Short Questions – Class 10 -Science-Biology-Chapter 5 – Life Processes

Class 10 -Science-Short  Questions – Biology-Chapter 5 – Life Processes

Q1. What is sequence of steps in photosynthesis? How is it different in desert plants and those in temperate regions?

Ans :

Chloroplast (chlorophyll), on exposure to light energy, becomes activated by absorbing light energy, and splits water (photolysis of water) to oxygen and hydrogen. Hydrogen reduces CO2 , and synthesizes glucose. In plants of temperate regions, stomata open during day to take in CO2 and release O2 . Desert plants open stomata at night to check excessive loss of water hence sequence of steps of photosynthesis are slightly different. These plants take up carbon dioxide at night and prepare an intermediate which is acted upon by the energy absorbed by the chlorophyll during the day.

Q2(a) Define excretion.

(b) Name the basic filtration unit present in the kidney.

(c) Draw excretory system in human beings and label the following organs of excretory system which perform following functions:

(i) form urine

(ii) is a long tube which collects urine from kidney

(iii) store urine until it is passed out.

Ans:

(a) The biological process involved in the removal of wastes, produced during various metabolic activities in the body from the body of an organism is called excretion. The wastes are non-gaseous nitrogenous wastes like ammonia, urea, uric acid, etc., along with excess of water, salts and pigments.

(b) Basic filtration unit present in kidney is nephron.

(c) Refer to answer 36.

(i) Kidney

(ii) Ureter

(iii) Urinary bladder

Q3. What is the composition of urine? Are glucose and proteins normally present in urine? Why? How is volume of urine regulated?

Ans : The urine contains mainly water, various salts, urea and uric acid. No, they are not present in urine as glucose is reabsorbed by nephron while protein are not filtered from blood in glomerulus in a healthy kidney. Volume of urine is regulated by a. The amount of excess water. b. The amount of dissolved waste in blood.

Q4. a. What is the role of mucus in stomach?

b. What are the two vital functions of human kidney?

Ans:

a. To protect the stomach lining from the action of acid and pepsin.

b. The two vital functions of human kidney are:

(i) Excretion – Removal of toxic wastes like urea, uric acid.

(ii)Osmoregulation – The process of maintaining the right amount of water and proper ionic balance in body. It is done by controlling the amount of water and salts reabsorbed by nephron – tubules.

Q5.a How is oxygen and carbon dioxide exchanged between blood and tissue? How are the gases transported in human being?

b. What is haemoglobin?

Ans : a. Exchange of gases in tissues occurs through diffusion. Oxygen is carried as oxyhaemoglobin from lungs to tissues. It dissociates and carbon dioxide diffuses out into blood from tissues. It is transported in dissolved form and reaches lungs where again it diffuses to alveoli. b. Respiratory pigment: Haemoglobin is a red coloured protein present in red blood cells. Haemoglobin has affinity for O2 .

Q7. If a plant is kept covered with a polythene sheet, we notice some water drops on the inner side of the sheet after some time. What are they due to? Name and define the process. What is the significance of this process in plants and in nature? How does transpiration help in upward movement of water from roots to leaves?

Ans : If a plant is kept covered with a polythene sheet, we notice some water drops on the inner side of the sheet after sometime due to transpiration. The loss of water in the form of vapour from the aerial parts of the plant is known as transpiration. This process helps in the absorption and upward movement of water and minerals dissolved in it from roots to the leaves. It also helps in temperature regulation.

Q8. Leaves of a healthy potted plant were coated with Vaseline to block the stomata. Will this plant remain healthy for long? Stage three reasons for your answer. 

Ans : No, the plant will not stay healthy for a long time. The reasons are: a. It will not be able to exchange O2 and CO2 , hence respiration will be affected adversely. b. Photosynthesis will also be affected as CO2 will not be available. c. Transpiration will not take place hence there will be no ascent of sap, hence no water absorption from the soil.

Q9. What is the need to have a transport system in complex organisms?  

Ans : The transport system of an animal moves substances to where they are needed in the body. Even the smallest animal must have the means of transporting substances around its body. Oxygen and food molecules must move to all the cells, and the waste products must be removed from the cells and expelled into the environment. It occurs through diffusion mainly. In a multicellular organism, all cells are not in contact with the surrounding hence diffusion will be insufficient for it. A variety of fluid systems, called vascular systems, help such transport in most members of the animal kingdom.

Q10. How is food transported in a plant?

Ans :  The food prepared by plant may be sucrose, amino acids or other materials. It is done with the help of living cells- sieve tubes and companion cell of phloem tissue by utilizing energy of ATP. The movement occurs both upwards and down ward from the place of formation (leaves) to storage organ (roots or stems) from storage organ to organ of its utilization (growing buds) depending upon the situation.

a. Translocation: Transport of organic food from the leaves to the other parts of the plants through the sieve tubes of phloem tissue is called translocation.

b. Importance: It is an essential process as every part of the plant requires food. For energy, building and maintenance. c. Sugars are synthesized in the leaves whereas hormones are synthesized in the growing parts of roots and shoots.

Q11. What are the main events occurring in the small intestine?

Ans : The main events occurring in the small intestine are as follows: a. Bile emulsifies fat present in the food (emulsification means breaking of fat molecules into smaller globules).

b. Pancreatic juice containing trypsin for digesting proteins and pancreatic amylase for starch act upon the food.

c. Bicarbonate ions secreted by duodenal wall make the medium alkaline because it is required for the action of pancreatic enzynies.

d. Enzymes produced in intestinal juice complete the digestive process.

e. Digested food – amino acids, sugar are absorbed by the blood capillaries present in the villi of intestine.

f. Digested fats are absorbed by lymph vessels present in the villi of intestine.

Q12.  a.Mention any two components of blood.

b. Trace the movement of oxygenated blood in the body.

c. Write the function of valves present in between atria and ventricles.

d. Write one structural difference between the composition of artery and veins.

Ans:

b. Pulmonary vein from lungs ” left atrium left ventricle ”  aorta ”  arteries to all organs.

c. Valves prevent backflow of blood from ventricles to atria when latter are contracting.

d. Arteries have thick, muscular and elastic walls. Veins have thinner, less muscular walls but have valves.