Question

There are three varieties of banana.

Variety A:

Number of chromosomes in a leaf cell = 22

Growth rate of fruit = 2.9

Breaking strength of leaf = 10.8

Variety B:

Number of chromosomes in a leaf cell = 33

Growth rate of fruit = 6.9

Breaking strength of leaf = 9.4

Variety C:

Number of chromosomes in a leaf cell = 44

Growth rate of fruit = 7.2

Breaking strength of leaf = 7.8

Banana growers can only grow new variety B plants by producing lateral shoots near the base of the stem. Explain using cell division how growing variety B on a large scale will affect the genetic diversity of bananas.

Answer 1

Genetic diversity: Genetic diversity can be defined as a genetic variation or a total number of different alleles in a population. A greater number of different alleles of species have greater genetic diversity of that species.

Genetic diversity can be caused by random fertilization, random mating, mutation (formation of new allele), and recombination or crossing over during meiosis ( a cell division process to produce gamete).

Cell division occurs via -

1. Mitosis- daughter cell is genetically identical to the parent cell ( no genetic diversity occurs).
2. Meiosis - daughter cell is genetically different from the parent cell ( genetic diversity occurs). Meiosis generally not happens in the species of odd numbers of chromosomes.

Now, in the given question, the banana growers can only grow variety B plants by producing the lateral shoot it means only the mitosis process happens because the number of chromosomes in variety B is 33 (odd number). The meiosis process can not occur in this plant variety so there is no genetic diversity occurs in offsprings.

Affect of a large scale of growing variety B on genetic diversity:

1. Low genetic diversity because all are produced by the only mitosis ( will have the same DNA/genes/alleles, or will be genetically identical)
2. Low genetic diversity because not produced by meiosis (means no independent segregation or crossing over happened so no genetically different)