bio exam 4
A diploid organism that has two identical alleles for a given trait is called ________ for that trait. A) homozygous B) heterozygous C) dominant D) recessive E) codominant
a
A scientist wants to study histones. Histones are: a. proteins that double-stranded DNA molecules wrap around in eukaryotes. b. proteins that double-stranded DNA molecules wrap around in prokaryotes and eukaryotes. c. proteins that regulate checkpoints in the mitotic cell cycle. d. proteins that serve as the spindle fiber to pull sister chromatids apart during anaphase. e. proteins that required for the activity of Cdk enzymes.
a
A somatic cell from a garden pea normally contains 14 chromosomes. How many sister chromatids would that cell contain during G1 of the cell cycle? a. 0 b. 7 c. 14 d. 28
a
All animal cells are diploid except a. gametes. b. muscle cells. c. nerve cells. d. germ-line cells. e. somatic cells.
a
Before cell division of somatic cells, each chromosome must be replicated. After replication, the resulting two parts of each chromosome are held together by cohesin at the centromere. These two parts are referred to as: a. Sister chromatids b. Homologous chromosomes c. Daughter chromosomes d. Kinetochores e. Genes
a
During anaphase I, which best represents segregation of the chromatids that make up one pair of homologues? (M represents a maternal chromatid and P represents a paternal chromatid. Assume no crossing over occurs.) a. M and M to one pole; P and P to the other pole. b. M and P to one pole; M and P to the other pole. c. M to one pole; P to the other pole. d. half of M and half of P to each pole. e. the segregation of these chromatids is completely random.
a
Edouard van Beneden proposed that an egg and a sperm, each containing half the complement of chromosomes found in somatic cells, fuse to produce a single cell called a(n) ________. a. zygote b. karyotype c. embryo d. oocyte
a
Embryonic cell cycles allow the rapid division of cells in the early embryo. These mitotic cell cycles are much shorter in length than the mitotic cell cycles of cells in a mature organism. In the embryonic cell cycles, mitosis takes approximately the same amount of time as it does in the cell cycles of mature cells. What do you think is a result of the embryonic cycle? a. Resulting daughter cells are smaller than the mother cell in the embryonic cell cycles. b. Resulting daughter cells do not contain the same genetic information as the mother cell in the embryonic cell cycles. c. Resulting daughter cells cannot form a mitotic spindle in the embryonic cell cycle. d. Mother cells in the embryonic cell cycle spend the majority of their time in G
a
If a cell contained a mutation in the gene that encodes FtsZ, which process would be affected? a. Septation b. Cytokinesis c. Prophase d. DNA Synthesis e. Cohesin cleavage
a
If an individual allele has more than one effect on the phenotype, this is called A) pleiotropy. B) epistasis. C) blending inheritance. D) multiple alleles. E) polygenic inheritance.
a
If there are 32 sister chromatids in a normal somatic cell, what is the haploid number for that cell? a. 8 b. 16 c. 32 d. 64
a
If there were no suppression of DNA replication between meiotic divisions but cytokinesis proceeded normally, what is the most likely outcome of meiosis? a. 4 diploid cells b. 2 diploid cells c. 4 haploid cells d. 2 haploid cells e. 2 diploid cells and 2 haploid cells
a
In G2, there are typically high levels of the mitotic cyclin. Why is cdc2 not active during G2 if the mitotic cyclin is present? a. Cdc2 is also regulated by phosphorylation. b. Cdc2 does not bind to the mitotic cyclin. c. Cdc2 requires ubiquitination to be activated. d. Cdc2 also has to bind to cohesin to be activated.
a
In bacterial cell division, the cell divides into two nearly equal halves. This process is referred to as: a. binary fission b. mitosis c. fusion d. meiosis e. cytokinesis
a
In later chapters, you will learn more about the regulation of gene expression. One way to regulate gene expression is to make changes to the histone proteins to alter how tightly the DNA is coiled and wrapped. The more tightly coiled and wrapped a particular region of DNA is, the less likely it is that the genes in that region will be expressed. Bearing this in mind, how tightly do you think regions of heterochromatin are compacted? a. Very tightly b. Moderately c. Loosely d. Not at all
a
In plants and animals, the zygote develops by which of the following processes? a. mitosis b. meiosis c. syngamy d. synapsis e. reduction division
a
In white tigers, the absence of fur pigmentation is caused by a recessive allele that also causes the tigers to be cross-eyed. If two tigers heterozygous for this allele mate, what do you expect to see among the offspring? A) 1/4 will be both white and cross-eyed, 3/4 will be orange with normal eyes. B) 1/4 will be white with normal eyes, 1/4 will be white and cross-eyed, 1/4 will be orange with normal eyes, and 1/4 will be orange and cross-eyed. C) 1/16 will be white and cross-eyed, 15/16 will be orange with normal eyes. D) 1/3 will be both white and cross-eyed, 2/3 will be orange with normal eyes. E) 1/4 will be orange with normal eyes, 3/4 will be both white and cross-eyed.
