Life Processes (Class 10): Notes और MCQ Practice

आसान भाषा में

Life Processes वो basic biological activities हैं जो किसी भी living organism को ज़िंदा रखने और body maintenance के लिए जरूरी होती हैं। इस chapter में 4 major processes हैं: Nutrition (food से nutrients लेना), Respiration (nutrients से ATP energy बनाना), Transportation (substances का transport), और Excretion (toxic wastes को बाहर निकालना)।

Important Definitions & Reactions

1. Photosynthesis Equation:

6CO₂ + 12H₂O + Sunlight + Chlorophyll → C₆H₁₂O₆ + 6O₂ + 6H₂O

1. Breakdown of Glucose:

• Cytoplasm: Glucose (6C) → Pyruvate (3C)
• Yeast (Absence of O₂): Ethanol + CO₂ + Energy
• Muscle cells (Lack of O₂): Lactic acid + Energy (cramps का कारण)
• Mitochondria (Presence of O₂): CO₂ + H₂O + Energy (ATP)

1. Digestion Enzymes: Mouth में Salivary Amylase (Starch → Sugar), Stomach में Pepsin (Proteins), Small Intestine में Trypsin (Proteins) और Lipase (Emulsified Fats)।
2. Transportation:

• Xylem: Water & minerals transport (unidirectional, passive suction).
• Phloem: Food/Sucrose transport (bidirectional translocation, needs ATP).

1. Excretion (Nephron): Glomerular Filtration → Selective Reabsorption (glucose, amino acids, salts, water) → Urine formation.

2 Memory Tricks

• A for Artery = Away: Arteries carry blood Away from heart (thick-walled). Veins bring blood towards the heart (have Valves).
• Xy-Phy (ज़ाई-फाई) Trick: Xylem = Jal (Water) transport; Phloem = Food transport.

2 Common Board Mistakes

1. Pulmonary Artery vs Vein Exception: अक्सर बच्चे भूल जाते हैं कि normal arteries oxygenated blood ले जाती हैं, लेकिन Pulmonary Artery deoxygenated blood (heart to lungs) ले जाती है और Pulmonary Vein oxygenated blood लाती है।
2. Lactic Acid vs Ethanol: Muscle cells के anaerobic respiration में CO₂ नहीं बनती (केवल Lactic acid + Energy), जबकि Yeast fermentation में CO₂ release होती है।

Life Processes - Class 10 Notes

1. Chapter in Short

All living organisms perform basic maintenance functions to stay alive, repair tissues, and prevent damage, even when resting. These maintenance jobs are called Life Processes.

This chapter covers four essential processes:

1. Nutrition: Taking in food and converting it into energy and raw materials for body building.
2. Respiration: Breaking down nutrients inside cells using oxygen to release usable energy (ATP).
3. Transportation: Moving nutrients, gases, and waste products from one part of the body to another.
4. Excretion: Filtering and removing toxic metabolic waste products out of the body.

2. Key Concepts Explained Simply

A. Nutrition

• Autotrophic Nutrition (Plants): Plants prepare their own food using carbon dioxide, water, and sunlight trapped by chlorophyll.
• Photosynthesis Events:

1. Absorption of light energy by chlorophyll.
2. Conversion of light energy into chemical energy and splitting of water molecules into hydrogen and oxygen.
3. Reduction of carbon dioxide to carbohydrates.

• Stomata: Tiny pores on leaves guarded by kidney-shaped guard cells. Guard cells swell when water flows into them, opening the pore; they shrink when water leaves, closing the pore.

