Class 10 Science Chapter 5 Life Processes NCERT Solutions 2026 PDF Download

Ans:

• Autotrophic: Organisms synthesize their own food using simple inorganic substances ($CO_2, H_2O$) and sunlight. Example: Green Plants.
• Heterotrophic: Organisms depend on other organisms for food. They consume complex organic substances. Example: Animals, Fungi.

Ans: 1. Carbon Dioxide: From the atmosphere through stomata.
2. Water: Absorbed from the soil by roots.
3. Sunlight: Absorbed by chlorophyll in leaves.
4. Nutrients (N, P, Fe, Mg): Absorbed from the soil.

Ans: Hydrochloric Acid (HCl) in the stomach:
1. Creates an acidic medium required for the enzyme Pepsin to digest proteins.
2. Kills harmful bacteria entering with food.

Ans: Digestive enzymes are biological catalysts that break down complex, insoluble food molecules into simple, soluble molecules that can be absorbed by the blood.
Ex: Amylase breaks starch, Lipase breaks fats, Trypsin breaks proteins.

Ans: The inner lining of the small intestine has millions of tiny finger-like projections called Villi. These villi:
1. Increase the surface area for maximum absorption.
2. Are richly supplied with blood vessels to transport absorbed food to every cell of the body.

Ans: Terrestrial organisms breathe oxygen from the atmosphere (21% $O_2$), whereas aquatic organisms use oxygen dissolved in water (low concentration). Since the amount of dissolved oxygen is low, aquatic animals have to breathe much faster than terrestrial animals to get enough oxygen.

Ans: 1. Heart: Pumps blood to all parts of the body.
2. Blood: Transport medium. RBCs carry Oxygen; Plasma carries food, $CO_2$, and waste; Platelets help in clotting.
3. Blood Vessels: Arteries carry blood away from the heart; Veins bring blood back to the heart; Capillaries allow exchange of materials.

Ans: Nephron is the structural unit of the kidney. It consists of a cup-shaped Bowman’s capsule containing a cluster of capillaries called Glomerulus.
Function: Blood is filtered in the Glomerulus under high pressure. Useful substances (Glucose, amino acids, salts, water) are reabsorbed in the tubular part, and waste (Urea, excess salts) is left behind as urine.

Ans: Bile Juice (secreted by Liver, stored in Gall Bladder):
1. Makes the acidic food coming from the stomach alkaline for pancreatic enzymes to act.
2. Performs Emulsification of fats (breaks large fat globules into smaller ones) for easier digestion by lipase.

Ans: Aquatic animals utilize oxygen dissolved in water. The amount of dissolved oxygen in water is fairly low compared to the amount of oxygen in the air. Therefore, they breathe faster to absorb the required amount of oxygen.

Ans: Veins carry blood from body parts back to the heart. The blood pressure in veins is low. To prevent the backflow of blood (due to gravity), veins possess valves. Arteries do not need valves as blood flows under high pressure from the heart.

Ans:

• Xylem: Transports water and minerals from roots to leaves. Flow is unidirectional (upwards).
• Phloem: Transports food (sucrose) from leaves to other parts (Translocation). Flow is bidirectional.

Ans: Loss of water in the form of vapour from the aerial parts of the plant (stomata).
Functions:
1. Helps in the absorption and upward movement of water and minerals (Transpiration pull).
2. Helps in temperature regulation (cooling effect).

Ans: Glucose (6-Carbon) is first broken down into Pyruvate (3-Carbon) in the cytoplasm (Glycolysis).
1. Absence of Oxygen (Yeast): Pyruvate → Ethanol + $CO_2$ + Energy (Fermentation).
2. Lack of Oxygen (Muscle Cells): Pyruvate → Lactic Acid + Energy (Causes cramps).
3. Presence of Oxygen (Mitochondria): Pyruvate → $CO_2$ + $H_2O$ + High Energy.

Ans: Blood flows through the heart twice in one cycle:
1. Pulmonary Circulation: Deoxygenated blood moves from Heart (Right Ventricle) to Lungs and Oxygenated blood returns to Heart (Left Atrium).
2. Systemic Circulation: Oxygenated blood moves from Heart (Left Ventricle) to Body and Deoxygenated blood returns to Heart (Right Atrium).
Significance: It separates oxygenated and deoxygenated blood, ensuring highly efficient oxygen supply for energy production (essential for warm-blooded animals).

Ans: Stomata are tiny pores surrounded by two kidney-shaped Guard Cells.
Opening: When water flows into guard cells, they swell and become turgid, causing the pore to open.
Closing: When guard cells lose water, they shrink and become flaccid, causing the pore to close.

Ans: Atria only have to pump blood to the adjacent ventricles. Ventricles, however, have to pump blood to distinct organs (Right Ventricle to Lungs, Left Ventricle to entire Body) under high pressure. Hence, they have thicker, more muscular walls to withstand the pressure.

Ans: Bacteria present in the mouth act on sugars left from food to produce acids. This acid lowers the pH of the mouth below 5.5, demineralizing the tooth enamel (calcium hydroxyapatite) and causing cavities.

Ans: 1. Colour: Blood is red (due to Haemoglobin); Lymph is colourless/pale yellow.
2. Composition: Lymph contains less protein than blood and lacks RBCs.
3. Function: Blood transports gases and nutrients; Lymph carries digested fat and drains excess tissue fluid back to blood.

Ans: It is a medical device used to filter the blood of a person whose kidneys have failed. It removes nitrogenous waste (Urea) from the blood via dialysis fluid, which has the same osmotic pressure as blood but lacks nitrogenous waste.

Ans: Haemoglobin. It is found in the Red Blood Corpuscles (RBCs). It has a very high affinity for Oxygen.

Ans: The transport of soluble products of photosynthesis (food/sucrose) from the leaves to other parts of the plant (storage organs, roots, fruits) via the Phloem tissue is called Translocation.

Ans: Rings of Cartilage present in the throat/trachea ensure that the air passage does not collapse when the air pressure drops during exhalation.