Biology is the study of living things and all living things are called Organisms. Different organisms perform different types of biological processes. The processes that together keep the organism live and perform the main role to maintain the body are known as Life processes. In unicellular organisms, all these processes carried out by that single cell, but in multicellular organisms, well-developed systems are present to carry out the processes. All living things perform different life processes that include growth, movement, sensitivity, respiration, excretion, reproduction, and nutrition.

1. Nutrition

The process, by which an organism takes food and utilizes for nourishment is called nutrition.

(a) Requirements for Nutrition: The organism requires lots of energy to perform various biological functions. The energy is provided by the nutrients and organisms (both plants and animals) require raw materials (as food) for growth and repairs. These raw materials are supplied by nutrients.

(b) Nutrients: materials or substances which provide nutrition to organisms are known as Nutrients. Carbohydrates, proteins and fats are the major source of nutrients and also called macronutrients. Similarly, minerals and vitamins are required in small amounts and so called micronutrients.

There are two main modes of nutrition, autotrophic and heterotrophic.

  1. Nutrition in plants: They are autotrophic in nature, can prepare their own food and animals eat them as their foods.
  2. Nutrition in animals: They are heterotrophic in nature and depend on plants or other for food.
  • Some autotrophic organisms including green plants and some bacteria use simple food material obtained from in organic sources obtained from inorganic sources in the form of carbon dioxide and water.
  • Other organisms utilize complex substances, which are break down in to simpler one by the help of bio-catalyst called enzymes.
  • Thus the heterotrophs survival depends directly or indirectly on autotrophs, that includes animal and fungi.

1.1 Autotrophic nutrition:

  • If an organism can nourish itself by making its own food using sunlight or chemicals such mode of nutrition is called autotrophic nutrition.
  • Some autotrophic organisms including green plants and some bacteria use simple food material obtained from in organic sources obtained from inorganic sources in the form of carbon dioxide and water.
  • Plants photosynthesis (use sunlight) and are called photoautotrophs.
  • Some bacteria use chemicals to derive energy are called chemoautoitrophs

This type of autotrophic nutrition is fulfilled by the process, by which autotrophs in take CO2  and H2O and converts these into carbohydrate in the presence of chlorophyll, sunlight is called photosynthesis.


Carbohydrates are the main source of energy in plants, which are not used immediately and extra carbohydrates are stored in theform of starch. Starch is serving as the internal energy reserve and to be used during the plant requirement.

  • Notes:

Some similar condition like starch, energy derived from the food is stored in the form of glycogen in our body.

1.2 Photosynthesis in plant:

  • The process by which green plants prepare their own food is called photosynthesis.
  • During photosynthesis, the solar energy is converted in to chemical energy and carbohydrates are formed.
  • Green leaves are main site of photosynthesis, because it contains a pigment known as chloroplast, chlorophyll (green pigment).
  •  The whole process of photosynthesis can be representing in a single equation:

(a) Raw materials for photosynthesis:

  • Sunlight: it is the major source of energy.
  • Chlorophyll: sunlight absorbed by chloroplast.
  • CO2: Carbon dioxide is enters through stomata and oxygen (O2) is release as a by product through stomata present in leaf.
  • Water: water along with dissolved minerals like nitrogen, phosphorus etc., are taken by the root. Waters come from the soil through the xylem tissue in root and stem.

(b) Steps of photo synthesis:

  1. Absorption of light by chlorophyll.
  2. Conversion of light energy in to chemical energy and breaking of water in to hydrogen and oxygen.
  3. Reduction of CO2 in to carbohydrate (C6H12O6).
  4. Sunlight activates chlorophyll pigments, which leads to break the water molecules.
  5. The hydrogen, release by the breaking of water is utilized for the reduction of CO2 to carbohydrate (C6H12O6).
  6. Oxygen and water is the by-product of photosynthesis.
  7. Carbohydrates are subsequently converted in to starch and stored in leaves and other storage parts.
  8. This breaking of water is a part of light reaction.

