AP BIOLOGY

ANIMAL REPRODUCTION AND DEVELOPMENT

SEXUAL REPRODUCTION

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Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]

If a species of plant has 58 chromosomes in their normal body cell, then how many chromosomes will be in the pollen (sex cell)?

A	58
B	116
C	29
D	about 20

Explanation:

Detailed explanation-1: -Pollen grains are haploid. The endosperm in gymnosperms is haploid. Hence, both cells of endosperm and pollen grain will have 16 chromosomes.

Detailed explanation-2: -The correct option is (3). The microspore mother cell (MMC) is diploid and produces four haploid pollen grains. If the amount of DNA is 20pg and number of chromosomes is 16 in pollen grain, then amount of DNA and number of chromosomes in MMC will be 80pg and 32 chromosomes respectively in G2 phase.

Detailed explanation-3: -Homologous chromosomes have the same genes, though they may have different alleles. So, though homologous chromosomes are very similar, they are not identical. The homologous chromosomes are separated when gametes are formed. Therefore, gametes have only 23 chromosomes, not 23 pairs.

Detailed explanation-4: -Chromosome number in pollen grain is 6.

There is 1 question to complete.