Genetics exam 2- quizzes

In the absence of recombination, how many genetically different types of gametes can an organism with five homologous chromosome pairs produce? a. 32 b. 10 c. 64 d. 5

a. 32. in the absence of recombination gametes with 5 homologous chromosomes can produce 32 2^5

Consider an diploid animal cell that has eight chromosomes (four pairs of homologous chromosomes) in G1 phase. What is the total number of sister chromatid pairs that the cell will have at mitotic prophase? a. 8 b. 4 c. 16

a. 8 chromatid pairs at mitotic prophase

In the F2 generation, how many genotypic classes could be generated from a dihybrid cross of two heterozygotes in which the genes involved show complete dominance? a. 9 b. 12 c. 3 d. 8 e. 4

a. 9 genotypic classes could be identified from an AaxAa in which genes involved show complete dominance

In his experiments, Mendel noted that when two traits are involved in a genetic cross, they are inherited independently of each other. The reason for this is that a. genes on different chromosomes separate during the formation of gametes. b. alleles on the same chromosome separate during the formation of gametes. c. genes on the same chromosome separate during the formation of gametes. d. chromosomes often recombine. e. alleles on the same gene separate during the formation of gametes.

a. genes on different chromosomes separate during the formation of gametes... independent assortment

Red-green color blindness in humans is an X-linked recessive trait. What will the progeny ratios be if a carrier female is mated with a normal male? a. Half the sons will be color blind; half the daughters will be carriers. b. All the sons and half the daughters will be color blind. c. Half the sons will be color blind; all the daughters will be carriers. d. All the sons and all the daughters will be normal. e. All the sons will be color blind; all the daughters will be normal.

a. half the sons will be colorblind; half the daughters will be carriers

In peas, tall plants are dominant to short plants. A cross between a tall pea plant and a short pea plant results in half the progeny being tall, and the other half being short. Therefore, the tall parent plant is genotypically a. heterozygous. b. monozygous. c. homogeneous. d. homozygous. e. hemizygous.

a. heterozygous

Which of the following does NOT occur during PCR? a. Synthesis of oligonucleotide primers b. Changes in the reaction temperature by a thermal cycler c. Denaturation at high temperatures d. Extension of primers by DNA polymerase e. Annealing of oligonucleotide primers

a. synthesis of oligonucleotide primers does NOT occur in polymerase chain rxns

S and Y assort independently. A dihybrid cross of SsYy and SsYy yields 320 offspring. How many are expected to resemble the homozygous recessive parental? a. 16 b. 20 c. 10 d. 180 e. 60

b. 20 are expected to be homozygous recessive

In an organism with 16 chromosomes per cell, how many DNA molecules are present in a cell undergoing anaphase of mitosis? a. 16 b. 32 c. 24 d. 64 e. 8

b. 32 DNA molecules are present in anaphase of mitosis for a cell with 16 chromosomes

The ant, Myrmecia pilosula, is found in Australia and is named bulldog because of its aggressive behavior. It is particularly interesting because it carries all its genetic information in a single pair of chromosomes. In other words, 2n = 2. (Males are haploid and have just one chromosome.) For the purposes of this question, assume that a G1 somatic cell nucleus in a female Myrmecia pilosula contains 2 picograms of DNA. How much DNA would be expected in a metaphase I cell of a female? a. 1 picogram b. 4 picograms c. 16 picograms d. 32 picograms e. 8 picograms

b. 4 picograms; in the cell cycle, replication of DNA has occured after G2. 2x2=4

If A is one gene and B is another gene, which of the following genotypes would not usually be represented in a gamete? a. AB b. AA c. Ab d. ab e. aB

b. AA

Phenotypically, a female (XX) mouse embryo that was transformed with a small piece of a Y chromosome bearing the SRY gene would develop as a. a male initially, then revert to female after birth. b. a male. c. an intersex individual. d. a female initially, then revert to male after birth. e. a female.