(c) Stomata:

  • These are the tiny pore present on the surface of the leaves.
  • Large amount of gaseous exchange and water loss takes place through thin tiny pore during photosynthesis.
  • The opening and closing of stomata is regulated by the turgidity of guard cells.
Fig 1.1: opening and closing of stomata
  • Opening of stomata: Guard cells uptake water from surrounding cells and swell to become a turgid body, which become enlarge and open the pore.
  • Closing of stomata: water is release from the guard cells and it become flaccid and shrinking to close the pore.

(d) Importance of photo synthesis:

  • Photosynthesis is the major process through which solar energy is made available for all living organism.
  • Plants are the main producer of food in the ecosystem and all other organisms directly or indirectly depends on preen plants for food.
  • 0Photosynthesis is also help in maintaining the concentration of CO2 and O2 in the atmosphere or air.

1.3 Heterotrophic nutrition:

  • If an organism takes food from another organism is called heterotrophic nutrition.
  • Organisms other than green plants and blue green algae and green plants follow the heterotrophic mode of nutrition.

Heterotrophic nutrition is divided into following types;

  1. Saprophytic Nutrition: This type of nutrition, organisms secretes the digestive juices on the food. The food is digested outside the body or organism, while it is still to be ingested by the organism.  The digested food is then ingested by the organism. Examples: Decomposers, some insects like houseflies etc.
  • Holozoic Nutrition: In this type of nutrition, the digestion is takes place inside the body of the organism, i.e. after food is ingested. Most of the organisms follow this mode of nutrition.
  • Parasitic Nutrition: In this mode of nutrition, organism live inside or outside of the another organism (called host) and derives food from it is known as parasite and this type of nutrition is known as parasitic nutrition. Example: Cuscuta, tick etc.

1.4 Nutrition process in Amoeba:

Amoeba is a unicellular organism that follow holozoic mode of nutrition. It get the nutrients followed by five steps of the holozoic nutrition i.e. ingestion, digestion, absorption, assimilation, and egestion.

Fig 1.2: Nutrition in amoeba
  1. Ingestion: The process of taking food inside the body is called ingestion.
  2. Digestion: The process of break down complex food molecules in to simple molecules is called digestion. Simple molecules then easily absorbed by the body.
  3. Absorption: the process of absorption of digested food is called absorption.
  4. Assimilation: the process by which digested food id used for energy, growth and repair is called assimilation.
  5. Egestion: the process of removing undigested food from the body is called egestion.

E.g. Amoeba takes in food using temporary finger-like projecting pseudopodia co the cell surface which fuses over the food particle forming a food-vacuole. Inside the food vacuole, complex substances are broken down in to simpler one which then diffuses in to the cytoplasm.  The remaining undigested food materials is moved to the cell surface and thrown out.

1.5 Nutrition in Human beings:

  • Human beings are complex animals, which have complex digestive system.
  • The human digestive system composed of an alimentary canal and some accessory glands.
  • Alimentary canal: it includes mouth, oesophagus, stomach, small intestine and large intestine.
  • Associated /Accessory glands: main associated glands are salivary gland, gastric gland, liver and pancreas.

(a) Mouth and Buccal cavity:

Fig 1.3: processing of food inside the mouth
  • The mouth has teeth and tongue. Salivary glands are present in the mouth.
  • Teeth help in breaking down of the food in to smaller particle so that swallowing of food become easier.
  • The tongue has gustatory receptors which perceives the sense of taste and helps in turning over the food so that saliva can be perfectly mixed inn to the food.
  • There are four types of teeth in human beings, i.e. incisors teeth: cutting the food, canine teeth: tearing the food and cracking hard substances, premolar teeth: coarse grinding of food, molar teeth: fine grinding of food.
  • Saliva makes the food slippery which makes is easy to swallow the food.
  • Saliva also contains some enzyme known salivary amylase or ptyalin, which digests starch and convert in to sucrose or maltose.

(b) Oesophagus:

  • Human beings are complex animals, which have complex digestive system.
  • The human digestive system composed of an alimentary canal and some accessory glands.
  • Alimentary canal: it includes mouth, oesophagus, stomach, small intestine and large intestine.
  • Associated /Accessory glands: main associated glands are salivary gland, gastric gland, liver and pancreas.
  • Make a passage for food from mouth to stomach by peristaltic movement. Rhythmic contraction of the muscles of the lining of the alimentary canal to push the food forward is known as peristaltic movements.

