Question

Given diagram shows a pair of homologous chromosomes during meiosis.

Maximum crossing over will occur between genes

• A. $A$ and $a$, $D$ and $d$
• B. $C$ and $d$, $c$ and $D$
• C. $B$ and $c$, $b$ and $C$
• D. $A$ and $d$, $a$ and $D$

Answer 1

Answer: (D)

Increase in distance between two genes increases the frequency of crossing over while closeness of the genes reduces the chances of crossing over. Since $A$ and $d$ and a and $D$ are located far away, maximum crossing over would occur between them.