cell cycle and genes

A benign tumor differs from a malignant tumor in that a benign tumor a. does not metastasize. b. never causes health problems. c. can only arise in the brain, whereas a malignant tumor can arise anywhere in the body. d. is cancerous. e. spreads from the original site.

a

After telophase I of meiosis, the chromosomal make-up of each daughter cell is a. haploid, and the chromosomes are composed of two chromatids. b. tetraploid, and the chromosomes are composed of two chromatids. c. diploid, and the chromosomes are composed of a single chromatid. d. haploid, and the chromosomes are composed of a single chromatid. e. diploid, and the chromosomes are composed of two chromatids.

a

The drug cytochalasin B blocks the function of actin. Which of the following aspects of the animal cell cycle would be most disrupted by cytochalasin B? a. cleavage furrow formation and cytokinesis b. DNA synthesis c. cell elongation during anaphase d. spindle formation e. spindle attachment to kinetochores

a

During which stage of meiosis do synapsis and the formation of tetrads occur? a. prophase I b. metaphase I c. interphase I d. interphase II e. prophase II

a

Eukaryotic cells spend most of their cell cycle in which phase? a. interphase b. metaphase c. telophase d. prophase e. anaphase

a

If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis I would be a. 2x. b. 0.25x. c. 4x. d. 0.5x. e. x.

a

In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous offspring of red and white homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red: 2 roan: 1 white? a. roan x b. The answer cannot be determined from the information provided. c. white x roan d. red x white e. red x roan

a

Increases in the enzymatic activity of some protein kinases important for the regulation of the cell cycle are due to a. activation of inactive kinases by binding to cyclins. b. cleavage of the inactive kinase molecules by cytoplasmic proteases. c. kinase synthesis by ribosomes. d. a decline in external growth factors to a concentration below the inhibitory threshold. e. conversion of inactive cyclins to active kinases by means of phosphorylation.

a

Referring to a plant sexual life cycle, which of the following terms describes the process that leads directly to the formation of gametes? a. gametophyte mitosis b. sporophyte meiosis c. alternation of generations d. gametophyte meiosis e. sporophyte mitosis

a

Sickle-cell disease represents a. codominance and blended inheritance. b. multiple alleles, pleiotropy, and blended inheritance.c. codominance and pleiotropy. d. multiple alleles and pleiotropy. e. codominance and multiple alleles.

a

Sister chromatids are a. tightly linked together at a centromere.b. made only of DNA. c. unique to prokaryotes. d. formed when chromatids separate during cell division. e. found right after a cell divides.

a

The process by which the cytoplasm of a eukaryotic cell divides to produce two cells is called a. cytokinesis. b. mitosis. c. binary fission. d. spindle formation. e. telophase.

a

What is the probability that a couple's first-born child is female and the second-born child is male? a. 25% b. 100% c. 75% d. None of the choices are correct. e. 50%

a

Which of the following is an example of polygenic inheritance? a. skin pigmentation in humans b. white and purple flower color in peas c. the ABO blood groups in humans d. Huntington's disease in humans e. pink flowers in snapdragons

a

A cell containing 92 chromatids at metaphase of mitosis would, at its completion, produce two nuclei containing how many chromosomes? a. 23 b. 46 c. 16 d. 92 e. 12

b

A person with AB blood illustrates the principle of a. blending inheritance. b. codominance. c. incomplete dominance. d. pleiotropy. e. polygenic inheritance.

b

How do the two members of a pair of homologous chromosomes differ from each other? a. their length b. the precise sequence of the DNA within each of the chromosomes c. their staining (banding) patterns d. the identity and relative position of the genes present on each of the chromosomes e. the position of the centromere within each of the chromosomes

b

Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because is interferes with the assembly of microtubules, its effectiveness must be related to a. inhibition of regulatory protein phosphorylation. b. disruption of mitotic spindle formation. c. myosin denaturation and inhibition of cleavage furrow formation. d. inhibition of DNA synthesis. e. suppression of cyclin production.

b

What is a genetic cross between an individual showing a dominant phenotype (but of unknown genotype) and a homozygous recessive individual called? a. an F1 cross b. a testcross c. a dihybrid cross d. a self-cross e. a hybrid cross

b

Which of the following best explains why dominant alleles that cause lethal disorders are less common than recessive alleles that cause lethal disorders? a. The presence of a lethal dominant allele causes sterility. b. Most individuals that have 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. c. Unlike lethal disorders caused by recessive alleles, lethal disorders caused by dominant alleles usually cause death in the embryo. d. 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. e. Lethal disorders caused by dominant alleles are usually more severe than lethal disorders caused by recessive alleles.

