CSIR NET 2023 | Life Science: Inheritance Biology | 08 June

The maternal-effect of shell coiling in snail (Limnaea peregra) is well established. The dextral coiling depends on dominant allele D and sinistral coiling depends upon recessive allele d. A female F1 progeny of dextral (Dd) type is crossed with a male sinistral (dd) snail. What will be the ratio of heterozygous:homozygous individuals in its F3 progeny?

In a genetic assay, randomly generated fragments of yeast DNA were cloned into a bacterial plasmid containing gene ‘X’ essential for yeast viability on minimal media. The recombinant plasmid was used to transform a yeast strain deficient in recombination and lacking ‘X’ gene. Transformants, which survive on minimal media and form colonies should essentially have:

An experiment was conducted in E. coli to map the following genes (pro, his, bio, met, phe and trp) on a circular map using three different Hfr strains:

* Strain 1, order of transfer (early to late) : trp met his pro

* Strain 2, order of transfer (early to late) : his met trp bio

* Strain 3. order of transfer (early to ,late) : pro phe bio trp

Based on the results, what is the most likely map?

The a₁, a₂, and a₃ are three alleles of a gene in Neurospora.
 
Crosses between different mutants gave the following results. Consider the following processes:
A) gene conversion
B) forward mutation
C) non-homologous recombination
D) incomplete dominance

The process which best explains this result is

Ankita and Ram are having their first child. Ankita knows her blood type is A, but Ram does not know his blood type. However, Ram knows that his mother and father were B blood type. Their first child is a boy named Ankish. Ankish has type O blood. Of course, Ankita and Ram do not understand how this happened. You could explain this to them using which of the following choices?