore throat
Syphilis Treponema Any part -1o small round chancre after 3 -Blood test Safe sex
pallidum of the weeks of infection -use of abstinence
-it is a body -2o skin rash on palms and feet, antibiotics to
bacterium not itchy, sore throat, head- treat e.g
ache, swollen lymph nodes, ceftriaxone
fever, weight loss, aching azithromycin
joints, hair-loss
doxycycline
-latent has no symptoms
-3oblindness, deafness, mental
illness, memory loss, heart
diseases
Genital Herpes Mucus -blisters inside mouth or -Visual Safe sex
herpes simplex membrane anywhere touched by examination abstinence
virus Pelvis infected area, they ulcerate -blood
nerve -swelling of lymph nodes examination
cells -Headaches, Fever, Body -antiretroviral
aches drugs
-babies born with it may
develop blindness, brain
damage, and death

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10.2VIRUSES AND BACTERIA

 Viruses are smaller than bacteria and can't survive without a living host.
 A virus attaches itself to cells and usually reprograms them to reproduce itself.
 Also, unlike bacteria, most viruses do cause disease.
 Some virus-caused diseases include the common cold, AIDS, herpes, and chickenpox.
10.3.1 MALARIA, TYPHOID, EBOLA, CHOLERA
Disease Pathogen Signs and symptoms Treat / cure Prevention
Malaria Plasmodium Chills, fever, headache, Prophylactic drugs, chloroquine,
vivax muscle ache, shivering, quinine, primaquine, fancida
sweating, enlarged Vaccines, Empty stagnant water,
spleen spray breeding sites with DTT, cut tall
grass, mosquito repellants
Typhoid Salmonella Fever, rash with rose Use of antibiotics Proper sanitation
typhimurium/ colored spots, stomach Rehydrate Drink warm
enterica pains, headache, loss of Proper sanitation beverages
Transmitted appetite, diarrhea, Eat cooked food
by water vomiting, constipation Vaccination, peel
fruits
Ebola Ebola virus 8-10 days after exposure -blood test -practice hygiene
Transferred Fatigue, diarrhea, -Vaccine -refrain from
by body headache, fever, muscle -maintain fluids touching corpse
fluids and stomach pain, of the body -avoid contact
vomiting, un explained -Treating co- with wildlife
bleeding existing diseases
Cholera Vibrio Severe dehydration, Oral rehydration, Proper sanitation
cholerae diarrhea, fever, vomiting antibiotics, and personal
nausea abdominal pains, tetracycline, hygiene
chloramphenicol
10.3.2 LIFE CYCLE OF ANOPHELES’ MOSQUITO

