Biology Chapters 8&9
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
A testcross is A) a mating between an individual of unknown genotype and an individual homozygous recessive for the trait of interest. B) a mating between an individual of unknown genotype and an individual heterozygous for the trait of interest. C) a mating between an individual of unknown genotype and an individual homozygous dominant for the trait of interest. D) a mating between two individuals heterozygous for the trait of interest. E) a mating between two individuals of unknown genotype.
A
At the start of mitotic anaphase, A) the centromeres of each chromosome come apart. B) sister chromatids separate. C) the chromatid DNA replicates. D) daughter chromosomes begin to move toward opposite poles of the cell. E) equivalent and complete collections of chromosomes have reached the two poles.
A
Cancer is not usually inherited because A) the chromosomal changes in cancer are usually confined to somatic cells. B) people with cancer usually die before reproducing. C) cancer typically causes disruptions of meiosis. D) the causes of cancer are not usually genetic. E) the cancerous cells usually interfere with the ability to produce gametes.
A
Eukaryotic cells spend most of their cell cycle in which phase? A) interphase B) prophase C) metaphase D) anaphase E) telophase
A
For most sexually reproducing organisms, Mendel's laws A) cannot strictly account for most patterns of inheritance. B) explain the reasons why certain genes are dominant. C) help us understand the global geographic patterns of genetic disease. D) indicate if a particular genotype will cause a certain phenotype. E) clarify the phenomenon of incomplete dominance.
A
How many generations does it take to develop a new plant species by nondisjunction? A) one B) two C) ten D) twenty E) fifty
A
If the S phase were eliminated from the cell cycle, the daughter cells would A) have half the genetic material found in the parent cell. B) be genetically identical to each other. C) be genetically identical to the parent cell. D) synthesize the missing genetic material on their own. E) continue to function without the normal amount of DNA.
A
Imagine that beak color in a finch species is controlled by a single gene. You mate a finch homozygous for orange (pigmented) beak with a finch homozygous for ivory (unpigmented) beak and get numerous offspring, all of which have a pale, ivory-orange beak. This pattern of color expression is most likely to be an example of A) incomplete dominance. B) codominance. C) pleiotropy. D) polygenic inheritance. E) crossing over.
A
Independent orientation of chromosomes at metaphase I and random fertilization are most like A) shuffling cards and dealing out hands of poker. B) cutting up a pie into eight even-sized slices. C) alphabetizing files in a filing cabinet. D) pairing up similar socks after washing your clothes. E) stringing beads onto a string to make a necklace.
A
Looking into your microscope, you spot an unusual cell. Instead of the typical rounded cell shape, the cell has a very narrow middle separating two bulging ends. It sort of looks like the number 8! Then you realize that this cell is A) undergoing cytokinesis. B) in the S phase of interphase. C) in the G1 phase of interphase. D) in the G2 phase of interphase. E) about to undergo mitosis.
A
Mendel conducted his most memorable experiments on A) peas. B) roses. C) guinea pigs. D) fruit flies. E) clones
A
Sickle-cell disease is an example of A) codominance and pleiotropy. B) codominance and blended inheritance. C) multiple alleles, pleiotropy, and blended inheritance. D) codominance and multiple alleles. E) multiple alleles and pleiotropy.
A
The creation of offspring carrying genetic information from a single parent is called A) asexual reproduction. B) sexual reproduction. C) a life cycle. D) regeneration. E) spontaneous generation.
A
Two chromosomes in a nucleus that carry loci for the same traits in the same positions on the chromosome but specify different versions of some traits constitute a pair of A) homologous chromosomes. B) heterologous chromosomes. C) complementary chromosomes. D) polyploid chromosomes. E) parallel chromosomes.
A
Which of the following is a feature of plant cell division that distinguishes it from animal cell division? A) formation of a cell plate B) formation of a cleavage furrow C) lack of cytokinesis D) production of four (rather than two) new cells per mitotic division E) disappearance and subsequent reappearance of the nucleolus
A
Which of the following is probably the main factor responsible for the phenomenon of density-dependent inhibition? A) a local accumulation of growth-inhibiting factors B) availability of growth factors C) cells' innate ability to "sense" when the organ of which they are a part has no need for additional cells D) a local deficiency of nutrients E) physical contact of cell-surface proteins between adjacent cells.
