Why is the husk of a coconut hard, but the stalk of a leaf can bend without breaking?
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Why is the husk of a coconut hard, but the stalk of a leaf can bend without breaking?
Need a reminder? The key ideaShow
Parenchyma: alive, thin walls, stores food. Collenchyma: alive, thick at the corners, flexible. Sclerenchyma: dead, lignin, hard. Epidermis protects and has stomata; cork is dead and waterproof.
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. The husk. It is made of sclerenchyma: dead cells with very thick walls hardened by lignin.
Step 2. The stalk. It has collenchyma: living cells with walls thick only at the corners, which give support but can bend.
Answer: sclerenchyma makes the husk hard; collenchyma lets the stalk bend.
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