Here are the clear, correct answers to your Class 10 Science (NCERT, CBSE) — Life Processes (Nutrition, Respiration, Transportation & Excretion) questions:
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📘 Life Processes — Answers
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✅ Q1.
The kidneys in human beings are part of:
🎯 (c) excretion.
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✅ Q2.
The xylem in plants is responsible for:
🎯 (a) transport of water.
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✅ Q3.
Autotrophic nutrition requires:
🎯 (d) all of the above (CO₂, water, chlorophyll, sunlight).
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✅ Q4.
Breakdown of pyruvate to CO₂, water & energy occurs in:
🎯 (b) mitochondria.
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✅ Q5.
How are fats digested? Where?
• Fats are broken down into fatty acids & glycerol by lipase.
• Bile salts (from the liver) emulsify fats into tiny droplets → easier for enzymes.
• This happens in the small intestine.
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✅ Q6.
Role of saliva:
• Contains enzyme salivary amylase, which converts starch → sugars.
• Makes food moist & easier to swallow.
• Slightly alkaline, helps digestion.
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✅ Q7.
Conditions for autotrophic nutrition:
• Carbon dioxide
• Water
• Chlorophyll
• Sunlight
By-products:
• Oxygen
• Glucose
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✅ Q8.
Aerobic vs Anaerobic respiration:
Feature Aerobic Anaerobic
Oxygen required? Yes No
Products CO₂ + water + energy Alcohol/lactic acid + less energy
Energy produced High Low
Examples of anaerobes:
• Yeast, some bacteria, muscle cells (temporarily).
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✅ Q9.
How alveoli maximise gas exchange:
• Millions of alveoli → very large surface area.
• Thin walls → easy diffusion.
• Surrounded by capillaries → efficient transport of gases.
• Moist surface → helps dissolve gases.
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✅ Q10.
Consequence of haemoglobin deficiency:
• Less oxygen carried in blood.
• Fatigue, weakness → condition called anaemia.
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✅ Q11.
Double circulation:
• Blood passes through heart twice in one full cycle:
1️⃣ Pulmonary circulation (heart → lungs → heart)
2️⃣ Systemic circulation (heart → body → heart)
• Necessary because it separates oxygen-rich & oxygen-poor blood → efficient oxygen delivery.
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✅ Q12.
Transport in xylem vs phloem:
Feature Xylem Phloem
Transport what? Water & minerals Food (sugars)
Direction Upwards only Both directions
Living/dead? Mostly dead cells Living cells
Energy? Passive process Requires energy
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✅ Q13.
Alveoli vs Nephrons — Structure & Function:
Feature Alveoli (Lungs) Nephrons (Kidneys)
Function Gas exchange (O₂ & CO₂) Filtration of blood, urine formation
Structure Thin-walled sacs, huge surface area Tiny tubules with glomerulus & tubules
Transport medium Blood (capillaries) Blood (capillaries) & urine
Efficiency Maximised by large area & thin walls Maximised by filtration, reabsorption
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