Question

The salivary gland chromosomes in the dipteran larvae are useful in gene mapping because

(a) These are much longer in size

(b) These are easy to stain

(c) These are fused

(d) They have endoreduplicated chromosomes

Answer 1

Correct option (d) They have endoreduplicated chromosomes

Explanation :

Balbiani (1881) was the first person who observed salivary gland chromosomes in the salivary glands of Chironomus larvae. These chromosomes are very useful in gene mapping because they have endoreduplicated chromosomes. These chromosomes are formed due to the process of endoduplicatton or endopolyploidy or endomitosis. In this process the nuclear membrane does not rupture but chromosomes become double and they do not separate from each other.