What is the number of chromosomes in the gamete cells of a housefly?

Read the following statements and identify the correct ones.
$(1)$ Linkage and recombination were first understood in $Lathyrus$ $odoratus$.
$(2)$ Mendel's work was rediscovered by Correns,Tschermak,and de Vries,which was published in $1900$.
$(3)$ $T.H.$ Morgan is considered the father of experimental genetics.
$(4)$ $A$ child born to parents with thalassemia major can be affected by thalassemia.
$(5)$ In birds,the female is homogametic and the male is heterogametic.

In a plant,three dominant genes $A$,$B$,and $C$ must be expressed together to produce purple flowers. If any one or all three genes are in the recessive state,the flowers become colorless.
Raw material $\xrightarrow{A} X \xrightarrow{B} Y \xrightarrow{C} Z$ (Pigment)
$A$ purple-flowered plant with genotype $AABBCC$ is crossed with a colorless plant with genotype $aabbcc$. This results in $F_1$ hybrid purple offspring. What will be the proportion of purple-flowered plants in the $F_2$ generation produced by selfing the $F_1$ generation?

Give differences: Incomplete dominance and Co-dominance.

What is $HbA_2$ composed of?

Match List $I$ with List $II$:

List $I$	List $II$
$A$. Two or more alternative forms of a gene	$I$. Backcross
$B$. Cross of $F_1$ progeny with homozygous recessive parents	$II$. Ploidy
$C$. Cross of $F_1$ progeny with any of the parents	$III$. Allele
$D$. Number of chromosome sets in plant	$IV$. Test cross

Choose the correct answer from the options given below: