CB Exam 4

(Q024) The plasmodesmata in plants are functionally most similar to which animal cell junction? a. gap junction b. tight junction c. desmosome d. adherens junction

a. gap junction

(Q014) Tight junctions a. allow small, water-soluble molecules to pass from cell to cell. b. are formed from claudins and occludins. c. interact with the intermediate filaments inside the cell. d. are found in cells in connective tissues.

b. are formed from claudins and occludins.

(Q014) A diploid cell containing 32 chromosomes will make a haploid cell containing __________ a. 16 b. 8 c. 64 d. 30

a. 16

(Q044) Which of the following statements about apoptosis is TRUE? a. Apoptosis can be promoted by the release of cytochrome c into the cytosol from mitochondria. b. The prodomain of procaspases contains the catalytic activity necessary for procaspase activation. c. Bax and Bak promote apoptosis by binding to procaspases in the apoptosome. d. Cells that constitutively express Bcl2 will be more prone to undergo apoptosis.

a. Apoptosis can be promoted by the release of cytochrome c into the cytosol from mitochondria.

Q013) Which of the following statements most correctly describes meiosis? a. Meiosis involves a single round of DNA replication followed by two successive cell divisions. b. Meiosis involves a single round of DNA replication followed by four successive cell divisions. c. Meiosis involves four rounds of DNA replication followed by two successive cell divisions. d. Meiosis involves two rounds of DNA replication followed by a single cell division.

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

Q017) Hemidesmosomes are important for a. attaching epithelial cells to the extracellular matrix. b. forming the basal lamina. c. tubulation of epithelial sheets. d. linkages to glycosaminoglycans.

a. attaching epithelial cells to the extracellular matrix.

(Q027) An adult hemopoietic stem cell found in the bone marrow a. can undergo self-renewing divisions for the lifetime of a healthy animal. b. will express all the same transcription factors as those found in an unfertilized egg. c. will occasionally produce epidermal cells when necessary. d. can produce only red blood cells.

a. can undergo self-renewing divisions for the lifetime of a healthy animal.

(Q043) Apoptosis differs from necrosis in that necrosis a. causes cells to swell and burst, whereas apoptotic cells shrink and condense. b. involves a caspase cascade. c. requires the reception of an extracellular signal. d. causes DNA to fragment.

a. causes cells to swell and burst, whereas apoptotic cells shrink and condense.

(Q019) A cell that is terminally differentiated will a. dismantle the cell-cycle control system. b. reenter the cell cycle only once a year. c. arrest after S phase. d. replicate its DNA.

a. dismantle the cell-cycle control system.

(Q006) During sexual reproduction, novel mixtures of alleles are generated. This is because a. during meiosis, the segregation of homologs is random such that different gametes end up with different alleles of each gene. b. in all diploid species, two alleles exist for every gene. c. a diploid individual has two different alleles for every gene. d. every gamete produced by a diploid individual has several different alleles of a single gene.

a. during meiosis, the segregation of homologs is random such that different gametes end up with different alleles of each gene.

(Q016) At desmosomes, cadherin molecules are connected to a. intermediate filaments. b. actin filaments. c. gap junctions. d. microtubules.

a. intermediate filaments.

(Q021) Kinesins and dyneins a. often move in opposite directions to each other. b. move along both microtubules and actin filaments. c. have tails that bind to the filaments. d. derive their energy from GTP hydrolysis.

a. often move in opposite directions to each other.

Q026) When a terminally differentiated cell in an adult body dies, it can typically be replaced in the body by a stock of a. proliferating precursor cells. b. Wnt proteins. c. cells more apically located than the terminally differentiated cells. d. induced pluripotent cells.

a. proliferating precursor cells.

(Q001) Both multicellular plants and animals have a. tissues composed of multiple different cell types. b. cells with cell walls. c. a cytoskeleton composed of actin filaments, microtubules, and intermediate filaments. d. cells capable of locomotion.

a. tissues composed of multiple different cell types.

(Q030) Which letter is associated with the line that is pointing to the interpolar microtubules in Figure 18-29? a. B b. E c. D d. A e. C

b. E

(Q003) Which of the following statements is FALSE? a. Asexual reproduction typically gives rise to offspring that are genetically identical. b. Mutations in somatic cells are passed on to individuals of the next generation. c. Sexual reproduction allows for a wide variety of gene combinations. d. Gametes are specialized sex cells.

b. Mutations in somatic cells are passed on to individuals of the next generation.