b. a male

Familial hypercholesterolemia is a genetic disease that affects approximately one in 500 people worldwide. There is more than one genetic cause of the disease. Class I is often described as an autosomal dominant disease. Affected individuals have cholesterol levels >250 as children and often >300 as adults. However, homozygotes have cholesterol levels of >600 as children and can die of heart attacks in their 20s. These individuals entirely lack a functional LDL receptor. Which of the following would be the best description of the inheritance of this form of hypercholesterolemia? a. codominance b. incomplete dominance c. recessive epistasis d. complementation e. dominant epistasis

b. incomplete dominance

A _______ inversion includes the centromere. a. concentric b. pericentric c. epicentric d. paracentric e. chromocentric

b. pericentric

Which of the following will result in modifications to the expected Mendelian ratios? a. Incomplete penetrance b. All of these c. Incomplete dominance d. Gene interaction e. Epistasis

b. results of modification to the expected ratios could be incomplete penetrance, incomplete dominance, gene interaction, or epistasis (a form of phenotypic interaction)

In human males, genes on the X chromosome are a. homozygous b. hemizygous. c. heterozygous. d. homogametic. e. heterogametic.

b. the correct genetics terminology is hemizygous

In a pea plant that is heterozygous for seed color, what proportion of gametes will carry the recessive allele? a. 1/4 b. 3/4 c. 1/2 d. 1/8

c. 1/2 of the gametes will carry the recessive allele for seed color

Which of the following statements most correctly describes meiosis? a. Meiosis involves a single round of DNA replication followed by four successive cell divisions. b. Meiosis involves four rounds of DNA replication followed by two successive cell divisions. c. Meiosis involves a single round of DNA replication followed by two successive cell divisions. d. Meiosis involves two rounds of DNA replication followed by a single cell division.

c. Meiosis involves a single round of replication followed by two successive cell divisions

In order for the nonautonomous dissociation element (Ds) mutations in corn to remain in the same position, a. the Ds must contain the gene for transposition. b. an autonomous Ac element must be present. c. an autonomous Ac element must not be present. d. None of these. e. the DNA must not be replicated.

c. an autonomous Ac element must not be present

Flower color in foxgloves is determined by two genes. In foxgloves, a wild-type allele d produces a light red pigment seen in flowers, and a mutant allele D produces a dark red flower pigment. At another gene, allele w is a wild-type allele that allows for distribution of pigment throughout the flower. A mutant allele W restricts pigment to the throat of the flower. Dihybrid F1 plants (Dd/Ww) have white flowers with dark red pigment at the throat. Those F1 plants are crossed, with the resulting progeny being 36 plants with white flowers with pigment confined to throat 9 plants with dark red pigment throughout the flowers 3 plants with light red pigment throughout the flowers. The most likely explanation about these observations is a. Incomplete pentrance b. Codominance c. Dominant epistasis d. Incomplete dominance e. Variable expressivity

c. dominant epistasis

A pond in a park is home to a population of ducks. Two ducks from a nature preserve fly to the pond and join the pond population. This is an example of a. natural selection b. selective mating c. gene flow d. mutation

c. gene flow

There are moles divided by a large river that they cannot cross except for winter. The moles on the west side of the river have a higher frequency of black noses while the moles on the east side of the river have a higher frequency of brown noses. One summer, a fast-moving wildfire kills a majority of the moles on the east side of the river. The frequency of the black nose allele increases in the total population. This is an example of a. natural selection b. migration c. genetic drift d. mutation

c. genetic drift

A population of almond trees are exposed to drought in Southern California. Without human intervention with irrigation, some of the trees survive and pass on their alleles to the next generation, while other succumb to drought. This is an example of a. genetic drift b. gene flow c. natural selection d. mutation

c. natural selection

Which of the following is not used in traditional PCR amplification of DNA? a. heat-resistant DNA polymerase called taq polymerase b. ds DNA template that melts into two single stranded DNA molecules c. rNTPs d. Buffers e. primers that flank the sequence of interest

c. rNTPs are not used in the amplification of DNA in polymerase chain rxns

Manx cats have no tails. When two Manx cats are bred together there is always a one third chance that a kitten will have a tail. When a Manx cat is bred to a cat with a normal tail there is a one-half chance that a kitten will have a tail. Which of the following is the best explanation for this? a. The Manx genotype exhibits variable expression. b. The Manx phenotype is a result of heteroplasmy. c. The Manx phenotype is dominant, but the allele is a recessive lethal. d. The Manx phenotype is caused by gene interactions. e. The Manx phenotype is dominant epistatic.

c. recessive lethal

Individuals with neurofibromatosis may have a range of phenotypes, from pigment spots on the skin to tumorlike growths. This observation is an example of a. incomplete penetrance. b. gene magnification. c. variable expressivity. d. age of onset. e. X-inactivation.

c. variable expressivity

Polydactyly is expressed when an individual has extra fingers and/or toes. Having extra digits is caused by a dominant allele. Assume that a man with six fingers on each hand and six toes on each foot marries a woman with a normal number of digits. The couple has a son with normal hands and feet, but the couple's second child has extra digits. What is the probability that their next child will have polydactyly? a. 3/4 b. 1/32 c. 7/16 d. 1/2 e. 1/8

d. 1/2.

