Complete the table below by calculating the number of chromo

Complete the table below by calculating the number of chromosomes indicated by each letter (A-F) in the table. Explain how you arrived at your answers.

Polar Bear

Rattlesnake Fern

n

A.

92

Number of chromosomes before mitosis

74

D.

Number of chromosomes after mitosis

B.

184

Number of chromosomes before meiosis

C.

E.

Number of chromosomes after meiosis

37

F.

Solution

n is the haploid number which indicates the number of chromosomes in one set in a somatic cell (cells which are other than reproductove cells). For example in humans, n=23. Humans are diploid (2n) so each somatic cell has 23 * 2 = 46 chromosomes. Each somatic cell in humans has 46 chromosomes. Whereas each reproductive cell contains haploid number which is 23 chromosomes. Polar bear and Rattle snake fern both are diploid in nature.

(A) The number of chromosomes before mitosis will be the diploid number of chromosomes (2n) . So in Polar Bear if number of chromosomes before mitosis (2n) is 74, the value of n will be 37.

(B) After mitosis, each somatic cell having the diploid number of chromosomes, divides into two new cells having the same diploid number of chromosomes as the parent cell. So value of (B) will be 74.

(C) Number of chromosomes before meiosis is 2n. Meiosis starts with diploid cell and ends with two haploid cells. The number of chromosomes is reduced by half after meiosis. So value of (C) will be 2n = 74.

(D) For Rattlesnake Fern, n=92. So number of chromosomes before mitosis is diploid = 2n= 2*92. Value of (D) is 184.

(E) The number of chromosomes before meiosis is diploid 2n. So value of (E) is 184

(F) The number of chromosomes after meiosis is haploid n. So value of (F) is 92