Question

When two genes are situated very close to each other in a chromosome then
A- the percentage of crossing over between them becomes very high
B-no crossing over can ever take place between them
C- hardly and crossing over is detected
D-only double crossing over can be detected them

Answer 1

Option B is correct because when two genes are very close to each other linkage exist between them and due to linkage crossing over become hard for them more the distance they apart more is the chance for linkage

Answer 2

The correct answer is option B-no crossing over can ever take place between them.

In case, the genes are present very close to one another, the chances for the separation of the genes during recombination is reduced to a significant level.  The two genes would represent the linkage in between them and during the process of crossing over, both the genes are transferred or none of them are transferred. So, the crossing over did not take place in between them.