(Q002) Which of the following statements about plant cell walls is TRUE? a. Because plant cell walls are rigid, they are not deposited until the cell has stopped growing. b. The microtubule cytoskeleton directs the orientation in which cellulose is deposited in the cell wall. c. The cellulose found in cell walls is produced as a precursor molecule in the cell and delivered to the extracellular space by exocytosis. d. The molecular components of the cell wall are the same in all plant tissues.

b. The microtubule cytoskeleton directs the orientation in which cellulose is deposited in the cell wall.

(Q034) A metastasis is a. a part of the primary tumor that has invaded the surrounding tissue. b. a secondary tumor in a different part of the body that arises from a cell from the primary tumor. c. the portion of the cancerous tumor that displays genetic instability. d. a cell that is dividing in defiance of normal constraints.

b. a secondary tumor in a different part of the body that arises from a cell from the primary tumor.

(Q031) Loss-of-function mutations a. cause the production of proteins that are active in inappropriate circumstances. b. are usually recessive. c. will usually show a phenotype when heterozygous. d. are only present in a population at barely detectable levels.

b. are usually recessive.

(Q018) After the first meiotic cell division, a. the number of chromosomes will vary depending on how the paternal and maternal chromosomes align at the metaphase plate. b. cells are produced that contain the same number of chromosomes as somatic cells. c. two haploid gametes are produced. d. DNA replication occurs

b. cells are produced that contain the same number of chromosomes as somatic cells.

(Q025) At the end of DNA replication, the sister chromatids are held together by the a. histones. b. cohesins. c. kinetochores. d. securins.

b. cohesins.

(Q018) Cells in the G0 state a. have entered this arrest state from either G1 or G2. b. do not divide. c. cannot reenter the cell cycle. d. have duplicated their DNA.

b. do not divide.

Mitogens are a. kinases that cause cells to grow in size. b. extracellular signals that stimulate cell division. c. transcription factors important for cyclin production. d. produced by mitotic cells to keep nearby neighboring cells from dividing.

b. extracellular signals that stimulate cell division.

(Q016) The Retinoblastoma (Rb) protein blocks cells from entering the cell cycle by a. marking cyclins for destruction by proteolysis. b. inhibiting cyclin transcription. c. activating apoptosis. d. phosphorylating Cdk.

b. inhibiting cyclin transcription.

(Q013) A basal lamina a. is attached to the apical surface of an epithelium. b. is a thin layer of extracellular matrix underlying an epithelium. c. is a thin layer of connective-tissue cells and matrix underlying an epithelium. d. separates epithelial cells from each other.

b. is a thin layer of extracellular matrix underlying an epithelium.

(Q033) A malignant tumor is more dangerous than a benign tumor because a. it causes neighboring cells to mutate. b. its cells invade other tissues. c. its cells are proliferating faster. d. its cells attack and phagocytose neighboring normal tissue cells.

b. its cells invade other tissues.

(Q034) Which of the following structures shorten during muscle contraction? a. myosin filaments b. sarcomeres c. actin filaments d. flagella

b. sarcomeres

(Q031) The artificial introduction of three key __________ into an adult cell can convert the adult cell into a cell with the properties of ES cells. a. viruses b. transcription factors c. chromosomes d. hormones

b. transcription factors

(Q007) Which of the following does not describe a situation of asexual reproduction? a. using a part of a plant to create a new independent plant b. using in vitro fertilization to combine a sperm and an egg to create an embryo c. a bacterium multiplying by simple cell division d. the parthenogenetic development of eggs produced by some species of lizards

b. using in vitro fertilization to combine a sperm and an egg to create an embryo

(Q002) Which of the following statements about the cytoskeleton is TRUE? a. The three cytoskeletal filaments perform distinct tasks in the cell and act completely independently of one another. b. All eukaryotic cells have actin, microtubules, and intermediate filaments in their cytoplasm. c. Actin filaments and microtubules have an inherent polarity, with a plus end that grows more quickly than the minus end. d. The cytoskeleton provides a rigid and unchangeable structure important for the shape of the cell.

c. Actin filaments and microtubules have an inherent polarity, with a plus end that grows more quickly than the minus end.

(Q030) Which of the following reasons was essential for Mendel's law of independent assortment? a. Mendel observed chromosomal segregation in pea-plant cells. b. Mendel carried out his experiments on plants and not on fungi. c. All the traits that Mendel examined involved genes that did not display linkage. d. Several of the phenotypes that Mendel examined involved color.

c. All the traits that Mendel examined involved genes that did not display linkage.

