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Life Process-Class 10


Life process



The basic functions performed by any living organisms to maintain their life on this earth are called life processes.

    Various life process are:

  1. Nutrition
  2. Respiration
  3. Transportation
  4. Excretion
  5. Reproduction

Every living organism needs energy to perform various life processes.


A process of taking food (nutrients like carbohydrates, fats, proteins, minerals, vitamins and water) & breakdown of complex food nutrients into simpler forms and their utilisation to get energy for various life processes taking place in the body is called nutrition.

    Sub process of Nutrition

  1. Taking food
  2. Breakdown of complex food nutrients into simpler forms
  3. Utilization of these nutrients

    Five steps during the process of Nutrition in Animals

    They are: Ingestion, Digestion, Absorption, Assimilation and Egestion.

  1. Ingestion: It is the process of taking food in to the body by the animal. In the process, we put food in to our mouth with hands.

  2. Digestion: Digestion is a process in which the food material containing large, insoluble molecules is broken down in to small one, water soluble molecules which can be absorbed by the body.

  3. Absorption: Absorption is a process in which the digested food is passed through the intestinal wall in to blood stream. After completion of the digestion , food molecules become small and soluble in water. The small and soluble molecules of the food passes through the walls of intestine and goes into the blood.

  4. Assimilation: Assimilation is a process in which the absorbed food is taken in by the body cells and used for energy, growth and repair.

  5. Egestion: Egestion is a process in which the undigested food is removed from the body. The whole food that we eat is not digested by our body, a part of the food remains undigested which cannot be used by the body and so it is removed from the body in the form of faeces during toilet.

How do living things get their food?

Autotrophic Nutrition

Some organisms synthesise their food from simple inorganic compounds like carbon dioxide and water present in the surroundings (with the help of sunlight energy).

These organism are called autotrophs such as green plants, some bacteria and some protists.

Autotrophs make their food by photosynthesis process.

Photosynthesis is a chemical process, by which green plants make their own food from carbon dioxide and water by using sunlight energy in the presence of chlorophyll.

  • Photosynthesis process happens in the green leaves of a plant.
  • The food is prepared by green leaves of a plant in the form of a simple sugar called glucose.
  • The extra glucose is changed into another form of food called starch & starch is stored in the leaves of the plant. Further starch serves as the internal energy reserve to be used as and when required by the plant.
  • The green plants convert sunlight energy into chemical energy by making carbohydrates.
  • Carbohydrates are utilised for providing energy to the plant.

Process of photosynthesis

  • For photosynthesis process, plants take in carbon dioxide (CO2) from the air and water (H2O) from soil & transforms the water into oxygen and the carbon dioxide into glucose.
  • Oxygen is released back into the air, and plant stores energy within the glucose molecules.

    The following events occur during this process

  1. Absorption of light energy by chlorophyll.
  2. Conversion of light energy to chemical energy.
  3. Splitting of water molecules into hydrogen and oxygen.
  4. Reduction of carbon dioxide to carbohydrates.

The green pigment ‘chlorophyll’ is one essential requirements for photosynthesis, which is present in the chloroplasts of green plants and some bacteria.

This pigment is essential for ‘capturing’ sunlight which then drives the overall process of photosynthesis.

Stomata: which are tiny pores present on the surface of the leaves. Massive amounts of gaseous exchange takes place in the leaves through these pores for the purpose of photosynthesis.

    Conditions necessary for photosynthesis:

  1. Sunlight
  2. Chlorophyll
  3. Carbon dioxide
  4. Water

Green leaves make starch as food. Starch gives a blue black color with iodine solution.

    Raw materials for photosynthesis:

  1. Carbon dioxide
  2. Water

Heterotrophic Nutrition

The mode of nutrition in which organisms depend upon other organisms for food to survive is known as Heterotrophic mode of nutrition. Cows, dogs, humans, amoeba, cats, fishes etc. are all heterotrophs. All of them depend upon plants and other animals for their food.

