fund cell bio exam 2 prac. questions

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

d. undergo a sexual reproductive cycle that involves an alternation of haploid cells

with the generation of diploid cells

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.

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.

a. Sexual reproduction permits enhanced survival because the gametes that carry

alleles enhancing survival in harsh environments are used preferentially during

fertilization.

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.

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

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.

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.

n the absence of recombination, how many genetically different types of gametes

can an organism with five homologous chromosome pairs produce?

a. 5

b. 10

c. 32

d. 64

c. 32

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.

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

cell divisions.

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.

b. chiasmata hold chromosomes together.

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.

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

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.

(a) Unlike E. coli, budding yeast can alternate between a diploid state and a haploid state.

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.

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

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.

(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.

Which of the following statements is TRUE?

A) Because endocrine signals are broadcast throughout the body, all cells will

respond to the hormonal signal.

B) The regulation of inflammatory responses at the site of an infection is an example

of paracrine signaling.

C) Paracrine signaling involves the secretion of signals into the bloodstream for

distribution throughout the organism.

D) The axons of neurons typically signal target cells using membrane-bound

signaling molecules that act on receptors in the target cells.

B) The regulation of inflammatory responses at the site of an infection is an example of paracrine signaling.

Which of the following statements is TRUE?

A) Extracellular signal molecules that are hydrophilic must bind to a cell-surface

receptor so as to signal a target cell to change its behavior.

B) To function, all extracellular signal molecules must be transported by their

receptor across the plasma membrane into the cytosol.

C) A cell-surface receptor capable of binding only one type of signal molecule can

mediate only one kind of cell response.

D) Any foreign substance that binds to a receptor for a normal signal molecule will

always induce the same response that is produced by that signal molecule on the

same cell type

A) Extracellular signal molecules that are hydrophilic must bind to a cell-surface

receptor so as to signal a target cell to change its behavior.

The following happens when a G-protein-coupled receptor activates a G protein.

A) The β subunit exchanges its bound GDP for GTP.

B) The GDP bound to the α subunit is phosphorylated to form bound GTP.

C) The α subunit exchanges its bound GDP for GTP.

D) It activates the α subunit and inactivates the βγ complex

C) The α subunit exchanges its bound GDP for GTP.

You are interested in cell-size regulation and discover that signaling through a GPCR

called ERC1 is important in controlling cell size in embryonic rat cells. The G protein

downstream of ERC1 activates adenylyl cyclase, which ultimately leads to the activation

of PKA. You discover that cells that lack ERC1 are 15% smaller than normal cells, while

cells that express a mutant, constitutively activated version of PKA are 15% larger than

normal cells. Given these results, which of the following treatments to embryonic rat

cells should lead to smaller cells?

A) addition of a drug that causes cyclic AMP phosphodiesterase to be hyperactive

B) addition of a drug that prevents GTP hydrolysis by Gα

C) addition of a drug that activates adenylyl cyclase

D) addition of a drug that mimics the ligand of ERC1

A) addition of a drug that causes cyclic AMP phosphodiesterase to be hyperactive

The local mediator nitric oxide stimulates the intracellular enzyme guanylyl cyclase by

A) activating a G protein.

B) activating a receptor tyrosine kinase.

C) diffusing into cells and stimulating the cyclase directly.

D) activating an intracellular protein kinase

C) diffusing into cells and stimulating the cyclase directly.

The growth factor Superchick stimulates the proliferation of cultured chicken cells.

The receptor that binds Superchick is a receptor tyrosine kinase (RTK), and many

chicken tumor cell lines have mutations in the gene that encodes this receptor. Which of

the following types of mutation would be expected to promote uncontrolled cell

proliferation?

A) a mutation that prevents dimerization of the receptor

B) a mutation that destroys the kinase activity of the receptor

C) a mutation that inactivates the protein tyrosine phosphatase that normally

removes the phosphates from tyrosines on the activated receptor

D) a mutation that prevents the binding of the normal extracellular signal to the

receptor

C) a mutation that inactivates the protein tyrosine phosphatase that normally

removes the phosphates from tyrosines on the activated receptor

A protein kinase can act as an integrating device in signaling if it

A) phosphorylates more than one substrate.

