LIFE PROCESSES

GRADE 10

Nutrition: The process by which an organism takes food and utilizes it, is called nutrition.

Need for Nutrition: Organisms need the energy to perform various activities. The energy is
supplied by the nutrients. Organisms need various raw materials for growth and repair. These
raw materials are provided by nutrients.

Nutrients: Materials which provide nutrition to organisms are called nutrients.

Carbohydrates, proteins and fats are the main nutrients and are called macronutrients.
Minerals and vitamins are required in small amounts and hence are called micronutrients.

Modes of Nutrition
1. Autotrophic Nutrition.
2. Heterotrophic Nutrition.
Heterotrophic Nutrition
The mode of nutrition in which an organism takes food from another organism is called
heterotrophic nutrition. Organisms, other than green plants and blue-green algae follow the
heterotrophic mode of nutrition. Heterotrophic nutrition can be further divided into three
types, viz. saprophytic nutrition, holozoic nutrition, and parasitic.
Saprophytic Nutrition: In saprophytic nutrition, the organism secretes the digestive juices
on the food. The food is digested while it is still to be ingested. The digested food is then
ingested by the organism. All the decomposers follow saprophytic nutrition. Some insects,
like houseflies, also follow this mode of nutrition.
Holozoic Nutrition: In holozoic nutrition, the digestion happens inside the body of the
organism. i.e., after the food is ingested. Most of the animals follow this mode of nutrition.
Parasitic Nutrition: The organism which lives inside or outside another organism (host) and
derives nutrition from it is known as parasites and this type of mode of nutrition is called
parasitic nutrition. For example Cuscuta, tick etc.

Autotrophic Nutrition
The mode of nutrition in which an organism prepares its own food is called autotrophic
nutrition. Green plants and blue-green algae follow the autotrophic mode of nutrition.

Main Events for Photosynthesis:

 Absorption of light energy by chlorophyll.
 Conversion of light energy into chemical energy + splitting (breaking) of water
into hydrogen and oxygen.
 Reduction of CO2 to carbohydrates.

Raw Materials for Photosynthesis:

 Sunlight: Sun light absorbed by chlorophyll
 Chlorophyll: present in chloroplast
 Water: Water + dissolved minerals like nitrogen, phosphorous etc., are taken up
by the roots from the soil.
  CO2: Enters through stomata, and oxygen (O2) is released as a byproduct
through stomata on the leaf. The opening and closing of stomatal pores are
controlled by the turgidity of guard cells. When guard cells uptake water from
surrounding cells, they swell to become a turgid body, which enlarges the pore
in between (Stomatal Opening). While, when water is released, they become
flaccid shrinking to close the pore (Stomatal Closing).

Site of Photosynthesis: Chloroplast in the leaf. Chloroplast contains chlorophyll (green

pigment)

Significance of Photosynthesis:
 Photosynthesis is the main way through which solar energy is made available
for different living beings.
 Green plants are the main producers of food in the ecosystem. All other
organisms directly or indirectly depend on green plants for food.
 The process of photosynthesis also helps in maintaining the balance of carbon
dioxide and oxygen in the air.

Steps of Holozoic Nutrition:

 Ingestion: The process of taking in the food is called ingestion.
 Digestion: The process of breaking complex food substances into simple
molecules is called digestion. Simple molecules, thus obtained, can be absorbed
by the body.
 Absorption: The process of absorption of digested food is called absorption.
 Assimilation: The process of utilization of digested food, for energy and for
growth and repair is called assimilation.
 Egestion: The process of removing undigested food from the body is called
egestion.
Nutrition in Amoeba
Amoeba is a unicellular animal which follows the holozoic mode of nutrition. The cell
membrane of amoeba keeps on protruding into pseudopodia. Amoeba surrounds a food
particle with pseudopodia and makes a food vacuole. The food vacuole contains food particle
and water. Digestive enzymes are secreted in the food vacuole and digestion takes place.
After that, digested food is absorbed from the food vacuole. Finally, the food vacuole moves
near the cell membrane and undigested food is expelled out.

.
Nutrition in Human Beings
Structure of the Human Digestive System:
The human digestive system comprises of the alimentary canal and associated digestive
glands.
Alimentary Canal: It comprises of mouth, oesophagus, stomach, small intestine and large
intestine.
Associated Glands: Main associated glands are- Salivary gland, Gastric Glands, Liver,
Pancreas
Mouth or Buccal Cavity:
 The mouth has teeth and tongue. Salivary glands are also present in the mouth.
 The tongue helps in turning over the food so that saliva can be properly mixed
in it.
 Teeth help in breaking down the food into smaller particles so that, swallowing
of food becomes easier.
 There are four types of teeth in human beings. Incisor- cutting ,canine- tearing
premolars- coarse grinding, molars -fine grinding of food.
Oesophagus: Taking food from mouth to stomach by Peristaltic movement which involves
rhythmic contraction of muscles of the lining of the alimentary canal to push the food
forward.