a
Interphase is made up of what stages of the cell cycle? a. G1+ G2+ S b. S + cytokinesis c. prophase + metaphase + anaphase + telophase d. cytokinesis + mitosis e. G0+ G1+ G2
a
Let P = purple flowers and p = white, and T = tall plants and t = dwarf. If the uppercase letters represent the dominant alleles, what is the phenotype of a plant with the genotype PpTt? A) purple flowers, tall B) purple flowers, dwarf C) white flowers, tall D) white flowers, dwarf E) pale purple flowers, intermediate height
a
The drug Taxol, or Paclitaxel, is used to treat patients with a variety of cancers, including breast, lung and ovarian cancers. The drug works by stabilizing microtubules, and preventing their disassembly. The goal of the drug is to prevent dividing cells from being able to complete mitosis. As a result, cancerous cells can no longer divide. In a cell treated with Taxol, at what stage of mitosis will the cells arrest? a. Prior to metaphase b. Anaphase c. Telophase d. Cytokinesis
a
The first detailed and quantitative studies on inheritance were carried out by an Austrian monk named ________. A) Mendel B) Darwin C) Mendeleev D) Benedict
a
The fusion of a male gamete with a female gamete is called a. syngamy. b. meiosis. c. mitosis. d. recombination. e. synapsis.
a
The observable expression of the genes present in an organism is called its A) phenotype. B) genotype. C) pedigree. D) karyotype.
a
The phenotypic ratio for the F1 generation that results from a testcross between a homozygous recessive individual and a heterozygous individual is A) 1:1 B) 2:1 C) 3:1 D) 1:2:1
a
The portion of the cell cycle when the cell is growing and does not contain a replicated genome is referred to as: a. G1 b. S c. G2 d. Mitosis e. Cytokinesis
a
The stage of mitosis characterized by the physical separation of sister chromatids is called: a. Anaphase b. Metaphase c. Prometaphase d. Telophase
a
These structures are held together by cohesin: a. Sister chromatids b. Nucleosomes c. Homologous chromosomes d. Solenoids
a
What is one of the roles of the APC/C during anaphase? a. To directly target the mitotic cyclins for destruction. b. To directly target cohesin for destruction. c. To directly target separase for destruction. d. To directly target microtubules for destruction.
a
What is the portion of the cell cycle during which the chromosomes are invisible under the light microscope because they are not yet condensed? a. Interphase b. Prophase c. Metaphase d. Anaphase e. Telophase
a
Which best describes the process of independent assortment? a. The way one pair of homologues lines up along the metaphase plate does not affect how any other pair lines up. b. Segregation of chromosomes during meiosis I is independent of their segregation during meiosis II. c. During synapsis, chromosomes pair up at random. d. Crossing over along one pair of chromosomes is independent of crossing over along the other pairs. e. During synapsis, homologues pair independently of each other
a
Which structures indicate where crossing over has occurred? a. chiasmata b. centromeres c. kinetochores d. centrioles e. spindle fibers
a
You are comparing the events of meiosis I in cells from several different organisms. You come across one species in which you do not observe any chiasmata. The best conclusion to make is a. there is no crossing over between nonsister chromatids b. kinetochores of sister chromatids do not fuse c. the chromosome pairs will not assort independently d. chiasmata will form during meiosis II
a
You are conducting a genetic screen using Caenorhabditis elegans embryos to isolate mutations affecting anaphase (A). Therefore, you need to look for embryos in which a. the centromeres do not move toward the poles. b. the poles do not move apart. c. the spindle apparatus does not disassemble. d. sister chromatids are mismatched and therefore fail to separate.
a
You are examining the effect of maturation-promoting factor (MPF) in sea urchin cells, which have a diploid number of 36. If you fuse a dividing sea urchin cell with a G1 arrested oocyte, what would be the outcome? a. The G1cell would enter mitosis, but would likely arrest at the spindle checkpoint because the chromosomes have not been properly replicated. b. The G1cell would undergo mitosis and its daughter cells would each have 36 chromosomes. c. The G1cell would undergo mitosis and its daughter cells would each have 18 chromosomes. d. The G1cell would first go through S phase and then mitosis. Its daughter cells would have 36 chromosomes.
