Etiolation In Plants

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1. Introduction
Etiolation is a process which occurs in plants which are grown without light. This process increases the chance of a plant to reach the light and to actually photosynthesise. Certain characteristics occur with plants grown in the dark, these are:
• Long, weak stems - Due to etiolation a plant can increase the possibility that it will reach a light source, often it will have to go higher. Therefore the stems are often longer. The stems are also strongly attracted to light and it will actually elongate towards the light.
• Longer internodes – As shown on the right, plants have three nodes. The internode is the space in between the nodes. Plants grown in the dark have much longer internodes. This can be explained, as the stems
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The hormone cytokinin causes this after the exposure of light. Chloroplasts contain chlorophyll and due to this the plant turns green.

1.1 Research question
For this experiment, I want to find out what will happen to cress seeds that are etiolising (growing in the dark) when they are then exposed to light. To conduct this experiment, I came up with the following research question:
‘Will exposure to light after a set period of etiolation cause a plant to de-etiolize?’

2. Hypothesis
If a plant is exposed to light after a set period of etiolation, then a plant will de-etioize and the production of chloroplasts instead of etioplasts will be stimulated.

2.1 Motivation
Plants that have etiolation, have etioplasts. Due to the lack of light, there is a lack of chlorophyll and the plant turns yellowish. After being exposed to light, the etioplasts will be stimulated to develop into chloroplasts. These chloroplasts contain chlorophyll and this causes the plant to turn green. The plant will de-etiolize seeing as the etioplasts are replaced for the chloroplasts and the plant will not etiolize anymore, it will photosynthesise.

3. Procedure

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