Stomach
Stomach is a bag-like organ. Highly muscular walls of the stomach help in churning the food.

Small Intestine: It is a highly coiled tube-like structure. The small intestine is longer than the
large intestine but its lumen is smaller than that of the large intestine. The small intestine is
divided into three parts, like duodenum, jejunum and ileum.

Liver: Liver is the largest organ in the human body. The liver manufactures bile, which gets
stored in the gall bladder. From the gall bladder, bile is released as and when required.

Pancreas: Pancreas is situated below the stomach. It secretes pancreatic juice which contains
many digestive enzymes.

The inner wall in the ileum is projected into numerous finger-like structures, called villi. Villi
increase the surface area inside the ileum so that optimum absorption can take place.
Moreover, villi also reduce the lumen of the ileum so that food can stay for a longer duration
in it, for optimum absorption. Digested food is absorbed by villi.

Large Intestine:
Large intestine is smaller than the small intestine.
Undigested food goes into the large intestine.
Some water and salt are absorbed by the walls of the large intestine. After that, the undigested
food goes to the rectum, from where it is expelled out through the anus.

Respiration: Respiration is a process where food is oxidized to produce energy.

Mitochondria is the site of respiration and the energy released is stored in the form of ATP
(adenosine triphosphate).

Respiration involves
Gaseous exchange: Intake of oxygen from the atmosphere and release of CO2 → Breathing.
Breakdown of simple food in order to release energy inside the cell → Cellular respiration
Types of Respiration –
Pain in leg muscles while running:
 During running, the energy demand from the muscle cells increases. This is
compensated by anaerobic respiration and lactic acid is formed in the process.
 The deposition of lactic acid causes pain in the leg muscles. The pain subsides
after taking rest for some time.

The characteristics of an ideal respiratory surface:

1. It should be thin (1mm or less) to allow diffusion effectively.

2. The respiratory surface must have a large surface area for maximum oxygen uptake in
minimum time.
3. It must be richly supplied with blood vessels for maximum oxygen uptake.

Exchange of gases:
 Diffusion is the method which is utilized by unicellular and some simple
organisms for this purpose.
 In plants also, diffusion is utilized for exchange of gases. Plants use stomata
(found in leaves) and lenticels (found in stems) and root hair actively involved
in the gaseous exchange. Respiration in plants happens throughout the day and
night thereby carbon dioxide is produced. However, during the daytime, the rate of
photosynthesis is more hence amount of carbon dioxide released is negligible
compared to the amount of oxygen produced.
 Gills are the respiratory organs for fishes. Fishes take in oxygen which is
dissolved in water through gills. Since, availability of oxygen is less in the
aquatic environment, so the breathing rate of aquatic organisms is faster.
  Insects have a system of spiracles and trachea which is used for taking in
oxygen.
Human respiratory system
Following are the main structures in the human respiratory system:
1. Nostrils: There are two nostrils which converge to form a nasal passage. The
mucus and the hair present here help in filtering the dust particles out from
inhaled air. Further, air is warmed up when it enters the nasal passage.
2. Pharynx: It is a tube-like structure which continues after the nasal passage.
3. Larynx: This part comes after the pharynx. This is also called voice box.
4. Trachea: This is composed of rings of cartilage. Cartilaginous rings prevent the
collapse of trachea in the absence of air.
5. Bronchi: A pair of bronchi comes out from the trachea, with one bronchus
going to each lung.
6. Bronchioles: A bronchus divides into branches and sub-branches inside the
lung.
7. Alveoli: These are air sacs at the end of bronchioles. The alveolus is composed
of a very thin membrane and is the place where blood capillaries open. This is
alveolus, where the oxygen mixes with the blood and carbon dioxide exits from
the blood. The exchange of gases, in alveoli, takes place due to the pressure
differential.

Passage of air through the respiratory system in human beings:

Breathing Mechanism

Transport of oxygen and carbon dioxide-

1.Haemoglobin in red blood cells have high affinity to bind with oxygen to form
oxyhaemoglobin in this form it is transported from lungs to body parts.
2. Carbon dioxide is highly soluble in water, so it is transported in dissolved
form through plasma.
Transportation
Transportation in Human Beings: The circulatory system is responsible for transport of
various substances in human beings. It is composed of the heart, arteries, veins and blood
capillaries. Blood plays the role of the carrier of substances.

