Question

A newly discovered species of dung beetle has 2n = 16 chromosomes. It mates with a closely related beetle species that has 2n = 12 chromosomes. How many chromosomes would there be in an amphidiploid beetle produced from this cross?

Answer 1

Answer:

Option 3, 20 or 22

Explanation:

A newly discovered species of dung beetle has 2n = 16 chromosomes. It mates with a closely related beetle species that has 2n = 12 chromosomes. How many chromosomes would there be in an allotriploid beetle produced from this cross?  

1. 40 or 44
2. 20 or 22
3. 20 or 22
4. 36 or 48
5. 40 or 44

Solution

An allotriploid is a species which contains  three sets of chromosomes of different species .Crossing can result in triploid offspring with diploid gamete of one species and regular haploid gamete of other offspring  

Case I - Resulting offspring (3n) = Gamete I (2n) + Gamete II (n)  

OR

Case II - Resulting offspring (3n) = Gamete II (2n) + Gamete I (n)  

Case I  

$2* 8 + 6 \\= 16 + 6 \\= 22$

Case II

$2* 6 + 8\\= 12 + 8\\= 20$

Hence, option 3 is correct