Question

1 One form of Retinitis Pigmentosa is a Y- linked genetically inherited disease of the eye in which the cells of the retina produce defective. Symptoms include a progressive loss of sight starting with decreased night vision, loss of peripheral vision, and eventually blindness. If a father has the disease and a woman who does not, have a son what are the chances their son will also have the disease?

A) not enough information

B) 25%

C) 0%

D) 50%

E) 100%

#2 In mice, for brown fur, is dominant to the gene for white fur, the gene for long tails is incompletely dominant to short tails, and the gene for big ears is dominant to small ears. A white, medium- tailed, big-eared (heterozygous) mouse, mates with a mouse heterozygous for brown fur, has a short tail, and small ears. What is the probability of these two parents having white, short-tailed, big-eared- babies?

#3 In a specific plant, assume that the trait for blue flowers (B) is dominant to white flowers (b), and the trait for round seeds (R) is dominant to wrinkled seeds (r). The probability of an offspring having blur flowers and wrinkled seeds 3/16. Which of the following genotypes most likely represent the parents?

A) BbRr x bbRr

B) bbRr x Bbrr

C) BBRR x BbRr

D) BbRr x BbRR

E) BbRr x BbRr

#4 Hair length in cats shows regular dominance. A cat that is heterozygous for long hair and a cat with short hair have a little of 6 kittens that all have short hair. Then, they have another litter of 8 kittens, how many of these kittens would you expect to have short hair?

A) 8

B) 0

C) 2

D) 4

E) 6

#5 Danon Disease is a X- linked DOMINANT disorder and results in abnormal cardiac muscle cells. A father who has it and a mother who does not, have a girl, what are the chances that she has it?

A) 100%

B) 25%

C) 50%

D) 75%

E) 0%

#6 Two plants with pink flowers are crossed, and the F1 generation shows the following ratio 1 red: 2 pink: 1 white. The best explanation for this phenomenon is that alleles for this flower color are

A) crossed over

B) independently assorted

C) dominant and recessive

D) codominant

E) incompletely dominant

#7 Red petals are incompletely dominant to yellow petals. What are the chances that an orange flower and a red flower have yellow offsprings?

A) 0%

B) 100%

C) 25%

D) 50%

E) 75%

Answer 1

1. 100%

Father is affected.

Mother is normal.

The characteristic feature of Y linked traits is that they are always transmitted from Father to Son and then to grandson. The males are always affected because they contain Y chromosome. The females and never affected because they do not have Y chromosome. The transmission is always from male to male. So if one male is affected, then males in its future generations will also be affected for sure.

2. BbRr × BbRr (last)

It is given that 3 out of 16 progenies have blur flower and wrinkled seeds. 16 progenies will only be formed when both of the parents will give rise to 4 gametes.

If the genotype of both the parents is BbRr, than BR, Br, bR, br gametes will be formed. This will result in the formation of 16 progenies.

According to the guidelines, only first question can be answered. Please give a good rating.