Question

1. If a true-breeding white flowered plant is bred with a true-breeding purple flowered plant, what are the genotypes of the offspring?
A. heterozygous
B. homozygous dominant and heterozygous
C. heterozygous dominant
D. homozygous dominant and homozygous recessive
E. homozygous dominant, heterozygous, and homozygous recessive

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. heterozygous
B. w
C. homozygous recessive
D. hemizygous recessive
E. pw

3. Coat color for a breed of cattle is determined by two co-dominant alleles, one for white (W) and one for red (R). A heterozygote will be a mixed color, called roan. Crossing two roans produces an equal number of white or red offspring and twice as many roans. If a farmer wanted a herd of cattle that were all roans, what color should the two parents be?

A. Roan and roan.
B. Roan and white.
C. Roan and red.
D. White and red.
E. Red and red.

Answer 1

Answer 1: Option C, heterozygous dominant

Explanation: For example the genotypes of these true breeding white and purple flowers is pp and PP, respectively, then the offsprings would be all Pp. This is a heterozygous genotype and it will express dominant trait only.

Answer 2: Option C, homozygous recessive

Explanation: If the trait is recessive, then it will express only when both the alleles of the genotype are recessive alleles. And this would be homozygous state. For example, 'pp' would be the genotype for white flowers.

Answer 3: Option D, white and red

Explanation: If we want that all offsprings should be heterozygous, then parents should be true breeding, which means homozygous. Here, roan is a heterozygous trait [WR]. So both parents should be homozygous, like RR and WW. Then only all offsprings would be heterozygous.