Q002) Which of the following statements is TRUE? a. All sexually reproducing organisms must have two copies of every chromosome. b. Gametes have only one chromosome. c. Another name for the fertilized egg cell is the zygote. d. Diploid organisms reproduce only sexually.

c. Another name for the fertilized egg cell is the zygote.

(Q016) Which of the following statements about meiosis is TRUE? a. Meiosis produces four genetically identical cells. b. In general, meiosis is faster than mitosis. c. During meiosis, the paternal chromosomes pair with the maternal chromosomes before lining up at the metaphase plate. d. Unicellular organisms that have a haploid state undergo meiosis instead of mitosis during cell division.

c. During meiosis, the paternal chromosomes pair with the maternal chromosomes before lining up at the metaphase plate.

(Q006) Which of the following descriptions is consistent with the behavior of a cell that lacks a protein required for a checkpoint mechanism that operates in G2? a. The cell would pass through M phase more slowly than normal cells. b. The cell would be unable to enter M phase. c. The cell would enter M phase under conditions when normal cells would not. d. The cell would be unable to enter G2.

c. The cell would enter M phase under conditions when normal cells would not.

Programmed cell death occurs a. only during embryonic development. b. rarely and selectively only during animal development. c. by means of an intracellular suicide program. d. only in unhealthy or abnormal cells.

c. by means of an intracellular suicide program.

(Q017) During recombination a. the synaptonemal complex keeps the sister chromatids together until anaphase II. b. sister chromatids undergo crossing-over with each other. c. chiasmata hold chromosomes together. d. one crossover event occurs for each pair of human chromosomes.

c. chiasmata hold chromosomes together.

(Q003) Which of the following molecules is NOT found in plants? a. lignin b. cellulose c. collagen d. pectin

c. collagen

(Q029) Mouse embryonic stem (ES) cells a. can only be grown in the laboratory. b. can give rise to all tissues and cell types in the body except germ cells. c. come from the inner cell mass of early embryos. d. can be made in the lab from human iPS cells.

c. come from the inner cell mass of early embryos.

(Q008) Levels of Cdk activity change during the cell cycle, in part because a. Cdk degradation precedes entry into the next phase of the cell cycle. b. the Cdks phosphorylate each other. c. cyclin activity change during the cycle. d. the Cdks activate the cyclins.

c. cyclin activity change during the cycle.

(Q023) Which of the following does not occur during M phase in animal cells? a. breakdown of nuclear envelope b. condensation of chromosomes c. growth of the cell d. attachment of chromosomes to microtubules

c. growth of the cell

(Q025) Figure 19-24 diagrams one of Mendel's experiments using the round and wrinkled seed traits. If you crossed the round-seeded plants obtained in the F1 generation with a true-breeding strain of round-seeded plants, how many wrinkle-seeded plants would you expect to obtain in the next generation? a. 25% b. 75% c. none d. all

c. none

(Q008) Fibroblasts organize the collagen of the extracellular matrix by a. processing procollagen into collagen. b. twisting fibrils together to make ropelike fibers. c. pulling the collagen into sheets or cables after it has been secreted. d. cutting and rejoining the fibrils.

c. pulling the collagen into sheets or cables after it has been secreted.

(Q007) Progression through the cell cycle requires a cyclin to bind to a Cdk because a. cyclin binding inhibits Cdk activity until the appropriate time in the cell cycle. b. without cyclin binding, a cell-cycle checkpoint will be activated. c. the binding of a cyclin to Cdk is required for Cdk enzymatic activity. d. the cyclins are the molecules with the enzymatic activity in the complex.

c. the binding of a cyclin to Cdk is required for Cdk enzymatic activity.

(Q026) Figure 19-24 diagrams one of Mendel's experiments using the round and wrinkled seed traits. If you crossed the round-seeded plants obtained in the F1 generation with a true-breeding strain of wrinkle-seeded plants, how many round-seeded plants would you expect to obtain in the next generation? a. 25% b. 75% c. 100% d. 50%

d. 50%

(Q004) Which of the following statements about cellulose is FALSE? a. The sugar monomers necessary for the synthesis of a cellulose polymer are transported across the plasma membrane. b. Cellulose synthase enzyme complexes are integral membrane proteins. c. An array of microtubules guides the cellulose synthase complex as it moves in the membrane. d. Microtubules are directly attached to the outside surface of the plasma membrane to form tracks that help orient the cellulose polymers.

d. Microtubules are directly attached to the outside surface of the plasma membrane to form tracks that help orient the cellulose polymers.

