Read the following statements carefully $:-$
$(a)$ Linkage is physical association of genes on a chromosome.
$(b)$ In $Drosophila$, genes of body colour and eye colour are tightly linked on $X$-chromosome.
$(c)$ In honey bee a fertilised egg develops as a male $(drone)$.
$(d)$ In grasshopper males have only one $X$-chromosome besides the autosomes.
$(e)$ $Drosophila$ can complete their life cycle in about two months.
Choose the correct option having all correct options.

The color of mashed fruit (or fruit skin color in certain varieties) is an example of ........

Read the following statements carefully:
$(1)$ Ploidy is a structural chromosomal abnormality.
$(2)$ Hemophilia is an autosomal recessive disorder in which blood does not clot.
$(3)$ Recombination is one of the factors responsible for evolution.
$(4)$ Genetic mapping allows the determination of the specific location of a gene on a chromosome.
$(5)$ Snapdragon plant is an example of incomplete dominance.
$(6)$ $ABO$ blood grouping shows both dominance and codominance.
Identify the correct and incorrect statements from the given options.

What is $HbA_2$ composed of?

Choose the correct option for the given descriptions:
$(i)$ The heterozygous female transmits the disease to the son.
$(ii)$ Change in the shape of the $RBC$ from biconcave disc to elongated sickle-like structure.
$(iii)$ Mentally retarded.
$(iv)$ Haemoglobin is not formed in the proper amount in the blood.

Theoretically,the phenotype is expressed only when an enzyme converts a substrate into its product. During which of the following conditions is the phenotype affected?