Genetic studies of an animal show that eye color is controlled by an autosomal gene with the dominant
allele (R) for red eye color and the recessive allele (r) for yellow eye color. A second autosomal gene
has the dominant allele (T) leading to paws with thumbs while the recessive allele (t) codes for paws
without thumbs. The genetic cross RRTT ? rrtt creates offspring with genotype RrTt. One of those
dihybrids is mated in a testcross (RrTt ? rrtt). Based on the principle of independent assortment the
testcross should produce offspring with the phenotype ratio
a. 3 red-eyed with thumbs: 1 yellow-eyed without thumbs.
b. 1 red-eyed with thumbs: 1 yellow-eyed with thumbs: 1 red-eyed without thumbs: 1
yellow-eyed without thumbs.
c. 1 red-eyed with thumbs: 1 yellow-eyed without thumbs.
d. 9 red-eyed with thumbs: 3 yellow-eyed with thumbs: 3 red-eyed without thumbs: 1
yellow-eyed without thumbs.
e. 3 yellow-eyed with thumbs: 1 red-eyed without thumbs.
B
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What will be an ideal response?
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What will be an ideal response?
It is essential for heart muscle cells to beat in a coordinated fashion. The cell junctions that would best facilitate this are
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