Question

4. Identify two meiotic events that promote genetic variability.

5. If a cell has a diploid number of 4, then how many genetically different combinations can result from independent assortment alone?

Answer 1

Answer 4:

Two meiotic events that promote genetic variability are—

a) Crossing over: In the pachytene stage of prophase-I of meiosis-I recombination of genes between two homologous chromosomes occurs due to crossing over. Crossing over is the process by which the exchange of chromosomal segment is done between two non-sister chromatids of two homologous chromosomes. Crossing over results in meiotic recombination and promotes genetic variability.

b) Random orientation of homologue pairs of chromosome: Meiosis-I is known as reduction division, because 2n number of chromosome reduce into n number of chromosome after this step. Homologous chromosomes are randomly oriented with independent assortment rule whichpromotes genetic variability.

Answer 5:

The formula for calculation of how many genetically different combinations can result from independent assortment alone is 2n; where n = haploid number of chromosome.

Here, diploid number of chromosome = 4, i.e., 2n = 4

So, haploid number of chromosome = (4/2) = 2 (as, 2n/2 = n), i.e., n = 2

So, the number of genetically different combinations can result from independent assortment alone = 2n = 22 = 4

Thus, if a cell has a diploid number of 4, then 4 genetically different combinations can result from independent assortment alone.