(c) Stomach:

  • Stomach is a bag-like organ. Muscular wall of stomach help in churning of the food.
  • The wall of stomach secretes hydrochloric acids, which may kills the germs present in food and makes acidic medium inside the stomach. The acidic medium is necessary for gastric enzymes to work.
  • The enzyme pepsin, secretes in the stomach, does partial digestion of protein.
  • The mucus, secreted by the wall on the stomach maintains the inner lining of stomach form getting damaged from hydrochloric acid (HCL).
Fig 1.4: Processing of food in stomach

(d) Small Intestine:

  • It is a highly coiled tube and longer than large intestine, but its lumen is smaller than that of large intestine.
  • The small intestine is divided in to three parts, like duodenum, jejunum, ileum.
Fig 1.5: Processing of food in small intestine

(e) Pancreas:

  • It is situated lower part of the stomach. It secretes pancreatic joice which contain many digestive enzymes.
  • Biles and pancreatic juices go to the duodenum through a duct known as hepatopancreatic duct.
  • The process by which biles break down fats in to smaller particles is known as emulsification. After that the enzyme lipase digests fats in to fatty acids and glycerol.
  • Trypsin and chymotrypsin are enzymes which digests protein in to amino acids.
  • The complex carbohydrates digested in to glucose and major part of digestion takes place in the duodenum.

No digestion takes place in the jejunum. The inner lining of the ileum is projected in to various finger-like projecting cells, called villi. Villi increase the surface area and reduce the lumen so the optimum absorption of food is takes place in this place. 

Fig 1.4: Human alimentary canal

(f) Large Intestine:

  • The large intestine is smaller than the small intestine. It is dividing in to three parts coecum, colon and rectum.
  • Some water and salts are absorbed by the wall of the large intestine. Then the undigested food moves to the rectum from where it excreted out through the anus.

2. Respiration

  • The process, by which living organism utilises the food to get energy, is called respiration.
  • It is an oxidative process in which carbohydrates is oxidised to produce energy.
  • Mitochondria are the site of respiration and energy is stored in the form of ATP (adenosine triphosphate),it release as per need.

(a) Types of respiration:

  • Aerobic respiration: This type of respiration is takes place in the presence of oxygen. Pyruvic acid is converted in to carbon dioxide and energy is release along with water molecule at the end of the process.
  • Anaerobic respiration: This type of respiration happens in the absence of oxygen. Pyruvic acid is converted in to ethanol (ethyl alcohol) or lactic acid. Ethyl alcohol is commonly form in the anaerobic respiration of microbes e.g. yeast, or bacteria. Lactic acid is formed in some microbes as well as in the muscle cells.

(b) Steps of respiration:

   Break down of glucose in to pyruvate:

  • This breaking down of glucose to pyruvic acid is takes place in cytoplasm.
  • 6-carbon compound glucose is breakdown into 3-carbon compound i.e. pyruvic acid.
Fig 2.1: Breakdown of glucose by various pathways

Fate of pyruvic acid:

  • The breakdown of pyruvic acid is takes place inside the mitochondria.
  • Then pyruvic acid is under goes aerobic and anaerobic respiration.


Pain in leg muscles while running:

  • When someone run too fast, he experience throbbing pain in the leg muscle, because of anaerobic respiration taking place in the muscle.
  • While running, the energy demands from the muscle cells increases this compensated by anaerobic respiration and lactic acid is formed in the muscle which cause pain in the leg muscle. The pain subsides after taking rest for some time.

2.1 Exchange of gases:

  • For aerobic respiration, organisms need a continuous supply of oxygen and carbon dioxide is removed from the body. Different organisms use different methods for the intake of oxygen and expulsion of carbon dioxide.
  • Diffusion process is utilised by unicellular and some simple organism. In plants, diffusion is also used for exchange of gases.
  • Plants exchange gases through stomata and intra-cellular space ensure that all cell are contact with air. At night, in the absence of of photosynthesis eliminatrion of CO2 is the major activity. But, during day time CO2 generated during respiration is used for photosynthesis and O2 is released to atmosphere.
  • In complex organism respiratory system does the function of exchange of gases;
  • Gills: it is the respiratory organ of fishes and intake dissolve oxygen form the water through gills. Due to presence of less amount of free oxygen in the aquatic environment the respiration process is faster in case of aquatic organism.
  • In case of insects, they have spiracles and tracheas for the intake of oxygen.
  • Terrestrial organisms have developed lungs for the exchange of gases. Concentration of oxygen is not a problem for them so breathing rate is slower than that of fishes. They use atmospheric oxygen for respiration.
  • Concentration of O2 in atmosphere is higher in comparison to dissolve oxygen (water).