Solid black, black with tan belly, and agouti coat color in mice are all caused by alleles of the agouti gene. All three colors can be true-breeding. When using mice from true-breeding strains: (1) Black × Agouti F1s are all agouti, (2) Black × Black with Tan belly F1s are all black and tan, and (3) Black with Tan belly × Agouti F1s are all agouti. If you were to cross the F1s from (1) with the F1s from (2), what proportion of the resulting offspring would you expect to be black with a tan belly? a. 1/2 b.None c. 3/16 d. 1/4 e. 1/16

d. 1/4 *how is this modified

In lilies, white flowers (W) are dominant to purple flowers (w). If two plants that are heterozygous for flower color are mated, the genotypic ratio of the offspring would be a. 1:1:1:1 b. 1:1 c. 3:1 d. 1:2:1 e. 9:3:3:1

d. 1:2:1

(2) For a gene with four alleles in nature, what is the maximum number of alleles that one diploid individual may have? a. 1 b. 5 c. 4 d. 2 e. 3

d. 2 allele is the max for a diploid individual

In humans, dimples (D) is completely dominant to normal cheeks (d). A man with dimples marries a woman without dimples and they have three daughters without dimples. What are the genotypes of the man and the woman, respectively? a. dd and dd b. Dd and Dd c. DD and Dd d. Dd and dd e. DD and DD

d. Dd and dd

Huntington's disease is an autosomal dominant disease caused by an allele that has a trinucleotide repeat expansion in the sequence. Researchers have noticed that the repeats can expand through the generations (from parent to child), so that Huntington disease appears earlier and has the disease phenotype is more severe in subsequent generations. Which of the following genetic terms best describes this observed phenomenon in Huntington's disease? a. Dominant epistasis b. Recessive epistasis c. Incomplete penetrance d. Genetic anticipation

d. genetic anticipation

Which of the following types of chromosomal mutation is least likely to revert to the wild-type state? a. dupliction b. translocation c. inversion d. large deletion

d. large deletion

A gene that influences several traits is termed a. polygenic b. none of these c. multifactorial d. pleiotropic e. paralogous

d. pleiotropic

A sizable population was analyzed for SNPs in a certain DNA region. Two possible variants were found, with the following sequences and frequencies SNP 1: GGTCTAGGA; frequency = 0.91 SNP 2: GGTGTAGGA; frequency = 0.09 If the population is in Hardy-Weinberg equilibrium, what is the frequency pf the heterozygotes at this SNP locus? a. 0.828 b. 0.30 c. 0.009 d.0.95 e. 0.164

e. 0.164 use 1=p^2 + 2pq +q^2

A plasmid used as a cloning vector in E. coli has a. selectable marker b. an ori sequence c. unique restriction enzyme sites d. multiple cloning site e. all of these

e. all of these are present in the bacterial plasmid used as a cloning vector

T/F: Restriction enzymes are exonucleases.

false exonucleases cleaves nucleases one at a time from the end endonucleases cleave from the middle: restriction enzymes are endonucleases

(3) T/F: Hemophilia is X-linked recessive. A woman who is heterozygous for the hemophilia allele has a 100% chance of having an affected son.

false, the woman has a 50% chance of having an affected son

Indicate whether each of the following is true for meiosis, mitosis, both, or neither. genetic recombination can occur genetically identical parent products DNA rep happens once prior to the process

meiosis, mitosis, both

Match the term with the description. Each term is only used once. physical manifestation of a trait allele that is expressed in the heterozygote always involves the alleles of two genes genetic makeup of an organism one parent must be homozygous recessive allele that has to be homozygous can be expressed always involves alleles of a single gene

phenotype, dominant allele, dihybrid cross, genotype, test cross, recessive allele, monohybrid cross

Match the description with the term. Each answer can only be used once. three copies of one chromosome three full sets of chromosomes more than two full sets of chromosomes a normal number of chromosomes a chromosome number that is not an exact multiple of haploid set of chromosomes

trisomic, triploid, polyploid, euploid, aneuploid