Chapter 12 Multiple Choice Identify the choice that best completes the statement or answers the question. 1. What did Gregor Mendel do to study different characteristics in his genetics experiments? a. He studied only asexual plants. b. He studied only tall and short pea plants. c. He cross-pollinated plants. d. He cross-pollinated both plants and animals. 2. What does the notation TT mean to geneticists? a. two dominant alleles b. heterozygous alleles c. at least one dominant allele d. one dominant and one recessive allele 3. What is the probability of producing a tall pea plant from a genetic cross between two hybrid tall pea plants? a. one in four b. two in four c. three in four d. four in four 4. What does a Punnett square show? a. all the possible outcomes of a genetic cross b. only the dominant alleles in a genetic cross c. only the recessive alleles in a genetic cross d. all of Mendel s discoveries about genetic crosses 5. A purebred chicken with white feathers is crossed with a purebred chicken that has black feathers. Each of their offspring has both black and white feathers. Why does this happen? a. Both alleles for feather color are dominant. b. Both alleles for feather color are recessive. c. The alleles for feather color are neither dominant nor recessive. d. Several alleles work together to determine the trait. 6. What is the chromosome theory of inheritance? a. Chromosomes are carried from parents to offspring on hybrids. b. Genes are carried from parents to offspring on chromosomes. c. Hybrid pairs of chromosomes combine to form offspring. d. Codominant genes combine to form new hybrids. 7. What happens during meiosis? a. Two sex cells combine. b. Chromosome pairs separate and are distributed into new sex cells. c. Each sex cell copies itself to form four new chromosomes. d. Chromosome pairs remain together when new sex cells are formed. 8. Which term refers to physical characteristics that are studied in genetics? a. traits b. offspring c. generations d. hybrids 9. An organism s genotype is its a. genetic makeup. b. feather color. c. physical appearance. d. stem height. 10. Which of the following traits is influenced by both inheritance and environmental factors? a. the ability to sing well b. the ability to cough c. natural hair color d. dyed hair color 11. In Mendel s experiments, what proportion of the plants in the F 2 generation had a trait that had been absent in the F 1 generation? a. none b. one fourth c. half d. three fourths 12. Factors that control traits are called a. genes. b. purebreds. c. recessives. d. parents.
13.Scientists call an organism that has two different alleles for a trait a a. hybrid. b. dominant. c. purebred. d. factor. 14. What does the notation Tt mean to geneticists? a. two dominant alleles b. two recessive alleles c. homozygous alleles d. one dominant allele and one recessive allele 15. What is probability? a. the actual results from a series of events b. a number that describes how likely it is that an event will occur c. the way the results of one event affect the next event d. the number of times a coin lands heads up 16. If a homozygous black guinea pig (BB) is crossed with a homozygous white guinea pig (bb), what is the probability that an offspring will have black fur? a. 25 percent b. 50 percent c. 75 percent d. 100 percent 17. An organism s physical appearance is its a. genotype. b. phenotype. c. dominance. d. allele. 18.Walter Sutton discovered that the sex cells of grasshoppers have a. 12 times the number of chromosomes found in the body cells. b. twice the number of chromosomes found in the body cells. c. the same number of chromosomes found in the body cells. d. half the number of chromosomes found in the body cells. 19. When sex cells combine to produce offspring, each sex cell will contribute a. one fourth the number of chromosomes in body cells. b. half the number of chromosomes in body cells. c. the normal number of chromosomes in body cells. d. twice the number of chromosomes in body cells. 20. The different forms of a gene are called a. alleles. b. factors. c. masks. d. traits. 21. An organism that has two identical alleles for a trait is a. a phenotype. b. tall. c. homozygous. d. heterozygous. 22. A heterozygous organism has a. three different alleles for a trait. b. two identical alleles for a trait. c. only one allele for a trait. d. two different alleles for a trait. 23. Chromosomes are made up of a. one pair of alleles. b. a phenotype and a genotype. c. male and female sex cells. d. many genes joined together.