(Q001) What would be the most obvious outcome of repeated cell cycles consisting of S phase and M phase only? a. The cells would not be able to replicate their DNA. b. The mitotic spindle could not assemble. c. The cells would get larger and larger. d. The cells produced would get smaller and smaller.

d. The cells produced would get smaller and smaller.

(Q026) Which of the following statements is TRUE? a. The contractile ring is made largely of microtubules and actin filaments. b. The contractile ring divides the nucleus in two. c. The mitotic spindle is largely made of intermediate filaments. d. The mitotic spindle helps segregate the chromosomes to the two daughter cells.

d. The mitotic spindle helps segregate the chromosomes to the two daughter cells.

(Q009) The formation of a bivalent during meiosis ensures that a. one chromatid from the mother and one chromatid from the father will segregate together during meiosis I. b. recombination will occur between identical sister chromatids. c. the sex chromosomes, which are not identical, will line up separately at the metaphase plate during meiosis I. d. all four sister chromatids remain together until the cell is ready to divide.

d. all four sister chromatids remain together until the cell is ready to divide.

(Q004) In which phase of the cell cycle do cells check to determine whether the DNA is fully and correctly replicated? a. during M b. when cells enter G0 c. at the transition between G1 and S d. at the end of G2

d. at the end of G2

(Q030) Induced pluripotent stem (iPS) cells a. can differentiate into a greater variety of adult tissues than embryonic stem cells. b. require a supply of donor egg cells, as is the case for embryonic stem cells. c. have been used to create human clones. d. can be created by the expression of a set of key genes in most somatic cell types, including cells derived from adult tissues.

d. can be created by the expression of a set of key genes in most somatic cell types, including cells derived from adult tissues.

(Q028) A pluripotent cell a. is considered to be terminally differentiated. b. can only be produced in the laboratory. c. can only give rise to stem cells. d. can give rise to all the tissues and cell types in the body.

d. can give rise to all the tissues and cell types in the body.

(Q025) Cells that are terminally differentiated a. no longer produce RNAs. b. are unable to move. c. will undergo apoptosis within a few days. d. can no longer undergo cell division.

d. can no longer undergo cell division.

(Q028) The principal microtubule-organizing center in animal cells is the a. centromere. b. kinetochore. c. cell cortex. d. centrosome.

d. centrosome.

(Q009) The concentration of mitotic cyclin (M cyclin) a. is highest in G1 phase. b. is activated by phosphorylation. c. rises markedly during M phase. d. falls toward the end of M phase as a result of ubiquitylation and degradation

d. falls toward the end of M phase as a result of ubiquitylation and degradation

(Q004) Somatic cells __________. a. are not necessary for sexual reproduction in all eukaryotic organisms. b. are used to produce germ-line cells when organisms reach sexual maturity c. do not contain sex chromosomes. d. leave no progeny.

d. leave no progeny.

(Q029) Which word or phrase below best describes the phase in mitosis depicted in Figure 18-29? a. prometaphase b. anaphase c. S-phase checkpoint d. metaphase

d. metaphase

(Q023) Plasmodesmata a. are found only in animal cells. b. provide tensile strength. c. are closed by the neurotransmitter dopamine. d. permit small molecules to pass from one cell to another.

d. permit small molecules to pass from one cell to another.

(Q038) Ras is a GTP-binding protein that is often defective in cancer cells. A common mutation found in cancer cells causes Ras to behave as though it were bound to GTP all the time, which will cause cells to divide inappropriately. From this description, the normal Ras gene is a/an a. gain-of-function mutation. b. tumor suppressor. c. oncogene. d. proto-oncogene.

d. proto-oncogene.

(Q027) Sister chromatid separation occurs because __________ are destroyed by the APC/C. a. condensins b. kinetochores c. cohesins d. securins

d. securins

(Q001) Organisms that reproduce sexually a. create zygotes that are genetically identical to each other. b. can reproduce only with a partner that carries the same alleles. c. must be haploid, unlike organisms that reproduce asexually. d. undergo a sexual reproductive cycle that involves an alternation of haploid cells with the generation of diploid cells.

d. undergo a sexual reproductive cycle that involves an alternation of haploid cells with the generation of diploid cells.