Life Processes and Nutrition

Life Processes

• Living things perform various processes to maintain their life
• These processes are called life processes
• Examples include growth, digestion, respiration, circulation, excretion, and nutrition

Examples of Life Processes

• Growth: Increase in size and complexity of an organism
• Digestion: Breakdown of complex food into simpler substances
• Respiration: Release of energy from food
• Circulation: Movement of substances within the organism
• Excretion: Removal of waste products from the organism
• Nutrition: Obtaining and utilizing food

Nutrition

• Autotrophic nutrition: Organisms that make their own food (e.g., plants through photosynthesis)
  • Use inorganic materials like CO2, water, etc
• Heterotrophic nutrition: Organisms that obtain food from other organisms (e.g., animals)
  • Depend on plants or other animals for food supply (directly/indirectly)
    • Examples include:
    • Holozoic nutrition: Intake of solid food and breakdown inside the body (e.g., animals)
    • Saprophytic nutrition: Feeding on dead & decaying matter (e.g., fungi)
    • Parasitic nutrition: Deriving nutrition from a host organism (e.g., cuscuta)

Autotrophic Nutrition (Photosynthesis in Plants)

• Equation: 6CO₂ + 12H₂O → C₆H₁₂O₆ + 6O₂ + 6H₂O

• Raw Materials: Sunlight, CO₂, water

• Chlorophyll: Green pigment in chloroplasts where photosynthesis occurs

• Site: Chloroplasts in leaves

• Main Events:

  • Absorption of light energy by chlorophyll
  • Conversion of light energy into chemical energy
  • Splitting of water into hydrogen and oxygen
  • Reduction of CO₂ to carbohydrates

• Stomata: Tiny pores on leaves for gas exchange (O₂ out, CO₂ in)

Nutrition in Humans

• Stages: Ingestion, digestion, absorption, assimilation, egestion
• Organs involved: Mouth, teeth, tongue, salivary glands, esophagus, stomach, small intestine, large intestine (with other glands like liver, pancreas)
  • Different parts of the alimentary canal secrete digestive juices (enzymes) to break down different types of food
• Mechanism: food is broken down in different parts of the alimentary canal with the use of enzymes and mechanical actions. Different parts absorb different substances

Respiration

• Types:
  • Aerobic Respiration: In the presence of oxygen (produces more energy)
  • Anaerobic Respiration: In the absence of oxygen (produces less energy). e.g. muscle fatigue involves lactic acid formation during anaerobic respiration in muscle cells
• Equation (Aerobic): C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy
• Equation (Anaerobic): Glucose --> Lactic Acid + Energy

Human Respiratory System

• Passage of air: Nostril → Nasal passage → Nasal cavity → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli (where gaseous exchange occurs)
• Mechanism of Breathing: Inhalation (chest cavity expands, air enters) vs. Exhalation (chest cavity contracts, air exits)

Exchange of Gases

• Alveoli are tiny air sacs where oxygen from the air diffuses into the blood and carbon dioxide from the blood diffuses into the air.
• Haemoglobin in red blood cells binds with oxygen in the lungs to transport it throughout the body.
• CO₂ is released in tissues.
• Oxygen (O₂) and carbon dioxide (CO₂) are exchanged between alveoli, blood, and tissues; in alveoli O₂ is bound to haemoglobin in red blood cells, and CO₂ is dissolved in blood.

Transportation in Humans

• Circulatory System: Heart (pump), blood vessels (arteries, veins, capillaries), blood (circulatory Medium)
• Blood circulation (in brief): Oxygenated blood from lungs → Left side of Heart → Body → Deoxygenated blood → Right side of Heart → Lungs.
• Parts of the heart: Four chambers (atria and ventricles) ensuring blood flow in one direction.

Transportation in Plants

• Xylem: Transports water and minerals from roots to other parts of the plant (passive process)
• Phloem: Transports food (products of photosynthesis) from leaves to other parts of the plant (active process needing energy)

Excretion in Humans

• Organs: Kidneys, ureters, urinary bladder, urethra
• Process: Filtration, reabsorption, secretion
• Waste: Urea (produced in the liver from ammonia) and other metabolic wastes are filtered out of blood by kidney to make urine; urine is then stored in the urinary bladder and expelled through the urethra