IGCSE Biology Core Concepts

📋 Course Outline

1. Photosynthesis and Cell Structures
2. Gas Exchange and Breathing
3. Digestion and Nutrition
4. Respiration and Osmosis
5. Experiments and Yeast Variables
6. Biological Calculations

📖 1. Photosynthesis and Cell Structures

★ Must-know

📐 Formula — The balanced equation for photosynthesis is $6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$.

📌 The rate of photosynthesis increases with light intensity until another factor, such as carbon dioxide concentration or temperature, becomes limiting.

• The chloroplast contains chlorophyll for photosynthesis.

• Ribosomes are the site of protein synthesis.

Further detail

• The permanent vacuole contains cell sap, while the cell wall strengthens and supports plant cells.

💡 Memory Hook

More light increases photosynthesis until CO₂ or temperature becomes limiting.

📖 2. Gas Exchange and Breathing

🔑 Key Concepts & Definitions

• Alveoli : the main site of gas exchange

★ Must-know

• The trachea carries air to the bronchi and is supported by cartilage rings.

• Cartilage rings prevent the trachea and bronchi from collapsing.

Further detail

📌 A collapsed lung reduces oxygen uptake because less surface area is available for gas exchange.