Please answer all. 3) What is the probability of each of the following sets of p
ID: 218895 • Letter: P
Question
Please answer all.
3) What is the probability of each of the following sets of parents producing the given genotypes in their
offspring?
Parents Offspring Probability
a. BBDD x BbDD BbDD
b. BbDd x BbDd BBDd
c. BbDd x bbDd BbDD
d. bbDd X BBdd bbdd
4) Duchenne muscular dystrophy is due to a sex-linked recessive gene. A normal male and a
normal female have children. Their first child (a boy) has Duchenne muscular dystrophy.
What are the possible genotypes of a second son (if they had one)?
What are the chances their third son, if they had one, would have the disorder?
What are the genotypes of the mother and the father?
5) In a species of frog the gene for color shows codominance. Frogs that are black and frogs that
are yellow are homozygous. Frog with one black allele and one yellow allele are black and
yellow (i.e. their skin is black with yellow spots). For each of the following construct a
Punnett square and give phenotypic and genotypes and the ratios of the offspring.
a) a yellow frog mates with a black frog
b) a yellow frog mates with a black and yellow frog (i.e. black frog with yellow spots)
c) a black frog mates with a black and yellow frog (i.e. black frog with yellow spots)
d) two black and yellow frogs
6) What are the odds of a couple having a child with blood type Bi if the mother’s blood type is
heterozygous for A and their father’s blood type is heterozygous for B?
7) For each phenotype determine the genotype.
Black spots are dominant to brown spots
Homozygous black _________
Brown spots __________
Long ears are dominant to short ears
Heterozygous ____________
Homozygous for long ears ____________
8) White pigmentation is recessive to red.
Rr x Rr - What percentage of the offspring will be red?________
Rr x rr - What percentage of the offspring will be white? _______
Explanation / Answer
4. Ans-
To get the answer, we must construct a Punnett square. Here D is the normal allele and d represents the recessive allele that causes Duchenne muscular dystrophy.The mother must has heterozygous allele and the father has normal allele.Therefore, the genotype of mother and father are XDXd and XDY respectively.
XD Y
XD XD XD XDY
Xd XD Xd Xd Y
2 normal daughters(XD XD and XD Xd)
1 normal son ( XDY)
1 affected son (XdY).
There possible genotype of a second son is XDY.
There is a 1/4 chance that would have the disease.
The genotype of mother and father are XDXd and XDY respectively
6) Ans-
The mother’s genotype will be IAI or IAIA. Since she is heterozygous for A. Therefore, the genotype is IAIi. The genotype of the father is IBI. When crossed,
P1- IAI × IBI
F1- IAIB IAI IBI IBI
Therefore, 50% child with blood type IBI
7) Ans-
i)Let the symbols for black spots is B which is dominant over brown spot(b). When crossed, we found,
Bb × Bb
BB Bb Bb bb
BB= homozygous black, Bb= heterozygous black with brown spots, bb= homozygous brown.
Homozygous black- BB
Brown spots - Bb
ii) Let the symbols for long ears and short ears are: L and l respectively.
Ll × Ll
LL Ll Ll ll
LL= homozygous long ears, Ll = heterozygous for long ears, ll= homozygous for short ears
Heterozygous = Ll
Homozygous for long ears = LL
8) Ans-
i)R= Red , r= white
Rr x Rr
RR Rr Rr rr
75% of the offspring will be red (RR and Rr)
ii) Rr x rr
Rr Rr rr rr
50% of the offspring will be white(rr).