Biology – 6.1 Plant nutrition – photosynthesis | e-Consult
6.1 Plant nutrition – photosynthesis (1 questions)
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A cross-section of a leaf reveals several key structures that contribute to photosynthesis. The diagram should include the following, with labels and brief explanations:
- Epidermis (Upper and Lower): The outer protective layer of cells. The upper epidermis is transparent to allow light to reach the mesophyll. The lower epidermis contains stomata.
- Mesophyll (Palisade and Spongy): The internal tissue where most photosynthesis occurs. Palisade mesophyll is densely packed with chloroplasts for maximum light absorption. Spongy mesophyll has air spaces for gas exchange.
- Air Spaces: Pockets of air within the spongy mesophyll, facilitating the diffusion of CO2 and O2.
- Vascular Bundles (Veins): Contain xylem and phloem. Xylem transports water and minerals to the leaf, while phloem transports sugars produced during photosynthesis to other parts of the plant.
- Stomata: Pores on the lower epidermis, regulated by guard cells, allowing for gas exchange (CO2 uptake and O2 release).
- Guard Cells: Surround the stomata and regulate their opening and closing.
Role of each structure:
- Epidermis: Protection and light transmission.
- Mesophyll: Site of photosynthesis.
- Air Spaces: Efficient gas exchange.
- Vascular Bundles: Supply water and nutrients, and transport sugars.
- Stomata: Allow CO2 uptake and O2 release.
- Guard Cells: Regulate stomatal opening and closing.