Question

The chromosome of hexaploid wheat is 42. The basic chromosome number is?

• A. 21
• B. 7
• C. 42
• D. 84

Hint:

For Hexaploid wheat: Somatic number $2n = 42$, Haploid number $n = 21$, and Basic number $x = 7$ ($2n = 6x = 42$).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The basic chromosome number ($x$) represents the monoploid number of chromosomes in a single ancestral genome.

Step 2: Key Formula or Approach:
Hexaploid bread wheat (Triticum aestivum) is an allohexaploid with three distinct ancestral diploid genomes ($A, B, D$):
\[2n = 6x = 42\] Dividing the total somatic chromosome number ($2n = 42$) by the ploidy level ($6$):
\[x = \frac{42}{6} = 7\]

Step 3: Detailed Explanation:
The gametic haploid chromosome number is $n = 21$, while the basic chromosome number is $x = 7$.

Step 4: Final Answer:
Hence, the basic chromosome number is 7.