Life Processes: 10 CBSE Science Biology

Question: What are the final products produced after digestion of carbohydrates, proteins and fats?

Answer:
Carbohydrates – glucose
Proteins – amino acid
Fats – glycerol + fatty acid

Question: When a sportsman runs, he gets muscle cramps. Why?

Answer: In order to release more energy to perform sudden activity, pyruvate is converted into lactic acid in the absence of oxygen and produced lactic acid as the end product.

Formation of lactic acid in muscles causes cramps.

Question: How do desert plants perform photosynthesis process through their stomata remain closed during daytime?

Answer: Desert plants take-up CO₂ at night and prepare an intermediate molecule.
The intermediate molecule is acted upon by the energy absorbed by the chlorophyll during the day.

Question:

1. Why are the valves needed in the heart?
2. Leakage of blood from vessels reduces the efficiency of pumping system. How is the leakage prevented?

Answer:

1. Valves ensure that blood does not flow backward when the atria or ventricles contract.
2. To avoid leakage, blood has platelet cells which circulate around the body and plug the leakage by clotting the blood at the point of injury.

Question:

1. Why do aquatic animals breathe faster than terrestrial animals?
2. How are lungs designed in human beings to maximize the area for exchange of gases?

Answer:

1. Because amount of oxygen dissolved in water is comparatively low to the amount of oxygen in the air.
2. There are two millions of alveoli present in the lungs. These alveoli provide a very area for the exchange of gases.

Question: Name any two digestive enzymes secreted in the human digestive system and write their functions.

Answer:
Salivary amylase → starch into sugar (maltose)
Pepsin → digest proteins into amino acids
Trypsin → digest proteins into amino acids
Lipase → digest fats into fatty acids and glycerol

Question: Which is the internal energy reserve in plants? Do the animals have the same energy reserve?

Answer: Plants have starch as the storage carbohydrate which acts as internal energy reserve.

No, the animals have glycogen as internal energy reserve.

Question: Arteries have thick elastic walls while veins have valves, explain.

Answer: Arteries carry blood with a lot of pressure, hence have thick elastic walls.
Veins have valves to prevent black flow of blood.

Question: On which type of food does salivary amylase act at buccal cavity and write the name of the initial product due to the action of amylase.

Answer: Salivary amylase acts on starch at buccal cavity and sugar is the initial product when salivary amylase acts on starch.

Question: What are the factors needed for maintaining the direction of diffusion in plants?

Answer:

1. Environmental condition.
2. Requirement of the plant.

Question: What do the following transport:

1. Xylem
2. Pulmonary artery
3. Pulmonary vein
4. Phloem

Answer:

1. Xylem: Water and minerals in plants.
2. Pulmonary artery: Deoxygenated blood from heart to lungs.
3. Pulmonary vein: Oxygenated blood from lungs to heart.
4. Phloem: Synthesized food in plants.

Question: Assume that you are a veterinary surgeon and you had removed a good length of the small intestine of a bear that was suffering from a intestinal tumor. Now, would you suggest a plant based or an meat based diet for the bear after its recovery? Give reason for your answer.

Answer: I would suggest meat based diet. Because to digest plant based diet, bear will need a longer small intestine. Since the cellulose present in plant diet requires longer time for digestion.

Question: State two functions of stomata.

Answer: Massive amount of gaseous exchanges takes place in leaves through stomata. Large amount of water can be lost through stomata (transpiration).

Question: How do guard cells regulate the opening and closing of stomata pore?

Answer: The guard cells swell when water flows into them, causing the stomata pore to open. Similarly, the pore closes if the guard cells shrink.

Question: Explain the role of bile juice in digesting food.

Answer: The food coming from the stomach is acidic and has to be made alkaline for the pancreatic enzyme to act. Bile juice accomplishes this. Bile salts break sown larger globules of fats into smaller globules increasing the efficiency of enzyme action.

Question: Define transpiration. State its two functions.

Answer: The loss of water in the form of vapour from the aerial parts of the plant is known as transpiration.

Functions:

1. It helps in the absorption and upward movement of water and minerals dissolved in it from roots to the leaves.
2. It also helps in the temperature regulation.

Question: Explain how does Paramecium obtain its food.

Answer: In paramecium, the food is taken in at a specific spot and is moved to this spot by the movement of cilia which cover the entire surface of the cell.

Question:

1. Explain why do multi-cellular organism need a transportation system for carrying food oxygen?
2. Why does an organism require excretory system?

Answer:

1. In multi-cellular organisms, there are specialized tissues to uptake food and oxygen. As they are taken up at one place in the body of the organism while all parts of the body need them. So a transportation system is needed.
2. To throw out harmful by-products an organism require excretory system.

Question: Explain why transportation of material is necessary in animals.

Answer: The distribution of all the essential substances such as food, oxygen, water throughout the body is carried out through this system wastes from the cells of the body to the excretory organs from where they expelled from the body. Thus temperature and pressure throughout the body are kept uniform.

Question:

1. Why does a piece of bread taste sweet when chewed for some time?
2. Cellulose acts as roughage in man but as a source of nutrient in cow. Justify the statement.

Answer:

1. The saliva present in the mouth contains an enzyme called salivary amylase which breaks down starch present in the bread into sugar. That is why, a piece of bread tastes sweet when chewed for some time.
2. Cellulose requires time to digest. Herbivore animals like cow have longer intestine which allow cellulose to be digested whereas human beings have comparatively shorter intestine. Thus, it is not digested and serves mere as roughage.