2.5.2

Leaves

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Leaves

Leaves are examples of plant organs made up of different types of tissue:

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Epidermal tissue

  • Epidermal tissue covers the outer surface of leaves (as well as the rest of the plant).
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Palisade mesophyll

  • Palisade mesophyll is a row of cells located below the upper epidermis.
  • The cells are exposed to a lot of sunlight.
  • The cells have lots of chloroplasts (where photosynthesis takes place) to maximise the energy transfer in photosynthesis.
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Spongy mesophyll

  • Spongy mesophyll contains many air spaces, which help with gas exchange throughout the leaf.
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Stomata

  • Found in the lower epidermis, these gaps facilitate (make easier) the diffusion of gases in and out of the leaf, if they are open.
  • When necessary, specialised (perform a specific function) guard cells are capable of closing these gaps.
    • e.g. in hot weather to reduce water loss.

Jump to other topics

1Cell Biology

1.1What's in Cells?

1.2Cell Division

1.3Transport in Cells

2Organisation

2.1Principles of Organisation

2.2Enzymes

2.3Circulatory System

2.4Non-Communicable Diseases

2.5Plant Tissues, Organs & Systems

3Infection & Response

4Bioenergetics

5Homeostasis & Response

5.1Homeostasis

5.2The Human Nervous System

5.3Hormonal Coordination in Humans

5.4Plant Hormones

6Inheritance, Variation & Evolution

7Ecology

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