 The anopheles’ mosquito carries the plasmodium vivax in its salivary glands

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10.3SUBSTANCE USE AND ABUSE

10.3.1 TOBACCO SMOKING
 Tobacco smoke is incredibly harmful to your health.
 There’s no safe way to smoke. Replacing your cigarette with a cigar, pipe, or hookah
won’t help you avoid the health risks.
 Cigarettes contain about 600 ingredients, many of which can also be found in cigars
and hookahs.
 When these ingredients burn, they generate more than 7,000 chemicals, according to
the American Lung Association.
 Many of those chemicals are poisonous and at least 69 of them are linked to cancer.
10.3.1.1 HEALTH EFFECTS
CENTRAL NERVOUS SYSTEM
 Nicotine reaches the brain and makes you feel more energized for a while. But as that
effect wears off, you feel tired and crave more. Nicotine is extremely habit-forming,
which is why people find smoking so difficult to quit.
 Physical withdrawal from nicotine can impair your cognitive functioning and make you
feel anxious, irritated, and depressed. Withdrawal can also cause headaches and sleep
problems.
RESPIRATORY SYSTEM
 When you inhale smoke, you’re taking in substances that can damage your lungs. Over
time, this damage leads to a variety of problems. Along with increased infections,
people who smoke are at higher risk for chronic nonreversible lung conditions such as:
 emphysema, the destruction of the air sacs in your lungs
 chronic bronchitis, permanent inflammation that affects the lining of the breathing tubes
of the lungs
 chronic obstructive pulmonary disease (COPD), a group of lung diseases
LUNG CANCER
 Withdrawal from tobacco products can cause temporary congestion and respiratory
discomfort as your lungs and airways begin to heal. Increased mucus production right
after quitting smoking is a positive sign that your respiratory system is recovering.
 Children whose parents smoke are more prone to coughing, wheezing, and asthma
attacks than children whose parents don’t. They also tend to have higher rates of
pneumonia and bronchitis.
CARDIOVASCULAR SYSTEM
 Smoking damages your entire cardiovascular system. Nicotine causes blood vessels to
tighten, which restricts the flow of blood. Over time, the ongoing narrowing, along with
damage to the blood vessels, can cause peripheral artery disease.
 Smoking also raises blood pressure, weakens blood vessel walls, and increases blood
clots. Together, this raises your risk of stroke.
 You’re also at an increased risk of worsening heart disease if you’ve already had heart
bypass surgery, a heart attack, or a stent placed in a blood vessel.
 Smoking not only impacts your cardiovascular health, but also the health of those
around you who don’t smoke. Exposure to secondhand smoke carries the same risk to
a nonsmoker as someone who does smoke. Risks include stroke, heart attack, and heart
disease.
INTEGUMENTARY SYSTEM (SKIN, HAIR, AND NAILS)
 The more obvious signs of smoking involve skin changes. Substances in tobacco smoke
actually change the structure of your skin. A recent study has shown that smoking
dramatically increases the risk of squamous cell carcinoma (skin cancer).

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 Your fingernails and toenails aren’t immune from the effects of smoking. Smoking
increases the likelihood of fungal nail infections.
 Hair is also affected by nicotine. An older study found it increases hair loss, balding,
and graying.
DIGESTIVE SYSTEM
 Smoking increases the risk of mouth, throat, larynx, and esophagus cancer. Smokers
also have higher rates of pancreatic cancer. Even people who “smoke but don’t inhale”
face an increased risk of mouth cancer.
 Smoking also has an effect on insulin, making it more likely that you’ll develop insulin
resistance. That puts you at increased risk of type 2 diabetes and its complications,
which tend to develop at a faster rate than in people who don’t smoke.
SEXUALITY AND REPRODUCTIVE SYSTEM
 Nicotine affects blood flow to the genital areas of both men and women. For men, this
can decrease sexual performance. For women, this can result in sexual dissatisfaction
by decreasing lubrication and the ability to reach orgasm. Smoking may also lower sex
hormone levels in both men and women. This can possibly lead to decreased sexual
desire.
10.3.1.2 HOW TO DEAL WITH ADDICTION
 Therapy
 Finding other recreational techniques like sports
10.3.2 ALCOHOL ABUSE
10.3.2.1 SIGNS AND SYMPTOMS OF ALCOHOL USE AND ABUSE
 A high concentration of alcohol in the blood causes symptoms, such as
1. slurred speech
2. slowing of reflexes
3. a decreased ability to control bodily movements
4. difficulty concentrating
5. gaps in memory, or brownouts
6. poor decision-making abilities
7. risky behavior
8. staying conscious but not having memory of your actions, which is called a blackout
9. breathing problems, coma, or death.
10. Many people use alcohol with no ill effects. But anyone can experience its
effects, such as illness, vomiting, or hangovers.
 Drinking alcohol can also lead to:
1. Accidents
2. falls
3. drowning
4. fighting
5. suicide
You shouldn’t attempt to drive or operate heavy machinery whilst under the influence of
alcohol. Also, refrain from engaging in social conversations that may be controversial as
they may easily turn into fights, then your wellbeing is compromised.

