Use independent assortment alone, and leave out crossing over…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Use independent assortment alone, and leave out crossing over.
- A pea plant has . How many kinds of gametes can it make?
- A fruit fly has . How many kinds of gametes can it make?
- A human has . How many kinds of gametes can a person make?
- How many kinds of zygotes can two fruit flies produce between them?
Need a reminder? The key ideaShow
Mitosis gives two identical diploid cells. Meiosis gives four haploid cells that differ. A cell with pairs of homologues makes kinds of gamete by independent assortment. Non-disjunction gives gametes with or chromosomes.
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.
Given. , and .
Plan. Use . For the zygotes, multiply the kinds of gamete of the two parents.
Step 1. Pea. .
Step 2. Fruit fly. .
Step 3. Human. , which is over million.
Step 4. Zygotes. .
Answer: ; ; ; .
Check. Each extra pair doubles the number of kinds.
Watch out. Crossing over adds many more kinds. The numbers are the lowest count.
Source. Clark, Douglas and Choi (2018), OpenStax Biology 2e, chapter 11.1 ( arrangements of the tetrads in humans, over million).
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