Biology – Nutrition and Photosynthesis

Nutrition  

- The process of obtaining food and using it for metabolic activities is called nutrition.  

Photosynthesis  

- Plants prepare their own food through photosynthesis.  

- Requirements:  

  - Carbon dioxide from the air  

  - Water from the soil  

  - Sunlight  

  - Chlorophyll (green pigment in leaves)  

- Definition: Photosynthesis is the process by which green plants make food using carbon dioxide and water in the presence of sunlight and chlorophyll.  

Types of Nutrition  

- Autotrophic Nutrition:  

  - Green plants (autotrophs) make their own food.  

- Heterotrophic Nutrition:  

  - Non‑green plants (heterotrophs) cannot prepare their own food and depend on others.  

Products and By‑products  

- Glucose is the immediate product of photosynthesis.  

- Oxygen is released, refreshing the air.  

Factors Affecting Photosynthesis  

- Light  

- Carbon dioxide  

- Chlorophyll  

- Temperature  

- Water  

Gas Exchange  

- Takes place through stomata.  

- Guard cells (kidney‑shaped) surround each stoma and regulate opening/closing.  

Importance  

- Photosynthesis is the only natural process that removes carbon dioxide and adds oxygen to the atmosphere.