A
Which of the following statements is false? A) Incomplete dominance supports the blending hypothesis. B) Heterozygotes for hypercholesterolemia have blood cholesterols about twice normal. C) The four blood types result from various combinations of the three different ABO alleles. D) ABO blood groups can provide evidence of paternity. E) The impact of a single gene on more than one character is called pleiotropy.
A
Which of the following statements regarding prokaryotes is false? A) Prokaryotic chromosomes are more complex than those of eukaryotes. B) Most prokaryotes reproduce by binary fission. C) Prokaryotic cells are generally smaller and simpler than eukaryotic cells. D) In prokaryotes, daughter chromosomes are separated by an active movement away from each other and the growth of a new plasma membrane between them. E) Daughter prokaryotic chromosomes are separated by some sort of active movement away from each other and the growth of new plasma membrane between them.
A
Which of the following variations of the sentence "Where is the cat" is most like a chromosomal deletion? A) Where is cat? B) Where is the the cat? C) Where the is cat? D) Where is cat the the cat? E) Where is is is is the cat?
A
A pair of male human sex chromosomes is most like A) a pair of blue jeans. B) a bride and groom. C) a knife, fork, and spoon. D) identical twins. E) the letters of the alphabet.
B
A person with AB blood illustrates the principle of A) incomplete dominance. B) codominance. C) pleiotropy. D) polygenic inheritance. E) blending inheritance.
B
All the offspring of a cross between a black-eyed mendelien and an orange-eyed mendelien have black eyes. What is the expected phenotypic ratio of a cross between two orange-eyed mendeliens? A) 3 black-eyed:1 orange-eyed B) 0 black-eyed:1 orange-eyed C) 1 black-eyed:3 orange-eyed D) 1 black-eyed:0 orange-eyed E) 1 black-eyed:1 orange-eyed
B
As a patch of scraped skin heals, the cells fill in the injured area but do not grow beyond that. This is an example of A) density-independent inhibition. B) density-dependent inhibition. C) anchorage independence. D) growth factor inhibition. E) anchorage-dependent inhibition.
B
Asexual reproduction requires ________ individual(s). A) 0 B) 1 C) 2 D) 3 E) 4
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
Both mitosis and meiosis are preceded by A) prometaphase. B) interphase. C) prophase. D) telophase. E) anaphase.
B
During which stage of meiosis does synapsis and the formation of tetrads occur? A) interphase I B) prophase I C) interphase II D) prophase II E) metaphase I
B
If a chromosome fragment breaks off and then reattaches to the original chromosome, but in the reverse direction, the resulting chromosomal abnormality is called a(n) A) deletion. B) inversion. C) translocation. D) nondisjunction. E) reciprocal translocation.
B
Karyotyping A) shows chromosomes as they appear in metaphase of meiosis II. B) can reveal alterations in chromosome number. C) examines points of crossing over. D) reveals the results of independent orientation of chromosomes during meiosis I. E) reveals the presence of cancerous genes.
B
Most genetic disorders of humans are caused by A) multiple alleles. B) recessive alleles. C) drinking during pregnancy. D) a mutation that occurs in the egg, sperm, or zygote. E) dominant alleles.
B
Research since Mendel's time has established that the law of the segregation of genes during gamete formation A) applies to all forms of life. B) applies to all sexually reproducing organisms. C) applies to all asexually reproducing organisms. D) applies only to unicellular organisms. E) is invalid.
B
Sister chromatids are A) found right after a cell divides. B) tightly linked together at a centromere. C) formed when chromatids separate during cell division. D) made only of DNA. E) unique to prokaryotes.
B
The cell cycle control system is most like A) a row of dominoes falling down, each one triggering the fall of the next. B) the control device of an automatic washing machine. C) an orchestra directed by a conductor. D) a light switch turning on a set of room lights. E) a video game controller.
B
The chromosome theory of inheritance states that A) chromosomes that exhibit mutations are the source of genetic variation. B) the behavior of chromosomes during meiosis and fertilization accounts for patterns of inheritance. C) the behavior of chromosomes during mitosis accounts for inheritance patterns. D) humans have 46 chromosomes. E) the inheritance pattern of humans is predetermined from chromosomes.
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 phase of mitosis during which the nuclear envelope fragments and the nucleoli disappear is called A) interphase. B) prophase. C) metaphase. D) anaphase. E) telophase.