Short Answer 24. A(n) organism is the offspring of many generations of organisms that have the same trait. 25. If a(n) allele is present, its trait will appear in the organism. 26. Mendel used the principles of to predict what percent of offspring would show a particular trait. 27. Alleles that are neither dominant nor recessive produce an inheritance pattern known as 28. The process in which a parent cell divides twice to produce sex cells is called 29. In pea plants, the tall-stem allele and the short-stem allele are different forms of the same 30. If D represents the dominant allele of a gene, then represents the recessive allele. 32. A chart used to predict results of genetic crosses is known as a(n) 33. In a cross between two hybrid Tt pea plants, percent of the offspring will be Tt. 34. An organism that has two dominant or two recessive alleles is said to be for that trait. 35. Genes are carried from parents to their offspring on structures called 36. If all of the sex cells of an organism have the T allele, the genotype of that organism must be 37. An organism can be heterozygous for some traits and for others. 38. The chromosomes in a pair may each have different for each gene. 31. If each of ten events is equally likely to occur, the probability of each individual event occurring is percent.
39. Which trait white flowers or purple flowers is controlled by a dominant allele? Which is controlled by a recessive allele? How do you know? 40. In which generation are the parents purebred? In which generation are they hybrids? 41. In the F 1 generation, what is the genotype of the offspring? What is their phenotype? 42. In the F 2 generation, what percent of the offspring have purple flowers? What is the genotype of the purple-flowered offspring? 43. In the F 2 generation, what percent of the offspring have white flowers? What are the genotypes of the white-flowered offspring? 44. Suppose one of the parents of the F 2 generation had been ww instead of Ww. What percent of the offspring would have purple flowers? What percent would have white flowers? 45. In the Punnett square above, what is the probability that the offspring will have purple flowers? What is the probability that the offspring will have white flowers? 46. In an experimental field of F 2 generation offspring, a researcher counted 62 plants with purple flowers out of a total of 200 plants, or 31% purple plants. Explain how this is possible.
Modified True/False Indicate whether the statement is true or false. If false, change the identified word or phrase to make the statement true. If the statement is true, write true. If it is false, change the underlined word or words to make the statement true. 49. A pea plant that is heterozygous for tall stems has the alleles Tt. _ 47. A hybrid is the offspring of parents that have different alleles for a trait. _ 48. When Mendel crossed purebred short plants with purebred tall plants, all of the offspring were short. _ Essay 52. In pea plants, green pod color is controlled by a dominant allele. Yellow is controlled by a recessive allele. Explain why a plant with yellow pods can never be a hybrid. 50. The sex cells produced by meiosis have twice the number of chromosomes as the parent cells. _ 51. An organism s phenotype is its allele combinations. _ 53. A woman gives birth to a son. Two years later, she gives birth to another son. What is the probability that her third child will be a girl? Explain your reasoning. 54. Explain why Mendel s cross of purebred tall and short pea plants resulted in only tall plants. 55. Explain the function of meiosis. 56. Some clover plants have leaves with a white stripe. Other clover plants have leaves with a white spot. When these two types of plants are crossed, the leaves of the offspring have a white stripe and a white spot. Explain how this inheritance pattern occurs?
Chapter 12 - B Multiple Choice Identify the choice that best completes the statement or answers the question. 1. Cloning results in two organisms that are a. both adult mammals. b. produced from cuttings. c. genetically similar. d. genetically identical. 2. What is a genome? a. all the cells produced during meiosis b. all the plasmids produced from inserting DNA into a cell c. all the DNA in one cell of an organism d. all the alleles in a cell 3. What are multiple alleles? a. more than two genes that control a trait b. three or more forms of a gene that code for a single trait c. three or more chromosomes that determine a trait d. more than two codominant genes in a chromosome 4. In an attempt to produce a potato that tastes good and also resists disease, plant breeders crossed a potato variety that tastes good with a variety that resists disease. This technique is an example of a. genetic engineering. b. inbreeding. c. hybridization. d. cloning. Essay 5. A plant breeder clones a plant with beautiful flowers. Define cloning and explain how the cloned offspring