• Heterotrophic Nutrition (Animals & Fungi): Living beings that depend on others for food.
• Amoeba: Captures food using temporary finger-like projections called pseudopodia, forms a food vacuole, digests it inside the cell, and throws out undigested waste.
• Human Digestive System:
• Mouth: Teeth chew food. Saliva contains salivary amylase which breaks starch into simple sugars.
• Oesophagus (Food Pipe): Pushes food downward by rhythmic wave-like contractions called peristaltic movements.
• Stomach: Secretes gastric juice containing:
• Hydrochloric acid (HCl): Creates an acidic medium for pepsin to act and kills bacteria.
• Pepsin: Digests proteins.
• Mucus: Protects the inner stomach lining from being eroded by HCl.
• Small Intestine (Site of complete digestion):
• Liver: Produces bile juice, which makes food alkaline and breaks large fat globules into smaller droplets (emulsification).
• Pancreas: Secretes pancreatic juice with trypsin (digests proteins) and lipase (digests emulsified fats).
• Intestinal enzymes: Convert carbohydrates to glucose, proteins to amino acids, and fats to fatty acids and glycerol.
• Villi: Millions of tiny finger-like projections in the inner wall of the small intestine that increase surface area for maximum absorption into blood vessels.
• Large Intestine: Absorbs excess water from unabsorbed food; remainder is expelled through the anus (egestion).

B. Respiration

Respiration is not just breathing; it is the breakdown of glucose inside cells to release energy.

• Breakdown of Glucose:
• In cytoplasm: Glucose (6-carbon molecule) is split into Pyruvate (3-carbon molecule).
• Pathway 1 (Absence of Oxygen - Anaerobic in Yeast): Pyruvate converts into Ethanol + Carbon dioxide + Energy (Fermentation).
• Pathway 2 (Lack of Oxygen - In Human Muscle Cells during heavy exercise): Pyruvate converts into Lactic acid + Energy. Accumulation of lactic acid causes painful muscle cramps.
• Pathway 3 (Presence of Oxygen - Aerobic in Mitochondria): Pyruvate converts into Carbon dioxide + Water + Lots of Energy.
• Human Respiratory System: Air passes through nostrils -> pharynx -> larynx -> trachea (supported by rings of cartilage so it does not collapse) -> bronchi -> bronchioles -> alveoli.
• Alveoli: Balloon-like structures providing a vast surface area surrounded by blood capillaries for gas exchange.
• Respiratory pigment: Haemoglobin in Red Blood Cells binds to oxygen and transports it because oxygen has low solubility in water.

C. Transportation

• In Humans:
• The Heart: A 4-chambered muscular pump.
• Right side: Receives deoxygenated blood from the body and sends it to the lungs.
• Left side: Receives oxygenated blood from the lungs and pumps it to the whole body.
• Separation of left and right sides prevents mixing of oxygenated and deoxygenated blood, ensuring high energy efficiency.
• Double Circulation: Blood travels through the heart twice during each complete cycle (Pulmonary circulation: Heart -> Lungs -> Heart; Systemic circulation: Heart -> Body -> Heart).
• Blood Vessels:
• Arteries: Thick, elastic walls; carry blood away from the heart under high pressure (no valves needed).
• Veins: Thin walls; carry blood back to the heart under low pressure; have valves to prevent backflow.
• Capillaries: Extremely thin, one-cell-thick walls for material exchange.
• Lymph: A pale fluid containing white blood cells that drains extracellular fluid back into the blood and carries digested fat.
• In Plants:
• Xylem: Transports water and minerals upward from roots. Driven by root pressure and transpiration pull (suction caused by evaporation of water from leaves).
• Phloem: Transports soluble products of photosynthesis (food/sucrose) from leaves to all growing parts (Translocation). It requires energy in the form of ATP.

D. Excretion

Removal of toxic nitrogenous wastes (like urea and uric acid) produced by cellular activities.

• Human Excretory System: Pair of kidneys -> pair of ureters -> urinary bladder -> urethra.
• Nephron (Functional filtration unit of kidney):
• Bowman's capsule & Glomerulus: High-pressure filter where initial filtrate (glucose, amino acids, salts, water, urea) is collected.
• Tubule: Useful substances (all glucose, amino acids, major water and salts) are selectively reabsorbed back into capillaries.
• Remaining fluid forms urine, which collects in the urinary bladder.
• Excretion in Plants: Plants excrete oxygen (byproduct of photosynthesis), excess water (via transpiration), store wastes in leaves that fall off, or store them as resins and gums in old xylem.

