Life Processes
Subject: General Science
Sample Practice Questions
Question 1: Which of the following statements about the alveoli is correct?
- They are present in the kidneys
- They have thick walls
- They provide a large surface area for gas exchange
- They transport oxygen to the heart
Explanation: Alveoli are balloon-like structures in the lungs with very thin walls. They provide a large surface area for the exchange of gases (oxygen and carbon dioxide) with blood.
Question 2: What is the function of stomata in plants?
- Absorb water
- Exchange gases
- Transport food
- Store starch
Explanation: Stomata are tiny pores present on the surface of leaves. They are responsible for the exchange of gases (oxygen and carbon dioxide) for photosynthesis and respiration.
Question 3: How do plants get rid of waste products like resins and gums?
- Through stomata
- By storing them in old xylem
- Through roots
- By diffusion
Explanation: Plants store waste products like resins and gums in old xylem tissue. Other methods include storing waste in cellular vacuoles, in leaves that fall off, or excreting them into the soil.
Question 4: Which enzyme is present in saliva that breaks down starch?
- Pepsin
- Trypsin
- Salivary amylase
- Lipase
Explanation: Saliva contains an enzyme called salivary amylase that breaks down starch (a complex carbohydrate) into simpler sugars. This is the first step in the digestion of carbohydrates.
Question 5: What is the function of the enzyme pepsin in the stomach?
- Digests carbohydrates
- Digests proteins
- Digests fats
- Emulsifies fats
Explanation: Pepsin is a protein-digesting enzyme secreted by the gastric glands in the stomach. It breaks down proteins into smaller peptides in the acidic medium of the stomach.
Question 6: Which respiratory pigment in human beings has a high affinity for oxygen?
- Chlorophyll
- Haemoglobin
- Myoglobin
- Cytochrome
Explanation: Haemoglobin is the respiratory pigment present in red blood corpuscles. It has a very high affinity for oxygen and helps in transporting oxygen from the lungs to all tissues in the body.
Question 7: What are the openings in plant leaves that allow gas exchange?
- Lenticels
- Stomata
- Hair
- Pores
Explanation: Stomata are tiny pores present on the surface of leaves. They allow for the exchange of gases (oxygen and carbon dioxide) during photosynthesis and respiration.
Question 8: What happens to the stomatal pore when guard cells swell with water?
- It closes
- It opens
- It remains unchanged
- It disappears
Explanation: When water flows into guard cells, they swell and become turgid. This causes the stomatal pore to open. When the guard cells shrink, the pore closes.
Question 9: Which plant tissue transports water and minerals from roots to other parts?
- Phloem
- Xylem
- Parenchyma
- Collenchyma
Explanation: Xylem is the plant tissue that transports water and minerals obtained from the soil to all parts of the plant. Phloem transports products of photosynthesis (food) from leaves to other parts.
Question 10: What happens during the process of selective reabsorption in nephrons?
- All substances are removed from filtrate
- Useful substances like glucose are reabsorbed
- Only water is reabsorbed
- No reabsorption occurs
Explanation: During urine formation, some substances in the initial filtrate such as glucose, amino acids, salts, and a major amount of water are selectively reabsorbed as the urine flows along the nephron tubule.