Life Processes NCERT Exemplar Problems

Short Answer Type

Part 3

Question 61: Name the energy currency in the living organisms. When and where is it produced?

Answer: ATP (Adenosine triphosphate) is the energy currency in living organisms. It is produced at the end of respiration and is produced in the mitochondria.

Question 62: What is common for cuscuta, ticks and leeches?

Answer: All of them are parasites.

Question 63: Why do veins have thin walls as compared to arteries?

Answer: Veins carry the blood towards the heart. The blood; entering the vein; does not enter because of a pumping action; unlike the way it enters an artery. So, the walls of veins can afford to be thin.

Question 64: Explain the role of mouth in digestion of food.

Answer: Mouth plays following roles in digestion of food:

Food is broken down into smaller pieces so that it becomes easier to swallow the food.
Smaller particles also ensure that saliva is properly mixed with the food.
Tongue plays the important role of mixing the food with saliva.
Digestion of starch takes place in the mouth.

Question 65: What are the functions of gastric glands present in the wall of the stomach?

Answer: Gastric glands serve following purposes:

They release mucus
They produce gastric acid
They release the gastric enzymes pepsin and rennin.

Question 66: Name the correct substrates for the following enzymes: (a) Trypsin (b) Amylase (c) Pepsin (d) Lipase

Answer: (a) Trypsin: peptide, (b) Amylase: starch, (c) Pepsin: protein, (d) Lipase: fat

Question 67: What will happen if platelets were absent in the blood?

Answer: Platelets play the important role of coagulation of blood. No blood coagulation would take place in the absence of platelets. This would be a dangerous situation; in case of an injury. No blood coagulation would result in excessive blood loss and can even prove lethal for the person.

Question 68: Plants have low energy needs as compared to animals. Explain.

Answer: Plants do not need to move from one place to another. Movements in a plant are usually at the cellular level and hence a far less amount of energy is required by plants. Animals, on the other hand, need to move from one place to another; in search of food. So, the energy need of animals is pretty higher than of plants.

Question 69: Why and how does water enter continuously into the root xylem?

Answer: Root pressure is responsible for transport of water up to root xylem.

Question 70: Why is transpiration important for plants?

Answer: Transpiration through stomata creates a transpiration pull in the underlying vascular tissue. This helps in pulling the water column and thus facilitates ascent of sap in plants. Moreover, transpiration is a way through which plants get rid of excess water. So, transpiration is important for plants.

Question 71: How do leaves of plants help in excretion?

Answer: Gaseous waste is removed through stomata in leaves. Some waste substances get accumulated in older leaves. These substances are removed along with the leaves, when a plant sheds its older leaves.

Question 72: Match the terms in Column (A) with those in Column (B)

Column A	Column B
(a) Trypsin	(i) Pancreas
(b) Amylase	(ii) Liver
(c) Bile	(iii) Gastric glands
(d) Pepsin	(iv) Saliva

Answer:(a) (i), (b) (iv), (c) (ii), (d) (iii)