On the basis of food intake, heterotrophs can be categories into 3 types-

1. Carnivores- organisms which eat only animals. Example- lion, snake.

2. Herbivores- organisms which eat only plants. Example- rabbit, elephant.

3. Omnivores- organisms which eat both plants and animals. Example- crow, dog.

Some organisms breakdown their food material outside the body and then absorb/intake it. Examples are fungi like bread moulds, yeast and mushrooms.

Some organisms take in whole food material and breakdown inside their bodies. Example- human, cat.

Some organisms derive their food from the body of other organisms without killing them. They are called parasite. Example- ticks, leeches

How do Organisms obtain their Nutrition?

Amoeba takes in food using temporary finger-like projections of the cell surface called pseudopodia and fuse over the food particle forming a food-vacuole.

Inside the food vacuole complex substances are broken down into simpler ones and then diffuse into the cytoplasm.

The remaining undigested food material is moved to the surface of the cell and thrown out.

Paramecium is a unicellular organism, it has a definite shape and food is taken in at a specific spot then food is moved to this spot by the movement of cilia which cover the entire surface of the cell.

Nutrition in Human Beings

Nutrition in multicellular organisms such as human beings takes place through a specialised system called digestive system.

The alimentary canal or the digestive tract or gastrointestinal tract is a long tube (9 metres long tube) extending from the mouth to the anus.

In mouth, teeth bite, tear, chew and grind the food. Food is mixed thoroughly with saliva secreted by salivary glands present in mouth and is swallowed with the help of muscular tongue


The food material taken in during the process of nutrition is used in cells to generate energy for various life processes.

Respiration is the process of breaking down of organic compounds (particularly glucose) to obtain energy.

Aerobic respiration, During this process breakdown of glucose occurs in the presence of oxygen.

Anaerobic respiration,During this process breakdown of glucose occurs in the absence of oxygen.

Breaking down of glucose can occur by different pathways;

In presence of oxygen: -

Breaking down of glucose into pyruvate (in cytoplasm) takes place in Mitochondria of a cell and End products are CO₂ , H₂O and energy.

Glycolysis is the breakdown of glucose in first step. Which common to both types of respiration. It occurs in cytoplasm. In glycolysis process, one molecule of glucose (6-carbon molecule) is broken down into two molecules of pyruvic acid or pyruvate (3-carbon molecule) with four molecules of ATP.

In insufficient presence of oxygen: -

In muscle cells, the cells undergoes anaerobic respiration due to insufficient presence of oxygen & forming Lactic acid and lot amount of energy.

In absence of Oxygen: -

In absence of Oxygen, glucose breakdown into pyruvate in cytoplasm only & final product are Ethanol, and small amount of energy

The energy obtained during cellular respiration is immediately used to synthesise a molecule called ATP which is used to fuel all other activities in the cell.

The respiratory system

The respiratory system, also known as pulmonary system, consists of several organs that function as a whole to oxygenate the body through the process of respiration (breathing).

Functions of The respiratory system :

  • Breathing – movement of air.
  • Sound Production.
  • Gas Exchange – oxygen and carbon dioxide.
  • Olfactory Assistance – sense of smell.
  • Protection – from dust and microbes entering body through cilia, mucus production, and coughing.

Human respiratory system parts:

  • Nose
  • Mouth
  • Throat (pharynx)
  • Voice box (larynx)
  • Windpipe (trachea)
  • Large airways (bronchi)
  • Small airways (bronchioles)
  • Lungs.


The nasal cavity and the mouth meet at the throat or pharynx . Which is at the back of the mouth & nose. It is the common part of the digestive system as well as the respiratory system because it carries both food and air.

At the bottom of the pharynx, this pathway divides in two pathways, one for food called the oesophagus which leads to the stomach and the other for air.

Voice box (larynx)

The larynx, is the top part of the air-only pipe.It is also called voice box. It is short tube contains a pair of vocal cords, which vibrate to make sounds.

