Question

You are very interested in alien genetics so you are working with alien life forms in a top secret lab. You know that in these diploid aliens, tall antennae (T) and one eye (C) are dominant traits. You know that short antennae (t) and two eyes (c) are recessive traits. You have a female alien who is Cyclops – one eye (C) with tall antennae (T) but you don’t know her genotype for sure.

A. Name the TYPE of cross you would use to help determine her genotype.

B. What are her potential genotypes?

C. Indicate the genotype AND phenotype of the male you would use.

D. After you conduct your cross, if you have aliens that are 50% Cyclops with tall antennae and 50% Cyclops with short antennae, what is the genotype of your female alien? SHOW how you got this answer for full credit! (hint: you should have four different matings to examine to help you determine this).

Answer 1

A) test cross that is male with recessive traits for these characters are crossed to the female.

B) female can be TtCc, TTCc,TtCC,TTCC.

C) genotype of the male we use is ttcc and his phenotype would be short antennae and two eyes.

D) there are 50% tall antennae and 50% short antenna so with respect to the eye female can be CC or Cc but for T locus she is Tt, the male is tt so the cross is Tt*tt

	T	t
t	Tt ( tall antenna)	tt( short antenna)

here tall antenna and short antenna are in the ratio1:1 that is 50% and 50% so the genotype of the female can be TtCC or TtCc