1. The product H substance is needed to express the blood antigen. A mating of I

Question

1. The product H substance is needed to express the blood antigen. A mating of IA IB Hh X IA IB hh should produce what ratio of blood types?

2. If purple (P) is dominant to white (p) and axial (A) is dominant to terminal (a), and in a cross of white, axial to purple, axial the ratio of offspring is

6/16 white, axial;
2/16 white, terminal;

6/16 purple, axial; 2/16 purple, terminal,

then what is the genotype of the parents?

3. In a cross of two flies +/vg Cy/+ +/se +/ab X +/vg +/+ se/se ab/ab what proportion of the offspring will be mutant in phenotype for all four markers?

4. Mating of two organisms produces a 1:1 ratio of phenotypes in the progeny. The parental genotypes are?

5. Color blindness is X-linked recessive and blood type is autosomal. If two parents who are both Type A and have normal vision produce a son who is color blind and type O, what is the probability that their next child will be a female who has normal vision and is type O?

6. scalloped (sd) is an X-linked recessive and ebony (e) is an autosomal recessive mutation. What proportion of scalloped, ebony females (relative to whole population) is expected in the F2 starting with a true breeding scalloped female which is wild type for ebony mating with a true breeding male mutant only for ebony?

Explanation / Answer

1. The cross would be like mentioned below and ratio would be= 1:1:2:2:1:1

4. If the progeny has ratio 1:1, then parents are Heterozygous and recessive homozygous.

Aa x aa Parental generation

A a a Gametes

Aa aa F1 generation

Hence we get ratio 1:1

IA H IA h IB H IB   h IA   h IA IA Hh IA IA hh IA IB Hh IA IB hh IB   h IA IB Hh IA IB hh IB IB Hh IB IB hh

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