Which of the following statements is not true of two genes that show 50% recombination frequency?

(1) the genes may be on different chromosomes 

(2) the genes are tightly linked

(3) the genes show independent assortment

(4) If the genes are present on the same chromosome, they undergo more than one crossovers in every meiosis

Mutations can be induced with 

(1) IAA

(2) ethylene

(3) gama radiations

(4) infra red radiations

Cri-du-chat syndrome in humans is caused by the :

(1) fertilization of an XX egg by a normal Y-bearing sperm

(2) loss of half of the short arm of chromosome 5

(3) loss of half of the long arm of chromosome 5

(4) trisomy of 21st chromosome.

A point mutation comprising the substitution of a purine by pyrimidine is called

(1) transition

(2) translocation

(3) deletion

(4) transversion

The "cri-du-chat" syndrome is caused by change in chromosome structure invloving

(1) deletion

(2) duplication

(3) inversion

(4) translocation