Try it on paper first. A hint, the key idea and the worked solution are here when you need them.
Write the four links in the chain that makes a pea plant tall, starting from the gene. Then say what happens to the plant if the gene is altered so that its enzyme works poorly.
DNA is the information source for making proteins; a gene is a section of DNA for one protein. Enzymes are proteins, and an enzyme can make a growth hormone that decides the height of a plant. Each body cell has two copies of every gene, one from each parent.
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 chain. Gene, then enzyme (a protein), then growth hormone, then a tall stem.
Step 2. An altered gene. The enzyme works poorly, so less growth hormone is made.
Step 3. The result. The stem does not grow as much, so the plant is short.
Answer: gene, enzyme, growth hormone, tall plant; with a poor enzyme, less hormone is made and the plant stays short.
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