a
You are leading a team of researchers at a pharmaceutical company. Your goal is to design drugs that help fight cancer. Specifically, you want to focus on drugs that bind to and inactivate certain proteins, thereby halting cell cycle progression. One of your team members suggests targeting the retinoblastoma (Rb) protein and inhibiting this protein. Will this approach be successful? Why or why not? a. This approach will not be successful. Rb is tumor-suppressor protein, and functions to inhibit the action of a number of cell cycle regulatory proteins. A drug designed to inactivate the Rb protein would essentially create the same situation as in as a cell that lacks both copies of the Rb gene. Lack of Rb activity would release the inhibition of cell cycle regulatory proteins, thereby promoting cell cycle progression, rather than halting it. b. This approach will be successful. Rb is an oncogene, and functions to activate a number of cell cycle regulatory proteins. A drug designed to inactivate the Rb protein would halt the cell cycle in cells that contain an active Rb. As a result, cancer cells expressing a constitutively active Rb protein would be good targets for this type of therapeutic. c. This approach will be successful. Rb is tumor-suppressor protein, and functions to inhibit the action of a number of cell cycle regulatory proteins. A drug designed to inactivate the Rb protein would activate cell cycle inhibition. Lack of Rb activity would therefore inhibit the cell cycle regulatory proteins. d. This approach will not be successful. Rb is an oncogene, and functions to activate a number of cell cycle regulatory proteins. A drug designed to inactivate the Rb protein would actually activate cell cycle progression. As a result, this drug would likely make this situation worse for patients whose cancer cells contain mutant Rb.
a
Mendel demonstrated which of the following about inherited traits? Check all that apply. A) traits can be hidden in some generations, but subsequently reappear unchanged in future generations. B) traits segregate among the offspring of a cross. C) certain traits are more likely to appear than their alternatives. D) some traits show blending inheritance. E) parents that both have the same trait can have offspring with an alternative trait.
a, b, c, e
Knight followed up on attempts of English farmers to improve varieties of agriculture with his studies on garden peas. When he crossed two true-breeding varieties, he found all of the following: Check all that apply. A) All the F1offspring had the dominant trait. B) If both parents have the same trait, then all of their offspring will also have that trait. C) Some F2offspring had the dominant trait and some had the recessive trait. D) Among the F2 offspring, more had the dominant trait and fewer had the recessive trait.
a, c, d
A cell biologist produces a karyotype of mouse somatic cells arrested in mitosis. She sees 40 chromosomes, which is completely normal for mice. Based on this information, what is the haploid number of chromosomes for mice? a. 10 b. 20 c. 40 d. 80 e. It cannot be determined from the information provided.
b
A cell in G2 before meiosis begins, compared with one of the four cells produced at the end of meiosis II, has a. twice as much DNA and twice as many chromosomes b. four times as much DNA and twice as many chromosomes c. twice as much DNA but the same number of chromosomes d. four times as much DNA and four times as many chromosomes e. twice as much DNA and half as many chromosomes
b
A duplicate copy of all of the hereditary information contained in the nucleus of eukaryotic cells is made during what stage of the cell cycle? a. G1 b. S c. G2 d. Mitosis e. Cytokinesis
b
A life cycle that regularly alternates between haploid and diploid stages is found in all of the following EXCEPT a. dogs b. the bacterium coli c. alfalfa plants d. the mold crassa
b
A person whose cells all contain a chromosome number of 2n+1 most likely has what type of condition? a. Monosomy b. Trisomy c. Cancer d. Obesity e. None, this is the normal chromosome number for humans.
b
An extensive study was conducted on identical twins who were separated at birth. Among other things, the study showed that the individual from each pair who received better nutrition during childhood tended to score higher on standardized intelligence tests. This can best be described as an example of how A) mutation alters phenotype. B) environment alters phenotype. C) environment alters genotype. D) mutation alters genotype. E) pleiotropic genes affect more than one trait.
b
Compared to asexual reproduction, the main advantage of sexual reproduction is that it a. requires less energy b. increases the genetic diversity of the offspring c. can produce more complex offspring d. can produce a greater number of offspring
b
Consider the cell cycle of a human cell. During G2, what is the state of the homologous chromosomes? a. The homologous chromosomes are lined up on the equator of the cell. b. The homologous chromosomes have all been copied through DNA replication and are beginning to condense. c. The homologous chromosomes have been pulled to their respective poles by the spindle apparatus. d. The homologous chromosomes have not been replicated yet. e. The homologous chromosomes are now in the haploid or n
b
Crossing over between homologous chromosomes takes place during a. prophase II. b. prophase I. c. interphase II. d. interphase I. e. metaphase II.
b
Diploid organisms use meiosis to produce haploid cells. Meiosis consists of how many rounds of nuclear division? a. One b. two c. Three d. Four e. None of these
b
During his experiments with pea plants, Mendel referred to the trait that was expressed in the F1 or first filial generation as A) recessive. B) dominant. C) codominant. D) independent. E) homozygous.
b
During this stage of mitosis, the chromosomes become attached to the spindle at their kinetochores. a. Prophase b. Prometaphase c. Metaphase d. Anaphase e. Telophase
b
Eukaryotic chromosomes are composed of a complex of 60% protein and 40% DNA. This complex is referred to as: a. The histone complex b. Chromatin c. The kinetochore d. Cohesin
b
Evidence of crossing over can often be seen under the light microscope as a structure called a ________. a. centromere b. chiasma c. kinetochore d. centriole
b
How does the organization of the bacterial genome differ from the organization of the eukaryotic genome? a. The compaction of the eukaryotic genome involves structural maintenance of chromosome (SMC) proteins, and the compaction of the bacterial genome does not. b. Most bacterial chromosomes are circular and the eukaryotic chromosomes contained in the nucleus are not. Bacterial chromosomes are made up of RNA and eukaryotic chromosomes are made up of DNA. c. The eukaryotic genome is found on chromosomes and there are no chromosomes in bacterial cells. d. Eukaryotic chromosomes have to be tightly packed to fit into the nucleus, and bacterial chromosomes do not require tight packing to fit into the cell.
