Second half of Test 3

48)Which of the following statements about cancer is false? (a)Viruses cause some cancers. (b)Tobacco use is responsible for more than 20% of all cancer deaths. (c)A mutation in even a single cancer-critical gene is sufficient to convert a normal cell into a cancer cell. (d)Chemical carcinogens cause cancer by changing the nucleotide sequence of DNA

A mutation in even a single cancer-critical gene is sufficient to convert a normal cell into a cancer cell.

49)Which of the following genetic changes cannot convert a proto-oncogene into an oncogene? (a)A mutation that introduces a stop codon immediately after the codon for the initiator methionine. (b)A mutation within the coding sequence that makes the protein hyperactive. (c)An amplification of the number of copies of the proto-oncogene, causing overproduction of the normal protein. (d) A mutation in the promo ter of the proto-oncogene, causing the normal protein to be transcribed and translated at an abnormally high level.

A mutation that introduces a stop codon immediately after the codon for the initiator methionine.

32) Which of the following statements about apoptosis is true? (a)Cells that constitutively express Bcl2 will be more prone to undergo apoptosis. (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) Apoptosis is promoted by the release of cytochrome c into the cytosol from mitochondria.

Apoptosis is promoted by the release of cytochrome c into the cytosol from mitochondria.

50) Which of the following statements about tumor suppressor genes is false? (a)Gene amplification of a tumor suppressor gene is less dangerous than gene amplification of a proto-oncogene. (b)Cells with one functional copy of a tumor suppressor gene will usually proliferate faster than normal cells. (c)Inactivation of tumor suppressor genes leads to enhanced cell survival and proliferation. (d)Individuals with only one functional copy of a tumor suppressor gene are more prone to cancer than individuals with two functional copies of a tumor suppressor gene

Cells with one functional copy of a tumor suppressor gene will usually proliferate faster than normal cells.

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

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

25) Which of the following events does notusually occur during interphase? (a)Cells grow in size. (b)The nuclear envelope breaks down. (c)DNA is replicated. (d)The centrosomes are duplicated.

The nuclear envelope breaks down.

38) Which of the following statements most correctly describes meiosis? (a)Meiosis involves two rounds of DNA replication followed by a single cell division. (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 a single round of DNA replication followed by two successive cell divisions.

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

35) Which of the following statements about the benefits of sexual reproduction is false? (a) Sexual reproduction permits enhanced survival because the gametes that carry alleles enhancing survival in harsh environments are used preferentially during fertilization. (b)Unicellular organisms that can undergo sexual reproduction have an increased ability to adapt to harsh environments. (c)Sexual reproduction reshuffles genes, which is thought to help species survive in novel or varying environments. (d)Sexual reproduction can speed the elimination of deleterious alleles.

Sexual reproduction permits enhanced survival because the gametes that carry alleles enhancing survival in harsh environments are used preferentially during fertilization.

40) Which of the following reasons was essential for Mendel to disprove the theory of blended inheritance? (a)The traits that Mendel examined all involved genes that did not display linkage. (b)The traits that Mendel examined all involved the reproductive structures of the pea plant. (c)Mendel pioneered techniques permitting the fusion of male and female gametes from the same plant to produce a zygote. (d) The traits that Mendel examined involved an allele that was dominant and an allele that was recessive.

The traits that Mendel examined involved an allele that was dominant and an allele that was recessive.

37) 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)all four sister chromatids remain together until the cell is ready to divide. (c)recombination will occur between identical sister chromatids. (d)the sex chromosomes, which are not identical, will line up separately at the metaphase plate during meiosis I.

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

47) Induced pluripotent stem (iPS) cells ______________________. (a)are created by the expression of a set of key genes in cells derived from adult tissues so that these cells can differentiate into a variety of cell types (b)require a supply of donor egg cells, such as embryonic stem cells (c)can differentiate into a greater variety of adult tissues than embryonic stem cells (d)are created by nuclear transplantation

are created by the expression of a set of key genes in cells derived from adult tissues so that these cells can differentiate into a variety of cell types

26) In which phase of the cell cycle do cells check to determine whether the DNA is fully and correctly replicated? (a) at the transition between G1and S (b)when cells enter G0 (c)during M (d)at the end of G2

at the end of G2

41) The single-nucleotide polymorphisms found in the human population __________________. (a)are important for genetic mapping because they represent mutations in genes important for human disease (b)are rarely found among blood relatives (c)can be linked into haplotype b locks (d)arose mainly during the past 10,000 years

can be linked into haplotype b locks

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

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

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

can no longer undergo cell division

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

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

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

centrosome

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

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

28) The concentration of mitotic cyclin (M cyclin) ________________. (a)rises markedly during M phase (b)is activated by phosphorylation (c)falls toward the end of M phase as a result of ubiquitylation and degradation (d)is highest in G 1phase

falls toward the end of M phase as a result

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

is a thin layer of extracellular matrix underlying an epithelium

34) 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)leave no progeny (d)do not contain sex chromosomes

leave no progeny

30) Disassembly of the nuclear envelope ________________. (a)causes the inner nuclear membrane to separate from the outer nuclear membrane (b)results in the conversion of the nuclear envelope into protein-free membrane vesicles (c)is triggered by the phosphorylation of integrins (d) must occur for kinetochore microtubules to form in animal cells

must occur for kinetochore microtubules to form in animal cells

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

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

44) A major distinction between the connective tissues in an animal and other main tissue types such as epithelium, nervous tissue, or muscle is _______________. (a)the ability of connective tissue cells such as fibroblasts to change shape (b)the amount of extracellular matrix in connective tissues (c)the ability of connective tissues to withstand mechanical stresses (d)the numerous connections that connective- tissue cells make with each other

the amount of extracellular matrix in connective tissues

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

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

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

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