NEET BIOLOGY

Detailed explanation-1: -Meiosis is a cell division process where a single parent cell divides twice to produce four daughter cell containing half the amount of the original genetic information. So, if a cell has 12 chromosomes at the begining of meiosis then the amount of chromosomes it will have at the end of the meiosis will be 12/2=6.

Detailed explanation-2: -So if a cell has 12 chromosomes at the end of meiosis I which is reduction division, it means that the parent cell would have had 24 chromosomes in prophase I. At the end of meiosis II (which is similar to mitosis and hence, equational division occurs) it would have 12 chromosomes.

Detailed explanation-3: -Correct. During metaphase each chromosome consists of two identical, double-stranded DNA molecules. Therefore, if a cell normally contains 12 chromosomes, there will be 24 molecules of DNA during metaphase.

Detailed explanation-4: -If the haploid number of chromosomes i.e. ‘n’ in Pinus is 12, The number of chromosomes in its root is 2n=24 and in endosperm n=12 because endosperm is a pre-fertilisation product and the plant body is diploid in gymnosperms.