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 The symptoms of alcoholism include:

1. a strong desire or craving to drink
2. an inability to control cravings
3. an inability to stop drinking
4. an increased tolerance for alcohol
5. lying about drinking
6. attempting to drink without others knowing
7. an inability to get through everyday activities without drinking
note that these are symptoms of alcoholism and not abuse of alcohol
SYMPTOMS OF ALCOHOL ABUSE
 drinking to relax
 driving under the influence of alcohol
 problems with family and friends because of drinking
 neglecting responsibilities
 having legal problems because of alcohol
 Therapy
 Finding other recreational techniques like sports
10.3.3 MANDRAX ABUSE
 First used to treat psychosis
 Reduced heart rate
 Increased sexual arousal
 Parenthesis (numbness of the fingers and toes)
 Slurred speech
 Headaches
 Convulsions
 Death through cardiac or respiratory arrest
 Rehabilitation therapy
 detox
10.3.4 CANNABIS ABUSE
 Euphoria, Relaxation, Drowsiness, Altered sense of time, Impaired memory, Slowed
reflexes and impaired motor skills, Bloodshot eyes, Increased appetite, Dry mouth,
Increased heart rate, Cognitive impairments, Paranoia.
 Respiratory problems: Marijuana smoke has many of the same irritating and lung-
damaging properties as tobacco smoke. Long-term users may develop a chronic cough
and are at higher risk of lung infections.
 Cardiovascular risk: Marijuana ingestion increases the heart rate for several hours,
increasing the chance of heart attack or stroke. This may aggravate pre-existing heart

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conditions in long-term users and those who are older—placing them at greater risk of
a cardiovascular event.
 Mental health effects: Long-term marijuana use can decrease an individual’s
performance on memory-related tasks and cause a decrease in motivation and interest
in everyday activities. Marijuana is also known to intensify symptoms in users with
schizophrenia.
 Child development: Marijuana use during pregnancy can affect the development of the
fetus’s brain and has been linked to behavioral problems in babies.
 Psychological dependence: Like most other drugs of abuse, individuals who use
marijuana for long periods of time can develop a dependence on it. Signs of dependence
in a user include the need to use marijuana to cope with everyday tasks and the
experience of cravings and anxiety when marijuana is not available.
 Rehabilitation therapy
 detox
10.3.5 SOLVENTS ABUSE
 Substances called hydrocarbons can be sniffed from glues, petrol, dry cleaning fluids,
typing correction fluid, nail polish and remover, and propellant gas from aerosols.
 Most sniffers sniff directly from the bottle or tube; others use a plastic bag held over
their mouth.
 When inhaled, they give an effect similar to alcohol, which includes:
1. Euphoria, then dizziness with blurring of vision, followed by feelings of unreality,
disorientation and irregular, jerky movements.
2. Visual hallucinations.
3. Stomach cramps.
4. Acute intoxication comes on very suddenly and disappears quickly once sniffing
stops. A mild hangover may be experienced.
 Risks include death from inhalation of vomit, from an accident or from an irregular
heartbeat.
 Solvents can cause acute kidney, liver and brain damage, related to individual
susceptibility rather than amount inhaled.
 Anti-social behavior is also common amongst adolescents who abuse solvents.
 Therapy
 Detox

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11 IMMUNITY
 Prevention of infection of the body
11.1 TYPES OF IMMUNITY
Type of DESCRIPTION OF HOW IT OCCURS
immunity
Passive Colostrum in breast milk contains live antibodies
No memory cells are formed
Active Live antibodies are injected
No memory cells formed
Natural Antibodies produced by the body upon infection
Memory cells formed
Artificial Vaccinations, injection of live or weak antibodies, to mimic an infection
Memory cells formed
 In Zimbabwe, children below the age of five are immunized against the six child killer
diseases namely,
1. Whooping cough
2. Diphtheria
3. Measles
4. Polio
5. Tetanus
6. Tuberculosis
 HIV is the seventh, though sadly, no effective vaccine has been discovered yet
11.2 ROLE OF WHITE BLOOD CELLS AND MEMORY CELLS
for white blood cells, refer to section 8.1
memory cells retain the information for the formation of pathogen specific antibodies.
11.3 HIV/AIDS
 HIV is a virus that damages the immune system.
 The immune system helps the body fight off infections.
 Untreated HIV infects and kills CD4 cells, which are a type of immune cell called T
cells.
 Over time, as HIV kills more CD4 cells, the body is more likely to get various types of
infections and cancers.
 Without treatment, a person with HIV is likely to develop a serious condition called
AIDS.
 At that point, the immune system is too weak to fight off other diseases and
infections.
 With antiretroviral therapy, HIV can be well-controlled and life expectancy can be
nearly the same as someone who has not contracted HIV.
AIDS
 AIDS is a condition that can develop in people with HIV, it’s the most advanced stage
of HIV.
 But just because a person has HIV doesn’t mean they’ll develop AIDS.

