MediumBiologyHigh School (9–10)GeneralHeredity and Evolution › Heredity and InheritanceConceptualBoard Exam
Mendel crossed tall plants with round seeds and short plants with wrinkled seeds…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Mendel crossed tall plants with round seeds and short plants with wrinkled seeds. In the second generation he found tall plants with wrinkled seeds. Use chromosomes to explain how this new mixture arose.
Need a reminder? The key ideaShow
Genes lie on chromosomes, which come in pairs in body cells. A gamete carries one chromosome of each pair, so fertilisation restores the full number and it stays constant. Genes on different chromosomes are passed on independently.
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. Two genes. The gene for height and the gene for seed shape lie on different chromosomes.
Step 2. Gametes. When gametes form, each chromosome pair is shared out independently of the others.
Step 3. A new mixture. So a gamete can carry the tall version of one gene with the wrinkled version of the other.
Answer: the two genes are on different chromosomes, which are passed on independently, so new mixtures such as tall and wrinkled appear.
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