Question

24. Niemann–Pick disease is a fatal lysosomal storage metabolic disorder caused by an autosomal recessive allele. A couple, both of whom are heterozygous for the allele, are wanting to start a family. They are hoping to have three children. What is the probability that if they have three children, none of them will have Niemann–Pick disease?

A. 1/4

B. 1/3

C. 2/3

D. 9/64

E. 27/64

25. A beetle with a striped carapace is crossed with one having striped wings, producing normal looking (no stripes on the carapace or wings) progeny. If two of these normal looking progeny mate with each other, what fraction of their progeny are expected to have striped carapaces and striped wings? (The genes conferring stripes or no stripes on carapace and on wings each have two alleles and are on different chromosomes).

A. 1/2
B. 3/8
C. 1/4
D. 1/16
E. There is insufficient information to make a prediction

Answer 1

Answer:

24). E). 27/64

Explanation:

Pp x Pp ---Parents

	P	p
P	PP (normal)	Pp (normal)
p	Pp (normal)	pp (Neimann-pick disease)

Normal = ¾

Neimann-pick disease = ¼

The probability that the three children are normal = ¾ * ¾ * ¾ = 27/64

25). D). 1/16

Explanation:

No stripes on the carapace = C

Stripes on the carapace = c

No stripes on the wing = W

Stripes on the wing = w

Striped carapace (ccWW) x striped wings (CCww) ----- Parents

CcWw (no stripes on the carapace or wings) --------Progeny

CcWw x CcWw ---F1 intercross

Cc x Cc = C_ (3/4) & cc (1/4)

Ww x Ww = W_ (3/4) & ww (1/4)

The fraction of their progeny are expected to have striped carapaces and striped wings = ccww = ¼ * ¼ = 1/16