Which of the following molecules is not found in plants?

Which of the following molecules is not found in plants?

(a) cellulose
(b) lignin
(c) collagen
(d) pectin

Answer: 

Which of the following statements about plant cell walls is true?

Which of the following statements about plant cell walls is true?

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

Answer: 

Both multicellular plants and animals have _______.

Both multicellular plants and animals have _______.

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

Answer: 

Finding co-inheritance of a SNP variant and a disease tells scientists that _________.

Finding co-inheritance of a SNP variant and a disease tells scientists that _________.

(a) everybody who carries this SNP will get the disease.
(b) sequences within the SNP cause the disease.
(c) a gene important for causing the disease is linked to the SNP.
(d) SNPs on other chromosomes will not be co-inherited with the disease.

Answer: 

Which of the following statements about genome-wide association studies (GWAS) is false?

Which of the following statements about genome-wide association studies (GWAS) is false?

(a) GWAS use SNPs to compare populations of people with disease and people without disease to look for SNPs more likely to be present in those with disease.
(b) GWAS can be used even if more than one gene can cause the disease of interest.
(c) Sometimes GWAS will identify SNPs that are associated with a disease but these SNPs do not affect the gene product of the gene that causes the disease.
(d) Studies using GWAS only examine SNPs that occur very rarely (<0.001%) in the population, as those SNPs are most likely to cause disease.

Answer: 

The single-nucleotide polymorphisms found in the human population ____.

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 blocks.
(d) arose mainly during the past 10,000 years.

Answer: 

Haplotype blocks can be seen in humans because _______.

Haplotype blocks can be seen in humans because _______.

(a) disease genes are found in haplotype blocks.
(b) modern humans descended from a relatively small population of about 10,000 individuals that existed about two thousand generations ago.
(c) some of our human ancestors interbred with Neanderthals.
(d) new mutations cannot be introduced into existing haplotype blocks.

Answer: 

Loss-of-function mutations _____.

Loss-of-function mutations _____.

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

Answer: 

Which of the following reasons was essential for Mendel's law of independent assortment?

Which of the following reasons was essential for Mendel's law of independent assortment?

(a) All the traits that Mendel examined involved genes that did not display linkage.
(b) Several of the phenotypes that Mendel examined involved color.
(c) Mendel observed chromosomal segregation in pea-plant cells.
(d) Mendel carried out his experiments on plants and not on fungi.

Answer: 

Which of the following reasons was essential for Mendel to disprove the theory of blended inheritance?

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.

Answer: 

Which of the following statements about the experiment diagrammed in Figure Q19-38 is true?

Which of the following statements about the experiment diagrammed in Figure Q19-38 is true?

(a) If you crossed all the round-seeded pea plants from the F2 generation with true-breeding wrinkle-seeded pea plants, you would get more round-seeded pea plants in the next generation than if you crossed all the round-seeded pea plants from the F1 generation with true-breeding wrinkle-seeded pea plants.
(b) The reason you do not see wrinkle-seeded pea plants in the F1 generation is because the round-seeded pea plants used to create the F1 generation were not true-breeding strains.
(c) The gene for round-seeded pea plants is on a different chromosome from the gene for wrinkle-seeded pea plants, which is why you get 25% wrinkle-seeded pea plants in the F2 generation.
(d) If you crossed the round-seeded pea plants from the F2 generation with the wrinkle-seeded pea plants from the F2 generation, you should get 100% round-seeded pea plants.

Answer: 

Which of the following statements about the round-seeded pea plants obtained in the F2 generation is false?

Which of the following statements about the round-seeded pea plants obtained in the F2 generation is false?

(a) These plants are phenotypically identical for seed shape.
(b) Two-thirds of these plants are expected to be heterozygous for the seed-shape allele.
(c) We expect 25% of these plants to be homozygous for the seed-shape allele.
(d) If these plants were crossed to wrinkle-seeded plants, some of these plants would produce only round-seeded plants.

Answer: 

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?

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) 50%
(c) 75%
(d) 100%

Answer: 

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?

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) none
(b) 25%
(c) 75%
(d) all

Answer: 

Which of the following could be considered a true-breeding strain for the seed-shape phenotype?

Which of the following could be considered a true-breeding strain for the seed-shape phenotype?

(a) all of the round-seeded plants produced in the F2 generation
(b) all of the wrinkle-seeded plants produced in the F2 generation
(c) all of the round-seeded plants produced in the F1 generation
(d) half of the round-seeded plants produced in the F2 generation

Answer: 

Which of the following statements about Mendel's experiments is false?

