Ch-5: Life Processes (जैव प्रक्रम) 🍎
1. Introduction (प्रस्तावना)
- The basic functions performed by living organisms to maintain life on earth are called Life Processes.
- वे सभी प्रक्रम जो सम्मिलित रूप से अनुरक्षण (Maintenance) का कार्य करते हैं, जैव प्रक्रम कहलाते हैं।
- Key processes: Nutrition, Respiration, Transportation & Excretion.
2. Nutrition (पोषण)
- Energy is needed even when we are resting to maintain our body.
- Autotrophic Nutrition: Organisms use simple inorganic materials ($CO_2$, $H_2O$) + Sunlight.
- उदाहरण: हरे पौधे और कुछ बैक्टीरिया।
Process of Photosynthesis (प्रकाश संश्लेषण)
$6CO_2 + 12H_2O \xrightarrow[\text{Sunlight}]{\text{Chlorophyll}} C_6H_{12}O_6 + 6O_2 + 6H_2O$
- (i) Absorption of light energy by chlorophyll.
- (ii) Conversion of light to chemical energy & splitting of $H_2O$.
- (iii) Reduction of $CO_2$ to Carbohydrates (Glucose).
3. Stomata (रंध्र)
- Tiny pores on leaf surface for gaseous exchange ($O_2$ & $CO_2$).
- Opening & Closing is controlled by Guard Cells.
- Guard cells swell (open) when water flows in, shrink (close) when water flows out.
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4. Heterotrophic Nutrition (विषमपोषी पोषण)
- Organisms depend on others for food.
- Holozoic: Take in solid food (Humans, Amoeba).
- Saprophytic: Feed on dead/decaying matter (Fungi).
- Parasitic: Derive nutrition without killing (Cuscuta, Ticks).
5. Nutrition in Amoeba
Food $\to$ Pseudopodia
(Finger-like)
(Finger-like)
→
Food Vacuole
(Digestion)
(Digestion)
→
Diffusion to
Cytoplasm
Cytoplasm
6. Human Digestive System (पाचन तंत्र)
- Mouth: Salivary Amylase breaks starch $\to$ sugar.
- Stomach: Gastric glands release HCl (acidic medium), Pepsin (digests proteins), & Mucus.
- Small Intestine: Longest part! Site of complete digestion.
- Bile (Liver): Makes medium alkaline & emulsifies fats.
- Pancreatic Juice: Trypsin (Proteins), Lipase (Fats).
- Villi: Finger-like projections for max absorption.
- Large Intestine: Absorbs water. Waste is exit via Anus.
Bio-Catalysts: Enzymes are biological catalysts that break complex food into simple ones.
Ex: Pepsin works only in acidic medium (thanks to HCl).
Ex: Pepsin works only in acidic medium (thanks to HCl).
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7. Respiration (श्वसन)
Breakdown of food (Glucose) to release energy.
Breakdown of Glucose Pathways
Glucose (6-C) $\xrightarrow{\text{Cytoplasm}}$ Pyruvate (3-C) + Energy
Absence of $O_2$ (Yeast)
$\to$ Ethanol + $CO_2$
$\to$ Ethanol + $CO_2$
Lack of $O_2$ (Muscles)
$\to$ Lactic Acid (Cramps!)
$\to$ Lactic Acid (Cramps!)
Presence of $O_2$ (Mitochondria)
$\to$ $CO_2 + H_2O + ATP$
$\to$ $CO_2 + H_2O + ATP$
- ATP: Energy currency of the cell ($30.5$ kJ/mol).
8. Human Respiratory System
- Nostrils: Hairs & mucus filter dust.
- Trachea: Supported by Rings of Cartilage (prevents collapse).
- Alveoli: Balloon-like structures. Max Surface Area! (~80 $m^2$) for gas exchange.
- Mechanism: We lift ribs & flatten Diaphragm $\to$ Chest cavity expands $\to$ Air sucked in.
9. Transportation of Gases
- Oxygen is carried by Haemoglobin (Respiratory Pigment) in RBCs.
- $CO_2$ is more soluble in water, so transported in dissolved form in plasma.
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10. Human Heart (हृदय)
- Muscular organ, size of a fist. 4 chambers to prevent mixing of $O_2$ and $CO_2$ blood.
- Double Circulation: Blood goes through heart Twice in one cycle.
(मनुष्य में दोहरा परिसंचरण होता है।)
11. Blood Vessels & Lymph
- Arteries: Carry blood Away from heart. Thick elastic walls (High pressure).
- Veins: Bring blood To heart. Thin walls, have Valves to prevent backflow.
- Platelets: Help in blood clotting at injury sites.
- Lymph: Colourless fluid, carries digested fats & drains excess fluid.
12. Transport in Plants
- Xylem: Transports Water & Minerals (Upwards). Uses Transpiration Pull.
- Phloem: Transports Food (Photosynthates). Uses Energy (ATP). Translocation!
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13. Human Excretory System (उत्सर्जन तंत्र)
- Main organs: Pair of Kidneys, Ureters, Urinary Bladder, & Urethra.
- Nitrogenous wastes (Urea/Uric acid) are filtered from blood in kidneys.
Structure of a Nephron (वृक्काणु)
“Functional unit of Kidney”
14. Mechanism of Urine Formation
- (i) Filtration: High pressure in Glomerulus.
- (ii) Selective Reabsorption: Glucose, Amino acids, Salts & Water are reabsorbed.
- (iii) Urine: Collected in duct $\to$ Ureter $\to$ Bladder.
15. Excretion in Plants
- $O_2$ is a waste of Photosynthesis!
- Excess water removed via Transpiration.
- Wastes stored in Cellular Vacuoles or as Resins & Gums.
- Lost through falling leaves or excreted into soil.
Dialysis: Artificial kidney used during kidney failure to filter waste from blood via diffusion.
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