Font size
WorksheetsBasic Genetics Problems HW Quiz
Total questions: 15
Worksheet time: 15mins
In guinea pigs, the allele for black hair(B) is dominant to the allele for brown hair(b). Two black-haired guinea pigs are crossed. One of the pigs is homozygous for black hair and one is heterozygous. What percentage of their offspring are expected to have black hair?
0%
25%
50%
75%
100%
A recessive gene causes a certain breed of goats to "faint" when they are startled. If two goats that faint are bred together, what percent chance do their offspring have of fainting?
0%
25%
50%
75%
100%
Purple flowers are dominant to white flowers. What is the expected phenotype ratio when 2 heterozygous plants are crossed?
1 PP: 2Pp: 1pp
3 purple: 1 white
3 white: 1 purple
2PP: 2pp
In pea plants, purple flower color is dominant to white flower color.
Fill in the Punnett square for the following cross by dragging the following labels to their appropriate locations:
Ff x Ff
FF
ff
Ff
In the cross shown, you can see that (a) (25 percent) has the genotype PP, one out of four (25 percent) has the genotype pp, and (b) (50 percent) have the genotype Pp. These percentages of genotypes are what you would expect in any cross between (c) . Of course, when just four offspring are produced, the actual percentages of genotypes may vary by chance from the expected percentages. However, if you considered hundreds of such crosses and thousands of offspring, you would get very close to the expected results, just like tossing a coin.
(a) are always shown in the phenotype, even if only one allele of the dominant trait is found the genotype. (b) are only shown in the phenotype if both alleles in the genotype are recessive.
Having two of the same genes for the trait (sometimes called purebred).
heterozygous
Genotypes: 100% Pp
Phenotypes: 100% purple
Genotypes: 50% Pp and 50% pp
Phenotypes: 50% purple: 50% white
Genotypes: 75% purple: 25% white
Phenotypes: 75%Pp: 25% pp
Genotypes: 25% PP, 50% Pp, 25% pp
Phenotypes: 75% purple, 25% white
Tay Sachs disease is a fatal recessive genetic disease that causes fats to build up in the brain, killing brain
cells and leading to a progressive loss of function. Both Linda and James are heterozygous for Tay Sachs.
What is the probability that Linda and James will have a child with Tay Sachs disease?
Answer: (a) %
Cystic fibrosis is a progressive, genetic disease that causes persistent lung infections and limits the ability
to breathe over time, due to the production of a defective transport protein. It is a recessive allele. A young
couple, Sara and Alex, comes to get genetic counseling to find out the chances that they could have a child
with cystic fibrosis. Sara is homozygous for the normal allele and Alex is a carrier of the cystic fibrosis
allele. The probability that they will have a child with cystic fibrosis is (a) .
Fruit flies are very useful model organisms that have been used to study genetics. One mutant trait in
fruit flies is called "eyeless" because it causes flies to have no eyes. In crossing an eyeless fly with a
normal fly, all offspring have eyes.
What does this tell us about the "eyeless" allele?
Eyeless is a dominant allele.
Eyeless is a recessive allele.
Eyeless is a rare allele.
Eyeless is a common allele.
Huntington's disease is a dominant trait that causes the production of a faulty protein that causes the brain
to degenerate in middle-aged adults. Tom is heterozygous for Huntington's disease and his wife, Jessica, is
homozygous for the normal allele. What is Tom's genotype?
Hh
hh
HH
He does not have Huntington's disease.
Huntington's disease is a dominant trait that causes the production of a faulty protein that causes the brain
to degenerate in middle-aged adults. Tom is heterozygous for Huntington's disease and his wife, Jessica, is
homozygous for the normal allele.
What are the chances that they will have a child that will eventually develop Huntington's disease?
0%
25%
50%
75%
100%