B
The process by which the cytoplasm of a eukaryotic cell divides to produce two cells is called A) mitosis. B) cytokinesis. C) binary fission. D) telophase. E) spindle formation.
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
Using a six-sided die, what is the probability of rolling either a 5 or a 6? A) 1/6 × 1/6 = 1/36 B) 1/6 + 1/6 = 1/3 C) 1/6 + 1/6 = 2/3 D) 1/6 + 1/6 = 1/12 E) 1/6
B
Which of the following helps maintain the structure of chromosomes and control the activity of genes? A) the nuclear membrane B) proteins C) centromeres D) ribosomes E) lipids
B
Which of the following is an example of incomplete dominance in humans? A) sickle-cell disease B) hypercholesterolemia C) skin color D) ABO blood groups E) phenylketonuria
B
Which of the following must occur for a plant or animal to grow and develop normally? A) The organism must receive a supply of the appropriate hormones from its parents. B) The organism must be able to control the timing and rate of cell division in different parts of its body. C) Sufficient light must be available to stimulate cell division. D) Sufficient oxygen must be available to stimulate cell division. E) Dividing cells must be freed from attachment sites.
B
Which of the following options correctly describes the behavior of a tetrad during anaphase I of meiosis? A) It goes intact to one pole of the dividing cell. B) It splits into two pairs of sister chromatids, and one pair goes to each pole of the dividing cell. C) It splits into two pairs of homologous, nonsister chromatids, and one pair goes to each pole of the dividing cell. D) It splits into four chromosomes, which distribute in random pairs to the two poles of the dividing cell. E) It splits into four chromosomes, which distribute in sister-chromosome pairs to the two poles of the dividing cell.
B
Which of the following statements about nondisjunction is false? A) Nondisjunction in meiosis can affect autosomes and sex chromosomes. B) In mammals, extra copies of the Y chromosome are typically inactivated. C) The absence of a Y chromosome results in "femaleness." D) In general, a single Y chromosome is enough to produce "maleness." E) Women with a single X chromosome have Turner syndrome and are sterile.
B
Which of the following statements best represents the theory of pangenesis developed by Hippocrates? A) Pregnancy is a spontaneous event, and the characteristics of the offspring are determined by the gods. B) Particles called pangenes, which originate in each part of an organism's body, collect in the sperm or eggs and are passed on to the next generation. C) Offspring inherit the traits of either the mother or the father, but not both. D) Fertilization of plants is dependent on an animal. E) Heritable traits are influenced by the environment and the behaviors of the parents.
B
Which of the following statements regarding mitosis and meiosis is false? A) Mitosis provides for growth and tissue repair. B) Meiosis provides for asexual reproduction. C) In mitosis, the chromosomes replicate only once in the preceding interphase. D) In meiosis, the chromosomes replicate only once in the preceding interphase. E) All the events unique to meiosis occur during meiosis I.
B
Which of the following statements regarding prenatal testing is false? A) Results from chorionic villus sampling come faster than from amniocentesis. B) Chorionic villus sampling is typically performed later in the pregnancy than amniocentesis. C) Ultrasound imaging has no known risk. D) The complication rate for chorionic villus sampling is about 2% and for amniocentesis is about 1%. E) Chorionic villus sampling and amniocentesis are usually reserved for pregnancies with higher than usual risks of complications.
B
Which of the following statements regarding the function of mitosis is false? A) Mitosis allows organisms to grow. B) Mitosis allows organisms to generate genetic diversity. C) Mitosis allows organisms to reproduce asexually. D) Mitosis allows organisms to repair tissues. E) Mitosis allows organisms to regenerate lost parts.
B
You are asked to culture an unidentified sample of animal tissue. You notice that the cells seem to fail to exhibit density-dependent inhibition. The source of this tissue sample is most likely A) a scar. B) a cancer. C) skin. D) a fetal liver. E) the sperm-producing tissue of the testis.
B
A benign tumor differs from a malignant tumor in that a benign tumor A) is cancerous. B) spreads from the original site. C) does not metastasize. D) never causes health problems. E) can only arise in the brain, whereas a malignant tumor can arise anywhere in the body.
C
A monohybrid cross is A) the second generation of a self-fertilized plant. B) a breeding experiment in which the parental varieties have only one trait in common. C) a breeding experiment in which the parental varieties differ in only one character. D) a triploid plant that results from breeding two very different plants. E) a breeding experiment in which the parental varieties have only one prominent trait.
