Class 10 Biology Chapter 1 - Life Process Most Important Questions

 

Class 10 Biology Chapter 1 - Life Process 

Most Important Questions 

Question 1.

Most of the digestion and absorption of the food takes place in the

(a) small intestine

(b) liver

(c) stomach

(d) large intestine. 

Answer:

(a) small intestine

Question 2.

Mention the raw materials required for photosynthesis. (Board Term I, 2016)

Answer:

Raw materials required for photosynthesis are carbon dioxide (CO2), water, light and chloroplast.

Question 3.

State the location and function of gastric glands. 

Answer:

Gastrifc glands are present in the wall of the stomach. They secrete gastric juices containing mucus, protein digesting enzymes pepsin, rennin and hydrochloric acid .

Question 4.

Name the glands present in the wall of the stomach that release secretions for digestion of food. Write the three components of secretion that are released by these glands. 

Answer:

Stomach’s muscular wall contains gastric glands. These glands secrete gastric juices which contain dilute hydrochloric acid, mucus and two protein digesting enzymes rennin and pepsin.

Question 5.

(a) State the role played by the following in the process of digestion :

(i) Enzyme trypsin

(ii) Enzyme lipase-

(b) List two functions of finger-like projections present in the small intestine. 

Answer:

(a) (i) Enzyme trypsin : This enzyme is produced by the pancreas in an inactive form called trypsinogen. Trypsin converts remaining proteins into peptones and the peptones into peptides and amino acids.

(ii) Enzyme lipase : It is secreted by pancreas and small intestine. Lipase converts fats into fatty acids and glycerol.

(b) Internally, the wall of the small intestine is provided with long finger-like projections called villi. Two functions of villi are :

(i) The villi greatly increase the absorptive surface area of the inner lining of small intestine.

(ii) The large surface area of small intestine helps in rapid absorption of digested food.

Question 6

Explain the significance of photosynthesis. Write the balanced chemical equation involved in the process. 

Answer :

Photosynthesis is important for a number of reasons:

(i) Food : By photosynthesis, green plants synthesise food from simple raw materials like CO2 and H2O. Thus, it sustains life on earth.

(ii) Oxygen : Oxygen released during the process of photosynthesis is needed by animals and humans for respiration. It is also required for respiration of microbes. Oxygen also supports combustion of fuels.

(iii) Fuels : Fossil fuels like coal, oil and natural gas are forms of stored solar energy synthesised millions of years ago through photosynthesis. Balanced chemical equation involved in the process of photosynthesis is given as :

Life Processes Class 10 Important Questions with Answers Science Chapter 6 Img 3

Question 7

Differentiate between autotrophs and hetero- trophs and give one example of each. 

Answer:

Autotrophs Heterotrophs

(i) These organisms are able to form organic substances from simple inorganic substances such as CO2 and H2S and water. They cannot produce organic compounds from inorganic sources and therefore completely rely on consuming other organisms for its food requirement.

(ii) They have chlorophyll to trap solar energy. Chlorophyll is absent, so they cannot trap solar energy.

(iii) They can be chemoautotroph and photoautotroph. They can be saprophytic, parasitic and holozoic in mode of nutrition.

(iv) Autotrophs are placed at the bottom of the food chain as producers. Heterotrophs are placed above autotrophs in the food chain as consumers.

(v) Green plants, some bacteria and some protists like Euglena are examples of autotrophs. Mushrooms, Euglena, cow, goat, etc., are examples of heterotrophs.

Question 8

Explain with the help of neat and well labelled diagrams the different steps involved in nutrition in Amoeba. 

Answer:

The mode of nutrition in Amoeba is holozoic. The process of obtaining food by Amoeba is called phagocytosis.

Amoeba ingests food by using its finger-like projections called pseudopodia.

The food is engulfed with a little surrounding water to form a food vacuole inside the Amoeba. The food is digested inside food vacuole by digestive enzymes.

Food is absorbed directly into the cytoplasm of Amoeba by diffusion.

Food is used to obtain energy and growth of Amoeba.

When considerable amount of undigested food collects inside Amoeba then its cell membrane ruptures at any place to throw out this undigested food.

Question 9

(a) What is peristaltic movement?

(b) ‘Stomata remain closed in desert plants during daytime’. How do they do photosynthesis? 

Answer:

(a) The relaxation of gut muscles to move the partially digested food downwards throughout the alimentary canal is called peristaltic movement.

(b) In desert plants, stomata open at night and take in carbon dioxide (CO2). Stomata remain closed during daytime to prevent the loss of water by transpiration. They store the CO2 in their cells until the sun comes out so that they can carry on with photosynthesis during the daytime.

Question 10

(a) Why is nutrition necessary for the human body?

(b) What causes movement of food inside the alimentary canal?

(c) Why is small intestine in herbivores longer than in carnivores?

(d) What will happen if mucus is not secreted by the gastric glands? (2020)

Answer:

(a) Human body continuously require energy for their life activities like respiration, circulation, excretion, etc. Energy is required even we are sleeping because a number of biological processes keep on occurring. All these processes require energy and this energy is obtained from nutrition. Nutrition is also needed for growth and repair of human body.Biology Courses

(b) The wall of alimentary tract contains muscles which can contract and expand alternately. The contraction and expansion movement of the walls of foodpipe is called peristaltic movement. The peristaltic movement moves the partially digested food in all the digestive organs throughout the alimentary canal.

(c) Herbivores eat plants which is rich in cellulose. Cellulose takes longer time for complete digestion by the enzymes present in symbiotic bacteria. Therefore, they have longer small intestine. Carnivores, feed on flesh which is easier to digest and do not contain cellulose also. Therefore, they have shorter intestine for digestion of food eaten by them.

(d) Gastric glands secrete HCl, mucus, rennin and pepsin enzymes. Mucus protects the inner lining of stomach from the action of HCl and enzymes. In the absence of mucus, there would be erosion of inner lining of stomach leading to acidity and ulcers.

Question 11

Diffusion is insufficient to meet the oxygen requirement of multicellular organisms like human. State reason. (Board Term 1,2017)

Answer:

Due to higher metabolic rate and the volume of human body is so large that oxygen cannot diffuse into all cells of the body quickly as oxygen will have to travel large distances to reach each and every cell. So diffusion is insufficient to meet the oxygen demand of multicellular organisms.

Question 12

(a) State reasons for the following:

(i) Herbivores need a longer small intestine while carnivores have shorter small intestine.

(ii) The lungs are designed in human beings to maximise the area for exchange of gases.

Answer:

(a) (i) Herbivores need a longer small intestine than that of carnivores because their diet is mostly grass and plants, that contains more fibres and cellulose which are hard to digest. Longer small intestine also hosts many small bacteria that process and break down cellulose into glucose which is a source of energy. Carnivores diet is not rich in cellulose so, they do not need to harbour bacteria for cellulose digestion.

(ii) Human lungs have a highly branched network of respiratory tubes. A primary bronchus divides into secondary bronchus, which in turn forms tertiary bronchus. Tertiary bronchus divides repeatedly into bronchioles which finally terminate into alveoli. Alveoli are small, rounded polyhedral pouches which are extremely thin- walled and possess a network of capillaries, for the exchange of gases. Due to vast surface area of alveoli, exchange of gases becomes a fast and effective process. Oxygen diffuses from alveoli into pulmonary blood capillaries and CO2 diffuses out from capillaries into alveoli.