Download Genetics Wkst #1-20 Word document

GENETICS WORKSHEET
1. In a certain organism, the gene for tall, T, is dominant to the gene for short, t. Write the
genotype and the phenotype for an organism that is A) heterozygous, B) homozygous
dominant, and C) homozygous recessive.
2. What is the probability of tossing a coin and getting heads three times in a row?
3. What is the probable ratio of alleles (M:m) produced in the gametes of an organism with
the genotype A) MM, B) Mm, and C) mm ?
4. In a certain plant, yellow fruit, Y, is dominant to white fruit, y. A heterozygous plant with
yellow fruit is crossed with a plant with white fruit. Determine the probable genotypic
and phenotypic ratios resulting from this cross.
5. In four-o’clocks, the gene for red flowers, R, is incompletely dominant to the gene for
white flowers, r. The heterozygous condition results in pink flowers. A gardener crosses
two red four-o’clocks. What are his expected genotypic and phenotypic ratios?
6. In fruit flies, long wing, L, is dominant to short wing, l. Two long-wing flies produced 49
short-wing and 148 long-wing offspring. What were the probable genotypes of the
parents? What proportion of the long-wing offspring should be heterozygous?
7. In man, brown eyes, B, are dominant to blue, b. A brown-eyed man marries a blue-eyed
woman. They have eight children, all of whom are brown-eyed. What are the probable
genotypes of each person in the family?
8. A blue-eyed man, both of whose parents were brown-eyed, marries a brown-eyed woman
whose father was brown-eyed and whose mother was blue-eyed. They have one child
who is blue-eyed. What are the most probable genotypes of the individuals mentioned?
9. A man and his wife are both heterozygous for brown eyes. They have six children, all of
whom have blue eyes. How is this explained? What are the chances that their next child
will have brown eyes? What are the chances that their next child will have blue eyes?
10. In Andalusian fowl, the gene for black plumage, B, is incompletely dominant to the gene
for white plumage, b. The heterozygous condition results in blue plumage. List the
genotypic and phenotypic ratios expected from the crosses (a) black X blue,
(b) blue X blue, (c) blue X white.
11. In cattle, black coat color is dominant to white coat color. A farmer has a black male of
undetermined genotype. How can the farmer determine the genotype of the male?
12. In guinea pigs, black coat color, B, is dominant to albino, b. Rough coat, R, is dominant
to smooth coat, r. Two animals are selected for breeding. Their genotypes are BBRR and
bbrr. A) Specify the genotypic and phenotypic ratios in the F1 generation, (b) specify the
phenotype ratios in the F2 generation, and (c) specify the genotype and phenotype ratios
among the offspring produced from crossing one of the F1 pigs with a pig having the
genotype BBRr.
13. A black smooth guinea pig was mated with an albino rough guinea pig. Their offspring
were black rough and black smooth. If these were the only types produced over a period
of years in a number of matings, what was the probable genotype of each parent?
14. In fruit flies, red eye, R, is dominant to magenta, r. Long wing, L, is dominant to short
wing, l. If a heterozygous red-eyed, short-winged male is bred with a magenta-eyed,
heterozygous long-winged female, what percentage of their offspring should have
magenta eyes and short wings?
15. What is the probable genotypic ratio among children born to a mother having the
genotype IAi and a father with type AB blood?
16. One parent has type A blood and the other parent has type B blood. What are their
genotypes if they produced a large number of children whose blood types were (a) all
AB, (b) ½ AB and ½ B, (c) ½ AB and ½ A, (d) ¼ AB, ¼ A, ¼ B, ¼ O?
17. A woman with blood type B has a child with blood type O. What are the genotypes of the
mother and child? Which genotypes could the father not have?
18. Explain how the cells of a human might contain two X chromosomes and one Y
chromosome. What sex would the person be?
19. In humans, the gene for blood clotting, H, is dominant to the gene for hemophilia, h. The
trait is sex-linked. A woman with normal blood clotting has four children. They are a
normal son, a hemophiliac son, and two normal daughters. The father has normal blood
clotting. What is the probable genotype of each member of the family?
20. In man, the gene for normal color vision, C, is dominant to the gene for red-green color
blindness, c. The trait is sex-linked. The gene for brown eyes, B, is dominant to the gene
for blue eyes, b. Calculate the probable genotypic and phenotypic ratios of the children
born to a blue-eyed woman who is a carrier and a heterozygous brown-eyed man who is
color blind.