Question

Which of the following is suitable for experiment on linkage ?

• A. $aaBB \times aaBB$
• B. $AABB \times aabb$
• C. $AaBb \times AaBb$
• D. $AAbb \times AaBB$

Answer 1

Answer: (B)

$AABB \times aabb$

Answer 2

Linked and unlinked genes can be easily known from breeding experiments. Unlinked genes show independent assortment in a dihybrid ratio of $9 : 3 :3 :1$ and the dihybrid or double test cross ratio of $1 : 1 : 1 : 1$ with two parental and two recombinant types. The linked genes do not show independent assortment but remain together and are inherited en block producing only parental type of progeny. They give a dihybrid ratio of $3 :1$ and a test cross ratio of $1 : 1$.
Linkage can be shown by a cross betwen homozygous dominant $AABB$ and homozygous recessive $aabb$.