Match the terms in column $I$ with their description in column $II$ and choose the correct option.

Column $-I$	Column $-II$
$(A)$ Dominance	$(i)$ Many genesgovern a single character
$(B)$ Codominance	$(ii)$ In a heterozygousorganism only one allele expresses itself
$(C)$ Pleiotropy	$(iii)$ In a heterozygousorganism both alleles express themselves fully
$(D)$ Polygenic	$(iv)$ A single gene inheritanceinfluences many characters

What is the correct sequence of the following events

$1.$Formation of the chromosome theory of heredity

$2.$Experiments which proved that $DNA$ is the hereditary material

$3.$Mendel's laws of inheritance-discovery

Code :

Select incorrect statement

$(A)$ Linked genes cause absolute lethality
$(B)$ Persons affected by $PKU$ do not show mental disorder
$(C)$ $F_{2}$ ratio in codominance and incomplete dominance are same
$(D)$ Sex of male Drosophila is dependent on $Y-$chromosome

Choose correct answer :

$(i)$ Queen Elizabeth shows a number of haemophilic descendents.

$(ii)$ Variation in blood group prevalences due to incomplete dominance.

$(iii)$ Drosophila has three pairs of autosomal chromosomes.

$(iv)$ In birds, female is heterozygous.

Pick out the correct statements.

$(1)$ Haemophilia is a sex­linked recessive disease.

$(2)$ Down’s syndrome is due to aneuploidy.

$(3)$ Phenylketonuria is an autosomal recessive gene disorder.

$(4)$ Sickle cell anaemia is an $X$-­linked recessive gene disorder.

Match the following:

Column $- I$	Column $- II$
$(1)$ Inheritance of two genes	$(a)\; ABO$ blood group
$(2)$ Incomplete dominance	$(b)\; 1:2:1$
$(3)$ Codominance	$(c)\;9:3:3:1$
$(4)$ Inheritance of one gene	$(d)\; 3:1$