Question

In the hexaploid wheat, the haploid $(n)$ and basic $(X)$ numbers of chromosomes are

• A. n = 21 and x = 21
• B. n = 21 and x = 14
• C. n = 21 and x = 7
• D. n = 1 andx = 21.

Answer 1

The Correct Option is C

To solve this problem, let's begin by understanding the basic definitions of terms involved:

• Haploid number (n): This is the number of chromosomes in a gamete, representing a single set inherited from either parent.
• Basic number (X): This refers to the number of distinct chromosomes in a single complete set.
• Hexaploid: An organism with six complete sets of chromosomes.

In tetraploid organisms, the relationship between the ploidy level and the chromosome numbers is:

\text{Ploidy level} = \text{Multiple of } X = 6X (because it's hexaploid)

From this, we can infer:

1. The haploid number n, which is half of the total chromosome number, is used in gametes. In hexaploid wheat, the haploid number is given as n = 21.
2. The basic number of chromosomes X for hexaploid wheat is the number of sets (which is 6X = total chromosomes) divided by 6.

Given the options, for hexaploid wheat:

• Total chromosome number = 6X = 42 for hexaploid wheat
• Therefore, X = 42 / 6 = 7
• Thus, n = 21 and X = 7

The correct answer is n = 21 and x = 7.

Let's rule out the other options using this reasoning:

• n = 21 and x = 21: This would mean 6X = 126, which is incorrect for hexaploid wheat.
• n = 21 and x = 14: This implies 6X = 84, which is also incorrect.
• n = 1 and x = 21: This is incorrect as the given haploid number isn't 1.