Quick Revision Notes: Class 10 Science

Chapter: Life Processes (जैव प्रक्रम)

Definition: The basic processes/functions performed by living organisms to maintain their life on Earth and prevent damage and breakdown are called Life Processes.
Core Life Processes: Nutrition, Respiration, Transportation, and Excretion.

Nutrition is the process of intake of nutrients (food) and its utilization by the body.

Modes of Nutrition:
1. Autotrophic (स्वपोषी): Organisms synthesize their own food from simple inorganic substances (e.g., Green plants, algae).
  - Photosynthesis Equation: 6CO_2 + 12H_2O + \text{Sunlight} + \text{Chlorophyll} \rightarrow C_6H_{12}O_6 + 6O_2 + 6H_2O
2. Heterotrophic (विषमपोषी): Organisms depend on other organisms for food.
  - Holozoic (प्राणसम): Complex food is ingested and digested internally (e.g., Amoeba, Humans).
  - Saprophytic (मृतजीवी): Feed on dead and decaying matter (e.g., Fungi, Bacteria).
  - Parasitic (परजीवी): Live on/inside other living hosts and derive nutrients without killing them immediately (e.g., Cuscuta, Cuscuta, Lice).
Nutrition in Human Beings (Human Alimentary Canal):
- Mouth: Saliva contains Salivary Amylase which converts Starch into Sugar.
- Stomach: Secretes Gastric juices containing:
  - Hydrochloric Acid (HCl): Creates acidic medium and kills germs.
  - Pepsin: Digests proteins.
  - Mucus: Protects the inner lining of the stomach.
- Small Intestine: Site of complete digestion of carbohydrates, proteins, and fats. Receives secretions from:
  - Liver: Bile juice (emulsifies fats).
  - Pancreas: Trypsin (for proteins) and Lipase (for fats).
- Villi: Finger-like projections in the small intestine that increase surface area for the absorption of digested food.

The process by which absorbed food is broken down in cells to release energy (in the form of ATP).

Breakdown of Glucose via Pathways:
1. Glucose (6-carbon molecule) $\xrightarrow{\text{Cytoplasm}}$ Pyruvate (3-carbon molecule) + Energy
2. Absence of Oxygen (in Yeast - Anaerobic): Ethanol + Carbon Dioxide + Energy
3. Lack of Oxygen (in Human Muscle cells during vigorous exercise): Lactic Acid + Energy (causes muscle cramps)
4. Presence of Oxygen (in Mitochondria - Aerobic): Carbon Dioxide + Water + Energy
Key Differences:
- Aerobic Respiration: Occurs in presence of $O_2$, high energy release, end products are $CO_2$ and $H_2O$.
- Anaerobic Respiration: Occurs in absence of $O_2$, low energy release, end products include alcohol or lactic acid.
ATP (Adenosine Triphosphate): The energy currency of the cell.

Transportation in Plants:
- Xylem (जाइलम): Transports water and minerals from roots to other parts of the plant. (Unidirectional)
- Phloem (फ्लोएम्): Transports food (sugars) from leaves to other parts of the plant. (Bidirectional)
- Transpiration: Loss of water in the form of vapor from the aerial parts of plants. Helps in upward suction of water and minerals.
Transportation in Humans (Human Circulatory System):
- Heart: A muscular pumping organ. It has 4 chambers (2 Atria and 2 Ventricles) to prevent mixing of oxygenated and deoxygenated blood.
- Blood Vessels:
  - Arteries: Carry oxygenated blood away from the heart to body organs (except Pulmonary artery). Thick, elastic walls.
  - Veins: Carry deoxygenated blood from organs back to the heart (except Pulmonary vein). Thin walls with valves.
  - Capillaries: Extremely thin vessels where exchange of materials between blood and cells takes place.
- Double Circulation: Blood passes through the heart twice in one complete cycle of the body (Systemic and Pulmonary circulation). This is found in birds and mammals.
- Blood Platelets: Help in blood clotting at the site of an injury.
- Lymph: Another fluid involved in transportation; carries digested and absorbed fat from intestine and drains excess fluid from extracellular space back into the blood.

The biological process of removal of harmful metabolic wastes from the body.

Excretion in Human Beings:
- Main excretory organs: A pair of Kidneys, Ureters, Urinary Bladder, and Urethra.
- Nephron: The basic structural and functional filtration unit of the kidney.
- Mechanism of Urine Formation in Nephron:
  1. Glomerular Filtration: Blood is filtered under high pressure in the Bowman's capsule.
  2. Tubular Reabsorption: Useful materials like glucose, amino acids, salts, and major amount of water are selectively reabsorbed as the filtrate flows along the tubule.
  3. Secretion: Extra salts and $H^+$ ions are secreted into the tubule. Urine is finally collected in the urinary bladder.
Excretion in Plants:
- Plants get rid of excess water by transpiration.
- Waste products may be stored in leaves that fall off, in cellular vacuoles, or as resins and gums in old xylem. Some waste substances are excreted into the soil.

Always draw clean, well-labeled diagrams for Human Alimentary Canal, Human Heart, and Nephron for high-scoring answers.
Remember the word equations for Photosynthesis and the 3 pathways of Glucose breakdown; they are frequently asked in 2-3 mark questions.
Understand the distinction between Xylem and Phloem, and Arteries and Veins in tabular form.