B) catalyzes its own phosphorylation.

C) is activated by two or more proteins in different signaling pathways.

D) initiates a phosphorylation cascade involving two or more protein kinases.

C) is activated by two or more proteins in different signaling pathways

Which of the following statements is TRUE?

A) MAP kinase is important for phosphorylating MAP kinase kinase.

B) PI 3-kinase phosphorylates a lipid in the plasma membrane.

C) Ras becomes activated when an RTK phosphorylates its bound GDP to create GTP.

D) Dimerization of GPCRs leads to Gα activation.

B) PI 3-kinase phosphorylates a lipid in the plasma membrane.

When Ras is activated, cells will divide. A dominant-negative form of Ras clings too

tightly to GDP. You introduce a dominant-negative form of Ras into cells that also have a

normal version of Ras. Which of the following statements is TRUE?

A) The cells you create will divide less frequently than normal cells in response to

the extracellular signals that typically activate Ras.

B) The cells you create will run out of the GTP necessary to activate Ras.

C) The cells you create will divide more frequently compared to normal cells in

response to the extracellular signals that typically activate Ras.

D) The normal Ras in the cells you create will not be able to bind GDP because the

dominant-negative Ras binds to GDP too tightly.

A) The cells you create will divide less frequently than normal cells in response to

the extracellular signals that typically activate Ras.

The lab you work in has discovered a previously unidentified extracellular signal

molecule called QGF, a 75,000 -dalton protein. You add purified QGF to different types

of cells to determine its effect on these cells. When you add QGF to heart muscle cells,

you observe an increase in cell contraction. When you add it to fibroblasts, they

undergo cell division. When you add it to nerve cells, they die. When you add it to glial

cells, you do not see any effect on cell division or survival. Given these observations,

which of the following statements is most likely to be TRUE?

A) Because it acts on so many diverse cell types, QGF probably diffuses across the

plasma membrane into the cytoplasm of these cells.

B) Glial cells do not have a receptor for QGF.

C) QGF activates different intracellular signaling pathways in heart muscle cells,

fibroblasts, and nerve cells to produce the different responses observed.

D) Heart muscle cells, fibroblasts, and nerve cells must all have the same receptor

for QGF

B) Glial cells do not have a receptor for QGF.

Which of the following statements about the cytoskeleton is FALSE?

a. The cytoskeleton is made up of three types of protein filaments.

b. The cytoskeleton controls the location of organelles in eukaryotic cells.

c. Covalent bonds between protein monomers hold together cytoskeletal filaments.

d. The cytoskeleton of a cell can change in response to the environment.

c. Covalent bonds between protein monomers hold together cytoskeletal filaments.

Intermediate filaments help protect animal cells from mechanical stress because

filaments

a. directly extend from the interior of the cell to the extracellular space and into the

next cell, linking one cell to the next, helping to distribute locally applied forces.

b. in each cell are indirectly connected to the filaments of a neighboring cell through

the desmosome, creating a continuous mechanical link between cells.

c. remain independent of other cytoskeletal elements and keep the mechanical

stress away from other cellular components.

d. make up the desmosome junctions that connect cells; these junctions are more

important than the internal network of filaments for protecting cells against

mechanical stress.

b. in each cell are indirectly connected to the filaments of a neighboring cell through

the desmosome, creating a continuous mechanical link between cells.

Keratins, neurofilaments, and vimentins are all categories of intermediate filaments.

Which of the following properties is not true of these types of intermediate filaments?

a. They strengthen cells against mechanical stress.

b. Dimers associate by noncovalent bonding to form a tetramer.

c. They are found in the cytoplasm.

d. Phosphorylation causes disassembly during every mitotic cycle.

d. Phosphorylation causes disassembly during every mitotic cycle.

