Question

Which of the following crosses can never result in a recessive phenotype?

(a) Tt Pp X Tt Pp

(b) TT Pp X tt pp

(c) tt pp X TT PP

(d) tt pp X Tt Pp

The question was posed to me in an international level competition.

This intriguing question originated from Numerical Problems topic in division Mendelian Genetics of Cytogenetics

Answer 1

Correct choice is (c) tt pp X TT PP

For explanation I would say: In case of this cross although one is homozygous recessive the other is homozygous dominant, so all the progeny will be heterozygous expressing the dominant trait. In case of TT Pp X tt pp the recessive trait can be seen in case of P locus.