Life Processes

Key Concepts

Introduction to Life Processes

Life processes are the essential maintenance functions that occur in all living organisms, even during periods of rest or inactivity. These processes are vital for preventing damage and maintaining the structural integrity of the organism. Since these functions require energy, they involve the intake of nutrients from external sources.

Nutrition

Nutrition is the process of acquiring energy (food) from outside the body. It is broadly categorized into two types:

• Autotrophic Nutrition: Organisms like green plants and some bacteria synthesize their own food from inorganic sources (CO₂ and water) using sunlight and chlorophyll through photosynthesis.
• Heterotrophic Nutrition: Organisms like animals and fungi depend on complex organic substances prepared by other organisms. These substances must be broken down by bio-catalysts called enzymes.

Photosynthesis Process:

1. Absorption of light energy by chlorophyll.
2. Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.
3. Reduction of carbon dioxide to carbohydrates (glucose), which is stored as starch.

Respiration

Respiration is the process of acquiring oxygen from the environment and using it to break down food sources for cellular energy needs.

• Aerobic Respiration: Occurs in the presence of oxygen within the mitochondria. It breaks down pyruvate into CO₂, water, and a large amount of energy.
• Anaerobic Respiration: Occurs in the absence of oxygen. In yeast, it produces ethanol and CO₂ (fermentation). In human muscle cells during heavy activity, it produces lactic acid, which can cause cramps.
• ATP (Adenosine Triphosphate): The "energy currency" of the cell. Energy released during respiration is used to synthesize ATP, which fuels all cellular activities.

Transportation

Transportation systems are necessary in multi-cellular organisms to carry food, oxygen, and waste products to and from various parts of the body.

In Human Beings:

• The Heart: A muscular pumping organ. It ensures the separation of oxygen-rich blood and carbon dioxide-rich blood through a four-chambered structure (left/right atria and ventricles).
• Double Circulation: Blood passes through the heart twice in one complete cycle, ensuring efficient oxygen delivery.
• Blood Vessels: Arteries (thick-walled, carry blood from heart), veins (thin-walled, with valves, bring blood back to heart), and capillaries (extremely thin-walled for material exchange).
• Lymph: A colorless tissue fluid that drains excess fluid and carries digested fats.

In Plants:

• Xylem: Transports water and minerals from roots to leaves using root pressure and transpiration pull.
• Phloem: Transports products of photosynthesis (translocation) from leaves to storage and growing parts using ATP.

Excretion

Excretion is the biological process of removing harmful metabolic waste products, particularly nitrogenous wastes, from the body.

In Human Beings:

• Kidneys: The primary excretory organs that filter blood to produce urine.
• Nephrons: The basic filtration units of the kidney. They involve filtration in Bowman's capsule and selective reabsorption of glucose, amino acids, salts, and water.
• Urine: Stored in the urinary bladder and released through the urethra.

In Plants:

• Plants use varied strategies: oxygen as a byproduct of photosynthesis, transpiration for excess water, storing wastes in cellular vacuoles or falling leaves, and producing resins and gums in old xylem.