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
During which phase of mitosis do the chromosomes line up on a plane equidistant from the two spindle poles? A) interphase B) prophase C) metaphase D) anaphase E) telophase
C
Independent orientation of chromosomes at metaphase I results in an increase in the number of A) gametes. B) homologous chromosomes. C) possible combinations of characteristics. D) sex chromosomes. E) points of crossing over.
C
Mr. and Mrs. Smith have three sons in elementary school. Two of their children are progressing normally, but their last son, Charles, has been much slower than his siblings at developing speech and language skills. His parents are concerned that he has a learning disability and decide to investigate further. Since some learning disabilities can be genetically based, their pediatrician recommends a chromosomal analysis. The results show that Charles has a trisomy of the sex chromosomes, diagnosed as XYY, which is caused by nondisjunction in the formation of the father's sperm. The nondisjunction resulted in an extra copy of the Y chromosome. The extra copy was passed on to Charles during fertilization. Most often, this chromosomal change causes no unusual physical features or medical problems, but those with trisomy of the sex chromosomes do have a higher than normal risk of delays in learning development. 1) During which stage of meiosis must this nondisjunction have occurred? A) anaphase I B) metaphase I C) metaphase II D) anaphase II E) prophase II
C
Strictly speaking, the phrase "like begets like" refers to A) all forms of reproduction. B) sexual reproduction only. C) asexual reproduction only. D) production of gametes from a premeiotic cell. E) sexual reproduction between different species.
C
The genetic material is duplicated during A) the mitotic phase. B) G1. C) the S phase. D) G2. E) mitosis.
C
When animal cells are grown in a petri dish, they typically stop dividing once they have formed a single, unbroken layer on the bottom of the dish. This arrest of division is an example of A) cancer. B) cell constraint. C) density-dependent inhibition. D) cell division repression. E) growth factor desensitization.
C
Which of the following features likely accounts for the difference between plant and animal cell cytokinesis? A) Animal cells lack the microfilaments required for forming a cleavage furrow. B) Animal cells lack chloroplasts. C) Plant cell division must maintain the integrity of the cell wall. D) Plant cells have two sets of chromosomes; animal cells have one set of chromosomes. E) Plant and animal cells do not have a common ancestor.
C
Which of the following shows the greatest promise as a cancer chemotherapy agent? A) a drug that causes cells to divide at a right angle from their usual orientation B) a drug that interferes with cellular respiration C) a drug that prevents sister chromatids from separating at anaphase D) a drug that prevents crossing over E) a drug that prevents tetrad formation
C
Which of the following statements best explains why dominant alleles that cause lethal disorders are less common than recessive alleles that cause lethal disorders? A) Lethal disorders caused by dominant alleles are usually more severe than lethal disorders caused by recessive alleles. B) Unlike lethal disorders caused by recessive alleles, lethal disorders caused by dominant alleles usually cause the death of the embryo. C) Most individuals carrying a lethal dominant allele have the disorder and die before they reproduce, whereas individuals carrying a lethal recessive allele are more likely to be healthy and reproduce. D) The presence of a lethal dominant allele causes sterility. E) Many lethal recessive alleles cause enhanced disease resistance when they are present in the heterozygous state, and carriers of these alleles have more children, on average, than other people.
C
Which of the following statements regarding genetic diversity is false? A) Genetic diversity is enhanced by random fertilization. B) Genetic diversity is enhanced by independent orientation of chromosomes at metaphase I. C) Genetic diversity is enhanced by mitosis of somatic cells. D) Genetic diversity is enhanced by crossing over during prophase I of meiosis. E) Genetic diversity is enhanced by random mutations of the DNA.
C
Which of the following statements regarding mitosis and meiosis is false? A) Meiosis only occurs in the ovaries and testes. B) All sexual life cycles involve an alternation of diploid and haploid stages. C) Mitosis produces daughter cells with half the number of chromosomes as the parent cell. D) A normal human zygote has 46 chromosomes. E) A haploid cell has half the chromosomes of a diploid cell.
C
Which of the following statements regarding sickle-cell disease is false? A) Sickle-cell disease is common in tropical Africa. B) Persons who are heterozygous for sickle-cell disease are also resistant to malaria. C) Sickle-cell disease causes white blood cells to be sickle-shaped. D) All of the symptoms of sickle-cell disease result from the actions of just one allele. E) About one in ten African-Americans is a carrier of sickle-cell disease.
