A gardener wants four things. Name the effect of auxin that helps in each case…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A gardener wants four things. Name the effect of auxin that helps in each case.
- A rose cutting must grow roots.
- A tea bush must be made bushy, with many side branches.
- A tomato must make fruit without fertilisation.
- A lawn must be freed of dicot weeds.
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.
Step 1. (a) Auxin, as IBA or NAA, helps a stem cutting to form roots.
Step 2. (b) Cutting off the tip removes the source of auxin, so apical dominance ends and the lateral buds grow out.
Step 3. (c) Auxin causes parthenocarpy, so the tomato fruit develops without fertilisation.
Step 4. (d) 2,4-D is a synthetic auxin that kills dicot weeds and does not harm the monocot grass.
Answer: (a) rooting; (b) ending apical dominance; (c) parthenocarpy; (d) 2,4-D as a weed killer.
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