State the functions of the following:
Cuticle on leaves:
Topic: Cuticle
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Pick an option and check your answer. The full worked answer is below either way.
Answer
(b) Reduces transpiration.
The CUTICLE is a waxy, water-impermeable layer secreted over the leaf epidermis. Being impermeable, it REDUCES the water lost directly through the epidermal surface — cuticular transpiration.
Why the others fail: (a) The cuticle is TRANSPARENT, so light passes through it freely. It does not prevent photosynthesis — if it did, the leaf could not function at all. (c) Protection from grazing comes from thorns, spines or bitter chemicals, not from a microscopic wax layer. (d) Colour comes from CHLOROPHYLL in the chloroplasts, not from the cuticle.
NOTE WHERE IT IS THICKEST: on the UPPER surface, which faces direct sunlight and would otherwise lose water fastest — and thicker still in desert plants, which is a xerophytic adaptation.
Reduces transpiration.