C
Which of the following types of organisms commonly demonstrates polyploidy? A) mammals B) reptiles C) flowering plants D) amphibians E) fish
C
A karyotype is most like A) a map showing the hidden location of buried treasure. B) a movie showing the stages of the reproductive cycle of a beetle. C) a necklace formed by stringing beads onto a string. D) photographs of every couple at a high school prom. E) the answer key to a multiple-choice exam.
D
All the offspring of a cross between a black-eyed mendelien and an orange-eyed mendelien have black eyes. This means that the allele for black eyes is ________ the allele for orange eyes. A) codominant to B) recessive to C) more aggressive than D) dominant to E) better than
D
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
Amniocentesis and chorionic villus sampling allow for ________ and ________ of the fetus so that it can be tested for abnormalities. A) imaging . . . biochemical testing B) imaging . . . karyotyping C) sexing . . . imaging D) karyotyping . . . biochemical testing E) direct observation . . . biochemical testing
D
Genes located close together on the same chromosomes are referred to as ________ genes and generally ________. A) associated . . . sort independently during meiosis B) linked . . . sort independently during meiosis C) homologous . . . are inherited together D) linked . . . do not sort independently during meiosis E) codependent . . . do not sort independently during meiosis
D
Imagine that we mate two black Labrador dogs with normal vision and find that three of the puppies are like the parents, but one puppy is chocolate with normal vision and another is black with PRA (progressive retinal atrophy, a serious disease of vision). We can conclude that A) both of the parents are homozygous for both traits. B) one of the parents is homozygous for both traits. C) the same alleles that control coat color can also cause PRA. D) the alleles for color and vision segregate independently during gamete formation. E) the alleles for color and vision segregate dependently during gamete formation.
D
Mature human nerve cells and muscle cells A) remain undifferentiated unless an injury occurs. B) become cancerous more easily than other cell types. C) continue to divide throughout their lifetime. D) are permanently in a state of nondivision. E) cease dividing after a predetermined number of cell generations.
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
Nondisjunction occurs when A) a portion of a chromosome breaks off and is lost. B) chromosomes replicate too many times. C) two chromosomes fuse into one. D) members of a chromosome pair fail to separate. E) an entire pair of chromosomes is lost during meiosis I.
D
Virchow's principle, stated formally in 1858, was that A) animals must always reproduce. B) photosynthesis is the center of all life. C) animals must develop. D) every cell comes from a cell. E) all life evolves.
D
Which of the following is essentially the opposite of pleiotropy? A) incomplete dominance B) codominance C) multiple alleles D) polygenic inheritance E) blending inheritance
D
Which of the following occurs during interphase? A) a reduction in the size of the nuclear membrane B) duplication of the chromosomes C) cytokinesis D) cell growth and duplication of the chromosomes E) separation of newly formed DNA to opposite ends of the cell
D
Which of the following statements is false? A) A typical body cell is called a somatic cell. B) Gametes are haploid cells. C) Somatic cells are diploid. D) Gametes are made by mitosis. E) A zygote is a fertilized egg.
D
Which of the following statements regarding cross-breeding and hybridization is false? A) The offspring of two different varieties are called hybrids. B) Hybridization is also called a cross. C) The parental plants of a cross are the P generation. D) The hybrid offspring of a cross are the P1 generation. E) The hybrid offspring of an F1 cross are the F2 generation.
D
Which of the following statements regarding domestic dogs is false? A) Dogs originated in East Asia. B) Dogs of different breeds can be identified through genetic analysis. C) Shar-pei and Akita are genetically very similar to the wolf. D) All dogs are descended from wolves. E) Humans have bred dogs for thousands of years.
D
Which of the following statements regarding genotypes and phenotypes is false? A) The genetic makeup of an organism constitutes its genotype. B) An organism with two different alleles for a single trait is said to be heterozygous for that trait. C) Alleles are alternate forms of a gene. D) An allele that is fully expressed is referred to as recessive. E) The expressed physical traits of an organism are called its phenotype.
D
Which of the following statements regarding hypotheses about inheritance is false? A) The theory of pangenesis incorrectly suggests that reproductive cells receive particles from somatic cells. B) Contrary to the theory of pangenesis, somatic cells do not influence eggs or sperm. C) The blending hypothesis does not explain how traits that disappear in one generation can reappear in later generations. D) The blending hypothesis suggests that all of the traits of the offspring come from either the mother or the father. E) Aristotle suggested that inheritance is the potential to produce body features.
