In an Avena curvature test, each coleoptile tip that stood on an agar block adds 3 degrees of…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
In an Avena curvature test, each coleoptile tip that stood on an agar block adds degrees of curvature, in the straight part of the calibration line. The block is placed on one side of a decapitated coleoptile in the dark.
- A block stood under tips. What curvature does it give?
- Another block gives degrees. Under how many tips did it stand?
- Does the coleoptile bend towards the block or away from it?
Need a reminder? The key ideaShow
Auxins are indole compounds made at growing tips. IAA and IBA are natural; NAA and 2,4-D are synthetic. They help cuttings to root, keep apical dominance, cause parthenocarpy, prevent early fruit and leaf drop, and 2,4-D kills dicot weeds. In Went's Avena test a coleoptile bends away from an agar block that holds auxin, and a bigger angle means more auxin.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. degrees for each tip.
Step 1. (a) degrees.
Step 2. (b) tips.
Step 3. (c) The side below the block grows faster, so the coleoptile bends away from the block.
Answer: degrees; tips; away from the block.
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