Experimental prediction: The effect of light on the amount and distribution of auxin in the coleoptile tip
Based on the observations of Went and others, you hypothesize that light does not affect the amount of auxin produced in the coleoptile tip. You further hypothesize that light causes auxin to move from the illuminated side to the shaded side of the tip. To test your hypothesis, you set up the following experiment.
In tips A and B, the tip and the agar beneath it are both divided by a piece of plastic that permits light to pass through but is impermeable to water-soluble compounds such as auxin. (The plastic was inserted into the tips and agar in the dark.)
In tip C, the plastic completely divides the agar, but only partially divides the coleoptile tip. (Again, the plastic was inserted in the dark.)
Tip A is kept in the dark, while tips B and C are illuminated with directional light as shown.
Based on Went’s experiments, agar blocks 1 and 2 should contain the same amount of auxin. Assuming that your hypothesis is supported, sort the remaining agar blocks according to whether you would expect them to have less auxin, the same amount of auxin, or more auxin than blocks 1 and 2.
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