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 HIV kills CD4 cells.

 Healthy adults generally have a CD4 count of 500 to 1,500 per cubic millimeter.
 A person with HIV whose CD4 count falls below 200 per cubic millimeter will be
diagnosed with AIDS.
 A person can also be diagnosed with AIDS if they have HIV and develop
an opportunistic infection or cancer that’s rare in people who don’t have HIV.
 An opportunistic infection, such as pneumonia, is one that takes advantage of a
unique situation, such as HIV.
 That makes the person vulnerable to a wide range of illnesses, including:
1. pneumonia
2. tuberculosis
3. oral thrush, a fungal infection in the mouth or throat
4. cytomegalovirus (CMV), a type of herpes virus
5. cryptococcal meningitis, a fungal infection in the brain
6. toxoplasmosis, a brain infection caused by a parasite
7. cryptosporidiosis, an infection caused by an intestinal parasite
8. cancer, including Kaposi’s sarcoma (KS) and lymphoma
HIV AND AIDS: WHAT’S THE CONNECTION?
 Cases of HIV progress through three stages:

stage 1: acute stage, the first few weeks after transmission
stage 2: clinical latency, or chronic stage
stage 3: AIDS
 As HIV lowers the CD4 cell count, the immune system weakens. A typical adult’s
CD4 count is 500 to 1,500 per cubic millimeter. A person with a count below 200 is
considered to have AIDS.
 How quickly a case of HIV progresses through the chronic stage varies significantly
from person to person.
 People with HIV often have a near-normal lifespan with early treatment with
antiretroviral therapy.
 However, treatment can increase a person’s CD4 count to the point where they’re
considered to no longer have AIDS. (This point is a count of 200 or higher.) Also,
treatment can typically help manage opportunistic infections
HIV TRANSMISSION
 The virus doesn’t spread in air or water, or through casual contact.

 Anyone can contract HIV. The virus is transmitted in bodily fluids that include:
1. Blood
2. Semen

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3. vaginal and rectal fluids

4. breast milk
 Some of the ways HIV is spread from person to person include:
1. through vaginal or anal sex — the most common route of transmission, especially
among men who have sex with men
2. by sharing needles, syringes, and other items for injection drug use
3. by sharing tattoo equipment without sterilizing it between uses
4. during pregnancy, labor, or delivery from a woman to her baby
5. during breastfeeding
6. through “pre-mastication,” or chewing a baby’s food before feeding it to them
7. through exposure to the blood of someone living with HIV, such as through a
needle stick
8. The virus can also be transmitted through a blood transfusion or organ and tissue
transplant. However, rigorous testing for HIV among blood, organ, and tissue
donors ensures that this is very rare in the United States.
 It’s theoretically possible, but considered extremely rare, for HIV to spread through:
1. oral sex (only if there are bleeding gums or open sores in the person’s mouth)
2. being bitten by a person with HIV (only if the saliva is bloody or there are open
sores in the person’s mouth)
3. contact between broken skin, wounds, or mucous membranes and the blood of
someone living with HIV
 HIV does NOT spread through:
1. skin-to-skin contact, without a wound in the mouth
2. hugging, shaking hands, or kissing
3. air or water
4. sharing food or drinks, including drinking fountains
5. saliva, tears, or sweat (unless mixed with the blood of a person with HIV)
6. sharing a toilet, towels, or bedding
7. mosquitoes or other insects
It’s important to note that if a person with HIV is being treated and has a persistently
undetectable viral load, it’s virtually impossible to transmit the virus to another
person.
CAUSES OF HIV
 HIV is a variation of a virus that infects African chimpanzees.

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 Scientists suspect the simian immunodeficiency virus (SIV) jumped from chimps to
humans when people consumed infected chimpanzee meat.
 Once inside the human population, the virus mutated into what we now know as HIV.
WHAT TESTS ARE USED TO DIAGNOSE HIV?
 Several different tests can be used to diagnose HIV. Healthcare providers determine
which test is best for each person.
1. ANTIBODY/ANTIGEN TESTS
 Antibody/antigen tests are the most commonly used tests.
 They can show positive results typically within 18-45days after someone
initially contracts HIV.
 These tests check the blood for antibodies.
 An antibody is a type of protein the body makes to fight an infection.
 An antigen, on the other hand, is the part of the virus that activates the
immune system.
2. ANTIBODY TESTS
 these tests check the blood solely for antibodies.
 Between 23-90days after transmission, most people will develop detectable
HIV antibodies, which can be found in the blood or saliva.
 These tests are done using blood tests or mouth swabs, and there’s no
preparation necessary.
 Some tests provide results in 30 minutes or less and can be performed in a
healthcare provider’s office or clinic.
3. NUCLEIC ACID TEST (NAT)
 This expensive test isn’t used for general screening. It’s for people who
have early symptoms of HIV or have a known risk factor.
 This test doesn’t look for antibodies; it looks for the virus itself. It takes
from 5 to 21 days for HIV to be detectable in the blood.
 This test is usually accompanied or confirmed by an antibody test.
WHAT’S THE HIV WINDOW PERIOD?
 As soon as someone contracts HIV, it starts to reproduce in their body.

 The person’s immune system reacts to the antigens (parts of the virus) by producing
antibodies (cells that fight the virus).
 The time between exposure to HIV and when it becomes detectable in the blood is
called the HIV window period.
 Most people develop detectable HIV antibodies within 23 to 90 days after infection.

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 If a person takes an HIV test during the window period, it’s likely they’ll receive a
negative result.
 However, they can still transmit the virus to others during this time.
 Someone who tests negative during the window might benefit from post-exposure
prophylaxis (PEP).
 This is medication taken after an exposure to prevent getting HIV.
 PEP needs to be taken as soon as possible after the exposure; it should be taken no
later than 72 hours after exposure, but ideally before then.
 Another way to prevent getting HIV is pre-exposure prophylaxis (PrEP).
 A combination of HIV drugs taken before potential exposure to HIV, PrEP can lower
the risk of contracting or spreading HIV when taken consistently.
EARLY SYMPTOMS OF HIV
 The first few weeks after someone contracts HIV is called the acute infection stage.
 During this time, the virus reproduces rapidly. The person’s immune system responds
by producing HIV antibodies. These are proteins that fight infection.
 During this stage, some people have no symptoms at first. However, many people
experience symptoms in the first month or two after contracting the virus, but often
don’t realize they’re caused by HIV.
 This is because symptoms of the acute stage can be very similar to those of the flu or
other seasonal viruses. They may be mild to severe, they may come and go, and they
may last anywhere from a few days to several weeks.
EARLY SYMPTOMS OF HIV CAN INCLUDE:
 Fever
 Chills
 swollen lymph nodes
 general aches and pains
 skin rash
 sore throat
 headache
 nausea
 upset stomach

