Question

If the number of chromosome is an endosperm of seed is 21 ,what will be the chromosome number in the secondary nucleus?
17
228
314
421​

Answer 1

Explanation:

The endosperm is triploid in nature. Thus, 3n = 27. Whereas, the definitive nucleus is diploid in nature. Thus, the it will have 2n = 18 chromosomes.

Thus, the correct answer is option B.

Answer 2

Answer:

Option 3) 14

Explanation:

• The endosperm is the nutritive tissue for developing embryos in angiosperms. In angiosperms, it is formed by triple fusion i.e. fusion of three nuclei (two polar nuclei and a male gamete). This endosperm of the seed is triploid.

We know that no. of chromosome defines the ploidy.

As given,

no. of chromosome in the endosperm is 21,

i.e - 3n= 21 ⇒n= 7.

• The secondary nucleus is the fusion product of the two polar nuclei present in the central cell of a mature embryo sac.

So it is formed of two haploid polar nuclei.

Thus, secondary nuclei are diploid.

⇒ 2n= 14.

Hence option (3) is correct.