Which of the following statements about Mendel's experiments is false?

(a) The pea plants could undergo both cross-fertilization and self-fertilization.
(b) The true-breeding strains were homozygous for the traits that Mendel examined.
(c) The egg can carry either the allele from the maternal or the paternal chromosome.
(d) All traits that Mendel studied were recessive.

Answer: 

During fertilization in humans, _____.

During fertilization in humans, _____.

(a) a wave of Ca2+ ions is released in the fertilized egg's cytoplasm.
(b) only one sperm binds to the unfertilized egg.
(c) a sperm moves in a random fashion until it encounters an egg.
(d) several sperm pronuclei compete in the cytoplasm to fuse with the egg nucleus.

Answer: 

A single nondisjunction event during meiosis ______.

A single nondisjunction event during meiosis ______.

(a) will block recombination.
(b) will occur only during meiosis II.
(c) cannot occur with sex chromosomes.
(d) will involve the production of two normal gametes if it occurs during meiosis II.

Answer: 

Which of the following would not lead to aneuploidy during meiosis?

Which of the following would not lead to aneuploidy during meiosis?

(a) sister chromatids segregating inappropriately
(b) non-sister chromatids segregating inappropriately
(c) a reciprocal rearrangement of parts between nonhomologous chromosomes (for example, the left arm of Chromosome 2 exchanging places with the right arm of Chromosome 3)
(d) an extra set of chromosomes produced during S phase (for example, if paternal Chromosome 3 were replicated twice)

Answer: 

In mammals, there are two sex chromosomes, X and Y, which behave like homologous chromosomes during meiosis. Normal males have one X chromosome and one Y chromosome, and normal females have two X chromosomes. Males with an extra Y chromosome (XYY) are found occasionally. Which of the following could give rise to such an XYY male? Explain your answer.

In mammals, there are two sex chromosomes, X and Y, which behave like homologous chromosomes during meiosis. Normal males have one X chromosome and one Y chromosome, and normal females have two X chromosomes. Males with an extra Y chromosome (XYY) are found occasionally. Which of the following could give rise to such an XYY male? Explain your answer.

(a) nondisjunction in the first meiotic division of spermatogenesis; normal meiosis in the mother
(b) nondisjunction in the second meiotic division of spermatogenesis; normal meiosis in the mother
(c) nondisjunction in the first meiotic division of oogenesis; normal meiosis in the father
(d) nondisjunction in the second meiotic division of oogenesis; normal meiosis in the father

Answer: 

After the first meiotic cell division _______.

After the first meiotic cell division _______.

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

Answer: 

During recombination ______.

During recombination ______.

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


Answer: B

Which of the following statements about meiosis is true?

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.

Answer: 

You examine a worm that has two genders: males that produce sperm and hermaphrodites that produce both sperm and eggs. The diploid adult has four homologous pairs of chromosomes that undergo very little recombination. Given a choice, the hermaphrodites prefer to mate with males, but just to annoy the worm, you pluck a hermaphrodite out of the wild and fertilize its eggs with its own sperm. Assuming that all the resulting offspring are viable, what fraction do you expect to be genetically identical to the parent worm? Assume that each chromosome in the original hermaphrodite is genetically distinct from its homolog.

You examine a worm that has two genders: males that produce sperm and hermaphrodites that produce both sperm and eggs. The diploid adult has four homologous pairs of chromosomes that undergo very little recombination. Given a choice, the hermaphrodites prefer to mate with males, but just to annoy the worm, you pluck a hermaphrodite out of the wild and fertilize its eggs with its own sperm. Assuming that all the resulting offspring are viable, what fraction do you expect to be genetically identical to the parent worm? Assume that each chromosome in the original hermaphrodite is genetically distinct from its homolog.

(a) all
(b) none
(c) 1/16
(d) 1/256

Answer: 

A diploid cell containing 32 chromosomes will make a haploid cell containing ___ chromosomes.

A diploid cell containing 32 chromosomes will make a haploid cell containing ___ chromosomes.

(a) 8
(b) 16
(c) 30
(d) 64

Answer: 

Which of the following statements most correctly describes meiosis?

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.

Answer: 

In the absence of recombination, how many genetically different types of gamete can an organism with five homologous chromosome pairs produce?

In the absence of recombination, how many genetically different types of gamete can an organism with five homologous chromosome pairs produce?

(a) 5
(b) 10
(c) 32
(d) 64

Answer: 

There are organisms that go through meiosis but do not undergo recombination when forming haploid gametes. Which of the following statements correctly describes the gametes produced by such an organism. (Assume that these organisms are diploid, that each of the two homologous chromosomes are genetically distinct as typically found in the wild, and that these organisms have more than one chromosome.)

