FACTORS WHICH MIGHT AFFECT STOMATAL OPENING (LIGHT)

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PROJECT A: FACTORS WHICH MIGHT AFFECT STOMATAL OPENING (LIGHT)

How light affects the stomatal opening in a leaf

Abstract  

My aim of this investigation was to check the affect of environmental factors affecting stomatal opening. My experiment was designed to check the stomata opening in light. Plants move in ways that may not seem obvious. The opening and closing of  is one example of this movement.

There are a large amount of growth conditions that can affect a plant. One of the most important of these conditions concerns the type of availability of light present for photosynthesis. By controlling the type of light that a plant receives, its growth can be affected. I chose to measure this growth by observing the number of stomata present on the underside of leaves exposed to the dark and to sunlight. Based on the idea that there are more open stomata present on leaves exposed to the sun, my hypothesis that ‘Factors which might affect stomatal opening’ (Light) there will be more stomata on the plants exposed to the light.

Hypothesis

I believe the results of my investigations will show that the more the light source the more the stomata will open.

Plan

My hypothesis is to determine factors which might affect the stomatal opening in leaves. A practical experiment can easily be set up to determine these factors. The following procedure should be followed:  

Select a plant that has been kept in the light and label the container e.g. "LIGHT." Clip two leaves from this plant. Prepare casts of the leaves surfaces by painting the adaxial (top surface) of one leaf and the abaxial (bottom surface) of the other leaf with clear nail polish. Allow the nail polish to dry for approximately 10 minutes. While the nail polish is drying, label microscope slides as either adaxial (top of the leaf) or abaxial (bottom of the leaf). Cut a piece of sellotape approximately 1.5 cm in length. Fold the tape over on itself leaving 0.5 cm of sticky surface exposed. Place the sticky tab of the tape at the edge of the leaf so that it sticks to the nail polish cast. Place the cast on the appropriately labelled slide. Place a cover slip over the cast. Repeat this step for the remaining leaf. Examine the slides under the microscope to determine which leaf surface has stomata.

Once this has been done, the environmental factors which affect stomatal opening (LIGHT) will be discussed.

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Before changing any conditions, remove a leaf and paint the appropriate surface with nail polish. Let the nail polish dry. This leaf will be used for initial stomatal conditions and for comparison with stomatal responses to different treatments. Now cut six pieces of aluminium foil so that they will each be large enough to entirely cover both sides of one leaf. Gently fold one piece of the foil over a leaf. Tape the edges of the foil together so that no light can reach the leaf surface. Now do the same to a leaf that has been kept in the ...

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