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THE VISUAL LEARNING STUDIO

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35 visual explanations across 29 chapters, with topic maps throughout the library.

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Study the expanded notes and the credited detailed textbook lessons. The current chapter index covers core topics; it is not a claim of exhaustive coverage of every examination syllabus. Check the official syllabus and primary references.

Nutrition and Photosynthesis — lesson overview

Autotrophic and heterotrophic nutrition

Autotrophs synthesise organic substances from inorganic sources using an energy source. Photoautotrophs use light; other autotrophs can use chemical energy.

Heterotrophs obtain organic nutrients from other organisms or their products. Feeding strategy and energy use are related but distinct aspects of nutrition.

Plants also respire. Photosynthetic ability does not remove their need to release usable chemical energy through cellular metabolism.

Photosynthesis: inputs and processes

In oxygenic photosynthesis, light energy supports conversion of carbon dioxide into organic compounds; water supplies electrons, and oxygen is released from water.

At school level, 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ is a simplified overall equation with light and chlorophyll conditions. The actual pathway contains many reactions rather than one direct step.

Light-dependent reactions occur in the thylakoid membrane system. Carbon-fixation reactions occur in the stroma of chloroplasts, using products of the light reactions.

Gas exchange and transport

Stomata are pores associated with guard cells. Changes in guard-cell turgor regulate pore opening, influencing gas exchange and water loss.

Carbon dioxide supply, light, temperature, and water conditions can affect photosynthetic rate. The limiting factor can change with conditions.

Leaves are adapted for exchange and light capture, but chloroplast-containing tissues elsewhere can also photosynthesise. A diagram should distinguish epidermis, guard cells, stomatal pore, and internal tissue.