NCERT Solutions Class 10 Science Chapter 5 – Life Processes
NCERT Solutions for Class 10 Science Chapter 5: Life Processes
Life Processes is one of the most important chapters in Biology, covering the essential functions that keep organisms alive. This chapter discusses nutrition, respiration, transportation, and excretion in plants and animals. Expect 8-10 marks from this chapter in board exams.
In-text Questions and Answers
Page 95 Questions
Q1. Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?
Answer: Diffusion is a slow process suitable only for short distances. In multicellular organisms like humans:
- Body size is large, so all cells are not in direct contact with the external environment
- The volume of the body is much larger compared to surface area
- Oxygen would take too long to reach deep-seated tissues by diffusion alone
- Therefore, specialized respiratory and circulatory systems are needed to transport oxygen quickly to all cells
Q2. What criteria do we use to decide whether something is alive?
Answer: The primary criterion to determine if something is alive is the presence of life processes:
- Movement: Molecular movements inside cells (even if external movement is absent)
- Nutrition: Intake and utilization of food
- Respiration: Exchange of gases and energy release
- Growth: Increase in size and cell number
- Excretion: Removal of metabolic wastes
- Response to stimuli: Reaction to environmental changes
Page 101 Questions
Q1. What are the differences between autotrophic nutrition and heterotrophic nutrition?
| Autotrophic Nutrition | Heterotrophic Nutrition |
|---|---|
| Organisms prepare their own food | Organisms depend on others for food |
| Use CO₂ and H₂O as raw materials | Use complex organic compounds |
| Require chlorophyll | No chlorophyll needed |
| Food is prepared in presence of sunlight | Can obtain food anytime |
| Examples: Green plants, algae | Examples: Animals, fungi, bacteria |
Q2. Where do plants get each of the raw materials required for photosynthesis?
Answer:
- Carbon dioxide: From atmosphere through stomata in leaves
- Water: From soil through roots and transported via xylem
- Sunlight: From the sun, absorbed by chlorophyll
- Chlorophyll: Present in chloroplasts of green plant cells
Exercise Questions
Q1. The kidneys in human beings are a part of the system for:
(a) nutrition (b) respiration (c) excretion (d) transportation
Answer: (c) excretion
Explanation: Kidneys are the main excretory organs that filter blood and remove nitrogenous wastes (urea, uric acid) in the form of urine.
Q2. The xylem in plants is responsible for:
(a) transport of water (b) transport of food (c) transport of amino acids (d) transport of oxygen
Answer: (a) transport of water
Explanation: Xylem tissue transports water and dissolved minerals from roots to all parts of the plant. Phloem transports food (sucrose) from leaves to other parts.
Q3. The autotrophic mode of nutrition requires:
(a) carbon dioxide and water (b) chlorophyll (c) sunlight (d) all of the above
Answer: (d) all of the above
Explanation: Photosynthesis (autotrophic nutrition) requires CO₂, H₂O, chlorophyll, and sunlight. The equation is: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
Human Digestive System Summary
| Organ | Enzyme/Secretion | Function |
|---|---|---|
| Mouth | Salivary amylase | Breaks starch into maltose |
| Stomach | Pepsin, HCl | Protein digestion begins |
| Liver | Bile | Emulsifies fats |
| Pancreas | Trypsin, Lipase, Amylase | Digests proteins, fats, carbs |
| Small Intestine | Intestinal juice | Complete digestion & absorption |
| Large Intestine | – | Water absorption, feces formation |
Key Takeaways
- Life processes are essential maintenance functions for survival
- Photosynthesis converts light energy to chemical energy in glucose
- Respiration releases energy from glucose (aerobic produces 38 ATP, anaerobic produces 2 ATP)
- Human digestive system mechanically and chemically breaks down food
- Double circulation in humans: pulmonary (heart-lungs) and systemic (heart-body)
- Kidneys filter blood, forming urine containing urea and excess salts
- Plants excrete through stomata, bark, and falling leaves
Key Concepts: Life Processes
Life Processes is one of the most important chapters in Class 10 Biology. It explains the basic functions that keep living organisms alive — nutrition, respiration, transportation, and excretion.
Nutrition
Nutrition is the process of obtaining energy from food. Two main types:
- Autotrophic Nutrition: Organisms make their own food (e.g., plants via photosynthesis). Equation: 6CO2 + 6H2O + Sunlight → C6H12O6 + 6O2
- Heterotrophic Nutrition: Organisms consume other organisms. Types include holozoic (animals), saprotrophic (fungi), and parasitic nutrition.
Human Digestive System: Mouth (saliva — amylase breaks starch) → Oesophagus → Stomach (HCl + pepsin digest proteins) → Small intestine (bile from liver emulsifies fats; pancreatic enzymes — lipase, trypsin, amylase) → Large intestine (water absorption) → Rectum → Anus.
Respiration
Respiration is the process of breaking down glucose to release energy (ATP).
- Aerobic Respiration: Uses oxygen. Complete breakdown of glucose: C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy (38 ATP). Occurs in mitochondria.
- Anaerobic Respiration: Without oxygen. In yeast: glucose → ethanol + CO2 + small energy. In muscles: glucose → lactic acid + small energy (causes cramps after intense exercise).
Transportation in Humans
The human circulatory system consists of the heart, blood, and blood vessels.
- Heart: 4-chambered pump (2 auricles + 2 ventricles). Pumps oxygenated blood (left side) and deoxygenated blood (right side).
- Blood vessels: Arteries carry blood away from heart (oxygenated, except pulmonary artery). Veins carry blood to heart (deoxygenated, except pulmonary vein). Capillaries allow exchange of materials.
- Lymphatic system: Drains excess fluid from tissues back into blood.
- Transportation in plants: Xylem transports water and minerals from roots to leaves. Phloem transports prepared food (sucrose) from leaves to all parts (translocation).
Excretion
Excretion is the removal of metabolic waste products from the body.
- Human excretory system: Kidneys (filter blood to form urine — water, urea, salts) → Ureters → Urinary bladder → Urethra
- Nephron: Structural and functional unit of kidney. Filtration → Reabsorption → Tubular secretion → Urine formation
- Dialysis: Artificial kidney function for kidney failure patients
- Excretion in plants: CO2 (respiration waste) released through stomata; excess water released through transpiration; waste stored in leaves (shed seasonally)
Important Board Exam Questions
- What is the role of HCl in the stomach?
- Why is the small intestine longer than the large intestine?
- Differentiate between aerobic and anaerobic respiration.
- What is the role of bile? Where is it produced and stored?
- Draw and label the human heart.
- What is the difference between arteries and veins?
- Explain the process of urine formation in nephrons.
- What is the difference between xylem and phloem?
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