In Drosophila, the sex is determined by
Whether the egg is fertilized or develops parthenogenetically
The ratio of number of $X$-chromosomes to the sets of autosomes
$X$ and $Y$ chromosomes
The ratio of pairs of $X$-chromosomes to the pairs of autosomes
Epicanthus is the symptom of
Polydactyly in man is due to
Lethal genes are
The mechanism that causes a gene to move from one linkage group to another is called
When a diploid female plant is crossed with a tetraploid male, the ploidy of endosperm cells in the resulting seed is