The frequency of certain genes in a population changes over generations. This is the essence of the idea of evolution.

In the following crosses,write the characteristics of the progeny:

Cross	Progeny
$(a)$ $RR YY \times RR YY$ (Round,yellow $\times$ Round,yellow)	..........
$(b)$ $Rr Yy \times Rr Yy$ (Round,yellow $\times$ Round,yellow)	..........
$(c)$ $rr yy \times rr yy$ (Wrinkled,green $\times$ Wrinkled,green)	..........
$(d)$ $RR YY \times rr yy$ (Round,yellow $\times$ Wrinkled,green)	..........

According to the evolutionary theory,the formation of a new species is generally due to:

It is a commonly held misconception that the mother's egg is responsible for determining whether the baby will be a boy or a girl. But actually,it is the father's sperm that decides this. Which of the following makes the sperm the decisive factor?

Study the following cross showing self-pollination in $F_1$ generation,fill in the blank,and answer the question that follows:
Parents: $RRYY \times rryy$
(Round,yellow) (Wrinkled,green)
$F_1$: $RrYy \times$ ?
(Round,yellow)

$(a)$ What function is performed by human arms,forelimbs of a dog,and forelimbs of whales?
$(b)$ Which type of organs are these?
$(c)$ Why are they called so?