b

Which of the following help maintain the structure of chromosomes and control the activity of genes? a. the nuclear membrane b. proteins c. centrosomes d. ribosomes e. lipids

b

Which of the following techniques involves the preparation of a karyotype? a. chorionic villus sampling b. both amniocentesis and chorionic villus sampling c. fetoscopy d. amniocentesis e. amniocentesis, chorionic villus sampling, and fetoscopy

b

Alleles of a gene are found at ____________________ chromosomes. a. different loci on homologous b. different loci on heterologous c. the same locus on homologous d. the same locus on heterozygous e. the same locus on homologous mitochondrial

c

Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the progeny of the cross BbTt x BBtt will have black fur and long tails? a. 9/16 b. 3/16 c. 1/2 d. 3/8 e. 1/16

c

Crossing over usually contributes to genetic variation by exchanging chromosomal segments between a. sister chromatids of a chromosome. b. chromatids of nonhomologues. c. nonsister chromatids of homologues. d. nonhomologous loci of the genome. e. autosomes and sex chromosomes.

c

How many different combinations of maternal and paternal chromosomes can be packaged in gametes made by an organism with a diploid number of 8 (2n = 8)? a. 32 b. 2 c. 16 d. 4 e. 8

c

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 has a pale, ivory-orange beak. This pattern of color expression is most likely to be an example of a. crossing over. b. pleiotropy. c. incomplete dominance. d. codominance. e. polygenic inheritance.

c

In a cross AaBbCc x AaBbCc, what is the probability of producing the genotype AABBCC? a. 1/8 b. 1/4 c. 1/64 d. 1/16 e. 1/32

c

In the cells of some organisms, mitosis occurs without cytokinesis. This will result in a. cells that are unusually small. b. destruction of chromosomes. c. cells with more than one nucleus. d. cells lacking nuclei. e. cell cycles lacking an S phase.

c

The cell-cycle control system a. receives messages from outside the cell that influence cell division. b. includes three key checkpoints to complete a cell cycle. c. All of the choices are correct. d. triggers and controls major events in the cell cycle. e. is influenced by growth factors that bind to cell receptors.

c

The creation of offspring carrying genetic information from a single parent is called a. life cycle. b. sexual reproduction. c. asexual reproduction. d. None of the choices are correct. e. regeneration.

c

What name is given to the process that restores the diploid number of chromosomes? a. the cell cycle b. meiosis c. fertilization d. mitosis e. asexual reproduction

c

Which life cycle state is found in plants but not in animals? a. gamete b. unicellular diploid c. multicellular haploid d. zygote e. multicellular diploid

c

Which of the following are primarily responsible for cytokinesis in plant cells? a. centrioles and basal bodies b. kinetochores c. Golgi-derived vesicles d. cyclin-dependent kinases e. actin and myosin

c

A human cell containing 22 autosomes and a Y chromosome is a. a zygote. b. a somatic cell of a male. c. a somatic cell of a female. d. a sperm cell.e. an ovum (egg cell).

d

Homologous chromosomes move toward opposite poles of a dividing cells during a. meiosis II. b. binary fission. c. mitosis. d. meiosis I. e. fertilization.

d

How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE? a. 16 b. 32 c. 4 d. 8 e. 64

d

Independent assortment of chromsomes is a result of a. the relatively small degree of homology share by the X and Y chromosomes. b. All of the choices are correct. c. the random distribution of the sister chromatids to the two daughter cells during anaphase II. d. the random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I. e. the random nature of the fertilization of ova (egg) by sperm.

d

The decline of MPF activity at the end of mitosis is due to a. the accumulation of cyclin. b. the destruction of the protein kinase Cdk. c. decreased synthesis of Cdk. d. the degradation of cyclin. e. synthesis of DNA.

d

The phase of mitosis during which the nuclear envelope fragments and the nucleoli disapper is called a. telophase. b. anaphase. c. interphase. d. prophase/prometaphase.e. metaphase.

d

What is a karyotype? a. the complete compliment of an organism's genes b. the set of unique physical characteristics that define an individual c. a collection of all the mutations present within a genome d. a display of every pair of homologous chromosomes within a cell, organized according to size, shape, and banding patterns e. a unique combination of chromosomes found in a gamete

d

Which of the following does not occur during mitosis? a. separation of sister chromatids b. disappearance of the nucleolus c. spindle formation d. synthesis of DNA e. condensing of chromosomes

d

A couple has three children, all of whom have brown eyes and blonde hair. Both parents are homozygous for brown eyes (BB), but one is a blond (rr) and the other is a redhead (Rr). What is the probability that their next child will be a brown-eyed redhead? a. 1 b. 1/4 c. 1/8 d. 1/16 e. 1/2

e

A particular cell has half as much DNA as some other cells in a mitotically active tissue. The cell in question is most likely in a. anaphase. b. metaphase. c. prophase. d. G2. e. G1.

