1. Define each of the following terms:
Allele
Gene
Haploid
Diploid
Homologous Chromosome
Genotype
Phenotype
Aneuploidy
Nondisjunction
2. Briefly describe how three different processes that occur during a sexual life cycle increase the genetic diversity of offspring.
3. Your biology class is collecting information on heredity. Michael realizes that he, along with three of his four brothers, are color blind, but his four sisters are not, and neither are his parents nor his grandparents. Can you help Michael understand what happened?
4. In 1981, a stray black cat with unusual rounded, curled-back ears was adopted by a family in Lakewood, CA. Hundreds of descendants of this cat have since been born, and cat fanciers hope to develop the "curl" cat into a show breed. The curl allele is apparently dominant and autosomal (carried on an autosome). Suppose you owned the first curl cat and wanted to breed it to develop a true-breeding variety. Describe tests that would determine whether the curl gene is dominant or recessive and whether it is autosomal or sex-linked. Explain why you think your tests would be conclusive. Describe a test to determine that a cat is true-breeding.
5. Complete the following table to complete mitosis and meiosis in humans.
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Mitosis
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Meiosis
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Number of chromosomal duplications
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Number of cell divisions
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Number of daughter cells produced
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Number of chromosomes in daughter cells
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How chromosomes line up during metaphase
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Genetic relationship of daughter cells to parent cell
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Functions performed in the human body
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1. Complete this table to show the difference between genotype and phenotype.
T is dominant for tall plants, t is recessive
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Genotype
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Homo-/Heterozygous
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Phenotype
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TT
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Heterozygous
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Short
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If a plant's phenotype is short, its genotype(s) can be ________________________.
If a plant's phenotype is tall, its genotype(s) can be __________________________.
2. Among humans, the allele for dark hair (D) is dominant to the allele for blonde hair (d). Consider the cross Dd x Dd. What is the chance that either parent will produce a gamete with a dominant allele?
Calculate the chance of a homozygous dominant offspring. Use the Punnett square to show your work.
3. In peas, tall plants (T) are dominant to short (t), purple (P) is dominant to white flower color (p), and round seeds (R) are dominant to wrinkled seeds (r). What is the phenotype of a plant with genotype TtppRr?
4. Tongue rolling is dominant. Bob can roll his tongue, but his mother cannot. His wife cannot roll her tongue. What are the genotypes of Bob, Bob's mother, and Bob's wife? What proportion of their children will be tongue rollers?
Bob's Mother's genotype________
Bob's genotype ______
Bob's wife's genotype ______
Proportion of children that are tongue rollers ______
5. In horses, B = black coat, b = brown coat, T = trotter, and t = pacer. What genotype is a black trotter that has a brown pacer offspring?
6. Hemophilia is a sex-linked recessive trait. A normal man marries a woman who is a carrier (heterozygote) for hemophilia. What percentage of their male and female offspring will have hemophilia?Fill in the Punnett square to show your work.
Male ____________
Female __________
7. In fruit flies, the gene for eye color is carried on the X chromosome. Red eyes are dominant over white eyes. What would be the result of a cross between a white-eyed male and a homozygous red-eyed female?
Male ____________
Female __________
In a cross between a white-eyed female and a red-eyed male?
Male ____________
Female __________
In a cross between a heterozygous red-eyed female and a red-eyed male?
Male ____________
Female __________
8. Two carriers of a recessive genetic disease (heterozygotes) marry. What are the chances that their children will have the disease?
9. Flower color in snapdragons shows incomplete dominance. A true breeding red flowered plant is crossed with a true breeding white flowered plant. What are the expected colors of their offspring.
10. A woman has type B blood and her child has type AB blood. List all of the possible blood types of the father. _______________
11. Among Herford cattle there is a dominant allele called polled; the individuals that have this allele lack horns. Suppose you acquire a herd consisting entirely of polled cattle, and you carefully determine that no cow in the herd has horns. Some of the calves born that year, however, grow horns. You remove them from the herd and make certain that no horned adult has gotten into your pasture. Despite your efforts, more horned calves are born the next year.
What is the reason for the appearance of the horned calves?
If your goal is to maintain a herd consisting entirely of polled cattle, what should you do?
12. An inherited trait among humans in Norway causes affected individuals to have very wavy hair, not unlike that of a sheep. The trait, called wool, is very evident when it occurs in families; no child possesses wooly hair unless at least one parent does. Imagine you are a Norwegian judge, and you have before you a woolly haired man suing his normal-haired wife for divorce because their first child has woolly hair but their second child has normal hair. The husband claims this constitutes evidence of his wife's infidelity.
Do you accept his claim? Justify your decision.
13. A man works in an atomic energy plant, and he is exposed daily to low-level background radiation. After several years, he has a child who has Duchenne muscular dystrophy, a recessive genetic defect caused by a mutation on the X chromosome. Neither the parents nor the grandparents have the disease. The man sues the plant, claiming that the abnormality in their child is the direct result of radiation -induced mutation of his gametes, and that the company should have protected him from this radiation. Before reaching a decision, the judge hearing the case insists on knowing the sex of the child.
Which sex would be more likely to result in an award of damages, and why?