D
Which of the following statements regarding sexual and asexual reproduction is true? A) Cell division only occurs after sexual reproduction. B) Only offspring from asexual reproduction inherit traits from two parents. C) Sexual reproduction typically includes the development of unfertilized eggs. D) Sexual reproduction is more likely to increase genetic variation than is asexual reproduction. E) Only asexual reproduction results from the union of a sperm and an egg.
D
Which of the following statements regarding the differences between mitosis and meiosis is false? A) In meiosis four daughter cells are produced, whereas in mitosis two daughter cells are produced. B) Cells produced by mitosis are diploid, whereas cells produced by meiosis are haploid. C) In mitosis cytokinesis occurs once, whereas in meiosis cytokinesis occurs twice. D) Crossing over is a phenomenon that creates genetic diversity during mitosis. E) Mitosis, but not meiosis, occurs in somatic cells.
D
Which of the following terms refers to a situation where a single phenotypic character is determined by the additive effects of two or more genes? A) incomplete dominance B) codominance C) pleiotropy D) polygenic inheritance E) blending inheritance
D
During which phase of mitosis does the nuclear envelope re-form and the nucleoli reappear? A) anaphase B) metaphase C) prophase D) interphase E) telophase
E
Eukaryotic chromosomes differ from prokaryotic chromosomes in that they A) are simpler. B) are circular in structure. C) include fewer proteins. D) are copied immediately after cell division. E) are housed in a membrane-enclosed nucleus.
E
If A is dominant to a and B is dominant to b, what is the expected phenotypic ratio of the cross: AaBb × AaBb? A) 16:0:0:0 B) 8:4:2:2 C) 4:4:4:4 D) 1:1:1:1 E) 9:3:3:1
E
If Charles gets married and starts a family, which of the following chromosomal abnormalities might be found in his children? A) XY B) XX C) XYY D) XO E) XXY
E
Prior to mitosis, each chromosome of a eukaryotic cell consists of a pair of identical structures called A) chromatin. B) sister chromosomes. C) DNA transcripts. D) nucleoli. E) sister chromatids.
E
The alleles of a gene are found at ________ chromosomes. A) the same locus on homologous mitochondrial B) the same locus on heterologous C) different loci on homologous D) different loci on heterologous E) the same locus on homologous
E
The individual features 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 phenotypic ratio resulting from a dihybrid cross showing independent assortment is expected to be A) 1:2:1. B) 3:1. C) 9:1:1:3. D) 3:9:9:1. E) 9:3:3:1.
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
Which of the following statements regarding Down syndrome is false? A) Trisomy 21 usually leads to Down syndrome. B) A human embryo with an abnormal number of chromosomes is usually spontaneously aborted. C) Down syndrome is the most common serious birth defect in the United States. D) People with Down syndrome usually have a life span much shorter than normal. E) Women with Down syndrome cannot reproduce.
E
Which of the following statements regarding cell division is false? A) Cell division can reproduce an entire organism. B) Cell division is necessary for development to occur. C) Cell division ensures the continuity of life from generation to generation. D) Cell division is the basis of both sexual and asexual reproduction. E) Cell division is common in eukaryotes but rare in prokaryotes.
E
Which of the following statements regarding genetic testing is false? A) Genetic testing before birth requires the collection of fetal cells. B) Carrier testing helps determine if a person carries a potentially harmful disorder. C) Most children with recessive disorders are born to healthy parents. D) The screening of newborns can catch inherited disorders right after birth. E) Most human genetic diseases are treatable if caught early.
E
Which of the following statements regarding the cell-cycle control system is false? A) The cell-cycle control system receives messages from outside the cell that influence cell division. B) The cell-cycle control system triggers and controls major events in the cell cycle. C) The cell-cycle control system is influenced by growth factors that bind to cell receptors. D) The cell-cycle control system includes three key checkpoints to complete a cell cycle. E) The cell-cycle control system operates independently of the growth factors.
E
With the exception of identical twins, siblings who have the same two biological parents are likely to look similar, but not identical, to each other because they have A) identical chromosomes, but different genes. B) identical genes but different chromosomes. C) the same combination of traits, but different genes. D) only a 20% chance of sharing the same combination of genes. E) a similar but not identical combination of genes.
E
