The bark of a young cherry twig has small horizontal lines…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
The bark of a young cherry twig has small horizontal lines. They are lenticels.
- What is a lenticel made of?
- Why does the stem need lenticels, when cork is airtight?
- How is a lenticel different from the cork round it?
Need a reminder? The key ideaShow
The cork cambium (phellogen) arises in the cortex and cuts off cells on both sides. Outward it makes the cork (phellem), whose dead cells have suberin in their walls and form a waterproof cover. Inward it makes the phelloderm (secondary cortex), made of living cells. The three make the periderm. A lenticel is a patch of loosely arranged cells in the cork, and it lets gases pass. Bark means all the tissues outside the vascular cambium.
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) Loosely arranged cells, with gaps between them, made by the cork cambium.
Step 2. (b) Cork has no gaps and is airtight. Living cells inside it need oxygen and must give out carbon dioxide. The lenticels let the gases pass.
Step 3. (c) The cork is a layer of dead, tightly packed cells with suberin. A lenticel is a patch of loose cells that air can pass between.
Answer: (a) loose cells; (b) for gas exchange; (c) loose cells, not tight cork.
Discussion (0)
Log in to join the discussion.
Loading…