In humans,sex-linked characters are mainly transmitted through:

$(a)$ In humans,males are heterogametic and females are homogametic. Explain. Are there any examples where males are homogametic and females heterogametic?
$(b)$ Also describe as to who determines the sex of an unborn child? Mention whether temperature has a role in sex determination.

Which type of sex determination mechanism is observed in insects?

Organism with male heterogamety $- P$
Organism with female heterogamety $- Q$
$I -$ Human,$II -$ Bird,$III -$ Drosophila,$IV -$ Grasshopper
Select the correct option for $P$ and $Q$.
$\quad P \quad\quad Q$

If the $X/A$ ratio of two Drosophila individuals is $0.6$ and $0.33$ respectively,what will be their sex?

Meta-females (super-females) in Drosophila have which of the following chromosome complements?