Blood: Blood is a connective tissue which plays the role of the carrier for various substances
in the body. Blood is composed of 1. Plasma 2. Blood cells 3. Platelets.
 Blood plasma: Blood plasma is a pale coloured liquid which is mostly
composed of water. Blood plasma forms the matrix of blood.
 Bloods cells: There are two types of blood cells, viz. Red Blood Cells (RBCs)
and White Blood Cells (WBCs).
(a) Red Blood Corpuscles (RBCs): These are of red colour because of the
presence of haemoglobin which is a pigment. Haemoglobin readily combines
with oxygen and helps in its transport.
(b) White Blood Corpuscles (WBCs): These are of pale white colour. They play
important role in the immunity.
(c)Platelets: Platelets are responsible for blood coagulation which prevents
excess loss of blood, in case of an injury.

1. Arteries:
 These are thick-walled blood vessels which carry oxygenated blood from the
heart to different organs.
 Pulmonary arteries are exceptions because they carry deoxygenated blood from
the heart to lungs, where oxygenation of blood takes place.
2. Veins:
 These are thin-walled blood vessels which carry deoxygenated blood from
different organs to the heart, pulmonary veins are exceptions because they carry
oxygenated blood from lungs to the heart.
 Valves are present in veins to prevent back flow of blood.

3. Capillaries: These are the blood vessels which have single-celled walls.

1. Heart: Heart is a muscular organ, which is composed of cardiac muscles.

 It is so small that, it can fit inside an adult’s wrist. The heart is a pumping organ
which pumps the blood.
  The heart is made up of four chambers: The upper two chambers are called auricles. The lower
two chambers are called ventricles.
 Septum separates right and left side of heart and prevents mixing of oxygenated and deoxygenated
blood.
 The heart wall is made up of three layers:
 The outer layer of the heart wall is called epicardium.
 The middle layer of the heart wall is called myocardium.
 The inner layer of the heart wall is called endocardium.
 The heart consists of four valves:
 The aortic valve that prevents the backflow of blood when it is pumped from left
ventricle to aorta.
 The bicuspid valve (mitral valve) that prevents the backflow of blood when pumped
from left atrium to left ventricle.
 The pulmonary valve that prevents backflow of blood when it flows from the right
ventricle to the pulmonary artery.
 The tricuspid valve that prevents backflow of blood when it is pumped from the right
atrium to right ventricle.

Double circulation: In the human heart, blood passes through the heart twice in one cardiac
cycle. This type of circulation is called double circulation. One complete heartbeat in which
all the chambers of the heart contract and relax once is called cardiac cycle..

Double Circulation
 Pulmonary circulation is a portion of circulation responsible for carrying deoxygenated blood
away from right ventricle to the lungs and then bringing oxygenated blood back to left atrium of
heart.
 Systemic circulation is another portion of circulation where the oxygenated blood is pumped
from left ventricle of heart to every organ , and deoxygenated blood comes back again to the
right atrium of heart.

Advantages of double circulation

Double circulation supports a strict separation of both oxygenated and deoxygenated blood.

This circulation ensures that the body has a dedicated supply of oxygen it improves body
efficiency for animals having higher energy needs such as birds and mammals.
 These animals use this energy to maintain their body temperatures.

Heart beat- One contraction and relaxation of heart is called heartbeat.

Heart rate- Number of times the heart beats in a minute(72 times/min)

Pulse rate- Throbbing sensation felt in the arteries each time blood is forced into it is called pulse
rate.

Blood pressure-

The pressure at which blood is pumped throughout the body by heart is called blood pressure.

The phase of heartbeat when heart contracts and pumps blood into arteries is called systolic
pressure (120mm of Hg)

The phase of heartbeat when heart relaxes ands allows the chambers to be filled is called diastole
and the pressure is called diastolic pressure(80mm of Hg)

Lymph:
 Lymph is similar to blood but RBCs are absent in lymph.
 Lymph is formed from the fluid which leaks from blood capillaries and goes to
the intercellular space in the tissues. This fluid is collected through lymph
vessels and finally return to the blood capillaries.
 Lymph also plays an important role in the immune system.
 Lymph a yellowish fluids escape from the blood capillaries into the intercellular
spaces contain less proteins than blood.
 Lymph flows from the tissues to the heart assisting in transportation and
destroying germs.

