Life Processes — Previous Year Questions (Class 10 Science)
Life Processes covers nutrition, respiration, transport, and reproduction in living organisms. It explains how organisms obtain and utilize energy and main
TL;DR: Life Processes covers nutrition, respiration, transport, and reproduction in living organisms. It explains how organisms obtain and utilize energy and…
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Life Processes covers nutrition, respiration, transport, and reproduction in living organisms. It explains how organisms obtain and utilize energy and main
Life Processes — Previous Year Questions with Solutions
Q (2023, 3 marks): Define nutrition. Distinguish between autotrophic and heterotrophic nutrition.
Answer: Nutrition is the process by which organisms obtain and utilize food for energy, growth, and repair.
Autotrophic nutrition:
- Organisms that can manufacture their own food
- Occur in plants and some bacteria
- Use sunlight energy in photosynthesis
- Example: Green plants synthesize glucose from CO2 and H2O
Heterotrophic nutrition:
- Organisms that cannot manufacture their own food
- Depend on other organisms for food
- Occur in animals and most bacteria
- Types: holozoic (ingestion and digestion), saprophytic (feeding on dead organic matter)
- Example: Humans, animals, fungi
Q (2022, 3 marks): Write the equation for aerobic respiration. Where does each stage occur in the cell?
Answer: Aerobic respiration equation:
C6H12O6 + 6O2 → 6CO2 + 6H2O + energy (38 ATP)
Stages and location:
1. Glycolysis: Occurs in cytoplasm
Glucose → 2 Pyruvate + 2 ATP + 2 NADH
2. Link reaction (Pyruvate oxidation): Occurs in mitochondrial matrix
Pyruvate → Acetyl-CoA + NADH + CO2
3. Krebs cycle (Citric acid cycle): Occurs in mitochondrial matrix
Produces CO2, NADH, FADH2, ATP
4. Electron transport chain: Occurs on inner mitochondrial membrane
NADH and FADH2 oxidized to produce maximum ATP
Q (2023, 2 marks): What is photosynthesis? Write the overall equation.
Answer: Photosynthesis is the process by which plants, algae, and some bacteria use sunlight energy to synthesize glucose from carbon dioxide and water, releasing oxygen as a byproduct.
Overall equation:
6CO2 + 6H2O + light energy → C6H12O6 + 6O2
This occurs in the chloroplasts of plants in two stages:
1. Light-dependent reactions (in thylakoid membrane)
2. Light-independent reactions/Calvin cycle (in stroma)
Q (2021, 3 marks): Explain the path of blood flow in the human circulatory system.
Answer: Blood circulation path:
Oxygen-rich blood (from lungs) → enters left atrium → passes through mitral valve → enters left ventricle → pumped out through aorta → to body tissues
Oxygen-poor blood (from body) → returns via superior and inferior vena cava → enters right atrium → passes through tricuspid valve → enters right ventricle → pumped to lungs through pulmonary artery
In lungs: CO2 is released, O2 is picked up → blood returns to left atrium via pulmonary veins
One complete cycle = systemic circulation + pulmonary circulation
Heart rate: 72 beats per minute (average adult)
Q (2022, 2 marks): What are the different modes of reproduction in animals? Give examples.
Answer: Modes of reproduction in animals:
1. Asexual reproduction:
- Budding: Hydra, yeast
- Binary fission: Bacteria, amoeba
- Fragmentation: Starfish, some worms
2. Sexual reproduction:
- Involves fusion of male and female gametes
- Examples: Most animals including mammals, birds, reptiles, fish
Q (2023, 3 marks): Describe the structure and function of the human kidney.
Answer: Structure of kidney:
- Bean-shaped organ, about 10 cm long
- Outer cortex, inner medulla, and pelvis
- Contains about 1 million functional units called nephrons
Function:
1. Excretion: Removes nitrogenous waste (urea) from blood
2. Osmoregulation: Maintains water and salt balance
3. Maintains blood pressure through fluid regulation
Urine formation (three steps):
1. Ultrafiltration: In Bowman's capsule, small molecules filtered from blood
2. Selective reabsorption: In proximal convoluted tubule, useful substances reabsorbed
3. Tubular secretion: In distal convoluted tubule, excess ions secreted
Final urine stored in bladder and excreted
Frequently Asked Questions
What is the difference between respiration and photosynthesis?
Respiration: Breaks down glucose to release energy (catabolic). Occurs in all cells. Produces CO2 and H2O. Energy stored in ATP. Photosynthesis: Builds glucose using light energy (anabolic). Occurs in green plants. Uses CO2 and H2O. Produces O2 as byproduct.
Why are arteries and veins structurally different?
Arteries carry high-pressure blood and have thick, elastic muscular walls to withstand pressure. Veins carry low-pressure blood and have thin walls. Veins have valves to prevent backflow of blood.
More Class 10 Science PYQs
- Chemical Reactions and Equations
- Light (Reflection and Refraction)
- Electricity
- Acids, Bases and Salts
- Metals and Non-metals
- Heredity and Evolution
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