b
If a cell has 32 chromosomes prior to S and undergoes mitosis followed by cytokinesis, each new daughter cell will have how many chromosomes? a. 64 b. 32 c. 16 d. 8
b
If a single gene has 3 or more alternative forms, this is called A) pleiotropy. B) multiple alleles. C) epistasis. D) blending inheritance. E) codominance.
b
If there are 32 sister chromatids in a normal somatic cell, how many chromosomes are there? a. 8 b. 16 c. 32 d. 64
b
In animals, the cells that will eventually undergo meiosis to produce gametes are set aside early in development. These are called a. somatic cells. b. germ-line cells. c. sex cells. d. gametophytes. e. reproductive cells.
b
In life cycles that alternate between haploid and diploid stages, fertilization doubles the number of chromosomes per cell while ________ reduces it in half. a. mitosis b. meiosis c. binary fission d. syngamy
b
Individuals that have 2 alleles for most gene loci are best described as A) haploid. B) diploid. C) dihybrid. D) homozygous. E) heterozygous.
b
Irene knows her blood type is A, but William does not know his blood type. However, William knows that his mother and father both had blood type B. Irene and William's first child is a boy with type O blood. Based on this information, William's blood type could be A) B only B) either B or O C) O only D) either AB or O E) A only
b
Let R = red pigment and r = no pigment. In carnations, RR offspring make a lot of red pigment, rr offspring make no pigment and Rr offspring make a small amount of red pigment, thus appearing pink. Pink carnations are therefore an example of A) codominance. B) incomplete dominance. C) epistasis. D) pleiotropy.
b
Let Y = yellow and y = green, and R = round and r = wrinkled. You cross YYRR peas with yyrr peas. All of the F1 individuals are yellow and round with a genotype of YyRr. You then perform an F2 cross and get the expected 9:3:3:1 phenotypic ratio. What proportion of the F2 plants are expected to be heterozygous for both traits? A) 1/16 B) 1/4 C) 1/2 D) 9/16
b
Mendel performed reciprocal crosses in which he used pollen from a white-flowered plant to fertilize a purple-flowered plant and pollen from a purple-flowered plant to fertilize a white-flowered plant. What did these reciprocal crosses demonstrate? A) The female gamete made a larger genetic contribution to the offspring than the male gamete. B) Each parent made an equal genetic contribution to the offspring. C) Flower color is a sex-linked trait. D) The traits of flower color and sex assort independently. E) The male gamete made a larger genetic contribution to the offspring than the female gamete.
b
Mendel used the ________ to determine whether an individual with the dominant phenotype was homozygous or heterozygous for that trait. A) backcross B) testcross C) dihybrid cross D) F2generation E) double cross
b
One of a pair of chromosomes with similar genetic information and from different sources like the sperm and egg. a. chiasma b. homologue c. kinetochore d. synapsis e. synaptonemal
b
Plant cells typically achieve cytokinesis by: a. binary fission. b. forming a cell plate across the middle of the cell. c. forming a cleavage furrow that pinches the cell into two. d. chromosome condensation. e. chromosome elongation.
b
The Principle of ________ states that the 2 alleles present at each gene locus separate from one another during gamete formation and remain distinct. A) Alleles B) Segregation C) Crossing over D) Dominance E) Independent assortment
b
The Rec8 protein holds sister chromatids together during meiosis. If an individual has a mutation that prevents degradation of Rec8, this would most likely prevent a. normal segregation during meiosis I. b. normal segregation during meiosis II. c. synapsis of homologous chromosomes. d. crossing over during prophase I.
b
The accommodation of the very long DNA strands that are part of a chromosome into the limited space of the nucleus is achieved by coiling the DNA around beads of histones into repeating subunits. These DNA-wrapped histones are called: a. Solenoids b. Nucleosomes c. Chromatin loops d. Rosettes
b
The allelic make up of a cell or individual is referred to as its A) blueprint. B) genotype. C) phenotype. D) pedigree.
b
The most common form of gene therapy involves inserting a normal gene into cells that contain a defective version of the gene. In order to use gene therapy to prevent a man from passing a defective gene on to future generations, you should try to insert normal copies of the gene into a. blood cells. b. germ-line cells. c. somatic cells in the testes. d. bone marrow cells.
b
The pairing of chromosomes along their lengths, which is essential for crossing over, is referred to as a. syngamy. b. synapsis. c. prophase. d. recombination. e. centromere.
