HardBiologyHigh School (9–10)GeneralHeredity and Evolution › Heredity and InheritanceNumericalBoard Exam
Imagine that human gametes carried all 46 chromosomes instead of half…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Imagine that human gametes carried all chromosomes instead of half. How many chromosomes would the first zygote have? If this went on, how many would a body cell have after three generations?
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. The first zygote. chromosomes.
Step 2. Three generations. chromosomes.
Step 3. The point. The DNA would keep doubling, which cannot go on. Halving in gametes keeps the number at .
Answer: in the first zygote, and after three generations.
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