What do the following symbols used in the topic on heredity represent?

(a) TT (b) tt

(c) XX (d) XY

(a) TT – Tall plant (T is a dominant gene).

(b)tt- dwarf plant (t is a recessive gene and there is no dominant gene to rule over it so dwarf height).

(c)XX- Female. (Female have both the sex chromosome as X X).

(d)XY- Male. (Male have One X chromosome and the other is Y chromosome as their sex chromosome).