The theory where ratio between the number of $X$-chromosomes and number of complete sets of autosomes will determine the sex is known as

Knowing that albinism is determined by a recessive gene in man; presence of albinism in children born to a couple proves that

The barr body is observed in

In a gene pool, along with beneficial mutations those mutations also exists which are damaging to an individual. It has been found that these mutations are irreversible because

$I.$ they have survival value

$II.$ they are acquired

$III.$ they are recessive and carried by heterozygous individuals only

$IV.$ they show genetic drift

Choose the incorrect option for given statement

Ischihara chart is used to detect