The epiglottis a small flap like tissue, covers the air-only passage when we swallow,preventing food and liquid from going into the lungs.

The trachea, also called windpipe, is the continuation of the airway below the larynx. Rings of cartilage are present in the throat. These ensure that the air-passage does not collapse. The trachea is also lined with cilia, which sweep fluids and foreign particles out of the airway so that they stay out of the lungs.

At the bottom end, the trachea divides into left and right air tubes known as bronchi, which connect to the lungs. Inside the lungs, Within the lungs, the passage divides into smaller and smaller tubes which finally terminate in balloon-like structures which are called alveoli.

where the exchange of oxygen and carbon dioxide actually takes place. Each person has hundreds of millions of alveoli in their lungs.

The lungs is made up of elastic tissues that allow them to inflate and deflate without losing shape.

The chest cavity, or thorax is the airtight box that houses the bronchial tree, lungs, heart, and other structures. The top and sides of the thorax are formed by the ribs and attached muscles, and the bottom is formed by a large muscle called the diaphragm. The chest walls form a protective cage around the lungs and other contents of the chest cavity.

Transportation in Human Beings

The transport system or circulatory system in human beings consist of network of arteries, veins, and capillaries, the heart, blood, and blood vessels.

Its primary role is to carry oxygen and nutrients to all cells of the body and to collect waste from the cells.

The human circulatory system circulates blood inside human body through two loops One for oxygenated blood from heart to different organs , another for deoxygenated blood from different organs to back into heart.

Arteries carry oxygen-rich blood from the heart to all of the body's tissues.

Veins carry low oxygen content blood and also rich in waste products that are to be excreted or removed from the body to heart.

Capillaries are small, thin blood vessels which connect the arteries and the veins. They have thin walls allow oxygen, nutrients, carbon dioxide, and other waste products to pass to and from our organ's cells.

Our pump — the heart

The heart serves as a pump to circulate the blood.It is a muscular organ located in the chest cavity, slightest to the left between the lungs.

It pumps oxygen and nutrient-rich blood throughout body to sustain life.

The heart is divided into four chambers – two upper chambers known as the right and left atria and two lower chambers known as the right and left ventricles.

Humans heart is consist of four chambers, namely:

  1. Left atrium
  2. Right atrium
  3. Left ventricle
  4. Right ventricle

The right atrium receives blood from the veins and pumps these blood to the right ventricle.

The right ventricle receives blood from the right atrium and pumps these blood to the lungs, where it is made oxygen rich.

The left atrium receives oxygenated blood from the lungs and pumps these blood to the left ventricle.

The left ventricle which is the strongest chamber pumps oxygen-rich blood to the rest of the body.

The left ventricle’s contractions create our blood pressure.

The atria and ventricles are connected by valves that ensure that blood flows only in one direction inside the heart.

Oxygen enters the blood in the lungs

The oxygen enters the bloodstream from the alveoli that is tiny sacs in the lungs where gas exchange takes place .

The transfer of oxygen into the blood is through diffusion.

The oxygen-rich blood returns to the heart.

Oxygen-rich blood is further pumped through the aorta, which is the large artery that receives blood directly from the heart.

From the aorta, oxygen-rich blood moves to the smaller arteries and, ultimately, to the capillaries, the smallest type of blood vessel.

The oxygen molecules move out from capillaries into the body cells by diffusion.

When oxygen moves out from the capillaries and into body cells, carbon dioxide moves out from the cells into the capillaries.

Carbon dioxide is brought back to the heart through the blood & then to the lungs. finally carbon diaoxide is released into the air during exhalation.

Blood pressure

Blood pressure is the pressure of circulating blood inside body against the walls of blood vessels.

Blood pressure creates force that moves blood through the circulatory system.

An individual should maintain a normal blood pressure 120 / 80 mm Hg.

Blood pressure denoted by two numbers, 120 – This is called systolic pressure and 80 – This is called diastolic pressure.

