Question

monohybrid crosses- crosses in which the expression of only one character is studied
two black female skinks are crossed with a brown male. in several clutches, female #1 produced 9 black and 7 brown offspring and female #2 produced 17 black offspring. from this information:
a. what assumptions can you make about how black and brown is inherited in skinks? (degree of dominance)
b. what are the genotypes of the three parents? explain your answer.
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12pt paragraph b i u a t² 8 1218

Explanation:

For part a: When female #1 (black) crossed with brown male gives both black and brown offspring, and female #2 (black) crossed with brown male gives only black offspring. This suggests that black is dominant over brown. If brown was dominant, we would not see the pattern of offspring as described. For part b: Let's assume the allele for black is \( B \) and for brown is \( b \). The brown male must be \( bb \) (since brown is recessive). Female #2 produced only black offspring when crossed with \( bb \), so female #2 must be \( BB \) (so all offspring get \( B \) from her and \( b \) from the male, resulting in \( Bb \)-black). Female #1 produced both black (\( Bb \)) and brown (\( bb \)) offspring. Since the male is \( bb \), female #1 must be \( Bb \) (so she can give either \( B \) or \( b \) allele).

Answer:

a. Black is dominant over brown.
b. Male: \( bb \) (because brown is recessive). Female #1: \( Bb \) (since she can produce both \( B \) (to make \( Bb \)-black) and \( b \) (to make \( bb \)-brown) offspring when crossed with \( bb \)). Female #2: \( BB \) (as all her offspring with \( bb \) male are \( Bb \)-black, she only donates \( B \) allele).