b
The pairing of homologous chromosomes is called a. syngamy. b. synapsis. c. alignment. d. independent assortment. e. crossing over.
b
The physical distribution of cytoplasmic material into the two daughter cells in plant cells is referred to as: a. The gap phase b. Cytokinesis c. Binary fission d. Interphase
b
The point of constriction on chromosomes that contains certain repeated DNA sequences that bind specific proteins is called: a. The kinetochore b. The centromere c. The cohesin complex d. The centriole e. The centrosome
b
The two copies of each type of chromosome found in normal somatic (body) cells in an organism, throughout the cell cycle, are called: a. Sister chromatids b. Homologous chromosomes c. Daughter chromosomes d. Kinetochores
b
This stage of mitosis is characterized by the disassembly of spindle apparatus, the reestablishment of the nuclear membrane, and the decondensation of the chromosomes: a. Prometaphase b. Telophase c. Anaphase d. Metaphase
b
What happens during Anaphase B? a. Kinetochores are pulled toward the poles. b. The spindle poles move apart. c. The spindle apparatus disassembles. d. The nuclear envelope reforms. e. The APC/C gets activated for the first time.
b
What immediately follows meiosis I? a. DNA replication b. prophase II c. metaphase II d. synapsis of homologues e. crossing over of homologues
b
What is the sequence of events in a typical eukaryotic cell cycle? a. G1 to G2 to S to mitosis to cytokinesis b. G1 to S to G2 to mitosis to cytokinesis c. G1 to S to G2 to cytokinesis to mitosis d. G1 to G2 to mitosis to S to cytokinesis e. S to G1 to G2 to mitosis to cytokinesis
b
Which best explains the process of meiosis? a. The cells that result from meiosis I are haploid, and each chromosome consists of 1 chromatid. b. The cells that result from meiosis I are haploid, and each chromosome consists of 2 chromatids. c. The cells that result from meiosis II are haploid, and each chromosome consists of 2 chromatids. d. The cells that result from meiosis I are diploid, and each chromosome consists of 2 chromatids. e. The cells that result from meiosis I are diploid, and each chromosome consists of 1 chromatid.
b
Which of the following produces new cells that are genetically identical to the original cell? a. meiosis b. mitosis c. crossing over d. independent assortment e. fertilization
b
Which of the following statements about crossing over is false? a. Crossing over takes place between nonsister chromatids. b. Crossing over takes place between sister chromatids. c. Crossing over occurs during prophase I. d. Sites of crossing over are called chiasmata. e. Crossing over is also called genetic recombination.
b
Which statement about the reductive division of meiosis is false? a. During the reductive division, homologues migrate to opposite poles of the cell. b. During the reductive division, sister chromatids migrate to opposite poles of the cell. c. During the reductive division, centromeres do not divide. d. At the end of the reductive division, each daughter nucleus has one-half as many centromeres as the parental nucleus.
b
Why does sexual reproduction require both meiosis and syngamy? a. The process of meiosis results in the production of gametes in which the number of chromosomes remains the same. During syngamy, two gametes fuse to form a new cell, and the number of chromosomes is restored to the full amount. Therefore, by coupling meiosis and syngamy, the organism ensures that the proper number of chromosomes will be maintained. b. The process of meiosis results in the production of gametes in which the number of chromosomes is reduced by half. During syngamy, two gametes fuse to form a new cell, and the number of chromosomes is restored to the full amount. Therefore, by coupling meiosis and syngamy, the organism ensures that the proper number of chromosomes will be maintained. c. The process of meiosis results in the production of gametes in which the number of chromosomes is doubled. During syngamy, gametes are reduced by half, and the number of chromosomes is restored to the full amount. Therefore, by coupling meiosis and syngamy, the organism ensures that the proper number of chromosomes will be maintained. d. No answer text provided.
b
Why is it so important that all of the chromosomes align on the metaphase plate during metaphase? a. This is the only place in the cell where the cyclins and Cdks are located. b. If they cannot, it suggests that they aren't properly attached to the spindle microtubules, and thus won't separate properly during anaphase. c. This is the location where the chromosomes can become attached to the spindle microtubules. d. This allows asters to form. e. This allows sister chromatids to form.
b
You are studying cell cycle progression in yeast cells. If you could prevent cdc2 from associating with the mitotic cyclin, the cells would: a. arrest in G1. b. arrest in G2. c. arrest in S. d. arrest in prometaphase. e. arrest in metaphase
b
You are studying meiosis in an organism where 2n = 28. How many chromosomes will be present in each cell after meiosis I is complete but before meiosis II begins? a. 7 b. 14 c. 28 d. 56
b
________ is a process of nuclear division that reduces the number of chromosomes per cell from 2 sets to 1 set. a. Mitosis b. Meiosis c. Binary fission d. Syngamy
b
Mendel chose the garden pea for his work on inheritance for which of the following reasons? Check all that apply. A) Some traits in pea plants are controlled by one dominant allele and one recessive allele. B) Earlier investigators had shown segregation among the offspring. C) A large number of true breeding varieties were available. D) The generation time was short; many offspring can be grown easily. E) He could choose to self- or cross-pollinate.
