Question

Root cells of hexaploid wheat have 42 chromosomes. Which one of the following is the basic chromosome number of wheat?
A.42
B.21
C.7
D.14

Answer 1

Hint: Wheat may be diploid, that is it may have 14 chromosomes, tetraploid that is it can have 28 chromosomes and hexaploid that is it could have 42 chromosomes. Each has different species of wheat which is used in various functions.

Complete answer:
Hexaploid species of wheat have 42 chromosomes. There is a ploidy level of an individual organism that tells the number of complete basic chromosome sets which means that hexaploid species has 6 sets of basic chromosomes in it. Therefore, the basic chromosome in the root cells of hexaploid wheat for 6n is 42 then x will be 7. T. durum is the example of the hexaploid wheat which is used commonly.
If an organism is monoploid it would contain 6n as 42 and x will be 42 as it has only one ploidy. If haploid chromosome number is one in gametes of an organism the gametes will contain half the chromosomes of the somatic cells. Therefore, the haploid chromosome number of hexaploid wheat is 21. In addition, the basic chromosome number is 7 then the diploid species have 2n as 14. The number of the ploidy is dependent on the chromosomes contained in the species of the wheat plant.

Hence the correct answer is OPTION(C)

Note: Polyploidy is very common in the wheat. There are various diploid, tetraploid and hexaploid varieties of the wheat. Wheat has various mutations and many varieties have been evolved in the wheat plant which leads to evolution of new species.