Question

is In guinea pigs, black coat color (B) is dominant to white (b), and rough color (R) dominant to smooth (o). What following crosses a) BBRR x bbrr b) BBrr x bbRR c) Bbrr x bbRr d) BBRr x BbRr e) BbRr x BbRr 2)The presence of one of the Rh antigens on the surface of the red blood cells (Rh+) in humans is produced by a dominant gene R. Th negative cells are produced by the recessive genotype rr. Oval shaped erythrocytes (elliptocytosis) are caused by a dominant gene E, its recessive allele,e produces normal red blood cells. A man positive elliptocytosis, whose mother had normally shaped erythrocytes and a homozy gous marries a normal Rh negative woman. (a) wha with Rh genotype and whose father was Rh negative and heterozygous for elliptocytosis, t is the genotype of the man and the woman he marries? (b) What are the probabilities of the offspring they can have and what ratios? (c) What is the probablity of their first child being Rh negative and elliptocytotie? (d) If their first child is Rh positive, what is the chance that it will also be elliptocytotic? Le Color may be red 3) The shape of radishes may be long (II), round (LL) or oval ). (RR), white (rr) or purple (Rr). If a long, white strain is crossed with a red, round strain, what phenotypic and genotypic proportions would be expected in the Fl and F2. Write the genotypes of the parents as well. 4. When Mexican Hairless dogs are crossed with normally haired dogs, about half the pups are hairless and half have hair. When, however, two Mexican Hairless dogs are mated, about a third of the pups produced have hair, about two thirds are hairless, and some deformed puppies are born dead. Explain these results (show the genotypes) 5. A dominant gene, A causes yellow color in rats. The dominant allele of another independent gene, R, produces black coat color. When the two dominants occur together (A/- R/-), they interact to produce gray. Rats of the genotype a/arir are cream colored. If a gray male and a yellow female, when mated, produce offspring approximately 3/8 of which are yellow, 3/8 gray, 1/8 cream and 1/8 black, what are the genotypes of the two parents? 6). A sex-linked recessive gene b produces red-green colorblindness in humans. A normal woman whose father was colorblind marries a colorblind man. (a) what genotypes are possible for the mother of the colorblind man? (b) What are the chances that the first child from this marriage will be a colorblind boy? (c) Of all the girls produced by these parents, what percentage is expected to be colorblind? (d) Of all the

Answer 1

la ek BR 2e BeR.saku

ade R. b R BBRん 3 BbpL