Class 10 Science Chapter 6 Life Processes Notes | NCERT Class 10

NCERT Class 10 Science Chapter 6

Chapter 6 "Life Processes" is the first chapter of biology class 10 of NCERT book.

In this chapter, we are going to look some amazing processes necessary for life taking place inside our body.

In this chapter, we have to study about nutrition/digestion, respiration, transportaion and excreation.

The life processes, we are going to study in this chapter, are based on the comparison or examples of human beings and plants.

Notes of Class 10 Life Processes

1. Life Processes

The necessary processes that must take place for an organism to stay alive.
(i) Nutrition, (ii) Respiration, (iii) Transportation, (iv) Excretion.

2. Nutrition

The process in which an organism feeds and utilize the food to get the energy to carry on processes such as growth, repair, and maintenance of its body.

3. Types of Nutrition

(i) Autotrophic nutrition
(ii) Heterotrophic nutrition

4. Autotrophic Nutrition

It is a process that autotrophic organisms use to take in substances such as carbon dioxide and water and convert them into useful things such as carbohydrates that then converted into energy.

Energy requirements of the autotrophs are fulfilled by a process known as photosynthesis.

In photosynthesis, the organism uses carbon dioxide and water to prepare its food, carbohydrates in the presence of sunlight and chlorophyll.

Equation of phtosynthesis
6CO2 + 6H2O + --> C6H12O6(Glucose) + 6H2O [In the prsense of sunlight and chlorophyll]

5. Heterotrophic Nutrition

(i) Saprophytic nutrition = Organisms that feed on dead decaying plants and animal material.
For ex = Fungi, Bacteria.

(ii) Parasitic Nutrition = The organisms that live on other organism's bodies (host) to take food from it.
Forex = Tapeworm, roundworm.

(iii) Holozoic Nutrition = Organisms that take in food and digest it inside the body by using various enzymes.
Forex = Amoeba, paramecium, most animals, human beings.

6. Nutrition In Human Beings

Human beings use holozoic nutrition to produce sufficient energy. We have an alimentary canal in which food is digested.

Alimnetary Canal = Mouth > Oesophagus > Stomach > Small Intestine > Large Intestine

7. Important Gland/Juices

(i) Mouth
Muth has salivary glands which release substance saliva which have salivary amylase that breaks down starch into sugar.

(ii) Stomach
The stomach has gastric glands which release gastric juices such as HCL, Pepsin, Mucus.

• HCL = It kills all harmful bacteria present in the food and makes the medium acidic.
• Pepsin = It digests protein present in the food.
• Mucus = It protects the inner lining of the stomach from the powerful acid HCL.

(iii) Small Intestine
From the liver, the bile juice releases to make the medium alkaline for the pancreatic enzymes to work, and bile salt is released to break down the large fat globules in the small intestine.

From the pancreas, the pancreatic juices are released into the small intestine which contains trypsin to digest protein and lipase to digest broken down fat(by bile salt).

There are many small fingers like projections that increase the area for the absorption of useful nutrients digested in the small intestine.

(iv) Large Intestine
In the large intestine, water is absorbed by small finger-like projection present on the walls of the large intestine known as villi.

(v) Anus
At the end of the alimentary canal waste material left is ejected via the anus. Anal Sphincter regulates the exit of waste material.

8. Respiration

The process by which the digested nutrients are broken down to get energy is known as respiration.

Types of Respiration = 

(i) Aerobic Respiration
It takes place in the presence of oxygen in the mitochondria and cytoplasm. In this, complete oxidation of glucose takes place.

Equation = Glucose converted into Pyruvate convertedto CO2 + H2O + Energy

(ii) Anaerobic Respiration
It takes place in the absence of oxygen in only the cytoplasm. In this incomplete oxidation of glucose takes place.

• In yeast: Equation = Glucose > Pyruvate > Ethanol + H2O + Energy.
• In muscle cells: Equation = Glucose > Pyruvate > Lactic acid + Energy.

9. Gaseous Exchange

(i) Gaseous Exchange In Plants
The gaseous exchange in plants is done by the simple process of diffusion.

During the daytime, the photosynthesis takes place on a large scale, converting carbon dioxide into oxygen.

During the night, Only respiration takes place, converting oxygen into carbon dioxide.
The respiration also takes place during the daytime on a very small scale.

(ii) Gaseous Exchange In animals

• Terrestrial animals = These animals take oxygen from the atmosphere.
• Aquatic Animals = These animals take oxygen dissolved in water. Since oxygen does not dissolve in water, the oxygen content in water is low. Therefore, they breathe fast.