e

A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism? a. Tt b. Hh c. tt d. HhTt e. HT

e

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. anchorage-dependent inhibition. b. density-independent inhibition. c. anchorage independence. d. growth factor inhibition. e. density-dependent inhibition.

e

Asexual reproduction and sexual reproduction are different in that a. individuals reproducing asexually transmit 100% of their genes to their progeny (offspring), whereas individuals reproducing sexually only transmit 50%. b. asexual reproduction produces offspring that are genetically identical to the parents, whereas sexual reproduction gives rise to genetically distinct offspring. c. asexual reproduction involves a single parent, whereas sexual reproduction involves two. d. asexual reproduction only requires mitosis, whereas sexual reproduction always involves meiosis. e. All of the choices are correct.

e

Black eyes are dominant to orange eyes, and green skin in dominant to white skin, Sam, a MendAlien with black eyes and green skin, has a parent with orange eyes and white skin. Carole is MendAlien with orange eyes and white skin. If Sam and Carole were to mate, the predicted ratio of their offspring would be: a. There is insufficient information to determine Sam's genotype. b. 3 black eyes, green skin: 3 black eyes, white skin: 9 orange eyes, green skin: 1 orange eyes, white skin c. 9 black eyes, green skin: 3 black eyes, white skin: 3 orange eyes, green skin: 1 orange eyes, white skin d. 1 black eyes, green skin: 3 black eyes, white skin: 3 orange eyes, green skin: 9 orange eyes, white skin e. 1 black eyes, green skin: 1 black eyes, white skin: 1 orange eyes, green skin: 1 orange eyes, white skin

e

Meiosis II is similar to mitosis in that a. the chromosome number is reduces. b. homologous chromosomes synapse. c. the daughter cells are diploid. d. DNA replicates before the division. e. sister chromatids separate during anaphase.

e

One difference between cancer cells and normal cells is that cancer cells a. are unable to synthesize DNA. b. are arrested at the S phase of the cell cycle. c. cannot function properly because they are affected by density-dependent inhibition. d. are always in the M phase of the cell cycle. e. continue to divide even when they are tightly packed together

e

People with sickle-cell trait a. are heterozygous for the sickle-cell allele. b. produce normal and abnormal hemoglobin. c. are usually healthy. d. have increased resistance to malaria. e. All of the choices are correct.

e

Tallness (T) is dominant to dwarfness (t), while red (R) flower color is dominant to white (r). The heterozygous condition results in pink (Rr) flower color. A dwarf, red snapdragon is crossed with a plant homozygous for tallness and white flowers. What are the genotype and phenotype of the F1 individuals? a. ttRr - dwarf and pink b. TTRR - tall and red c. TtRr - tall and red d. ttrr - dwarf and white e. TtRr - tall and pink

e

The immediate product of meiosis in a plant is a a. zygote b. gamete. c. gametophyte. d. sporophyte. e. spore.

e

Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely a. an animal cell in the process of cytokinesis. b. an animal cell in metaphase. c. a bacterial cell dividing. d. a plant cell in metaphase. e. a plant cell in the process of cytokinesis.

e

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 traints constitute a pair of a. heterologous chromosomes. b. sister chromatids. c. None of the choices are correct. d. complementary chromosomes. e. homologous chromosomes.

e

What is a genome? a. a specialized polymer of four different kinds of monomers. b. a specific segment of DNA that is found within a prokaryotic chromosome. c. an ordered display of chromosomes arranged from largest to smallest. d. a specific sequence of polypeptides within each cell. e. the complete complement of an organism's genes

e

What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants? a. Genes are composed of DNA. b. An organism that is homozygous for many recessive traits is at a disadvantage. c. There is considerable genetic variation in garden peas. d. Recessive genes occur more frequently in the F1 than do dominant ones. e. Traits are inherited in discrete units, and are not the results of "blending."

e

When a disease is said to have a multifactorial basis, it means that a. it tends to skip a generation. b. it has many different symptoms. c. it affects a large number of people. d. it is caused by a gene with a large number of alleles. e. many factors, both genetic and environmental, contribute to the disease.

e

Which of the following is the term for a human cell that contains 22 pairs of autosomes and two X chromosomes? a. a male somatic cell b. an unfertilized egg cell c. a sperm cell d. an unfertilized egg cell and a female somatic cell e. a female somatic cell

e