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Because these symptoms are similar to common illnesses like the flu, the person with
them might not think they need to see a healthcare provider. And even if they do, their
healthcare provider might suspect the flu or mononucleosis and might not even
consider HIV.
 Whether a person has symptoms or not, during this period their viral load is very high.
 The viral load is the amount of HIV found in the bloodstream. A high viral load
means that HIV can be easily transmitted to someone else during this time.
 Initial HIV symptoms usually resolve within a few months as the person enters the
chronic, or clinical latency, stage of HIV. This stage can last many years or even
decades with treatment.
WHAT ARE THE SYMPTOMS OF HIV?
 After the first month or so, HIV enters the clinical latency stage. This stage can last
from a few years to a few decades.
 Some people don’t have any symptoms during this time, while others may have
minimal or nonspecific symptoms.
 A nonspecific symptom is a symptom that doesn’t pertain to one specific disease or
condition.
 These nonspecific symptoms may include:
1. headaches and other aches and pains
2. swollen lymph nodes
3. recurrent fevers
4. night sweats
5. fatigue
6. nausea
7. vomiting
8. diarrhea
9. weight loss
10. skin rashes
11. recurrent oral or vaginal yeast infections
12. pneumonia
13. shingles
RASH RELATED TO HIV

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 HIV makes someone more susceptible to skin problems because the virus destroys
immune system cells that fight infection. Co-infections that can cause rash include:
1. molluscum contagiosum
2. herpes simplex
3. shingles
 In addition, women with HIV are at increased risk of:
1. recurrent vaginal yeast infections
2. other vaginal infections, including bacterial vaginosis
3. pelvic inflammatory disease (PID)
4. menstrual cycle changes
5. human papillomavirus (HPV), which can cause genital warts and lead to cervical
cancer
 While not related to HIV symptoms, another risk for women with HIV is that the
virus can be transmitted to a baby during pregnancy.
 However, antiretroviral therapy is considered safe during pregnancy.
 Women who are treated with antiretroviral therapy are at very low risk of passing
HIV to their baby during pregnancy and delivery.
 Breastfeeding is also affected in women with HIV.
 The virus can be passed to a baby through breast milk.
PREVENTION OF HIV
 Safer sex and abstinence
 Get tested for HIV. It’s important they learn their status and that of their partner.
 Get tested for other sexually transmitted infections (STIs). If they test positive for
one, they should get it treated, because having an STI increases the risk of contracting
HIV.
 Use condoms. They should learn the correct way to use condoms and use them every
time they have sex, whether it’s through vaginal or anal intercourse. It’s important to
keep in mind that pre-seminal fluids (which come out before male ejaculation) can
contain HIV.
 Limit their sexual partners. They should have one sexual partner with whom they
have an exclusive sexual relationship.
 Take their medications as directed if they have HIV. This lowers the risk of
transmitting the virus to their sexual partner.

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 Avoid sharing needles or other drug paraphernalia. HIV is transmitted through

blood and can be contracted by using contaminated materials.
 Consider PEP. A person who has been exposed to HIV should contact their
healthcare provider about obtaining post-exposure prophylaxis (PEP). PEP can reduce
the risk of contracting HIV. It consists of three antiretroviral medications given for 28
days. PEP should be started as soon as possible after exposure, but before 36 to 72
hours have passed.

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13.0 DEFINITIONS OF NEW TERMS

