Genetics
A carrier of a genetic disorder who does not show symptoms is most likely to be ________ to transmit it to offspring. a) heterozygous for the trait and able b) heterozygous for the trait and unable c) homozygous for the trait and able d) homozygous for the trait and unable e) heterozygous for the trait and unlikely
A
After crossing my pet black mouse, Zwart, with my pet white mouse, Blanca, eight offspring were produced. Two were black, four were gray and two were white. The gray offspring show an example of what type of allele interaction? a. incomplete dominance. b. autosomal recessive. c. polygenic effects. d. X-linkage. e. environmental effects
A
How would one explain a testcross involving F1 dihybrid flies in which more parentaltype offspring than recombinant-type offspring are produced? a. The two genes are closely linked on the same chromosome. b. The two genes are linked but on different chromosomes. c. Recombination did not occur in the cell during meiosis. d. Both of the characters are controlled by more than one gene.
A
If a homozygous dominant is crossed with a homozygous recessive for a given trait, the offspring will be __________. a. all of the dominant phenotype b. 1/4 of the recessive phenotype c. all homozygous dominant d. all homozygous recessive e. present in a 9:3:3:1 ratio
A
Mendel conducted his most memorable experiments on a) peas. b) roses. c) guinea pigs. d) fruit flies. e) clones.
A
What is the reason that closely linked genes are typically inherited together? a. The likelihood of a crossover event between these two genes is low. b. The number of genes in a cell is greater than the number of chromosomes. c. Chromosomes are unbreakable. d. Alleles are paired together during meiosis. e. Genes align that way during metaphase I of meiosis.
A
Which of the following statements correctly describes linkage? a. The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them. b. The observed frequency of recombination of two genes that are far apart from each other has a maximum value of 100%. c. All of the traits that Mendel studied-seed color, pod shape, flower color, and others-are due to genes linked on the same chromosome. d. Linked genes are found on different chromosomes.
A
A person with AB blood illustrates the principle of a) incomplete dominance. b) codominance. c) pleiotropy. d) polygenic inheritance. e) blending inheritance.
B
Assuming that the probability of having a female child is 50% and the probability of having a male child is also 50%, what is the probability that a couple's first-born child will be female and that their second-born child will be male? a) 20% b) 25% c) 50% d) 75% e) 100%
B
Crossing over ________ genes into assortments of ________ not found in the parents. a. recombines unlinked; genes b. recombines linked; alleles c. combines unlinked; alleles d. combines linked; genes
B
If AABBCC breeds with AaBbCc, what is the probability of the genotype AABBCC? a. ¼ * ½ * ¼ = 1/32 b. ½ * ½ * ½ = 1/8 c. ¼ * ¼ * ¼ = 1/12 d. ½ + ½ + ½ = 1½ e. ¼ * ¼ * ¼ = 1/64
B
If AaBbCc breeds with AaBbCc, what is the probability of the genotype AABBCC? a. ¼ * ½ * ¼ = 1/32 b. ¼ * ¼ * ¼ = 1/64 c. ¼ * ¼ * ¼ = 1/12 d. ½ + ½ + ½ = 1½
B
If one parent is blood type AB and the other is type O, what proportion of their offspring will be blood type A? a. 0.25 b. 0.5 c. 0.75 d. all of the above e. none of the above
B
If we were keeping track of 3 independently assorting genes, and the father's genotype was FfGghh, he could produce the following gamete genotypes: a. FFGgdh, FfGghh, FFgghh, and Ffgghh. b. FGh, Fgh, fGh, and fgh. c. FF, Ff, ff, GG, Gg, gg, HH, Hh, and hh. d. FGH, and fgh. e. F, f, G, g, and h.
B
In Sweet Peas, Purple flowers (P) is dominate to red flowers (p) and long pollen (L) is dominate to round pollen (l). These traits are closely linked on one chromosome, so crossing-over can be ignored. True breeding purple Long (PPLL) are bred with true breeding red round (ppll) individuals to produce heterozygous offspring. The F1 PpLl are crossed to similar F1 PpLl. What is the expected frequency of "red short" phenotype in the offspring? a. 0 b. 1/4 c. 1/2 d. 3/4 e. 9/16
B
Linked genes generally a) follow the laws of independent assortment. b) do not follow the laws of independent assortment. c) show incomplete dominance. d) reflect a pattern of codominance. e) show pleiotropy.
B
One map unit is equivalent to which of the following values? a. the physical distance between two linked genes b. 1% frequency of recombination between two genes c. 1 nanometer of distance between two genes d. the distance between a pair of homologous chromosomes e. the recombination frequency between two genes assorting independently
B
Pea plants are tall if they have the genotype TT or Tt, and they are short if they have genotype tt. A tall plant is mated with a short plant. Half the offspring are tall, and half are short. This allows us to conclude that the tall plant _____. a. was homozygous b. was heterozygous c. had two tall parents d. all of the above e. none of the above
B
The expression of both alleles for a trait in a heterozygous individual illustrates a) incomplete dominance. b) codominance. c) pleiotropy. d) polygenic inheritance. e) blending inheritance.
B
The vast majority of people afflicted with recessive disorders are born to parents who were a) both affected by the disease. b) not affected at all by the disease. c) slightly affected by the disease, showing some but not all of the symptoms. d) subjected to some environmental toxin that caused the disease in their children. e) affected by the disease but had subclinical symptoms.
B
A woman with type O blood is expecting a child. Her husband is type A. Both the woman's father and her husband's father had type B blood. What is the probability that the child will have type O blood? a. 100% b. 75% c. 50% d. 25% e. 0%
C
An AABb individual is mated with another AABb individual. The possible number of genetically distinct offspring is _____. a. 1 b. 2 c. 3 d. 4 e. 9
C
Cystic fibrosis can be inherited even if neither parent has the disease. This is because the disease _____. a. requires certain environmental conditions to be expressed b. occurs only in polyploid individuals c. is caused by a recessive allele d. is caused by a dominant allele e. occurs only in individuals who are already weak from other causes
C
Dr. Smith's parents have normal hearing. However, Dr. Smith has an inherited form of deafness. Deafness is a recessive trait that is associated with the abnormal allele d. The normal allele at this locus, associated with normal hearing, is D. Dr. Smith's parents could have which of the following genotypes? a) DD and dd b) dd and dd c) Dd and Dd d) DD and DD e) Dd and DD
C
Flower color in snapdragons is an example of incomplete dominance. If a red-flowered plant is crossed with a white-flowered plant, the F1 generation has pink flowers. If a pink-flowered plant is crossed with a pink-flowered plant, the progeny plants will be __________. a. 100% pink b. 100% red c. 25% red, 50% pink, and 25% white d. 50% pink and 50% red e. 25% white and 75% red
C
Genes located close together on the same chromosomes are referred to as ________ genes and generally ________. a. linked; sort independently during meiosis b. homologous; are inherited together c. linked; do not sort independently during meiosis d. codependent; do not sort independently during meiosis
C
Homologous pairs of chromosomes frequently _____. a. carry different genes for different traits b. differ in length c. contain different alleles d. are not both present in diploid cells e. are the X and Y chromosomes in humans
C
Huntington's disease is due to an autosomal dominant allele. If a heterozygous male marries a normal female, what percentage of the offspring will have Huntington's? a. 0% b. 25% c. 50% d. 75%
C
If a plant heterozygous for flower color (Pp) and homozygous recessive for seed color (rr) self-fertilizes, what is the probability of getting a double homozygous (pp and rr) offspring? a. ¼ * ½ * ¼ = 1/32 b. ¼ * ¼ * ¼ = 1/64 c. ¼ * 1 = ¼ d. ½ * 1 = ½
C
If an allele is homozygous recessive lethal, and two heterozygotes are breed, what is the ratio of genotypes in the offspring produces a. 1:2:1 b. 1:3:1 c. 1:2 d. 1:3 e. 1:4
C
If hair color, eye color, and the presence or absence of freckles were consistently inherited together, the best explanation would be that _____. a. these traits are recessive characteristics b. both parents have the same hair color, eye color, and freckles c. the genes for these traits are linked on the same chromosome d. gene duplications have occurred e. these traits are dominant to others
C
If two genes are on different chromosomes, what recombination frequency would you expect? a. 0% b. 25% c. 50% d. 100%
C
Pea flowers may be purple (P) or white (p). Pea seeds may be round (R) or wrinkled (r). What proportion of the offspring from the cross PpRr x PpRr will have white flowers and wrinkled seeds? a. 1/2 b. 1/4 c. 1/16 d. 1/64 e. none of them
C
Somatic cells have: a. no sex chromosomes but one of each autosome. b. one copy of each type of chromosome. c. two copies of each type of chromosome. d. four homologous copies of each type of chromosome. e. one copy of each autosome.
