Question

A koala species has 2n = 16. Karyotype identified that a particular koala is trisomic at chromosome 4. How many chromosomes would you most likely find in a gamete from this koala?

a) 8 or 9
b) 32 or 33
c) 12 or 13
d) 16 or 17

Answer 1

In a gamete from a trisomic koala with a normal diploid number of 2n = 16, we would expect to find either 8 or 9 chromosomes, as there is one extra chromosome due to trisomy. The answer is option (a) 8 or 9.

Step-by-step explanation:

If a koala species has 2n = 16 chromosomes, and we know that a particular koala is trisomic at chromosome 4, this means that instead of the normal pair, it has three copies of chromosome 4. The question requires us to determine the number of chromosomes in a gamete from this koala. Under normal circumstances, gametes from a diploid organism are haploid, which means they contain one set of chromosomes, or n. For a koala with a normal diploid number of 2n = 16, this would be 8 chromosomes (n).

However, with the trisomy present, there will be an extra chromosome (the third copy of chromosome 4) in the gametes. Thus, where we would expect 8 chromosomes in a normal koala gamete, we would expect 9 chromosomes in a gamete from this trisomic koala. Therefore, the correct answer to how many chromosomes would most likely be found in a gamete from this koala is either 8 or 9, which corresponds to option (a) 8 or 9.