Solved Examples on Molecular basis of inheritance

(1) Each chromosome at the anaphase stage of a bone marrow cell in our body has [CBSE PMT 1995]  

(a) Two chromatids

(b) No chromatids          

(c) Only one chromatid

(d) Several chromatids

Answer: c

Solution:

Each chromosome at the anaphase stage of a bone marrow cell in our body has only one chromatid.

(2) Lampbrush chromosomes are visible [CBSE PMT 1996]

(a) In diplotene of meiosis       

(b) In prophase of meiosis      

(c) In interphase  

(d) In mataphase of meiosis

Answer: a

Solution:

Lampbrush chromosomes are a special form of chromosomes that are found in the growing oocytes (immature eggs) of most animals, except mammals. During the diplotene stage of meiotic prophase I, chromosomes transform into the lampbrush form due to an active transcription of many genes.

(3) Number of autosomes in human sperm is [CPMT 1983, 84; DPMT 1985]

(a) 11

(b) 22

(c) 44

(d) 45

Answer: b

Solution:

Number of autosomes in human sperm is 22.