BIO101 ‒ Topic 10: Nutrition in Living Organisms
© Lesuyai Organic Guides 2025
Course Code: BIO 101
Course Name: General Biology
10.1 Definition and Importance of Nutrition
Nutrition is the process by which living organisms obtain and utilize food materials to
sustain life. Importance of Nutrition:
- Provides energy for growth and repair.
- Maintains body functions and temperature.
- Supports reproduction and immune system.
- Supplies raw materials for building body structures.
10.2 Types of Nutrition
1. Autotrophic Nutrition:
Organisms make their own food from simple substances.
- Photosynthesis: Using sunlight to make food (green plants).
- Chemosynthesis: Using chemical energy to make food (some bacteria). 2. Heterotrophic
Nutrition:
Organisms depend on others for food.
Includes holozoic, saprophytic, and parasitic modes.
10.3 Modes of Nutrition in Living Organisms
Photosynthesis:
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (in presence of chlorophyll and sunlight).
Text-Based Diagram: A leaf receiving sunlight, CO₂ through stomata, and water from
roots to produce glucose and oxygen. Chemosynthesis: Bacteria use chemical energy to
produce food.
Holozoic Nutrition: Ingestion, digestion, absorption, assimilation, and egestion.
Saprophytic Nutrition: Feeding on dead matter (e.g., fungi).
Parasitic Nutrition: Feeding on a host (e.g., tapeworms, mistletoe).
10.4 Nutrition in Plants
Photosynthesis Steps:
1. Absorption of light by chlorophyll.
2. Splitting of water (photolysis).
3. Formation of ATP.
4. Reduction of CO₂ to glucose. Factors Affecting Photosynthesis:
Light intensity, CO₂ concentration, temperature, water, and chlorophyll content.
© Lesuyai Organic Guides 2025
Course Code: BIO 101
Course Name: General Biology
10.1 Definition and Importance of Nutrition
Nutrition is the process by which living organisms obtain and utilize food materials to
sustain life. Importance of Nutrition:
- Provides energy for growth and repair.
- Maintains body functions and temperature.
- Supports reproduction and immune system.
- Supplies raw materials for building body structures.
10.2 Types of Nutrition
1. Autotrophic Nutrition:
Organisms make their own food from simple substances.
- Photosynthesis: Using sunlight to make food (green plants).
- Chemosynthesis: Using chemical energy to make food (some bacteria). 2. Heterotrophic
Nutrition:
Organisms depend on others for food.
Includes holozoic, saprophytic, and parasitic modes.
10.3 Modes of Nutrition in Living Organisms
Photosynthesis:
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (in presence of chlorophyll and sunlight).
Text-Based Diagram: A leaf receiving sunlight, CO₂ through stomata, and water from
roots to produce glucose and oxygen. Chemosynthesis: Bacteria use chemical energy to
produce food.
Holozoic Nutrition: Ingestion, digestion, absorption, assimilation, and egestion.
Saprophytic Nutrition: Feeding on dead matter (e.g., fungi).
Parasitic Nutrition: Feeding on a host (e.g., tapeworms, mistletoe).
10.4 Nutrition in Plants
Photosynthesis Steps:
1. Absorption of light by chlorophyll.
2. Splitting of water (photolysis).
3. Formation of ATP.
4. Reduction of CO₂ to glucose. Factors Affecting Photosynthesis:
Light intensity, CO₂ concentration, temperature, water, and chlorophyll content.
