Class 10 Science Chapter 5 Question Answers - Life Processes

Q1: State in brief the role of lungs in the exchange of gases.
Ans: Lungs have alveoli which provide a larger surface for exchange of gases and are richly supplied with blood vessels to enable faster exchange. So, lungs help in providing oxygen to various tissues of the body and removal of carbon dioxide from the body.

Q2: What is the basic unit of kidney called? Why is it composed of very thin blood capillaries?
Ans: The basic unit of kidney is called nephron. It is composed of a cluster of very thin blood capillaries as they help in filtration of blood and remove the nitrogenous wastes from the body in the form of urine.

Q3: How does the plant get rid of excretory products?
Ans: Excess oxygen and carbon dioxide removed through stomata.
Plant waste products are also removed by:

• Storage in cellular vacuoles
• Storage in leaves that fall off
• Storing as resins and gums in old xylem
• By excreting into the soil around them.

Q4: Tabulate two differences between renal artery and renal vein.
Ans: Renal Artery:

• Blood in renal artery contains glucose, oxygen and cellular waste products.
• It takes blood towards the kidney.

Renal Vein:

• Blood in renal vein is filtered, and is free from cellular waste and any other impurities.
• It takes blood away from the kidney towards the heart.

Q5: (a) What is the main toxic waste that kidney filters from the blood?
(b) Name any two substances which are selectively reabsorbed from the tubules of a nephron.
Ans: (a) Urea is the main excretory product removed by the kidneys of human beings.
(b) The substances selectively reabsorbed by the kidneys are water, glucose, electrolytes, etc.

Q6: What is excretion? How do unicellular organisms remove their wastes?
Ans: Removal of metabolic wastes from the body is called as excretion. Many unicellular organisms remove metabolic wastes from the body surface into the surrounding water by simple diffusion.

Q7: Write a function of (a) blood vessels (b) blood platelets.
Ans: (a) Blood vessels help in carrying blood to various parts of the body.
(b) Blood platelets help in the clotting of blood at the point of injury to prevent non-stop bleeding.

Q8: How are water and minerals absorbed by the plant?
Ans: The water and minerals in the soil are absorbed by plants with the help of root hairs present on their roots. Root hairs provide a larger surface area for absorption.

Q9: What are capillaries? Sate the function performed by them.
Ans: The capillaries are one-cell thick, small blood vessels which help in the exchange of materials between the blood and the surrounding tissues.

Q10: Mention the two main components of the transport system in plants. State one function of each one of these components.
Ans: The two main components of the transport system in the plants are xylem and phloem. Xylem helps to transport water and minerals to various parts of the plant. Phloem helps to carry food from leaves to the various parts of the plant.

Q11: During one cycle how many times does blood go to the heart of fish and why?
Ans: The blood passes only once through the heart in one cycle in fishes because the two-chambered heart of the fishes pump the blood to gills for oxygenation. The blood from gills is then directly passed to the various parts of the body in the fishes.

Q12: What would be the consequences of deficiency of haemoglobin in our bodies?
Ans: Haemoglobin helps in transport of oxygen to the body parts. Deficiency of haemoglobin will affect transport of oxygen and the person will suffer from improper metabolism, weakness, fatigue and pain.

Q13: Name the following:
(а) The process in plants that links light energy with chemical energy.
(b) Organisms that can prepare their own food.
(c) The cell organelle where photosynthesis occurs.
(d) Cells that surround a stomatal pore.
(e) Organisms that cannot prepare their own food.
(f) An enzyme secreted from gastric glands in stomach that acts on proteins.
Ans: (a) Photosynthesis
(b) Autotrophs
(c) Chloroplast
(d) Guard cells
(e) Heterotrophs
(f) Pepsin

Q14: “All plants give out oxygen during the day and carbon dioxide during night”. Do you agree with this statement? Give reason.
Ans: The rate of photosynthesis is higher than the rate of respiration during the daytime, so the net result is the evolution of oxygen. In the absence of photosynthesis at night, only respiration occurs in the plants so carbon dioxide is released at night.

Q15: How do the guard cells regulate opening and closing of stomatal pores?
Ans: The entry of water into the guard cells of the stomata causes an increase in turgor pressure in the guard cells which leads to opening of the stomata. The loss of water from the guard cells results in their shrinking and closes the stomata.

Q16: Two green plants are kept separately in oxygen free containers, one in the dark and the other in continuous light. Which one will live longer? Give reasons.
Ans: Plant kept in continuous light will perform photosynthesis and release oxygen for its respiration. Hence, it will live longer than the plant kept in the dark.

Q17: If a plant is releasing carbon dioxide and taking in oxygen during the day, does it mean that there is no photosynthesis occurring? Justify your answer.
Ans: During the day time the plants take in carbon dioxide and release oxygen as a by product of photosynthesis. Release of carbon dioxide and taking in air during the daytime means that either the rate of photosynthesis is too low or its not occurring at all.

Q18: Why do fishes die when taken out of water?
Ans: Fishes take water from mouth and send it to the gills which are richly supplied with blood capillaries for absorbing the oxygen dissolved in water. But the fishes cannot absorb gaseous oxygen, so they die soon after they are taken out of water.

Q19: Is ‘nutrition’ a necessity for an organism? Discuss.
Ans: Nutrition (food) is a necessity for an organism as:

• It provides energy for the various metabolic processes in the body.
• It is essential for the growth and repair of various cells and tissues.
• It helps to provide resistance against various diseases.

Q20: What would happen if green plants disappear from the Earth?
Ans: The green plants are the source of energy for the entire organisms on the Earth. Herbivores depend directly on the plants while the carnivores and omnivores depend either directly or indirectly on plants. So, all the organisms will die due to starvation if all the green plants disappear from the Earth.