There are organisms that go through meiosis but do not undergo recombination when forming haploid gametes. Which of the following statements correctly describes the gametes produced by such an organism. (Assume that these organisms are diploid, that each of the two homologous chromosomes are genetically distinct as typically found in the wild, and that these organisms have more than one chromosome.)

(a) All gametes formed during a single meiosis will be identical.
(b) Due to the random assortment of homologs, each of the gametes formed during a single meiosis will be different.
(c) This organism could potentially produce 2n genetically distinct gametes, where n is its haploid number of chromosomes.
(d) The fusion of any two gametes produced by such an organism that does not undergo recombination during meiosis will create a cell that is genetically identical to that individual.

Answer: 

Imagine meiosis in a diploid organism that only has a single chromosome. Like most diploid organisms, it received one copy of this chromosome from each of its parents and the two homologs are genetically distinct. If only a single homologous recombination event occurs during meiosis, which of the following choices below correctly describes the four gametes formed.

Imagine meiosis in a diploid organism that only has a single chromosome. Like most diploid organisms, it received one copy of this chromosome from each of its parents and the two homologs are genetically distinct. If only a single homologous recombination event occurs during meiosis, which of the following choices below correctly describes the four gametes formed.

(a) None of the gametes will contain chromosomes identical to the chromosomes found in the original diploid cell.
(b) All four of the gametes will have chromosomes identical to the chromosomes found in the original diploid cell.
(c) Three of the gametes will have chromosomes identical to the chromosomes found in the original diploid cell, while one of the gametes will have chromosomes that are different.
(d) Two of the gametes will have chromosomes identical to the chromosomes found in the original diploid cell, while two of the gametes will have chromosomes that are different.

Answer: 

The formation of a bivalent during meiosis ensures that _______.

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.

Answer: 

Both budding yeast and the bacteria E. coli are unicellular life. Which of the following statements explains why budding yeast can undergo sexual reproduction while E. coli cannot.

Both budding yeast and the bacteria E. coli are unicellular life. Which of the following statements explains why budding yeast can undergo sexual reproduction while E. coli cannot.

(a) Unlike E. coli, budding yeast can alternate between a diploid state and a haploid state.
(b) Unlike E. coli, budding yeast cannot multiply by undergoing cell division.
(c) Unlike E. coli, haploid budding yeast cells can undergo meiosis to produce the gametes necessary for sexual reproduction.
(d) E. coli DNA is unable to undergo homologous recombination, making it incapable of producing gametes.

Answer: 

Which of the following does not describe a situation of asexual reproduction?

Which of the following does not describe a situation of asexual reproduction?

(a) A bacterium multiplying by simple cell division.
(b) Using a part of a plant to create a new independent plant.
(c) Using in vitro fertilization to combine a sperm and an egg to create an embryo.
(d) The parthenogenetic development of eggs produced by some species of lizards.

Answer: 

During sexual reproduction, novel mixtures of alleles are generated. This is because ______.

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.

Answer: 

Which of the following statements about the benefits of sexual reproduction is false?

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.

Answer: 

Somatic cells ____.

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.

Answer: 

Which of the following statements is false?

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.

Answer: 

Which of the following statements is true?

Which of the following statements is true?

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

Answer: 

Organisms that reproduce sexually _________.

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.

Answer: 

Which of the following statements about apoptosis is true?

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.

Answer: 

Apoptosis differs from necrosis in that necrosis ________________.

Apoptosis differs from necrosis 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.

Answer: 

Programmed cell death occurs ________________.

Programmed cell death occurs ________________.

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

Answer: 

Which organelle fragments during mitosis?

Which organelle fragments during mitosis?

(a) endoplasmic reticulum
(b) Golgi apparatus
(c) mitochondrion
(d) chloroplast

Answer: 

Which of the following statements is false?

Which of the following statements is false?

(a) Cytokinesis in plant cells is mediated by the microtubule cytoskeleton.
(b) Small membrane vesicles derived from the Golgi apparatus deliver new cell-wall material for the new wall of the dividing cell.
(c) The phragmoplast forms from the remains of interpolar microtubules of the mitotic spindle.
(d) Motor proteins walking along the cytoskeleton are important for the contractile ring that guides formation of the new cell wall.

Answer: 

Which of the following statements is false?

Which of the following statements is false?

