Question

The primrose, with its 36 chromosomes, is likely to have formed from the hybridization and subsequent chromosome doubling of a cross between the two other species, each with its 18 chromosomes. What is the most likely process that led to the formation of the primrose?

1) Meiosis followed by fertilization
2) Mitosis followed by fertilization
3) Hybridization followed by chromosome doubling
4) Chromosome doubling followed by hybridization

Answer 1

The primrose likely formed through hybridization followed by chromosome doubling, overcoming hybrid sterility and creating a new fertile polyploid species. The correct answer is option 3.

Step-by-step explanation:

The formation of the primrose with its 36 chromosomes, likely a result of a hybridization event between two parent species with 18 chromosomes each, points to a specific process that leads to the doubling of chromosomes.

The correct option that describes this process is: 3) Hybridization followed by chromosome doubling. This sequence allows for the formation of a hybrid organism from two different species, after which a polyploid species is created when the chromosome count doubles.

This phenomenon overcomes hybrid sterility, allowing for the formation of a fertile organism capable of sexual reproduction, which is otherwise not possible when the hybrid's chromosomes cannot pair during meiosis due to differences inherited from two distinct parent species.