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Learning Activity 1: What are stomata? This activity assumes that learners already know that most plants absorb water through their roots and lose water vapour from their leaves by transpiration.

If you have a microscope:

  • Paint the upper and lower surfaces of a smooth (not furry) leaf with clear nail varnish. Allow it to dry and carefully peel off the transparent film. This thin, transparent sheet of nail varnish will have an impression of the leaf surface that you will be able to view under the microscope.

  • Look at a diagram of stomata so that you know what to look for under the microscope.

  • Compare the impressions of the upper and lower surfaces of the leaf under the microscope. Decide which surface of the leaf has more stomata (in most plants, the lower surface of the leaf has more stomata).

  • Draw the outline of the epidermal cells and stomata with guard cells that you can see under the microscope.

If you don’t have a microscope, draw diagrams of epidermal cells and stomata based on micrographs or scientific diagrams of the epidermis of a leaf.

  • Label your diagrams and describe in words the role of stomata (exchange of gases

for respiration and photosynthesis, loss of water vapour).

Learning Activity 2: How do leaves regulate water loss?

  • Take a copy of the diagram (overleaf) of a typical oval leaf with circles on it representing the stomata. Count the stomata.

  • In groups of four or five, use your leaf diagrams to model as many adaptations as possible to reduce water loss through the stomata. You may cut out your leaves, trim them, fold them, combine them with others, colour them in or use other substances to represent these adaptations.

  • Each group must demonstrate their leaf models to the rest of the class and explain, in terms of the stomata, how the adaptations they have modelled reduce water loss.

  • Once all groups have presented their models, compile an illustrated summary of the ways in which leaves are adapted to regulate water loss.

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Assessment tasks and tools

  • Diagram of leaf epidermis as observed under a microscope labelled with stomata and epidermal cells.

  • Learner explanation of the role of stomata.

Assessment tasks and tools

  • Educator and peers assess leaf models and oral explanations using a rubric.

  • Check individual summaries of class discussions to ensure these are accurate.

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