1. The Manx cat has a very short or no tail due to a dominant trait T . Cats who

Question

1. The Manx cat has a very short or no tail due to a dominant trait T.  Cats who inherit one dominant (T) and one recessive (t) allele will be tailless (Manx); cats who are homozygous recessive will have normal, long tails.  However, the homozygous dominant condition (TT) is lethal—the embryo will not develop.  If two Manx cats breed, what are the chances of Manx offspring or kittens with long tails?

A. There will be no offspring at all, since none of the embryos will develop.

B. All offspring will be Manx cats.

C. All offspring will be kittens with long tails.

D.Twice as many Manx as kittens with tails.

E. Equal chance of Manx or kittens with tails.

2. Given what we know about Mendelian genetics, what is the genotype of pea plants with white flowers?White is a recessive trait while purple is a dominant trait.

A. hemizygous recessive

B. pw

C. w

D. homozygous recessive

E. heterozygous

Explanation / Answer

1. The Manx cats are heterezygous (Tt). The possible genotypes for the surviving offspring are Tt and tt, with Tt having double the chances of tt (following the ratios of a heterozygous cross). Therefore we will have twice the number of Manx cats than kittens with tails. Option D is the correct option.

2. Option D, homozygous recessive. As ony other genotype containing a gene for purple flowers will result in purple flowers, and hemizygous plants are not common in the wild. Homozygous recessive has both genes as the gene for the white flower color.

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