2.2 Human respiratory system:

The human respiratory system is composed of a pair of lungs. The lungs are attached to a system of tunes which open on the outside through the nostril.

Structure of human respiratory system:

  1. Nostrils:  Two nasal passages present in nose are known as nostrils. The nostril is remains wet due to presence of mucous and inner lining of nostril contain hairy structure. These are help in filtering the dust particle present in air. From here, the air passes through the throats and into the lungs.
  • Pharynx: it is a part of the throats. It is look like a tube which is continues after the nasal passage.
  • Larynx: it is also a part of the throats and come after the pharynx. Ti is also called voice box.
  • Trachea: Rings of cartilages form this structure. These rings prevent the collapse of trachea in the absence of air.
  • Bronchi: a pair of bronchi (singular-bronchus) present after trachea and each bronchus connecting each lung. It is also known as windpipe.
  • Bronchioles: each bronchus divides in to sub-bronchus are called bronchioles.
  • Alveoli: these are air sacs present at the end of bronchioles. Alveolus (singular) composed of thin membrane and contains blood capillaries. In the alveolus due to pressure differentiation oxygen mixed with blood vessels and co2 release from blood.

Nostrils Nasal passage Nasal cavity Pharynx Larynx Trachea Bronchi Lungs Bronchioles Alveoli Blood capillaries. (Steps in exchange of gases in human)

Fig 2.1: Respiratory system in Human

(a) Breathing mechanism in human:

  • In breathing process, when any one inhale air the ribs are lift up and the diaphragm become flattened and the chest cavity become large.
  • This is because air is sucked in to the lungs and fills the alveoli with air.
  • The blood brings CO2 containing blood from other side of blood into the alveoli and intake oxygen by releasing CO2 to the alveoli.
  • Then O2 containing blood transported in to the other cell of the body.

The breathing mechanism is done through two processes i.e. inhalation and exhalation.

Mechanism of Breathing
Through inhalation, the chest cavity (thoracic) expands. Through exhalation, chest cavity contracts.
Ribs (thoracic bones) are lift upwards.Ribs are move downwards
Diaphragm become flattenedDiaphragm become dome shaped
Air enters the lungs and volume and size of lungs increase.Air release or exit from lungs and size of lungs decrease.

3. Transportation

3.1 Heart

  • Heart is a pump in human body that pump bloods throughout the body.
  • It is located in the chest just between the lungs behind the sternum and above the diaphragm. Its weight is about 250-300gm. It is surrounded by pericardium. 
  • The human heart is composed of four chambers, i.e. right atrium, right ventricle, left atrium and left ventricle.
  • It works through two processed i.e. systole and diastole. The contraction of cardiac muscle is called systole and relaxation of cardiac muscle is called diastole.
  • Arteries: These are thick walled blood vessels and circulate oxygenated blood from the heart to different organs.  Exception in arteries that carries deoxygenated blood from heart to lungs is known as pulmonary arteries.
  • Veins: these are thin walled and carry deoxygenated blood from different organ to the heart for purification. Exception in veins is pulmonary vein that carries oxygenated blood from lungs to the heart.
  • Capillaries: These are single-celled wall vessels help in exchange of food and gases to extracellular matrix or other site of the body.
  • Valves: two main valves present in between the atrium and ventricles. Valves present in between the right atrium and right ventricle is a tricuspid valve and valves present in between the left atrium and left ventricle is called bicuspid valve.
  • Veins and arteries have semilunar valve.
  • These are prevents the back blow of blood in to the heart.
Fig 3.1: Representing blood circulation in human heart

(a) Circulation in heart:

  • Human have double circulating heart.
  • Oxygen rich blood from the lungs comes to the left atrium, the left atrium relaxes when collecting the blood. Then it contracts to push the blood to the left ventricle. When the left ventricle contracts it pumped out the blood in to the body.
  • Deoxygenate blood comes from the body to the right atrium as it relax, when right atrium contracts pumps the deoxygenated blood to the right ventricle. Which in turns pump the blood in to lungs for oxygenation
  • Ventricles have thicker cell wall then atrium, so it pumps blood into various organ of the body.
  • Oxygen enters in to blood through lungs. Left side of heart always pump deoxygenated blood and right side of heart always pumps oxygenated blood.
Fig 3.2: Circulation of blood in human

Fish have two chambered heart and get oxygen through gills. Single circulation of heart is drrn in case of fish.

Types of heart present in different types of organism:

AnimalsTypes of Heart
Fish1 circuits, 2-chambered heart
Frogs2 circuits, 3-chambered heart
Turtles and Lizards2 circuits, 5-chambered heart
Crocodile2 circuits, 4-chambered heart
Birds2 circuits, 4-chambered heart
Mammsals2 circuits, 4-chambered heart

3.2 Blood

  • It is also known as fluid connective tissue. It transports food, oxygen and waste materials in our body. Blood is composed of blood plasma, blood cells and platelets.
  • Blood plasma: fluid medium of the blood is called plasma. It forms the matrix of the blood.
  • Blood cells: these are divided in to two types i.e. Red Blood Corpuscles (RBC) and White Blood Corpuscles (WBC).
  • RBCs: it contain haemoglobins, because of this its colour is red. Haemoglobin readily combines with oxygen and carbon dioxide. It helps in transport of oxygen throughout the body, but in parts carbon dioxide is also transported by the help of haemoglobin. It is also called as carrier of oxygen in the blood.
  • WBCs: these are white or colour cell, it don’t have haemoglobin. Its play an important role in immunity.
  • Platelets: plays an important role in blood coagulation. Blood coagulation is a defence mechanism which prevents excess loss of bloods, in case of injury.
  • Lymphs: Lymph is formed from the fluid which leaks from blood capillaries and goes to the intracellular space in the tissues. These fluids are collected through lymph vessels and finally return to the blood capillaries. It is similar to blood but RBCs are absent. It is a yellow colour fluid escape from blood capillaries in to intracellular space. It helps in destruction of germs and fight against infection.

Characteristics and difference between RBCs, WBCs and Platelets               

FeaturesRed Blood CellsWhite Blood CellsPlatelets
Other nameErythrocyteLeucocytesThrombocytes
OriginBone marrowLymphocyte- Lymph node and bone marrowBone marrow
ShapeBiconcave, circularIrregular shapeIrregular shape
ColourRed colourWhite colourPurple colour
FunctionTransport O2 and CO2Fight infectionBlood clotting

3.3 Blood pressure:

  • The force that blood exerts against the wall of vessels is called blood pressure.
  • Blood pressure is much greater in arteries than in veins.
  • The blood pressure have two units are, systolic pressure– the pressure of blood exert during ventricular systole in the artery and diastolic pressure– pressure in artery during ventricular diastole.
  • The normal systolic pressure is about 120mm of Hg and diastolic pressure is 80mm of Hg.
  • Blood pressure is measured with an instrument called Spgygmomanometer.
  • High blood pressure is also called hypertension and is caused by the constriction of arteries.

3.4. Transportation in Plants

Plants have specialised vesicular tissue for transportation of substances includes minerals, magnesium, calcium, nitrogenous product etc. there are two types of vesicular tissues in plants i.e. xylem and phloem.

Characteristics and difference between xylem and phloem.

