AP BIOLOGY

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HEREDITY

MONOHYBRID CROSS

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
In cocker spaniels the allele for a black coat color (B) is dominant over the allele for a brown coat color (b). If a brown cocker spaniel is crossed with a heterozygous black cocker spaniel, which of the following genotypic ratios can be expected?
A
0 BB:2 Bb:2 bb
B
1 BB:2 Bb:1 bb
C
2 BB:2 Bb:1 bb
D
2 BB:1 Bb:0 bb
Explanation: 

Detailed explanation-1: -In cocker spaniels, black coat color (B) is dominant over red (b), and solid color (S) is dominant over spotted (s).

Detailed explanation-2: -Mutations in somatic cells are called somatic mutations. Because they do not occur in cells that give rise to gametes, the mutation is not passed along to the next generation by sexual means.

Detailed explanation-3: -A karyotype test checks the chromosomes in your cells to: See whether you have a full set of 46 chromosomes. Having too many or too few chromosomes can cause serious problems with health, growth, and normal development, such as Down syndrome (extra chromosome 21) and Turner syndrome (missing X chromosome).

Detailed explanation-4: -Karyotypes can reveal changes in chromosome number associated with aneuploid conditions, such as trisomy 21 (Down syndrome). Careful analysis of karyotypes can also reveal more subtle structural changes, such as chromosomal deletions, duplications, translocations, or inversions.

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