3. Important Definitions, Reactions, and Facts

• Photosynthesis Equation:

6CO2 + 12H2O + Sunlight (absorbed by Chlorophyll) -> C6H12O6 (Glucose) + 6O2 + 6H2O

• Cellular Energy Currency: ATP (Adenosine Triphosphate).

• Emulsification: The breakdown of large fat globules into smaller globules by bile salts, increasing enzyme efficiency.

• Peristalsis: Rhythmic muscular contractions and relaxations of the gut wall that push food forward.

• Normal Human Blood Pressure: 120/80 mm of Hg (120 mm Hg systolic pressure / 80 mm Hg diastolic pressure), measured using a sphygmomanometer.

• Translocation: The transport of soluble products of photosynthesis through phloem using energy (ATP).

• Dialysis (Artificial Kidney): A medical procedure to clean the blood of a patient suffering from kidney failure using a semi-permeable dialysing fluid.

4. Solved Board-Exam Style Questions

Q1. Why is double circulation necessary in human beings?

Answer:

1. Humans are warm-blooded animals that need constant body temperature maintenance, which demands high amounts of energy.
2. Double circulation completely separates oxygen-rich blood from carbon-dioxide-rich blood.
3. This separation prevents mixing and ensures a highly efficient supply of oxygen to all body tissues.

Q2. How are the alveoli in lungs and nephrons in kidneys similarly designed for their functions?

Answer:

• Enormous Surface Area: Alveoli have balloon-like folding surfaces for gas exchange; nephrons have long, coiled tubular structures and glomerulus tufts for filtration.
• Rich Capillary Network: Both are surrounded by an extensive network of extremely thin blood capillaries.
• Thin Membranes: Both have very thin single-layered cellular walls to facilitate rapid diffusion and filtration.

Q3. Write the three pathways of glucose breakdown inside living cells.

Answer:

1. In cytoplasm: Glucose (6-carbon) splits into Pyruvate (3-carbon) + Energy.
2. Pathway A (Yeast - Anaerobic): Pyruvate -> Ethanol + CO2 + Energy
3. Pathway B (Human muscle cells during heavy work - Lack of O2): Pyruvate -> Lactic acid + Energy
4. Pathway C (Mitochondria - Aerobic): Pyruvate + O2 -> CO2 + H2O + Large amount of Energy

Q4. What will happen if the mucus is not secreted by the gastric glands in the stomach?

Answer:

The gastric glands secrete hydrochloric acid (HCl) along with pepsin. If mucus is not secreted, the inner lining of the stomach will not be protected from the corrosive action of hydrochloric acid. This will lead to erosion of the stomach lining and the formation of painful ulcers.

5. Common Mistakes and Quick Revision Points

• Mistake 1: Writing that all arteries carry oxygenated blood and all veins carry deoxygenated blood.
• Correction: The pulmonary artery carries deoxygenated blood (heart to lungs), and the pulmonary vein carries oxygenated blood (lungs to heart).
• Mistake 2: Confusing Excretion with Egestion.
• Correction: Egestion is the removal of undigested solid food waste through the anus. Excretion is the removal of nitrogenous metabolic wastes (like urea) generated inside cells.
• Mistake 3: Thinking plant transport in xylem requires ATP.
• Correction: Transport of water in xylem is mostly a physical passive process driven by transpiration pull and root pressure. Translocation of food in phloem actively uses energy (ATP).
• Quick Revision Tip on Digestive Enzymes:
• Mouth: Starch -> Salivary Amylase -> Maltose.
• Stomach: Proteins -> Pepsin (in acidic medium) -> Peptones.
• Small intestine: Proteins -> Trypsin -> Peptides/Amino acids; Fats -> Lipase -> Fatty acids + Glycerol.