Correct option is D
(d) Temperature sensitive, dominant
The key observation here is that the mutation causes a reduction in eye size at one temperature (29°C) but not at another (18°C), and this occurs even when the animals bear a single copy of the mutation. This suggests that the mutation is dominant, as the phenotype is observed with just one copy of the mutation. Additionally, the mutation’s effect is temperature-sensitive, as it is only expressed at 29°C and not at 18°C. Therefore, the correct description of the mutation is temperature sensitive and dominant.
Information Booster:
Temperature sensitive mutations are mutations whose phenotypic effects are only visible at certain temperatures. In this case, the eye size reduction is visible only at 29°C.
Dominant mutations are those where a single copy of the mutation (heterozygous state) is sufficient to express the phenotype.
The fact that the phenotype is present even with one copy of the mutation indicates dominance, as recessive mutations require two copies of the mutated gene for the effect to be observed.
Temperature insensitivity would imply that the mutation has the same effect at both temperatures, but this is not the case in this scenario.
A recessive mutation would not show the phenotype in a heterozygous individual (with one copy of the mutation), but the mutation is dominant, as it expresses the phenotype even in a single copy state.
