Life Processes Class 10 Notes — CBSE Science Chapter 5 Revision Sheet

Essential Exam Glossary

Life Processes

The basic essential functions performed by living organisms to maintain their life on Earth, such as nutrition, respiration, transportation, and excretion.

Autotrophic Nutrition

A mode of nutrition in which organisms synthesize their organic food from simple inorganic raw materials like carbon dioxide and water using sunlight.

Heterotrophic Nutrition

A mode of nutrition where organisms cannot make their own food and must depend directly or indirectly on autotrophs for energy.

Photosynthesis

The photochemical process by which green plants utilize carbon dioxide, water, and sunlight in the presence of chlorophyll to synthesize glucose and release oxygen.

Peristalsis

The rhythmic contraction and expansion of muscles along the wall of the alimentary canal that pushes food forward.

Double Circulation

A system of circulation where blood passes through the heart twice during one complete cycle of body circulation, consisting of pulmonary and systemic circulation.

Translocation

The active transport of soluble products of photosynthesis (food molecules) from leaves to other parts of the plant through the phloem.

Nephron

The microscopic structural and functional filtration unit of the human kidney responsible for urine formation.

Must-Remember Key Concepts

• Organisms use carbon-based food molecules and oxygen to generate energy in the form of ATP via metabolic pathways.
• Photosynthesis involves three steps: absorption of light energy by chlorophyll, conversion of light energy to chemical energy + splitting of water, and reduction of carbon dioxide to carbohydrates.
• In human digestion, salivary amylase starts starch breakdown in the mouth; pepsin digests proteins in the acidic medium of the stomach; trypsin and lipase act in the alkaline small intestine.
• Anaerobic respiration occurs in the cytoplasm of yeast (producing ethanol, CO2, and 2 ATP) and in human muscles during vigorous exercise (producing lactic acid and causing muscle cramps).
• Aerobic respiration occurs in the mitochondria of cells in the presence of oxygen, yielding carbon dioxide, water, and 36-38 molecules of ATP.
• The human heart is 4-chambered (two atria and two ventricles) to keep oxygenated and deoxygenated blood separated, ensuring high efficiency for temperature regulation.
• The human excretory system comprises a pair of kidneys, a pair of ureters, a urinary bladder, and a urethra.
• Plants remove wastes via transpiration (excess water), shedding leaves, storing resins/gums in old xylem, and secreting substances into the surrounding soil.

Deep Dive: Human Alimentary Canal & Digestion

The Human Digestive System consists of a long alimentary canal starting from the mouth and ending at the anus. Digestion begins in the mouth, where food is crushed by teeth and mixed with saliva. Salivary amylase breaks down complex starch into maltose. Food then moves down the esophagus via wave-like peristaltic movements to the stomach. The stomach wall contains gastric glands releasing hydrochloric acid (which creates an acidic medium and kills germs), pepsin (an enzyme digesting proteins), and mucus (which protects the stomach lining from self-digestion). Food next enters the small intestine, the primary site of complete digestion. It receives bile from the liver (which emulsifies fats by breaking down large globules into smaller ones) and pancreatic juice from the pancreas containing trypsin (for protein digestion) and lipase (for fat breakdown). Finger-like projections called villi on the walls of the small intestine increase the surface area to maximize the absorption of digested food into the blood.

Mechanism of Human Respiration

1. Inhalation — The diaphragm flattens, rib muscles contract pulling the chest upwards and outwards, increasing thoracic cavity volume and sucking air rich in oxygen into the lungs.
2. Alveolar Gas Exchange — Oxygen from the alveoli diffuses across the thin membrane into the surrounding capillary blood, while carbon dioxide from the blood diffuses into the alveoli.
3. Internal Oxygen Transport — Oxygen binds to haemoglobin in red blood cells (RBCs) and is carried throughout the body tissues.
4. Cellular Respiration — Cells utilize oxygen to break down glucose into carbon dioxide, water, and energy in the mitochondria.
5. Exhalation — The diaphragm relaxes, arching upwards, and ribs move downwards, compressing the lungs and forcing out air rich in carbon dioxide.

Differences Between Arteries and Veins

Board Exam Traps & High-Yield Areas

1. Equation Warning: Never miss writing the balanced chemical equation for photosynthesis and the breakdown of glucose (the 3 pathways diagram in NCERT) when writing answers. It gets you instant full marks.
2. Active vs. Passive Transport: Remind yourself that transport of water in plants (Xylem) is majorly driven by transpiration pull (passive), whereas food transport in plants (Phloem) is an active process utilizing ATP energy.
3. Labeling Practice: Keep a blank sheet of paper and practice sketching the schematic structure of the human heart, Alimentary Canal, and a single Nephron. Label the glomerulus and Bowman's capsule correctly!

Quick Revision Self-Check

• Why is double circulation necessary in human beings? It completely separates oxygenated and deoxygenated blood, ensuring highly efficient oxygen delivery to body tissues. This is crucial for warm-blooded humans to generate sufficient body heat and maintain constant body temperature.
• What is the function of HCl in our stomach? Hydrochloric acid (HCl) creates an acidic medium necessary for the protein-digesting enzyme pepsin to become active, and it also kills harmful bacteria ingested along with the food.
• How are alveoli (in lungs) and villi (in intestine) structurally similar? Both structures are extremely thin-walled, folded to enormously increase the surface area, and heavily supplied with networks of blood capillaries to optimize rapid transport and exchange.
• What causes muscle cramps during intense exercise? During heavy physical activity, insufficient oxygen leads to anaerobic respiration in muscle cells, causing the partial breakdown of glucose into lactic acid. The accumulation of lactic acid causes muscle cramps.

Frequently Asked Questions