Question

1) Why do genes on the same chromosome not segregate with “Mendelian Genetics”? Why/How do the frequencies of their co-segregation vary depending on their exact location?

2) Why does separating the left/right halves versus the dorsal/ventral halves of a two-cell stage amphibian embryo yield different results?

3) Why does the transplantation of an early blastopore lip induce head formation, while a late blastopore lip induces a tail?

Answer 1

2) cleavage in amphibian embryo is radially symmetrical and holoblastic

That mean it can be divided into two equal Half's when cut from the Midian axis.

But when we cut it from left /right it will be not the same as that when it is cut from the ventro/dorsal asix.

3) early blastopore lip in protostomians the blastopore develops into Head and in late blastopore , in duterostomians it develops into anus. This is beacuse protostomians have a spiral cleavage where as duterostomians have a radial cleavage. The outcome in protostomians is determinate where as in other group is Indeterminate