Short Questions Answer
1. What are life processes?
Answer: Life processes are the processes essential for maintaining life, such as nutrition, respiration, transportation, and excretion.
2. What is the source of energy for living organisms?
Answer: The energy for living organisms comes from food.
3. What is autotrophic nutrition?
Answer: It is a mode of nutrition in which organisms prepare their own food using sunlight, carbon dioxide, and water.
4. What is the role of chlorophyll in photosynthesis?
Answer: Chlorophyll absorbs light energy required for photosynthesis.
5. Name the raw materials required for photosynthesis.
Answer: Carbon dioxide and water.
6. What is heterotrophic nutrition?
Answer: It is a mode of nutrition where organisms depend on others for their food.
7. What is peristalsis?
Answer: The rhythmic contraction and relaxation of muscles in the alimentary canal to push food forward.
8. What is the function of bile juice?
Answer: Bile juice emulsifies fats and makes the medium alkaline for enzyme action.
9. Name the enzyme present in saliva.
Answer: Salivary amylase.
10. What is ATP?
Answer: ATP (Adenosine Triphosphate) is the energy currency of the cell.
11. Which respiratory pigment is present in human beings?
Answer: Haemoglobin.
12. What is transpiration?
Answer: The loss of water from plant leaves in the form of water vapour.
13. What is the basic filtration unit of the kidney?
Answer: Nephron.
14. What are the main excretory products in humans?
Answer: Urea, uric acid, and excess water.
15. Name the two conducting tissues in plants.
Answer: Xylem and phloem.
Long Questions Answer
1. Explain the process of photosynthesis.
Answer: Photosynthesis is the process by which green plants prepare food using sunlight, carbon dioxide, and water.
The process involves:
- Absorption of light energy by chlorophyll.
- Conversion of light energy into chemical energy.
- Splitting of water molecules into hydrogen and oxygen.
- Reduction of carbon dioxide to carbohydrates.
The overall equation is:
6CO2+6H2O → C6H12O6+6O2
2. Describe the process of digestion in humans.
Answer:
- Mouth: Food is chewed and mixed with saliva. Salivary amylase breaks starch into sugar.
- Stomach: Gastric glands secrete HCl, pepsin, and mucus. Proteins are digested to peptones.
- Small Intestine: Bile from the liver emulsifies fats; pancreatic enzymes digest proteins, fats, and carbohydrates.
- Large Intestine: Water is absorbed and waste is excreted through the anus.
3. Differentiate between aerobic and anaerobic respiration.
Answer:
| Aspect | Aerobic Respiration | Anaerobic Respiration |
|---|---|---|
| Oxygen Requirement | Occurs in presence of oxygen | Occurs in absence of oxygen |
| End Products | CO₂ and H₂O | Alcohol or lactic acid |
| Energy Produced | Produces more energy | Produces less energy |
| Location | Takes place in mitochondria | Takes place in cytoplasm |
4. Describe the human respiratory system.
Answer: Air enters through nostrils → passes through pharynx → trachea → bronchi → bronchioles → alveoli.
In alveoli, exchange of gases occurs between blood and air. Oxygen is absorbed and carbon dioxide is released. Haemoglobin in red blood cells transports oxygen throughout the body.
5. Explain transportation in human beings.
Answer: The circulatory system consists of the heart, blood, and blood vessels.
- Heart: Pumps blood.
- Arteries: Carry blood from the heart.
- Veins: Bring blood to the heart.
- Capillaries: Allow exchange of materials.
The lymphatic system transports excess fluid and fats. Platelets help in clotting blood.
6. What is double circulation? Why is it necessary?
Answer: Double circulation means blood passes through the heart twice during one complete cycle—once for oxygenation (pulmonary circulation) and once to supply the body (systemic circulation).
It keeps oxygenated and deoxygenated blood separate, ensuring efficient oxygen supply to body tissues.
7. Describe the transportation of water and minerals in plants.
Answer: Water and minerals are absorbed by roots and transported upward through xylem due to root pressure, capillary action, and transpiration pull.
Transpiration creates suction that pulls water upward from roots to leaves.
8. Explain the excretory system in human beings.
Answer: The system consists of two kidneys, two ureters, a urinary bladder, and a urethra.
Kidneys filter nitrogenous wastes like urea and uric acid through nephrons. The filtrate passes through ureters to the bladder, where urine is stored before being released via the urethra.
9. What are nephrons? Describe their structure and function.
Answer: Nephrons are the structural and functional units of kidneys. Each nephron consists of:
- Bowman’s capsule with a cluster of capillaries called glomerulus for filtration.
- Tubules for reabsorption of useful materials.
Function: Filtration of blood, reabsorption of water and salts, and formation of urine.
10. Explain how food is transported in plants.
Answer: Food is transported through the phloem by a process called translocation.
Sucrose and other products of photosynthesis are transferred into phloem using energy from ATP, increasing osmotic pressure. This moves the food from source (leaves) to sink (roots, fruits, seeds).
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