b, c, d, e
A Punnett square is generally used to A) determine the genotype of each parent from its phenotype. B) determine the phenotype of each parent from its genotype. C) predict the genotypic ratio among the offspring. D) predict the number of offspring that will exhibit each genotype.
c
A secretor (allele seS) is a person who secretes their blood type antigens into body fluids such as saliva. By comparison, a nonsecretor (allele seNS) does not. A person's status as a secretor or nonsecretor is independent of blood type. Consider the following inheritance pattern of this trait: Secretor (seS/seS) x Secretor (seS/seS) → All offspring are secretors Nonsecretor (seNS/seNS) x Nonsecretor (seNS/seNS) → All offspring are nonsecretors Secretor (seS/seS) x Nonsecretor (seNS/seNS) → All offspring are secretors Heterozygote secretor (seS/seNS) x Heterozygote secretor (seS/seNS) 75% secretors, 25% nonsecretors The most likely explanation for this inheritance pattern is that the secretor trait is A) incompletely dominant. B) recessive. C) dominant. D) codominant.
c
Animal cells typically achieve cytokinesis by: a. binary fission. b. forming a cell plate across the middle of the cell. c. forming a cleavage furrow that pinches the cell into two. d. chromosome condensation. e. chromosome elongation.
c
At the end of meiosis II, each of the four resulting cells contains a. one full set of chromosomes, each with 2 molecules of DNA. b. two full sets of chromosomes, each with 2 molecules of DNA. c. one full set of chromosomes, each with 1 molecule of DNA. d. two full sets of chromosomes, each with 1 molecule of DNA.
c
During this stage of mitosis, the nuclear envelope begins to break down and the spindle begins to form. a. Anaphase b. Metaphase c. Prophase d. Telophase e. Prometaphase
c
If a cell was capable of bypassing metaphase and going directly from prometaphase to anaphase, what is the most likely consequence of this? a. The resulting daughter cells would not have a nuclear envelope. b. The resulting daughter cells would have significantly different quantities of cytoplasmic materials. c. The resulting daughter cells would have different numbers of chromosomes. d. The resulting daughter cells would be completely normal.
c
If a chromosome contains a mutation such that it cannot bind to the kinetochore complex, what would be the consequence? a. That chromosome would not be able to be replicated. b. That chromosome would not be able to condense. c. That chromosome would not be able to bind to the mitotic spindle. d. That chromosome would not be able to interact with histone proteins.
c
In 95% of cases of Down's syndrome, there is one extra chromosome (number 21) in every cell. This aneuploid condition is most likely the result of a. failure to suppress DNA replication between meiosis I and meiosis II. b. failure of the chromosomes to assort independently during meiosis. c. failure of 1 homologous pair to segregate during meiosis. d. failure of 2 homologous pairs to segregate during meiosis. e. failure of the cytoplasm to divide at the end of meiosis II.
c
In Mendel's experiments on seed color in pea plants, when a dominant yellow seed-bearing plant was crossed with a recessive green seed-bearing plant, what was the approximate phenotypic ratio among the F2 generation? A) 1 yellow: 3 green B) 1 yellow: 1 green C) 3 yellow: 1 green D) all yellow E) 9:3:3:1
c
In modern terminology, Mendel's heredity "factors" are called A) DNA. B) chromosomes. C) genes. D) RNA.
c
In prophase, ribosomal RNA synthesis stops when the chromosomes condense, and as a result: a. the chromosomes lengthen. b. the nuclear envelope reforms. c. the nucleolus disappears. d. the chromosomes line up at the equator of the cell.
c
In rabbits, there is a gene that controls ear length, with a dominant allele "T" for long ears and a recessive allele "t" for short ears. At another gene locus, there are alleles "B" for black coat and "W" for white coat. Neither the B or W allele is dominant, and BW produces a gray coat. These two allele pairs assort independently. If a gray rabbit that is heterozygous at the gene locus controlling ear length is mated with a white rabbit that is also heterozygous at the gene locus controlling ear length, what proportion of the long-eared offspring will be homozygous for the long-eared trait? A) 1/8 B) 1/4 C) 1/3 D) 1/2
c
Let P = purple flowers and p = white, and T = tall plants and t = dwarf. Of the 16 possible gamete combinations in the dihybrid cross between 2 double heterozygotes, how many would produce the phenotype white, tall? A) none B) 1 C) 3 D) 9 E) 16
c
Non-disjunction is the failure of homologous chromosomes to separate during meiosis I, or the failure of sister chromatids to separate during meiosis II or mitosis. As a result, both homologous chromosomes or both sister chromatids migrate to the same pole of the cell. This produces daughter cells with an imbalance of chromosomes. A cell biologist examines the final products of meiosis in an earthworm (2n=36) and finds 2 cells with 20 chromosomes, and 2 cells with 16 chromosomes. Most likely this was because a. 2 pairs of sister chromatids failed to separate during meiosis II. b. 1 pair of sister chromatids failed to separate during meiosis II. c. 2 pairs of homologous chromosomes failed to separate during meiosis I. d. 1 pair of homologous chromosomes failed to separate during meiosis I.