Transportation in plants: Plants have specialized vascular tissues for transportation of

substances. There are two types of vascular tissues in plants.
 Xylem: Xylem is responsible for transportation of water and minerals. It is
composed of trachids, xylem vessels, xylem parenchyma and xylem fibre.
Tracheids and xylem vessels are the conducting elements. The xylem makes a
continuous tube in plants which runs from roots to stem and right up to the
veins of leaves.
 Carry water and minerals from the leaves to the other part of the plant.
 Phloem: Phloem is responsible for transportation of food. Phloem is composed
of sieve tubes, companion cells, phloem parenchyma and bast fibers. Sieve
tubes are the conducting elements in phloem.
 Carries product of photosynthesis from roots to other part of the plant.
Transportation in plants

Ascent of sap: The upward movement of water and minerals from roots to different plant
parts is called ascent of sap. Many factors are at play in ascent of sap and it takes place in
many steps. They are explained as follows :
 Root pressure: The walls of cells of root hairs are very thin. Water from soil
enters the root hairs because of osmosis. Root pressure is responsible for
movement of water up to the base of the stem.
 Capillary action: A very fine tube is called capillaiy, water, or any liquid, rises
in the capillary because of physical forces and this phenomenon is called
capillary action. Water, in stem, rises up to some height because of capillaiy
action.
 Adhesion-cohesion of water molecules: Water molecules make a continuous
column in the xylem because of forces of adhesion and cohesion among the
molecules.
 Transpiration pull: Loss of water vapour through stomata and lenticels, in
plants, is called transpiration. Transpiration through stomata creates vacuum
which creates a suction, called transpiration pull. The transpiration pull sucks
the water column from the xylem tubes and thus, water is able to rise to great
heights in even the tallest plants.
 Transport of food: Transport of food in plants happens because of utilization
of energy. Thus, unlike the transport through xylem, it is a form of active
transport. Moreover, the flow of substances through phloem takes place in both
directions, i.e., it is a two-way traffic in phloem.
Transpiration is the process of loss of water as vapour from aerial parts of the
plant.
Functions
 Absorption and upward movement of water and minerals by creating pull.
 Helps in temperature regulation in plant.
Transport of food from leaves (food factory) to different parts of the plant is called
Translocation.
Excretion – Life Processes Class 10 Notes
Human excretory system, excretion in plants.
Excretion in human beings:
 Removal of harmful waste from the body is called excretion.
 Many wastes are produced during various metabolic activities.
 These need to be removed in time because their accumulation in the body can
be harmful and even lethal for an organism.
Human Excretory System:
 The human excretory system is composed of a pair of kidneys.
 A tube, called ureter, comes out of each kidney and goes to the urinary bladder.
 Urine is collected in the urinary bladder, from where it is expelled out through
urethra as and when required.
Excretory system of human beings includes :
 A pair of kidneys.
 A urinary bladder.
 A pair of the ureter.
 A urethra.
Kidney:
 Kidney is a bean-shaped organ which lies near the vertebral column in the
abdominal cavity.
 The kidney is composed of many filtering units, called nephrons.
 Nephron is called the functional unit of kidney.
Nephron
 It is composed of a tangled mess of tubes and a filtering part, called glomerulus.
 The glomerulus is a network of blood capillaries to which renal artery is
attached.
 The artery which takes blood to the glomerulus is called afferent arteriole and
the one receiving blood from the glomerulus is called efferent arteriole.
 The glomerulus is enclosed in a capsule like portion, called bowman’s capsule.
The bowman’s capsule extends into a fine tube which is highly coiled.
 Tubes from various nephrons converge into collecting duct, which finally goes
to the ureter.

Urine formation in the kidney: The urine formation involves three steps:
 Glomerular filtration: Nitrogenous wastes, glucose, water, amino acid filter
from the blood into bowman’s capsule of the nephron.
 Tubular reabsorption: Now, useful substances from the filtrate are reabsorbed
back by capillaries surrounding the nephron.
  Secretion: Extra water, salts are secreted into the tubule which opens up into the
collecting duct and then into the ureter.
Urine produced in the kidneys passes through the ureters into the urinary bladder where it is
stored until it is released through the urethra.
The purpose of making urine is to filter out waste product from the blood i.e., urea which is
produced in the liver.
Haemodialysis: The process of purifying blood by an artificial kidney. It is meant for kidney
failure patient.
Excretion in Plants

 Other wastes may be stored in leaves, bark etc. which fall off from the plant.
 Plants excrete some waste into the soil around them.
 Gums, resin → In old xylem
 Some metabolic wastes in the form of crystals of calcium oxalates in the leaves
of colocasia and stem of Zamikand.