10. Human Respiratory System

External Nostrils > Nasal Cavity > Trachea > Bronchi > Bronchioles > Alveoli

(i) In human beings air is taken into the body by nostrils. The air passing through the nostrils is filtered by fine hairs and mucus.

(ii) Rings of cartilage present in the throat ensure that the air passage does not collapse.

(iii) When the air enters the lungs, the passage divides into finer and finer tubes which finally end in balloon-like structures called alveoli.

(iv) Walls of alveoli are connected with blood vessels from which the exchange of gasses takes place. Blood vessels bring CO2 from the body and take oxygen to the body from alveoli.

(v) Lungs always contain a small amount of oxygen to get sufficient time to breathe.

(vi) Hemoglobin present in the red blood cells delivers oxygen to all parts of the body.

11. Transportation In Human Beings

(i) Blood = It is a fluid connective tissue containing the fluid medium plasma in which red blood cells, white blood cells, and platelets are suspended.
Food, oxygen, carbon dioxide, nitrogenous wastes, etc. are transported by plasma.
Platelets = It stops the bleeding whenever their is leakage or cut in arteries or veins.

Functions of Blood = Blood transports respiratory gases, nutrients, and waste products. It also defends against infections.

(ii) Blood Vessels =

• Arteries: Arteries have thick walls and valves are absent. They carry oxygenated blood from the heart to the body.
• Veins: Veins have thin walls and are present. They carry deoxygenated blood from the body to the heart.
• Capillaries: They form a connection between arteries and veins. Capillaries have one cell thick walls for easy exchange of gases.

(iii) Lymph = It is a fluid present in intercellular spaces. It is similar to the plasma but contains comparatively less protein.
The function of lymph :

• It helps in the transportation of digested and absorbed fats from the small intestine.
• It helps the blood to drain the excess fluid from the intercellular spaces.

(iv) Heart = It is a strong muscular organ, which works as a pump in the circulatory system. It has four chambers. Two upper chambers are known as atria and two lower chambers are known as ventricles.

The function of Heart =
Left Side:

• Left atrium relaxes and the oxygenated blood from the lungs through the pulmonary vein enters it.
• Left atrium contracts and the blood through the valve enters the left ventricle.
• Left ventricle contracts and the blood is pumped to all parts of the body through the largest artery 'Aorta'.

Right Side:

• Right atrium relaxes and through the vena cava, the deoxygenated blood from the body enters it.
• Right atrium contracts and through the valves, the blood enters the right ventricle.
• Right ventricle contracts and the blood is carried to the lungs by the pulmonary artery.

12. Special Blood Vessels

(i) Valves = It is present in the heart to maintain the flow of blood in only one direction.

(ii) Pulmonary Vein = The only vein that carries oxygenated blood.

(iii) Aorta = The only artery that carries deoxygenated blood.

13. Double Circulation in Higher Animals

In human beings, in one complete cycle of circulation, the blood passes twice the heart.

14. Transportation In Plants

Since plants do not have to move they don't need much energy so they have a slow transportation system.

(i) Transportation of Water = Plants has a tissue known as Xylem present in roots, stem, leaves which transports water.
The plant cells present in roots, take ions from the soil which creates a difference of concentration between roots and soil by which the roots absorb water.

In very tall plants = The process of transpiration creates a suction by which the is pulled upwards. Transpiration also regulates the temperature in plants.

(ii) Transport of food = In plants phloem is used to transport food. Movement of food in plants is known as translocation.

15. Excretion

The process used by an organism to remove the harmful wastes from its body.

16. Excretion in Human Beings

(i) Organs of Excretory System = Kidneys > Ureters > Urinary Bladder > Urethra

(ii) Kidneys = There are two bean-shaped kidneys present in human beings in the abdomen on either side of the backbone.
These are used to filter and remove the nitrogenous waste and reabsorption of the vital nutrients.
The purification of blood by artificial kidneys, when original kidneys are damaged is known as dialysis.

(iii) Ureters = Used to transport the urine formed in the kidneys to the urinary bladder.

(iv) Urinary Bladder = It is a muscular bag like structure used to store urine.

(v) Urethra = It is used to remove the urine when the urinary bladder is full.

17. Excretion In Plants

(i) Gaseous Wastes = In plants, gaseous waste such as CO2 after respiration and O2 after photosynthesis is removed from the body by the process of diffusion.

(ii) Excess of Water = Plant removes excess of water by the process of transpiration.

(iii) Other Waste = In plants, other wastes are stored in cellular vacuoles present leaves that fall off or as gums, resins, etc. Also, plants remove some wastes in soil.

Conclusion

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