Introduction to Life Processes
Life processes are the activities performed by living organisms to maintain life. These processes include nutrition, respiration, transportation, and excretion.
Every living organism carries out certain life processes, which are essential for maintaining life and growth. These processes distinguish living organisms from non-living things.
Main Life Processes
- Nutrition: Process of obtaining and utilizing nutrients for growth and energy
- Respiration: Process of energy release from food
- Transportation: Movement of substances within the body
- Excretion: Removal of waste products from the body
Nutrition
Nutrition is the process of obtaining and utilizing nutrients (carbohydrates, proteins, fats, vitamins, minerals, water) for growth, energy, and repair of body parts.
Types of Nutrition
1. Autotrophic Nutrition (Photosynthesis)
- Organisms that can prepare their own food using light energy
- Mainly found in plants and some bacteria
- Process: 6CO₂ + 6H₂O + Light energy → C₆H₁₂O₆ + 6O₂
2. Heterotrophic Nutrition
- Organisms that depend on other organisms for food
- Found in animals and humans
- Types:
- Holozoic: Taking food as a whole (feeding by mouth) - humans, animals
- Parasitic: Living on/in host organism - tapeworm, malaria parasite
- Saprophytic: Feeding on dead organic matter - fungi, bacteria
Digestion in Humans
Digestion is the process of breaking down complex food molecules into simpler, absorbable forms.
Organs of Digestive System
- Mouth: Mechanical and chemical digestion
- Pharynx: Passage for food
- Esophagus: Food tube, moves food by peristalsis
- Stomach: Churning and chemical digestion
- Small Intestine: Main site of digestion and absorption
- Large Intestine: Absorption of water
- Anus: Excretion of feces
Steps of Digestion
- Ingestion: Taking food into mouth
- Propulsion: Swallowing and peristalsis
- Digestion: Chemical and mechanical breakdown
- Absorption: Nutrients absorbed in small intestine
- Egestion: Removal of waste (feces)
Respiration
Respiration is the process of oxidation of glucose/food to release energy in the form of ATP.
Types of Respiration
1. Aerobic Respiration (with oxygen)
- Glucose + Oxygen → Carbon dioxide + Water + Energy (38 ATP)
- Occurs in mitochondria
- Complete oxidation of glucose
2. Anaerobic Respiration (without oxygen)
- Occurs in absence of oxygen
- Example: Fermentation in yeast, lactic acid formation in muscles
- Produces less energy (2 ATP)
Aerobic Respiration Equation
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy
Transportation in Humans
Transportation is the movement of absorbed nutrients, oxygen, and hormones to different parts of the body.
Circulatory System
- Heart: Pumps blood
- Blood Vessels:
- Arteries: Carry oxygenated blood from heart
- Veins: Carry deoxygenated blood to heart
- Capillaries: Exchange of nutrients and gases
- Blood: Transports oxygen, nutrients, hormones, and waste
Blood Composition
- Plasma: Liquid part (90% water)
- RBCs: Transport oxygen
- WBCs: Defend against pathogens
- Platelets: Blood clotting
Excretion
Excretion is the removal of metabolic waste products from the body.
Excretory System in Humans
- Kidneys: Filter blood and form urine
- Ureters: Transport urine from kidneys to bladder
- Bladder: Stores urine
- Urethra: Passage for urine out of body
Kidney Function
- Filtration of blood
- Reabsorption of useful substances
- Formation and concentration of urine
- Regulation of water and ions
Key Terms and Definitions
- Photosynthesis: Process of making food using light energy
- Nutrition: Process of obtaining and utilizing nutrients
- Respiration: Release of energy from food
- Digestion: Breakdown of food into simple substances
- Peristalsis: Wave-like movement in digestive tract
- Absorption: Movement of nutrients into blood
- Circulation: Movement of blood in body
- Excretion: Removal of metabolic waste
Practice Questions
Very Short Answer Questions (1 Mark)
- What is the main product of photosynthesis?
- Name the enzyme that helps in protein digestion in stomach.
- How many chambers does the human heart have?
- What is the main function of kidneys?
Short Answer Questions (2-3 Marks)
- Explain the difference between aerobic and anaerobic respiration.
- Describe the path of food through the digestive system.
- What is the role of circulatory system in transportation?
Long Answer Questions (5 Marks)
- Explain all the life processes in humans with examples.
- Describe the structure and function of the human circulatory system.