A student cuts open a bean seed and a maize grain, and looks at the embryos…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A student cuts open a bean seed and a maize grain, and looks at the embryos.
- In the bean embryo, which part lies above the level of the cotyledons, and which part lies below?
- How many cotyledons has the maize embryo, and what is the cotyledon called?
- Which sheath covers the shoot apex of the maize embryo, and which covers the root tip?
Need a reminder? The key ideaShow
The zygote becomes the embryo, the PEN becomes the endosperm, the integuments become the seed coat, and the ovule becomes the seed. The embryo, the seed coat and the perisperm are diploid, and the endosperm is triploid. A mature seed has about to water. The dry matter does not change when the seed loses water.
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. A dicot seed and a monocot grain.
Plan. Use the pictures of the two embryos.
Step 1. The bean. The epicotyl, ending in the plumule, lies above the cotyledons. The hypocotyl, ending in the radicle, lies below.
Step 2. The maize. It has one cotyledon, the shield-shaped scutellum.
Step 3. The sheaths. The coleoptile covers the shoot apex, and the coleorhiza covers the radicle and the root cap.
Answer: (a) epicotyl above, hypocotyl below; (b) one, the scutellum; (c) the coleoptile and the coleorhiza.
Watch out. The root tip of the bean embryo is the radicle, with a root cap. Only the monocot has a coleorhiza.
More onPlant Biology
Discussion (0)
Log in to join the discussion.
Loading…