C
The inheritance of height and weight can best be described as _____. a. simple dominant-recessive inheritance b. being caused by microorganisms c. polygenic d. a trait that does not follow the rules of Mendelian inheritance e. the results of a bad lifestyle
C
The phenotype of an organism is determined by: a. its genotype. b. its environment. c. both its environment and its genotype. d. the size of the organism's cells. e. neither genotype nor environment influence phenotype.
C
Three genes (A, B, and C) at three loci are being mapped in a particular species. Each gene has two alleles, one of which results in a phenotype that is markedly. The unusual allele of gene A is inherited with the unusual allele of gene B or C about 50% of the time. However, the unusual alleles of genes B and C are inherited together 14.4% of the time. Which of the following statements describes what is happening regarding the inheritance of these genes? a. The three genes are showing independent assortment. b. The three genes are linked. c. Gene A is linked but genes B and C are not. d. Gene A is assorting independently of genes B and C, which are linked. e. Gene A is located 14.4 map units from genes B and C.
C
Traits that show a continuous distribution and a bell shaped curve are usually the result of a. codominance b. recessive traits c. a polygenic trait d. homozygous recessive lethal e. incomplete dominance
C
Which of the following matings can NOT produce a child with blood type O? The letters refer to blood types (phenotypes). a. A x A b. A x B c. O x AB d. O x O e. all of the above
C
Which would have the most recombination between them? A. Black body and Cinnabar eyes B. Cinnabar eyes and Brown eyes C. Short aristae and Brown eyes
C
In a certain plant, the alleles A, B, and C are dominant to the alleles a, b, and c. A plant with the genotype AABbcc will have the same phenotype as the plant with the genotype _____. a. AAbbcc b. aabbcc c. AaBBcc d. AABBCc e. none of the above
C. AaBBcc
All the offspring of a cross between a red-flowered plant and a white-flowered plant have pink flowers. This means that the allele for red flowers is ________ to the allele for white flowers. a) dominant b) codominant c) pleiotropic d) incompletely dominant e) recessive
D
If two genes are linked _____. a. they are on different chromosomes b. they assort independently c. they code for the same protein d. they are on the same chromosome e. they are on sex chromosomes
D
Mendel's law of independent assortment states that a) chromosomes sort independently of each other during mitosis and meiosis. b) genes sort independently of each other in animals but not in plants. c) independent sorting of genes produces polyploid plants under some circumstances. d) each pair of alleles segregates independently of the other pairs of alleles during gamete formation. e) genes are sorted concurrently during gamete formation.
D
Suppose we have a pea plant with purple flowers, determined by the dominant allele P. How might you determine whether the plant is homozygous (PP) or heterozygous (Pp)? a. Perform a testcross: Cross the plant with a known heterozygote, PP. b. Cross the plant with a true-breeding purple plant. c. Examine the plant's chromosomes with a microscope. d. Perform a testcross: Cross the plant with a white one, which must be homozygous recessive, or pp. e. Attempt to cross the plant with a pink-flowered snapdragon.
D
You are trying to determine the linkage map of a series of genes, X, Y, and Z, from Caenorhabditis elegans, a nematode worm commonly used in scientific research. From doing several crossover experiments, you know that the recombination frequency between X and Y is 11.5%, between Y and Z is 13%, and between X and Z is 25%. What is a possible sequence of these genes? A) X-Z-Y B) Y-Z-X C) Z-X-Y D) X-Y-Z
D
In Mendel's monohybrid cross of purple-flowered and white-flowered peas, all members of the F1 generation were of the __________ phenotype because their genotype was __________ for the flower-color gene. a. white-flowered ... homozygous recessive b. white-flowered ... heterozygous c. purple-flowered ... homozygous recessive d. purple-flowered ... homozygous dominant e. purple-flowered ... heterozygous
E
The individual features (phenotype) of all organisms are the result of a) genetics. b) the environment. c) genetics and cytoplasmic determinants. d) the environment and individual needs. e) genetics and the environment.
E
The mechanism that "breaks" the linkage between linked genes is a) incomplete dominance. b) pleiotropy. c) codominance. d) independent assortment. e) crossing over.
E
Varieties of plants in which self-fertilization produces offspring that are identical to the parents are referred to as a) hybrids. b) the F2 generation. c) monohybrid crosses. d) independent crosses. e) true-breeding.
E
