Chapter 5: Life Processes

5.1 What are Life Processes?

Life Processes: The fundamental maintenance functions of living organisms that prevent damage and breakdown, continuing even when they are asleep or inactive.
Molecular Movements: Continuous movement of molecules essential for repairing and maintaining highly organized structures (cells, tissues).
Nutrition: The process of transferring an energy source (carbon-based food) from outside the body to the inside.
Respiration: The process of acquiring oxygen from outside to break down carbon sources for cellular energy needs.
Transportation: A system required in multicellular organisms to carry food and oxygen from sites of uptake to all parts of the body.
Excretion: The removal of harmful metabolic waste by-products from the body.

5.2 Nutrition

Autotrophs: Organisms like green plants and bacteria that synthesize organic compounds from inorganic CO2 and water using external energy.
Photosynthesis: The chemical process where solar energy is absorbed by chlorophyll to convert carbon dioxide and water into glucose and oxygen.
Starch: The internal energy reserve in plants where excess carbohydrates are stored (similar to glycogen in humans).
Stomata: Tiny pores on leaf surfaces where massive gaseous exchange and transpiration occur, regulated by the opening and closing of guard cells.

Heterotrophs: Organisms whose survival depends directly or indirectly on autotrophs, using enzymes (bio-catalysts) to break down complex nutrients.
Saprophytes: Fungi like bread moulds, yeast, and mushrooms that break down food material outside the body and absorb it.
Parasites: Organisms (e.g., Cuscuta, ticks, leeches) that derive nutrition from hosts without killing them.
Amoeba Nutrition: Unicellular ingestion via temporary finger-like projections called pseudopodia which form food vacuoles.
Paramoecium: Unicellular organism where cilia move food particles to a specific intake spot.

Alimentary Canal: A long muscular tube extending from the mouth to the anus.
Salivary Amylase: Enzyme in saliva that initiates chemical digestion by breaking starch down into simple sugars.
Peristalsis: Rhythmic contraction of canal muscles that pushes food forward along the gut.
Stomach: Secretes hydrochloric acid (creates acidic environment), pepsin (digests proteins), and mucus (protects stomach lining).
Small Intestine: Site of complete digestion of carbohydrates, proteins, and fats. Uses bile juice (from liver) to emulsify fats, and pancreatic trypsin (proteins) and lipase (fats).
Villi: Richly vascularized finger-like projections of the inner intestinal lining that maximize surface area for absorption.

5.3 Respiration

Pyruvate: A three-carbon molecule produced in the cytoplasm during the first step of glucose breakdown.
Anaerobic Respiration: Breakdown of pyruvate in the absence of oxygen, producing ethanol, carbon dioxide, and low energy (e.g., in yeast fermentation).
Aerobic Respiration: Breakdown of pyruvate in mitochondria using oxygen to release carbon dioxide, water, and abundant energy.
Lactic Acid: A three-carbon compound formed during oxygen deficiency in muscle cells, leading to muscle cramps.
ATP: Adenosine Triphosphate, the universal energy currency synthesized using energy released from respiration.

Alveoli: Balloon-like structures at the termini of bronchioles in lungs that provide an extensive, thin surface for gas exchange.
Haemoglobin: Respiratory pigment with high oxygen affinity found in red blood cells, ensuring efficient oxygen delivery throughout large bodies.
Aquatic Breathing: Faster breathing rate in aquatic animals due to low concentrations of dissolved oxygen in water compared to atmospheric air.

5.4 Transportation

Heart: A muscular pumping organ with separate chambers to prevent the mixing of oxygenated and deoxygenated blood.
Double Circulation: Pathway where blood passes through the heart twice during each complete cycle in vertebrates (mammals and birds).
Arteries & Veins: Arteries have thick, elastic walls to carry blood away from the heart under high pressure; veins have thin walls with valves to prevent backflow.
Capillaries: One-cell thick microscopic vessels that allow material exchange between blood and surrounding tissues.
Platelets: Special blood cells that repair leaks by clotting blood at sites of injury.
Lymph: A pale, low-protein fluid that drains extra-cellular fluid back into blood and transports digested fats.

Xylem: Vascular tissue that moves water and soil-derived minerals upward, driven by root pressure and transpiration pull.
Transpiration: Evaporation of water from plant leaves which creates a continuous suction force to pull water up from the roots.
Phloem: Vascular tissue responsible for translocation of food, amino acids, and sucrose using active transport powered by ATP.

5.5 Excretion

Kidneys: Primary excretory organs that filter nitrogenous wastes like urea and uric acid from blood.
Nephrons: Microscopic, complex structural and functional units of kidneys that perform filtration and selective reabsorption.
Bowman's Capsule: The cup-shaped end of a nephron containing a capillary glomerulus cluster where initial blood filtration occurs.
Hemodialysis: An artificial kidney system that uses a semi-permeable dialysing membrane to remove toxic nitrogenous wastes from blood during kidney failure.

Plant Waste Disposal: Strategies include releasing oxygen through photosynthesis, losing leaves storing wastes, storing resins and gums in old xylem, and secreting wastes into surrounding soil.