TERM DEFINITION
Active uptake Transport of ions and substances against their concentration
gradient using pumps, channel proteins and energy.
Aerobic respiration Oxidation of glucose in excess oxygen producing carbon dioxide
and water
Anaerobic respiration Oxidation of glucose with limited, or without oxygen producing
lactate
Antibody Produced by lymphocytes to fight against infection by pathogens
Assimilation Usage of products of digestion
Bacteria Microorganisms which are responsible for some diseases in
organisms, though at times, they might have a biological
significance.
Balanced diet Meal containing all nutrients in correct proportions
Biodiversity Variation in organisms per given unit area
Cell Smallest function and structural unit of a living organism
Cellular respiration Oxidation of glucose in the cells
contraception Prevention of pregnancy
Diffusion Movement of particles from a region of high concentration to a
region of low concentration, down the concentration gradient
Digestion Breakdown of large insoluble macromolecules into smaller units
that can be absorbed and assimilated
Drug Chemical substance that can be used to alter the chemical nature
or reactions of the body
ecosystem Interaction of organisms and their natural environment
emulsification Breakdown of large molecules of fats into smaller ones
Fertilization Fusion of the male and female sex cells
Germination Develop of the seed into a seedling/plant
Gestation Period of pregnancy
Hypertonic When the external environment has a higher water potential than
the internal
Hypotonic When the external environment has a lower water potential than
the internal
Immune Resistance to infection, though the pathogen may get into the
body, it will have nos effect as it is quickly destroyed
Isotonic When the water potential of the outside environment is equal to
that of the internal
Magnification Increase of size of an object
Menstruation Shedding of the uterine wall when no fertilisation has taken place
Opiate Depressant drug
osmosis Movement of water molecules from a region of their higher
concentration to a region of their lower concentration through a
partially permeable membrane
Pathogen Viruses, bacteria, protozoa and other micro-organisms that can
cause an infection
Photosynthesis Production of glucose by leaves in the presence of sunlight and
chlorophyll
Plasmolysis Loss of water by the cells / decrease of water potential of the cell

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Pollination Transfer of pollen grains from the anther to the stigma

Reproduction Production of offspring to propagate the specie
Resolution Increasing clarity to distinguish between two objects that are close
together
solute Substance that dissolves in a solvent forming a solution
Solution Result of a process when a solute has completely dissolved in a
solvent
Solvent Medium that dissolves a solute
Transpiration Loss of water by the tree through its stomatal openings in the
leaves
Trophic level Feeding level, energy level in a pyramid of numbers, or biomass,
or food chain
turgid When the cell has maximum water potential
Virus Organisms which causes incurable diseases after infection

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14.0 REVISION QUESTIONS

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COMBINED SCIENCE STUDY PACK

5/23/2019 BIOLOGY SECTION O’LEVEL

COMBINED SCIENCE STUDY PACK

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

1.2 LABORATORY EQUIPMENT

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

2.0 CELLS AND LEVELS OF ORGANISATION

2.1.2 FUNCTIONS OF THE PARTS OF A MICROSCOPE

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

2.2 ANIMAL AND PLANT CELL STRUCTURES

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

2.4 SPECIALIZED CELLS

Root hair cells Normal Absorption of Large surface To absorb as much

Large Storage and

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

3.0 NUTRITION IN PLANTS

3.3 CROSS SECTION OF A LEAF

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

3.4 ADAPTATIONS OF A LEAF TO PHOTOSYNTHESIS

3.4 FACTORS AFFECTING RATE OF PHOTOSYNTHESIS

 With increase of amount of sunlight, there is increase in the rate of photosynthesis

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

3.4.3 CARBON DIOXIDE CONCENTRATION

 With increase of carbon dioxide, the rate of photosynthesis increases

3.5 EXPERIMENTS ON FACTORS NECESSARY FOR PHOTOSYNTHESIS

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

4.2 NATURAL AND ARTIFICIAL ECOSYSTEMS

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

4.3 FOOD CHAINS, WEBS AND PYRAMIDS OF BIOMASS

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

4.4 ENERGY FLOW IN AN ECOSYSTEM

Trophic Examples How energy is lost

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

4.4.1 CARBON CYCLE

4.4.2 NITROGEN CYCLE

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

5.0 NUTRITION IN ANIMALS

5.2 SEDENTARY, MANUAL, ADOLESCENT, BABY, PREGNANT WOMAN

5.3 CARE OF TEETH

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

5.3.2 ROTTING OF TEETH

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

5.6 MALNUTRITION AND DEFICIENCY DISEASES

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

Using the spot test to test fats

Using the emulsion test to test for fats

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

6.0 RESPIRATORY SYSTEMS

6.2 TESTS FOR OXYGEN AND CARBON DIOXIDE

6.4 GASEOUS EXCHANGE

COMBINED SCIENCE: ZIMSEC SYLLABUS CODE 4002

6.5 ADAPTATION OF THE ALVEOLI

6.6 AEROBIC AND ANAEROBIC RESPIRATION