c
Non-disjunction is the failure of homologous chromosomes to separate during meiosis I, or the failure of sister chromatids to separate during meiosis II or mitosis. As a result, both homologous chromosomes or both sister chromatids migrate to the same pole of the cell. This produces daughter cells with an imbalance of chromosomes. If 18 pairs of sister chromatids segregate normally during meiosis II in cats (n=19) but we have non-disjunction of 1 pair, then at the end of meiosis II we will have a. 3 cells with 20 chromosomes and 1 cell with 18. b. 2 cells with 20 chromosomes and 2 cells with 18. c. 2 cells with 19 chromosomes, 1 with 20, and 1 with 18. d. 3 cells with 18 chromosomes and 1 cell with 20.
c
Parent Blood Types A and B A and A B and O Child Blood Type O B AB Three babies were recently mixed up in a hospital. Based on the data in the table above, the couple with blood types A and B are the actual parents of the child with blood type A) O B) B C) AB D) None of these babies could be the child of the couple with blood types A and B.
c
The cell produced by the fusion of an egg and a sperm is the a. gamete. b. oocyte. c. zygote. d. germ line cell. e. somatic cell.
c
The observable outward manifestation of the genes of an individual is referred to as its A) blueprint. B) genotype. C) phenotype. D) genetic map. E) pedigree.
c
The point of connection between two sister chromatids, before anaphase II of meiosis separates them, is called the a. centriole b. kinetochore. c. centromere. d. spindle apparatus. e. centrosome.
c
The synaptonemal complex is a. a cluster of microtubules at each pole of the cell. b. a network of microtubules that forms the spindle apparatus. c. a network of proteins that holds homologues together. d. the area where microtubules attach to the centromere of each chromosome. e. a region of highly coiled DNA.
c
This stage of the cell cycle is characterized by growth and it contains a checkpoint to verify that all of the DNA has been replicated prior to mitosis. a. G1 b. S c. G2 d. Mitosis e. Cytokinesis
c
A geneticist examines a somatic cell from a fly during metaphase of mitosis and determines that 16 chromatids are present. If a germ-line cell from this species divides by meiosis, then at the end of meiosis I (including the first cytokinesis) each cell will contain a. 8 chromosomes with 8 DNA molecules. b. 8 chromosomes with 16 DNA molecules. c. 4 chromosomes with 4 DNA molecules. d. 4 chromosomes with 8 DNA molecules.
d
A person who has lost a large amount of blood but is still alive is found in a wrecked automobile under a highway bridge. Several people are helping the paramedics load the victim into the ambulance. After the ambulance has departed for the hospital, you overhear the following conversation from the persons who helped the paramedics. "I am certain that when that guy gets to the hospital, they will transfuse him with any blood that they have in the blood bank since he has lost so much blood." The other person says, "Yeah, I bet you're right!" Having had a biology course, you know which blood could be safely given to anyone. Select it below. A) A B) B C) AB D) O
d
A somatic cell from a corn plant normally contains 20 chromosomes. How many sister chromatids would that cell contain during G2 of the cell cycle? a. 0 b. 10 c. 20 d. 40
d
A woman with blood type O has a child with blood type O. She claims that a man named Ralph is the child's father. Her claim would be proven false if Ralph has blood type: Check all that apply. A) O B) A C) B D) AB
d
ABO blood group determination is an example of A) epistasis. B) incomplete dominance. C) polygenic inheritance. D) multiple alleles. E) pleiotropy.
d
All of the following increase genetic variation EXCEPT a. crossing over. b. random fertilization. c. independent assortment. d. mitosis. e. mutation.
d
Alternate forms of the same gene are called A) homologues. B) genotypes. C) cofactors. D) alleles.
d
An allele for a particular trait that is only expressed in the presence of a second copy of the same allele is called A) dominant. B) codominant. C) incompletely dominant. D) recessive. E) pleiotropic.
d
At what checkpoint(s) does the cell arrest in response to DNA damage? a. G1/S b. G2/M c. spindle d. G1/S and G2/M e. G2/M and spindle
d
During meiosis, sister chromatids are held together by a. a common centromere and kinetochore microtubules. b. a common centromere and chiasmata. c. a common centromere and polar microtubules. d. a common centromere and a protein called cohesion. e. the kinetochores and a protein called cohesion.