(a) The cleavage furrow is a puckering of the plasma membrane caused by the constriction of a ring of filaments attached to the plasma membrane.
(b) The cleavage furrow will not begin to form in the absence of a mitotic spindle.
(c) The cleavage furrow always forms perpendicular to the interpolar microtubules.
(d) The cleavage furrow always forms in the middle of the cell.

Answer: 

Cytokinesis in animal cells ________________.

Cytokinesis in animal cells ________________.

(a) requires ATP.
(b) leaves a small circular "scar" of actin filaments on the inner surface of the plasma membrane.
(c) is often followed by phosphorylation of integrins in the plasma membrane.
(d) is assisted by motor proteins that pull on microtubules attached to the cell cortex.

Answer: 

A cell with nuclear lamins that cannot be phosphorylated in M phase will be unable to ________________.

A cell with nuclear lamins that cannot be phosphorylated in M phase will be unable to ________________.

(a) reassemble its nuclear envelope at telophase.
(b) disassemble its nuclear lamina at prometaphase.
(c) begin to assemble a mitotic spindle.
(d) condense its chromosomes at prophase.

Answer: 

Which of the following precede the re-formation of the nuclear envelope during M phase in animal cells?

Which of the following precede the re-formation of the nuclear envelope during M phase in animal cells?

(a) assembly of the contractile ring
(b) decondensation of chromosomes
(c) reassembly of the nuclear lamina
(d) transcription of nuclear genes

Answer: 

When introduced into mitotic cells, which of the following is expected to impair anaphase B but not anaphase A?

When introduced into mitotic cells, which of the following is expected to impair anaphase B but not anaphase A?

(a) an antibody against myosin
(b) ATP?S, a nonhydrolyzable ATP analog that binds to and inhibits ATPases
(c) an antibody against the motor proteins that move from the plus end of microtubules to the minus end
(d) an antibody against the motor proteins that move from the minus end of microtubules toward the plus end

Answer: 

Which of the following statements is true?

Which of the following statements is true?

(a) Anaphase A must be completed before anaphase B can take place.
(b) In cells in which anaphase B predominates, the spindle will elongate much less than in cells in which anaphase A dominates.
(c) In anaphase A, both kinetochore and interpolar microtubules shorten.
(d) In anaphase B, microtubules associated with the cell cortex shorten.

Answer: 

Which of the following statements about the anaphase-promoting complex (APC) is false?

Which of the following statements about the anaphase-promoting complex (APC) is false?

(a) It promotes the degradation of proteins that regulate M phase.
(b) It inhibits M-Cdk activity.
(c) It is continuously active throughout the cell cycle.
(d) M-Cdk stimulates its activity.

Answer: 

A friend declares that chromosomes are held at the metaphase plate by microtubules that push on each chromosome from opposite sides. Which of the following observations does not support your belief that the microtubules are pulling on the chromosomes?

A friend declares that chromosomes are held at the metaphase plate by microtubules that push on each chromosome from opposite sides. Which of the following observations does not support your belief that the microtubules are pulling on the chromosomes?

(a) the jiggling movement of chromosomes at the metaphase plate
(b) the way in which chromosomes behave when the attachment between sister chromatids is severed
(c) the way in which chromosomes behave when the attachment to one kinetochore is severed
(d) the shape of chromosomes as they move toward the spindle poles at anaphase

Answer: 

Which of the following statements about kinetochores is true?

Which of the following statements about kinetochores is true?

(a) Kinetochores assemble onto chromosomes during late prophase.
(b) Kinetochores contain DNA-binding proteins that recognize sequences at the telomere of the chromosome.
(c) Kinetochore proteins bind to the tubulin molecules at the minus end of microtubules.
(d) Kinetochores assemble on chromosomes that lack centromeres.

Answer: 

Disassembly of the nuclear envelope ________________.

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.

Answer: 

The principal microtubule-organizing center in animal cells is the ____________.

The principal microtubule-organizing center in animal cells is the ____________.

(a) centrosome.
(b) centromere.
(c) kinetochore.
(d) cell cortex.

Answer: 

Which of the following statements is true?

Which of the following statements is true?

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

Answer: 

At the end of DNA replication, the sister chromatids are held together by the ___________.

At the end of DNA replication, the sister chromatids are held together by the ___________.

(a) kinetochores.
(b) securins.
(c) cohesins.
(d) histones.


Answer: 

Condensins ________________.

Condensins ________________.

(a) are degraded when cells enter M phase.
(b) assemble into complexes on the DNA when phosphorylated by M-Cdk.
(c) are involved in holding sister chromatids together.
(d) bind to DNA before DNA replication begins.

Answer: