Question

Plant species A has a diploid chromosome number of 12. Plant species B has a diploid number of 16. A new species, C, arises as an allopolyploid from A and B. The diploid number for species C would probably be
a. 14. b. 16. c. 28. d. 56.

Answer 1

Answer:

c. 28

Explanation:

Plant A has a dipoid chromosome number of 12, so its gametes will have an haploid number of 6 chromosomes.

Plant B has a dipoid chromosome number of 16, so its gametes will have an haploid number of 8 chromosomes.

Plant A                      Plant B

2n = 12                       2n = 16

 n = 6                          n = 8

The new species C arises as an allopolyploid from A and B. An allopolyploid usually originates from the breeding of two different species.

In this case, a gamete from plant A combines with a gamete from plant B to form a hybrid with 14 chromosomes (6 from A and 8 from B). These chromosomes are unpaired, so the hybrid is sterile.

In order to become a fertile diploid individual of species C, the most common mechanism is polyploidization, where the genome duplicates. That way, the resulting plant C has a diploid number of 14 x 2 = 28 chromosomes, of which 12 are A and 16 are B.