d
During what stages of the cell cycle are sister chromatids bound together by cohesin? a. G1, S, G2 b. S, G2 c. G1, S d. S, G2, prophase, metaphase e. S, G2, prophase, metaphase, anaphase, telophase
d
Following S phase, a human cell would have how many pairs of sister chromatids and individual DNA molecules? a. 23 pairs of sister chromatids and 46 individual DNA molecules b. 23 pairs of sister chromatids and 92 individual DNA molecules c. 46 pairs of sister chromatids and 46 individual DNA molecules d. 46 pairs of sister chromatids and 92 individual DNA molecules e. 46 pairs of sister chromatids and 184 individual DNA molecules
d
Height is a trait that shows continuous variation in humans. In pea plants, on the other hand, the tall allele is dominant over the short allele and there are no intermediate heights. What is the best explanation for this difference? A) The alleles that control height in pea plants are epistatic. B) The alleles that control height in pea plants are pleiotropic. C) The alleles that control height in humans are pleiotropic. D) Height is a polygenic trait in humans. E) Height is a polygenic trait in pea plants.
d
Homologous chromosomes pair along their length during prophase I of meiosis. While two homologues are paired, genetic exchange may occur between them in a process called ________. a. syngamy b. synapsis c. independent assortment d. crossing over
d
In a heterozygous individual, the allele being expressed is A) recessive. B) codominant. C) pleiotropic. D) dominant. E) epistatic.
d
Let P = purple flowers and p = white, and T = tall plants and t = dwarf. What are the genotypes of the gametes that are produced by a plant that is heterozygous for both traits? A) PpTt only B) PT and pt C) P, p, T, and t D) PT, Pt, pT, and pt E) Tt, TT, tt, Pp, PP, and pp
d
Meiosis results in a reassortment of maternal chromosomes (inherited from the mother) and paternal chromosomes (inherited from the father). If n=4 for a given species, and ignoring the effects of crossing over, what is the probability that a gamete will receive only paternal chromosomes? a. 1/2 b. 1/4 c. 1/8 d. 1/16
d
Mendel used the garden ________ plant for his studies on inheritance. A) lily B) carrot C) onion D) pea
d
Mendel's Principle of Independent Assortment states that different pairs of A) non-homologous chromosomes segregate independently of each other. B) sister chromatids segregate independently of each other. C) non-sister chromatids segregate independently of each other. D) alleles segregate independently of each other. E) gametes segregate independently of each other.
d
The division of a bacterial cell occurs as the: a. cell wall develops cracks around the equator of the cell. b. chromosomes are pulled toward the ends of the cell. c. actin and microtubules constrict the cytoplasm. d. new membrane and cell wall materials begin to grow and form a septum
d
The number of chromosomes in diploid eukaryotic cells a. is 46. b. can be predicted by the size of the organism. c. changes as each organism grows and ages. d. varies considerably from 2 to over 1000 in different species.
d
This is the stage of mitosis characterized by the alignment of the chromosomes in a ring along the inner circumference of the cell: a. Interphase b. Telophase c. Prophase d. Metaphase
d
What stage of mitosis is essentially the reverse of prophase? a. Anaphase b. Prometaphase c. Metaphase d. Telophase e. Cytokinesis
d
Which of the following events occurs first during meiosis? a. homologous chromosomes separate and are pulled to opposite poles of the cell b. sister chromatids separate and are pulled to opposite poles of the cell c. chromosomes decondense d. synapsis of homologous chromosomes e. pairs of homologous chromosomes align along the equatorial plate
d
You are assembling a model of a chromosome, but begin having some trouble when you get to the step of forming chromatin loops. If you are unable to resolve this problem, what step of chromosome structure would you be unable to achieve? a. Histone/DNA complex b. Nucleosome c. Solenoid d. Rosettes
d
________ cells contain one set of chromosomes. a. Germ-line b. Somatic c. Diploid d. Haploid
d
An allele that is present but unexpressed is A) codominant. B) dominant. C) pleiotropic. D) epistatic. E) recessive.
e
Chromosomes exchange genetic information by a. fertilization. b. mitosis. c. syngamy. d. DNA replication. e. crossing over.
e
If a drug that inhibited transport from the trans face of the Golgi was applied to plant cells, which stage of the cell cycle would be directly affected? a. G2 b. S c. Metaphase d. Anaphase e. Cytokinesis
e
Sometimes, one gene pair will interfere with the expression of a second gene pair in an interaction called A) incomplete dominance. B) codominance. C) blending inheritance. D) pleiotropy. E) epistasis.
e
The independent assortment of allele pairs is due to A) the independent segregation of homologous chromosome pairs during anaphase II. B) the random combination of gametes during fertilization. C) the independent segregation of sister chromatid pairs during anaphase I. D) the independent segregation of non-sister chromatid pairs during anaphase II. E) the independent segregation of homologous chromosome pairs during anaphase I.
e
The stage of the cell cycle during which the cytoplasm divides to form two cells is called: a. G1 b. S c. G2 d. Mitosis e. Cytokinesis
e
The zygote has a. one copy of each chromosome. b. one full haploid complement of chromosomes. c. chromosomes identical to those of a sperm cell. d. chromosomes identical to those of an egg cell. e. two copies of each chromosome.
e