Question

Select the incorrect statement(s).
(a) Linked genes cause absolute lethality
(b) Persons affected by PKU do not show mental retardation
(c) $F_2$ ratio in codominance and incomplete dominance is same
(d) Sex of Drosophila is determined by XX-XO chromosomes

• A. (a) and (b)
• B. (b) and (c)
• C. (a), (b) and (d)
• D. All of these

Answer 1

The correct option is C (a), (b) and (d)

Linked genes are genes that are likely to be inherited together because they are physically close to one another on the same chromosome. Linked genes are not lethal to all.

Phenylketonuria causes neurological problems that may include seizures and intellectual disability. It also causes delayed development and mental retardation.

In incomplete dominance and codominance, both phenotypic and genotypic ratios are identical ($1:2:1$) in $F_2$ generation.

Sex of Drosophila is determined by XX-XY chromosomes. Diploid cells with one $X$ and $Y$ chromosomes $\left(XY\right)$ are male and those with two $X$ chromosomes $\left(XX\right)$ are female.