The tubes – blood vessels


Lymph is a colorless fluid that is collected from tissues in most parts of the body and returned to the blood via the lymphatic system.

It contains about 95% water.

It has similar composition as plasma of blood, but contains less protein.

It is the part of immune system.


1. Protecting human body from illness-causing invaders.

2. Maintain body fluid levels.

3. Absorb digestive tract fats. Removing cellular waste.

Transportation in Plants

Transportation is the process which involves the movement of water and necessary nutrients to all parts of the plant for its survival.

There are two kind transport systems found in plant - xylem and phloem.

Transport of water


The xylem transports mainly water and minerals from the roots up the plant stem and into the leaves.

Most of the cells that make up the xylem in a mature flowering plant or tree are specialised cells called vessels.

Transportion in the xylem is a physical process. It does not require energy.

The water is absorbed by the root hair and that undergoes cell to cell movement by osmosis until it reaches the xylem.

This water is then transported through the xylem vessels to the leaves and is evaporated by the process of transpiration.

Transport of food and other substances


Phloem is a special tissue that moves sugar shich the plant has produced by the process of photosynthesis to other parts of where it is needed for processes such as:

• growth parts of the plant for immediate use.

• storage organs such as bulbs and tubers

• developing seeds

• respiration

Transport in the phloem is therefore both upwards and downward the stem.

The process of transportion of substances in the phloem is called translocation.

Phloem consists of living cells.

Transport of food and other substances


Excretion is this process of removal of waste toxic materials from the blood that are produced within a body during cellular respiration.

Excretion in Human Beings

The major wastes produced by human Beings are: Carbon dioxide and Urea.

1.Carbon dioxide is produced by the process of respiration

2. urea is produced by the decomposition of unused proteins in the liver.

The human body made up of a specialized system which purifies the blood. This system is termed as excretory system.

An excretory system is basically consists of the following components:

1. A pair of kidneys

2. A pair of ureters

3. Urinary bladder

4. Urethra

There are various other organs that help in excretion of such wastes from our body are Large Intestine,liver, lungs, skin, eyes, etc.


A pair of kidney is often considered the main organs of excretion.

The main function of the kidneys is the elimination of excess water and wastes from the bloodstream by the production of the liquid waste called urine.

The important structural and functional units of the kidneys are tiny structures called nephrons that filter materials out of the blood, return to the blood what is needed, and excrete the rest as urine.

The liver

The liver is also a important organ of excretion that breaks down many substances in the blood, including toxins.

For example, the liver transforms ammonia which is a poisonous by-product of protein catabolism into urea.


Ureter is muscular tube that carries urine from the kidneys to the urinary bladder from time to time.

Urinary Bladder

Urinary bladder is an organ that controls the passage of urine. Which is a muscular sac-like structure that stores urine.

The capacity of a human bladder is 400-600 ml. It holds urine until its capacity and expels it when it is full by the process of micturition. The bladder is lined by muscular tissue,that squeezes during micturition allowing the urine to flow out.

Artificial kidney (Hemodialysis)

Hemodialysis simply called dialysis is a process of purifying the blood of a person whose kidneys are not working normally by using artificial Kidney .
Which is a mechanical device operates outside the body as substitutes for the kidney. This process is used for removal urea and other nitrogenous waste products from the blood.


Excretion in Plants

Plants excrete excess carbon dioxide and oxygen. Carbon dioxide, which is a waste product of aerobic respiration in plant cells. Oxygen is also a waste product of photosynthesis.

Plants do not have any specialised excretory organs like animals. Extra carbon dioxide and oxygen are excreted from the plant through the stomata in the leaves.

Organ donation

Organ donation is a procedure in which healthy tissues or organs are removed from human beings. Then removed organs are transplanted to another needy person, legally by consent of the donor if they is alive or dead with the permission of the donor’s family.

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Related topics of CBSE CLASS 10

  • Control and codination
  • Heredity and Evolution
  • How do Organisms Reproduce?
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