Take out a piece of paper and pencil to solve the Dihybrid cross.
Rabbits have two unlinked allele pairs that affect fur color. The table shows how allele pairs affect fur color. The term “agouti” describes fur with pigmentation that gives the fur a banded appearance.
Rabbits with the aa allele pair are albino, regardless of the second allele-pair combination.
What is the probability of albinism in the offspring of a cross between two rabbits with AaBb alleles?
a
1/16
b
3/16
c
4/16
d
9/16
To solve this dihybrid cross, we need to consider both allele pairs separately and then multiply the probabilities together.
First, let's consider the fur color alleles. The cross is between rabbits with AaBb alleles. The dominant allele A produces agouti fur color, while the recessive allele a produces albino fur color.
The possible combinations for the fur color alleles in the offspring are as follows:
- AA allele pair: Agouti fur color
- Aa allele pair: Agouti fur color
- Aa allele pair: Agouti fur color
- aa allele pair: Albino fur color
Out of these 4 possible combinations, only one results in albino fur color. Therefore, the probability of albinism in the offspring for the fur color alleles is 1/4 or 4/16.
Next, let's consider the second allele pair, Bb. The dominant allele B produces banded fur color, while the recessive allele b produces non-banded fur color.
The possible combinations for the second allele pair in the offspring are as follows:
- BB allele pair: Banded fur color
- Bb allele pair: Banded fur color
- Bb allele pair: Banded fur color
- bb allele pair: Non-banded fur color
Out of these 4 possible combinations, none of them affect the fur color. Therefore, the probability of any effect on fur color for the second allele pair is 0/4 or 0/16.
Since these two allele pairs are unlinked, we can multiply the probabilities together:
Probability of albinism = Probability of albino fur color from fur color alleles * Probability of any effect on fur color from second allele pair
Probability of albinism = 4/16 * 0/16 = 0/256
Therefore, the probability of albinism in the offspring of a cross between two rabbits with AaBb alleles is 0, or option d) 9/16.