It carries water from root to leaves.Phloem carries food from leaves to growing parts and storage organs
Made up of dead cellsMade up og living cells
Conducting channels or treachery elements are tracheids and vessels.Conducting channels are sieve tubes.
Three of the four elements re dead (i.e. tracheids, vessels and fibres). Only xylem parenchyma is the living element.Three of four elements are living (i.e. sieve tubes, companion cells and phloem parenchyma while phloem fibres are dead elements)
Cells are star shapedCells are non-star shaped
It also provides mechanical strength to the plants. It is not perform mechanical function for the plants

3.5 Transport of water:

  • In the transportation of water ascent of sap have an important role. the upward movement of water and minerals from root to different plant parts is called ascent of sap. It includes many stapes in the transportation of water and minerals.
  • Root pressure: Root cell wall has many hairy structures called root hair. Water from soil enters to root hair due to osmotic pressure. Root pressure is responsible for upward movement of water from root to shoot.
  • Capillary action: A thin fine tubes present in stem is called capillary. Water move in capillaries due to physical forces and the phenomenon is called capillary action. Due to capillary action water and fluids move from stem to upward region.
  • Adhesion and cohesion: water molecules make a continuous column due to the adhesion and cohesion forces. In adhesion, water molecules attach with the wall of the xylem, but in cohesion, water molecules make a chain to combine with another water molecule and continue the upward movement.
  • Transcription pull: transpiration is a process in which water is loss through stomata and lenticels in plants. Due to transpiration through stomata create vacuum which create suction pressure is called transpiration pull. This pull sucks the water column from the xylem tubes and thus the water move greater high even the plant is tallest.


  • Help in temperature regulation in plants.
  • Help in transport of food from leaves to different part of the body.
  • Help in transport of water and minerals for plant growth, development and for photosynthesis.

4. Excretion

  • The biological process involve in removal of harmful metabolic wasted from the body is called excretion.
  • Different organisms have different excretory system; unicellular organism removes their wasted from the body by simple diffusion process. Multi-cellular organisms use specialised organ for excretion.
  • Excretion in Human:
  • The excretory nitrogenous product in human is urea. It is not that much harmful like nitrogenous waste ammonia and uric acid.
Fig 4.1: Excretory system in human
  • The main excretory organ in human is called kidney. A tube like urethra comes out from each kidney and goes to the urinary bladder. The urine is stored in the urinary bladder and expelled out when required.
  • Excretory system of human beings includes: A pair of kidney, a pair of bladder, a pair of ureter and a urethra.

(a) Kidney:

  • It is look like a bean, lies near the vertebral column in the abdominal cavity. It is composed of many numbers of filtering units, called nephron. Nephron is called as the functional unit of kidney.

(b) Nephron:

  • It contains a tangled mass of tubes and filtering parts, called glomerulus.
  • Glomerulus is a network of blood that connects with renal artery. The artery which carries blood to the glomerulus is called afferent arterioles and on artery which receives blood from the glomerulus is called efferent arterioles.
  • The glomerulus is enclose with a capsule is called bowmans capsule. It extends in to a coiled and fine tube. Tubes from various nephron connect in to a collecting duct, which finally goes to ureter.
Fig 4.2: Structure of nephron

4.1 Urine formation in kidney:

Following steps are involved in urine formation:

Step-1: Glomerular filtration

Glucose, water, amino acid and nitrogenous waste filter from the blood into bowman’s capsule of the nephron.

Step-2: Tubular reabsorption

The useful substances from the filtrate are /again re absorbed by capillaries surrounding the nephron.

Step-3: secretion

Excess water and salts are secreted out in to the tubule which open in to the collecting duct and then in to the ureter. Urines are then stored in the urinary bladder and release through the urethra.

Fig 4.3: Excretory product in different organism

Different types of excretory organs found in different organisms.

OrganismsExcretory organ
Porifera (sponges), coelenterate (hydra) etcGeneral body surfaces
Platyhelminthes (Tenia nad Faciola)Flame cell
Annelida (earth worm)Nephridea
Arthropods (cockroach)Malpighian tubules
SpiderCoxal gland
All vertebrates (Human)Kidney
Crustaceans (Peawn)Green gland

4.2 Hemodialysis:

An artificial kidney is used to remove nitrogenous waste product from the blood through dialysis. 

Fig 4.3: Mechanism of artificial Kidney.

4.3 Excretion in plants:

  • In plant oxygen is thought to be a waste product generated during photosynthesis. It also loss excess water by transpiration.
  • Plants outer parts are mostly dead, so extra loss takes place apart from leaves.
  •  In many plants Waste products are stored in form of cellular vacuole. Some wastes are stored in the form of resins and gum.
Categories: General


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