In Mendel's experiments with garden pea, round seed shape (RR) was dominant over wrinkled seeds (rr), yellow cotyledon (YY) was dominant over green cotyledon (yy). What are the expected phenotypes in the F₂ generation of the cross RRYY × rryy ?

Sickle cell anaemia has not been eliminated from the African population because-

If a colour blind woman marries a normal visioned man, their sons will be

Test cross involves-