Which of the following statements about the structure of microtubules is FALSE?

a. Microtubules are built from protofilaments that come together to make a hollow

structure.

b. The two ends of a protofilament are chemically distinct, with α-tubulin exposed at

one end and β-tubulin exposed at the other end.

c. Within a microtubule, all protofilaments are arranged in the same orientation,

giving the microtubule structural polarity.

d. α-Tubulin and β-tubulin are covalently bound to make the tubulin dimer that then

assembles into protofilaments.

d. α-Tubulin and β-tubulin are covalently bound to make the tubulin dimer that then

assembles into protofilaments.

The microtubules in a cell form a structural framework that can have all the following

functions except which one?

a. holding internal organelles such as the Golgi apparatus in particular positions in

the cell

b. creating long, thin cytoplasmic extensions that protrude from one side of the cell

c. strengthening the plasma membrane

d. moving materials from one place to another inside a cell

c. strengthening the plasma membrane

Which of the following statements regarding dynamic instability is FALSE?

a. Each microtubule filament grows and shrinks independently of its neighbors.

b. The GTP cap helps protect a growing microtubule from depolymerization.

c. GTP hydrolysis by the tubulin dimer promotes microtubule shrinking.

d. The newly freed tubulin dimers from a shrinking microtubule can be immediately

captured by growing microtubules and added to their plus end.

d. The newly freed tubulin dimers from a shrinking microtubule can be immediately

captured by growing microtubules and added to their plus end.

Which of the following statements about organellar movement in the cell is FALSE?

a. Organelles undergo saltatory movement in the cell.

b. Only the microtubule cytoskeleton is involved in organellar movement.

c. Motor proteins involved in organellar movement use ATP hydrolysis for energy.

d. Organelles are attached to the tail domain of motor proteins.

b. Only the microtubule cytoskeleton is involved in organellar movement.

Which of the following statements about the movement of materials in a nerve axon is

TRUE?

a. Movement along microtubules in the axon is slower than free diffusion, but

necessary due to the importance of directional transport.

b. The small jerky steps seen when vesicles move along microtubules are due to

the shrinkage of microtubules that occurs when axonal microtubules undergo

dynamic instability.

c. Microtubules within an axon are arranged such that all microtubules point in the

same direction with their minus ends toward the nerve cell body.

d. Microtubules within the axon support the unidirectional motion of materials from

the nerve cell body to the axon terminal, while materials transported back from

the axon terminal to the cell body move along intermediate filaments.

c. Microtubules within an axon are arranged such that all microtubules point in the

same direction with their minus ends toward the nerve cell body.

Which of the following items is not important for flagellar movement?

a. sarcoplasmic reticulum

b. ATP

c. Dynein

d. Microtubules

a. sarcoplasmic reticulum

For both actin and microtubule polymerization, nucleotide hydrolysis is important for

a. stabilizing the filaments once they are formed.

b. increasing the rate at which subunits are added to the filaments.

c. promoting nucleation of filaments.

d. decreasing the binding strength between subunits on filaments.

d. decreasing the binding strength between subunits on filaments.

Which of the following events does NOT usually occur during interphase?

a. Cells grow in size.

b. The nuclear envelope breaks down.

c. DNA is replicated.

d. The centrosomes are duplicated.

b. The nuclear envelope breaks down.

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 G1 and S

b. when cells enter G0

c. during M

d. at the end of G2

d. at the end of G2

Which of the following statements about the cell cycle is FALSE?

a. Once a cell decides to enter the cell cycle, the time from start to finish is the

same in all eukaryotic cells.

b. An unfavorable environment can cause cells to arrest in G1.

c. A cell has more DNA during G2 than it did in G1.

d. The cleavage divisions that occur in an early embryo have short G1 and G2

phases.

a. Once a cell decides to enter the cell cycle, the time from start to finish is the

same in all eukaryotic cells.

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 be unable to enter M phase.

b. The cell would be unable to enter G2.

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

d. The cell would pass through M phase more slowly than normal cells.

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

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.

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