Test 2 Practice Questions
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) G1. B) anaphase. C) metaphase. D) G2. E) prophase.
a
During which phase of mitosis do the chromatids become chromosomes? A) telophase B) anaphase C) prophase D) metaphase E) cytokinesis
a
How is natural selection related to sexual reproduction as opposed to asexual reproduction? A) Sexual reproduction results in many new gene combinations, some of which will lead to differential reproduction. B) Sexual reproduction utilizes far less energy than asexual reproduction. C) Sexual reproduction allows the greatest number of offspring to be produced. D) Sexual reproduction results in the most appropriate and healthiest balance of two sexes in the population. E) Sexual reproduction results in the greatest number of new mutations.
a
If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis? A) 10 B) 20 C) 30 D) 40 E) 80
a
If there are 20 chromatids in a cell, how many centromeres are there? A) 10 B) 20 C) 30 D) 40 E) 80
a
Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3 to 6 picograms per nucleus. In which stage of the cell cycle did the nucleus contain 6 picograms of DNA? A) G2 B) M C) G1 D) G0 E) S
a
Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol disrupts microtubule formation by binding to microtubules and accelerating their assembly from the protein precursor, tubulin. Surprisingly, this stops mitosis. Specifically, Taxol must affect A) the formation of the mitotic spindle. B) anaphase. C) formation of the centrioles. D) chromatid assembly. E) the S phase of the cell cycle.
a
The MPF protein complex turns itself off by A) activating a process that destroys cyclin components. B) activating an enzyme that stimulates cyclin. C) binding to chromatin. D) exiting the cell. E) activating the anaphase-promoting complex.
a
The centromere is a region in which A) chromatids remain attached to one another until anaphase. B) metaphase chromosomes become aligned at the metaphase plate. C) chromosomes are grouped during telophase. D) the nucleus is located prior to mitosis. E) new spindle microtubules form at either end.
a
The evolution of eukaryotic cells most likely involved A) endosymbiosis of an aerobic bacterium in a larger host cell-the endosymbiont evolved into mitochondria. B) an endosymbiotic fungal cell evolved into the nucleus. C) anaerobic archaea taking up residence inside a larger bacterial host cell to escape toxic oxygen-the anaerobic bacterium evolved into chloroplasts. D) acquisition of an endomembrane system, and subsequent evolution of mitochondria from a portion of the Golgi.
a
The muscles of a recently deceased human can remain in a contracted state, termedrigor mortis, for several hours, due to the lack of A) ATP needed to break actin-myosin bonds. B) phosphorylated myosin. C) calcium ions needed to bind to troponin. D) oxygen supplies needed for myoglobin. E) sodium ions needed to fire action potentials.
a
Which of the following does not occur during mitosis? A) replication of the DNA B) separation of sister chromatids C) spindle formation D) condensation of the chromosomes E) separation of the spindle poles
a
Which of the following is released by platelets in the vicinity of an injury? A) PDGF B) MPF C) protein kinase D) cyclin E) Cdk
a
Which of the following is true of a species that has a chromosome number of 2n = 16? A) Each cell has eight homologous pairs. B) A gamete from this species has four chromosomes. C) The species has 16 sets of chromosomes per cell. D) The species is diploid with 32 chromosomes per cell. E) During the S phase of the cell cycle there will be 32 separate chromosomes.
a
Which of the following types of molecules are the major structural components of the cell membrane? A) phospholipids and proteins B) proteins and cellulose C) nucleic acids and proteins D) phospholipids and cellulose E) glycoproteins and cholesterol
a
A cell with a predominance of free ribosomes is most likely A) enlarging its vacuole. B) producing primarily cytoplasmic proteins. C) producing primarily proteins for secretion. D) constructing an extensive cell wall or extracellular matrix. E) digesting large food particles.
b
All of the following are part of a prokaryotic cell except... A) a cell wall. B) an endoplasmic reticulum. C) ribosomes. D) a plasma membrane. E) DNA.
b
A plant-derived protein known as colchicine can be used to poison cells by blocking the formation of the spindle. Which of the following would result if colchicine is added to a sample of cells in G2? A) The cells would immediately die. B) The cells would be unable to begin M and stay in G2. C) The chromosomes would coil and shorten but have no spindle to which to attach. D) The chromosomes would segregate but in a disorderly pattern. E) Each resultant daughter cell would also be unable to form a spindle.
c
Eukaryotic sexual life cycles show tremendous variation. Of the following elements, which do all sexual life cycles have in common? I. Alternation of generations II. Meiosis III. Fertilization IV. Gametes V. Spores A) I, II, and IV B) I, IV, and V C) II, III, and IV D) I, II, III, IV, and V E) II, IV, and V
c
A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. How many picograms would be found at the end of S and the end of G2? A) 8; 8 B) 8; 16 C) 16; 8 D) 16; 16 E) 12; 16
d
For a species with a haploid number of 23 chromosomes, how many different combinations of maternal and paternal chromosomes are possible for the gametes? A) 460 B) 46 C) 23 D) about 8 million E) 920
d
If cells in the process of dividing are subjected to colchicine, a drug that interferes with the formation of the spindle apparatus, at which stage will mitosis be arrested? A) anaphase B) prophase C) telophase D) metaphase E) interphase
d
In which group of eukaryotic organisms does the nuclear envelope remain intact during mitosis? A) seedless plants B) dinoflagellates C) diatoms D) dinoflagellates and diatoms only E) seedless plants, dinoflagellates, and diatoms
d
Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3 to 6 picograms per nucleus. In which stage of the cell cycle did the nucleus contain 6 picograms of DNA? A) G0 B) G1 C) S D) G2 E) M
d
Movement of the chromosomes during anaphase would be most affected by a drug that A) increases cyclin concentrations. B) reduces cyclin concentrations. C) prevents elongation of microtubules. D) prevents shortening of microtubules. E) prevents attachment of the microtubules to the kinetochore.
d
Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells? A) 4 B) 8 C) 16 D) 32 E) 64
d
Suppose a biologist can separate one of a dozen pieces of chromatin from a eukaryotic (animal) nucleus. It might consist of which of the following? A) one-twelfth of the genes of the organism B) two chromosomes, each with six chromatids C) a single circular piece of DNA D) two long strands of DNA plus proteins E) two chromatids attached together at a centromere
d
Using which of the following techniques would enable your lab group to distinguish between a cell in G2 and a cell from the same organism in G1? A) fluorescence microscopy B) electron microscopy C) spectrophotometry D) radioactive-labeled nucleotides E) labeled kinetochore proteins
d
What causes the decrease in the amount of cyclin at a specific point in the cell cycle? A) an increase in production once the restriction point is passed B) the cascade of increased production once its protein is phosphorylated by Cdk C) the changing ratio of cytoplasm to genome D) its destruction by a process initiated by the activity of its complex with a cyclin E) the binding of PDGF to receptors on the cell surface
d
What is the most likely pathway taken by a newly synthesized protein that will be secreted by a cell? A) Golgi →ER →lysosome B) nucleus →ER →Golgi C) ER →lysosomes →vesicles that fuse with plasma membrane D) ER →Golgi →vesicles that fuse with plasma membrane E) ER → Golgi → nucleus
d
Cells can be described as having a cytoskeleton of internal structures that contribute to the shape, organization, and movement of the cell. Which of the following are part of the cytoskeleton? A) the nuclear envelope B) mitochondria C) microfilaments D) lysosomes E) nucleoli
A
Cyanide binds with at least one molecule involved in producing ATP. If a cell is exposed to cyanide, most of the cyanide would be found within the A) mitochondria. B) ribosomes. C) peroxisomes. D) lysosomes. E) endoplasmic reticulum.
A
Of the following, which cell structure would most likely be visible with a light microscope that has been manufactured to the maximum resolving power possible? A) mitochondrion B) microtubule C) ribosome D) largest microfilament E) nuclear pore
A
Recent evidence shows that the extracellular matrix can take part in regulating the expression of genes. A likely possibility for this might be which of the following? A) Mechanical signals of the ECM can alter the cytoskeleton, which can alter intracellular signaling. B) Intracellular signals might cause changes in the fibronectin binding to the cell surface. C) Orientation of microfilaments to the ECM can change the gene activity. D) Fibronectin binds to integrins built into the plasma membrane. E) Proteoglycans in the ECM become large enough in aggregate to force genetic alteration.
A
The fact that the outer membrane of the nuclear envelope has bound ribosomes allows one to most reliably conclude that A) at least some of the proteins that function in the nuclear envelope are made by the ribosomes on the nuclear envelope. B) the nuclear envelope is not part of the endomembrane system. C) the nuclear envelope is physically continuous with the endoplasmic reticulum. D) small vesicles from the Golgi fuse with the nuclear envelope. E) nuclear pore complexes contain proteins.
A
The mitochondrion, like the nucleus, has two or more membrane layers. How is the innermost of these layers different from that of the nucleus? A) The inner mitochondrial membrane is highly folded. B) The two membranes are biochemically very different. C) The space between the two layers of the nuclear membrane is larger. D) The inner membrane of the mitochondrion is separated out into thylakoids. E) The inner mitochondrial membrane is devoid of nearly all proteins.
A
Which of the following are capable of converting light energy to chemical energy? A) chloroplasts B) mitochondria C) leucoplasts D) peroxisomes E) Golgi bodies
A
Which of the following contains hydrolytic enzymes? A) lysosome B) vacuole C) mitochondrion D) Golgi apparatus E) peroxisome
A
Which of the following possesses a microtubular structure similar to a basal body? A) centriole B) lysosome C) nucleolus D) peroxisome E) ribosome
A
Which structure is the site of the synthesis of proteins that may be exported from the cell? A) rough ER B) lysosomes C) plasmodesmata D) Golgi vesicles E) tight junctions
A
Grana, thylakoids, and stroma are all components found in A) vacuoles. B) chloroplasts. C) mitochondria. D) lysosomes. E) nuclei.
B
In animal cells, hydrolytic enzymes are packaged to prevent general destruction of cellular components. Which of the following organelles functions in this compartmentalization? A) chloroplast B) lysosome C) central vacuole D) peroxisome E) glyoxysome
B
In the fractionation of homogenized cells using centrifugation, the primary factor that determines whether a specific cellular component ends up in the supernatant or the pellet is A) the relative solubility of the component. B) the size and weight of the component. C) the percentage of carbohydrates in the component. D) the number of enzymes in the fraction. E) the presence or absence of lipids in the component.
B
The liver is involved in detoxification of many poisons and drugs. Which of the following structures is primarily involved in this process and therefore abundant in liver cells? A) rough ER B) smooth ER C) Golgi apparatus D) Nuclear envelope E) Transport vesicles
B
Tubulin is a dimer, made up of 2 slightly different polypeptides, alpha and beta. Given the structure above, what is the most likely consequence to the structure of the microtubule? A) One "half-pipe" side of the tubule must be heavier in alpha and the other in beta subunits. B) One end of a microtubule can grow or release dimers at a faster rate than the other. C) Microtubules grow by adding a complete circular layer at a time rather than spiraling. D) Microtubules in cilia must never grow or become shorter. E) Tubulin molecules themselves must be rigid structures.
B
Under which of the following conditions would you expect to find a cell with a predominance of free ribosomes? A) a cell that is secreting proteins B) a cell that is producing cytoplasmic enzymes C) a cell that is constructing its cell wall or extracellular matrix D) a cell that is digesting food particles E) a cell that is enlarging its vacuole
B
Which of the following is a compartment that often takes up much of the volume of a plant cell? A) lysosome B) vacuole C) mitochondrion D) Golgi apparatus E) peroxisome
B
Which of the following is present in a prokaryotic cell? A) mitochondrion B) ribosome C) nuclear envelope D) chloroplast E) ER
B
Which of the following makes it necessary for animal cells, although they have no cell walls, to have intercellular junctions? A) Cell membranes do not distinguish the types of ions and molecules passing through them. B) Large molecules, especially proteins, do not readily get through one, much less two adjacent cell membranes. C) Cell-to-cell communication requires physical attachment of one cell to another. D) Maintenance of connective tissue shape requires cells to adhere to one another. E) The relative shapelessness of animal cells requires a mechanism for keeping the cells aligned.
B
Which of the following relationships between cell structures and their respective functions is correct? A) cell wall: support, protection B) chloroplasts: chief sites of cellular respiration C) chromosomes: cytoskeleton of the nucleus D) ribosomes: secretion E) lysosomes: formation of ATP
B
Which structure is not part of the endomembrane system? A) nuclear envelope B) chloroplast C) Golgi apparatus D) plasma membrane E) ER
B
Why is it important to know what microscopy method was used to prepare the images you wish to study? A) so that you can judge whether the images you are seeing are of cells or of organelles B) so that you can make a judgment about the likelihood of artifacts having been introduced in the preparation C) so that you can decide whether the image is actually of the size described D) so that you can know whether to view the image in color or not E) so that you can interpret the correct biochemical process that is occurring
B
Why isn't the mitochondrion classified as part of the endomembrane system? A) It only has two membrane layers. B) Its structure is not derived from the ER. C) It has too many vesicles. D) It is not involved in protein synthesis. E) It is not attached to the outer nuclear envelope.
B
A newspaper ad for a local toy store indicates that a very inexpensive microscope available for a small child is able to magnify specimens nearly as much as the much more costly microscope available in your college lab. What is the primary reason for the price difference? A) The ad agency is misrepresenting the ability of the toy microscope to magnify. B) The toy microscope does not have the same fine control for focus of the specimen. C) The toy microscope magnifies a good deal, but has low resolution and therefore poor quality images. D) The college microscope produces greater contrast in the specimens. E) The toy microscope usually uses a different wavelength of light source.
C
All of the following serve an important role in determining or maintaining the structure of plant cells. Which of the following are distinct from the others in their composition? A) microtubules B) microfilaments C) plant cell walls D) intermediate filaments E) nuclear lamina
C
If a modern electron microscope (TEM) can resolve biological images to the nanometer level, as opposed to the best light microscope, this is due to which of the following? A) The focal length of the electron microscope is significantly longer. B) Contrast is enhanced by staining with atoms of heavy metal. C) Electron beams have much shorter wavelengths than visible light. D) The electron microscope has much greater ratio of image size to real size. E) The electron microscope cannot image whole cells at one time.
C
Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules? A) lipids B) starches C) proteins D) steroids E) glucose
C
Of the following molecules of the ECM, which is capable of transmitting signals between the ECM and the cytoskeleton? A) fibronectin B) proteoglycans C) integrins D) collagen E) middle lamella
C
Plasmodesmata in plant cells are most similar in function to which of the following structures in animal cells? A) peroxisomes B) desmosomes C) gap junctions D) extracellular matrix E) tight junctions
C
Tay-Sachs disease is a human genetic abnormality that results in cells accumulating and becoming clogged with very large and complex lipids. Which cellular organelle must be involved in this condition? A) the endoplasmic reticulum B) the Golgi apparatus C) the lysosome D) mitochondria E) membrane-bound ribosomes
C
The advantage of light microscopy over electron microscopy is that A) light microscopy provides for higher magnification than electron microscopy. B) light microscopy provides for higher resolving power than electron microscopy. C) light microscopy allows one to view dynamic processes in living cells. D) A and B E) B and C
C
The difference in lipid and protein composition between the membranes of the endomembrane system is largely determined by A) the physical separation of most membranes from each other. B) the transportation of membrane among the endomembrane system by small membrane vesicles. C) the function of the Golgi apparatus in sorting membrane components. D) the modification of the membrane components once they reach their final destination. E) the synthesis of lipids and proteins in each of the organelles of the endomembrane system.
C
The nuclear lamina is an array of filaments on the inner side of the nuclear membrane. If a method were found that could cause the lamina to fall into disarray, what would you expect to be the most likely consequence? A) the loss of all nuclear function B) the inability of the cell to withstand enzymatic digestion C) a change in the shape of the nucleus D) failure of chromosomes to carry genetic information E) inability of the nucleus to keep out destructive chemicals
C
The volume enclosed by the plasma membrane of plant cells is often much larger than the corresponding volume in animal cells. The most reasonable explanation for this observation is that A) plant cells are capable of having a much higher surface-to-volume ratio than animal cells. B) plant cells have a much more highly convoluted (folded) plasma membrane than animal cells. C) plant cells contain a large vacuole that reduces the volume of the cytoplasm. D) animal cells are more spherical, while plant cells are elongated. E) the basic functions of plant cells are very different from those of animal cells.
C
When a potassium ion (K+) moves from the soil into the vacuole of a cell on the surface of a root, it must pass through several cellular structures. Which of the following correctly describes the order in which these structures will be encountered by the ion? A) plasma membrane → primary cell wall → cytoplasm → tonoplast B) secondary cell wall → plasma membrane → primary cell wall → cytoplasm → tonoplast C) primary cell wall → plasma membrane → cytoplasm → tonoplast D) primary cell wall → plasma membrane → tonoplast → cytoplasm → vacuole E) tonoplast → primary cell wall → plasma membrane → cytoplasm
C
When biologists wish to study the internal ultrastructure of cells, they most likely would use A) a light microscope. B) a scanning electron microscope. C) a transmission electronic microscope. D) A and B E) B and C
C
Which cell would be best for studying lysosomes? A) muscle cell B) nerve cell C) phagocytic white blood cell D) leaf cell of a plant E) bacterial cell
C
Which is one of the main energy transformers of cells? A) lysosome B) vacuole C) mitochondrion D) Golgi apparatus E) peroxisome
C
Which of the following contains its own DNA and ribosomes? A) lysosome B) vacuole C) mitochondrion D) Golgi apparatus E) peroxisome
C
Which of the following statements about the cytoskeleton is true? A) The dynamic aspect of cytoskeletal function is made possible by the assembly and disassembly of a large number of complex proteins into larger aggregates. B) Microfilaments are structurally rigid and resist compression, while microtubules resist tension (stretching). C) Movement of cilia and flagella is the result of motor proteins causing microtubules to move relative to each other. D) Chemicals that block the assembly of the cytoskeleton would cause little effect on the cell's metabolism E) Transport vesicles among the membranes of the endomembrane system produce the cytoskeleton.
C
Which of the following statements correctly describes some aspect of protein disposal from prokaryotic cells? A) Prokaryotes are unlikely to be able to excrete proteins because they lack an endomembrane system. B) The mechanism of protein excretion in prokaryotes is probably the same as that in eukaryotes. C) Proteins that are excreted by prokaryotes are synthesized on ribosomes that are bound to the cytoplasmic surface of the plasma membrane. D) In prokaryotes, the ribosomes that are used for the synthesis of secreted proteins are located outside of the cell. E) Prokaryotes contain large pores in their plasma membrane that permit the movement of proteins out of the cell.
C
Which statement correctly characterizes bound ribosomes? A) Bound ribosomes are enclosed in their own membrane. B) Bound and free ribosomes are structurally different. C) Bound ribosomes generally synthesize membrane proteins and secretory proteins. D) The most common location for bound ribosomes is the cytoplasmic surface of the plasma membrane. E) All of the above.
C
Which type of organelle is primarily involved in the synthesis of oils, phospholipids, and steroids? A) ribosome B) lysosome C) smooth endoplasmic reticulum D) mitochondrion E) contractile vacuole
C
A biologist ground up some plant leaf cells and then centrifuged the mixture to fractionate the organelles. Organelles in one of the heavier fractions could produce ATP in the light, while organelles in the lighter fraction could produce ATP in the dark. The heavier and lighter fractions are most likely to contain, respectively, A) mitochondria and chloroplasts. B) chloroplasts and peroxisomes. C) peroxisomes and chloroplasts. D) chloroplasts and mitochondria. E) mitochondria and peroxisomes.
D
A cell has the following molecules and structures: enzymes, DNA, ribosomes, plasma membrane, and mitochondria. It could be a cell from A) a bacterium. B) an animal, but not a plant. C) a plant, but not an animal. D) a plant or an animal. E) any kind of organism.
D
A cell lacking the ability to make and secrete glycoproteins would most likely be deficient in its A) nuclear DNA. B) extracellular matrix. C) Golgi apparatus. D) B and C only E) A, B, and C
D
A primary objective of cell fractionation is to A) view the structure of cell membranes. B) identify the enzymes outside the organelles. C) determine the size of various organelles. D) separate the major organelles so that their particular functions can be determined. E) crack the cell wall so the cytoplasmic contents can be released.
D
Cells of the pancreas will incorporate radioactively labeled amino acids into proteins. This "tagging" of newly synthesized proteins enables a researcher to track their location. In this case, we are tracking an enzyme secreted by pancreatic cells. What is its most likely pathway? A) ER → Golgi → nucleus B) Golgi → ER → lysosome C) nucleus → ER → Golgi D) ER → Golgi → vesicles that fuse with plasma membrane E) ER → lysosomes → vesicles that fuse with plasma membrane
D
Cells require which of the following to form cilia or flagella? A) centrosomes B) ribosomes C) actin D) A and B only E) A, B, and C
D
How does the cell multiply its peroxisomes? A) They bud off from the ER. B) They are brought into the cell from the environment. C) They are built de novo from cytosol materials. D) They split in two after they are too large. E) The cell synthesizes hydrogen peroxide and encloses it in a membrane.
D
If an individual has abnormal microtubules, due to a hereditary condition, in which organs or tissues would you expect dysfunction? A) limbs, hearts, areas with a good deal of contraction B) microvilli, alveoli, and glomeruli C) all ducts, such as those from salivary or sebaceous glands D) sperm, larynx, and trachea E) egg cells (ova), uterus, and kidneys
D
Motor proteins provide for molecular motion in cells by interacting with what types of cellular structures? A) sites of energy production in cellular respiration B) membrane proteins C) ribosomes D) cytoskeletons E) cellulose fibers in the cell wall
D
Organelles other than the nucleus that contain DNA include A) ribosomes. B) mitochondria. C) chloroplasts. D) B and C only E) A, B, and C
D
Quantum dots are small (15—30 nm diameter), bright particles visible using light microscopy. If the dots can be specifically bound to individual proteins on a plasma membrane of a cell, which of the following correctly describes the advantage of using quantum dots in examining proteins? A) The dots permit the position of the proteins to be determined more precisely. B) The dots permit the average distance between the proteins to be determined more precisely. C) The dots permit the size of the proteins to be determined more precisely. D) The dots permit the motion of the proteins to be determined more precisely. E) The dots permit visualization of proteins interacting with lipids.
D
The cell walls of bacteria, fungi, and plant cells and the extracellular matrix of animal cells are all external to the plasma membrane. Which of the following is a characteristic of all of these extracellular structures? A) They must block water and small molecules in order to regulate the exchange of matter and energy with their environment. B) They must permit information transfer between the cell's cytoplasm and the nucleus. C) They must provide a rigid structure that maintains an appropriate ratio of cell surface area to volume. D) They are constructed of materials that are largely synthesized in the cytoplasm and then transported out of the cell. E) They are composed of a mixture of lipids and carbohydrates.
D
The chemical reactions involved in respiration are virtually identical between prokaryotic and eukaryotic cells. In eukaryotic cells, ATP is synthesized primarily on the inner membrane of the mitochondria. Where are the corresponding reactions likely to occur in prokaryotic respiration? A) in the cytoplasm B) on the inner mitochondrial membrane C) on the endoplasmic reticulum D) on the inner plasma membrane E) on the inner nuclear envelope
D
The extracellular matrix is thought to participate in the regulation of animal cell behavior by communicating information from the outside to the inside of the cell via which of the following? A) gap junctions B) the nucleus C) DNA and RNA D) integrins E) plasmodesmata
D
The peroxisome gets its name from its interaction with hydrogen peroxide. If a liver cell is detoxifying alcohol and some other poisons, it does so by removal of hydrogen from the molecules. What, then, do the enzymes of the peroxisome do? A) combine the hydrogen with ATP B) use the hydrogen to break down hydrogen peroxide C) transfer the harmful substances to the mitochondria D) transfer the hydrogens to oxygen molecules
D
Which of the following contain the 9 + 2 arrangement of microtubules? A) cilia B) centrioles C) flagella D) A and C only E) A, B, and C
D
Which of the following is a major cause of the size limits for certain types of cells? A) the evolution of larger cells after the evolution of smaller cells B) the difference in plasma membranes between prokaryotes and eukaryotes C) the evolution of eukaryotes after the evolution of prokaryotes D) the need for a surface area of sufficient area to allow the cell's function E) the observation that longer cells usually have greater cell volume
D
Which of the following produces and modifies polysaccharides that will be secreted? A) lysosome B) vacuole C) mitochondrion D) Golgi apparatus E) peroxisome
D
Which structure is common to plant and animal cells? A) chloroplast B) wall made of cellulose C) central vacuole D) mitochondrion E) centriole
D
A biologist is studying kidney tubules in small mammals. She wants specifically to examine the juxtaposition of different types of cells in these structures. The cells in question can be distinguished by external shape, size, and 3-dimensional characteristics. Which would be the optimum method for her study? A) transmission electron microscopy B) cell fractionation C) light microscopy using stains specific to kidney function D) light microscopy using living unstained material E) scanning electron microscopy
E
A mycoplasma is an organism with a diameter between 0.1 and 1.0 µm. What does its size tell you about how it might be classified? A) It must be a single celled protist. B) It must be a single celled fungus. C) It could be almost any typical bacterium. D) It could be a typical virus. E) It could be a very small bacterium.
E
All of the following are part of a prokaryotic cell except A) DNA. B) a cell wall. C) a plasma membrane. D) ribosomes. E) an endoplasmic reticulum.
E
Centrioles, cilia, flagella, and basal bodies have remarkably similar structural elements and arrangements. This leads us to which of the following as a probable hypothesis? A) Disruption of one of these types of structure should necessarily disrupt each of the others as well. B) Loss of basal bodies should lead to loss of all cilia, flagella, and centrioles. C) Motor proteins such as dynein must have evolved before any of these four kinds of structure. D) Evolution of motility, of cells or of parts of cells, must have occurred only once. E) Natural selection for motility must select for microtubular arrays in circular patterns.
E
Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through A) plasmodesmata. B) intermediate filaments. C) tight junctions. D) desmosomes. E) gap junctions.
E
Microfilaments are well known for their role in which of the following? A) ameboid movement B) formation of cleavage furrows C) contracting of muscle cells D) A and B only E) A, B, and C
E
Recent evidence shows that individual chromosomes occupy fairly defined territories within the nucleus. Given the structure and location of the following parts of the nucleus, which would be more probably involved in chromosome location? A) nuclear pores B) the nucleolus C) the outer lipid bilayer D) the nuclear lamina E) the nuclear matrix
E
The Golgi apparatus has a polarity or sidedness to its structure and function. Which of the following statements correctly describes this polarity? A) Transport vesicles fuse with one side of the Golgi and leave from the opposite side. B) Proteins in the membrane of the Golgi may be sorted and modified as they move from one side of the Golgi to the other. C) Lipids in the membrane of the Golgi may be sorted and modified as they move from one side of the Golgi to the other. D) Soluble proteins in the cisternae (interior) of the Golgi may be sorted and modified as they move from one side of the Golgi to the other. E) All of the above correctly describe polar characteristics of the Golgi function.
E
The differences among the three categories of cytoskeletal elements would suggest that each of the following has specialized roles. Which of the following is a correct match? A) microfilaments and the nuclear lamina B) microtubules and cleavage furrow formation C) microfilaments and ciliary motion D) intermediate filaments and cytoplasmic streaming E) microtubules and chromosome movement
E
Which of the following contains enzymes that transfer hydrogen from various substrates to oxygen? A) lysosome B) vacuole C) mitochondrion D) Golgi apparatus E) peroxisome
E
Which of the following correctly lists the order in which cellular components will be found in the pellet when homogenized cells are treated with increasingly rapid spins in a centrifuge? A) ribosomes, nucleus, mitochondria B) chloroplasts, ribosomes, vacuoles C) nucleus, ribosomes, chloroplasts D) vacuoles, ribosomes, nucleus E) nucleus, mitochondria, ribosomes
E
Which structure-function pair is mismatched? A) nucleolus; production of ribosomal subunits B) lysosome; intracellular digestion C) ribosome; protein synthesis D) Golgi; protein trafficking E) microtubule; muscle contraction
E
Which of the following was a discovery that had to be made before human chromosomes could be correctly counted? A) how to use a hypotonic solution to swell nuclei B) how to visualize sperm nuclei C) how to visualize chromosomes D) when to see chromosomes separate from one another E) when to see chromosomes in pairs
a
You have the technology necessary to measure each of the following in a sample of animal cells: chlorophylls, organelle density, picograms of DNA, cell wall components, and enzymatic activity. Which would you expect to increase significantly from M to G1? A) organelle density and enzymatic activity B) cell wall components and DNA C) chlorophyll and cell walls D) organelle density and cell walls E) chlorophyll and DNA
a
Density-dependent inhibition is explained by which of the following? A) As cells become more numerous, they begin to squeeze against each other, restricting their size and ability to produce control factors. B) As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells and they stop dividing. C) As cells become more numerous, the protein kinases they produce begin to compete with each other, such that the proteins produced by one cell essentially cancel those produced by its neighbor. D) As cells become more numerous, more and more of them enter the S phase of the cell cycle. E) As cells become more numerous, the level of waste products increases, eventually slowing down metabolism.
b
For a newly evolving protist, what would be the advantage of using eukaryote-like cell division rather than binary fission? A) Binary fission would not allow for the formation of new organisms. B) Cell division would allow for the orderly and efficient segregation of multiple linear chromosomes. C) Cell division would be faster than binary fission. D) Cell division allows for lower rates of error per chromosome replication. E) Binary fission would not allow the organism to have complex cells.
b
How do cells at the completion of meiosis compare with cells that have replicated their DNA and are just about to begin meiosis? A) They have the same number of chromosomes and half the amount of DNA. B) They have half the number of chromosomes and one-fourth the amount of DNA. C) They have half the amount of cytoplasm and twice the amount of DNA. D) They have half the number of chromosomes and half the amount of DNA. E) They have twice the amount of cytoplasm and half the amount of DNA.
b
If an organism is diploid and a certain gene found in the organism has 18 known alleles (variants), then any given organism of that species can/must have which of the following? A) up to, but not more than, 18 different traits B) at most, 2 alleles for that gene C) a haploid number of 9 chromosomes D) up to 18 genes for that trait E) up to 18 chromosomes with that gene
b
If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis? A) 40 B) 10 C) 80 D) 20 E) 30
b
Mammalian blood contains the equivalent of 0.15M NaCl. Seawater contains the equivalent of 0.45 M NaCl. What will happen if red blood cells are transferred to seawater? A) The blood cells will expend ATP for active transport of NaCl into the cytoplasm. B) Water will leave the cells, causing them to shrivel and collapse. C) The blood cells will take up water, swell, and eventually burst. D) NaCl will passively diffuse into the red blood cells. E) NaCl will be exported from the red blood cells by facilitated diffusion.
b
Where do the microtubules of the spindle originate during mitosis in both plant and animal cells? A) centromere B) centrosome C) centriole D) chromatid E) kinetochore
b
Which of the following are primarily responsible for cytokinesis in plant cells but not in animal cells? A) kinetochores B) Golgi-derived vesicles C) actin and myosin D) centrioles and centromeres E) cyclin-dependent kinases
b
Which of the following describe(s) cyclin-dependent kinase (Cdk)? A) Cdk is present throughout the cell cycle and is an enzyme that attaches phosphate groups to other proteins. B) Cdk is present throughout the cell cycle. C) Cdk is an enzyme that attaches phosphate groups to other proteins. D) Cdk is inactive, or "turned off," in the presence of cyclin and it is present throughout the cell cycle. E) Cdk is inactive, or "turned off," in the presence of cyclin.
b
Which of the following is a reasonable explanation for why unsaturated fatty acids help keep any membrane more fluid at lower temperatures? A) Unsaturated fatty acids are more polar than saturated fatty acids. B) The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly. C) The double bonds result in shorter fatty acid tails and thinner membranes. D) Unsaturated fatty acids have a higher cholesterol content and therefore more cholesterol in membranes. E) The double bonds block interaction among the hydrophilic head groups of the lipids.
b
Which of the following triggers the cell's passage past the G2 checkpoint into mitosis? A) PDGF B) MPF C) protein kinase D) cyclin E) Cdk
b
Which structure is the site of the synthesis of proteins that may be exported from the cell? A) lysosomes B) rough ER C) free cytoplasmic ribosomes D) Golgi vesicles E) plasmodesmata
b
Why do chromosomes coil during mitosis? A) to increase their potential energy B) to allow the chromosomes to move without becoming entangled and breaking C) to allow the chromosomes to fit within the nuclear envelope D) to allow the sister chromatids to remain attached E) to provide for the structure of the centromere
b
For anaphase to begin, which of the following must occur? A) Chromatids must lose their kinetochores. B) Cohesin must attach the sister chromatids to each other. C) Cohesin must be cleaved enzymatically. D) Kinetochores must attach to the metaphase plate. E) Spindle microtubules must begin to depolymerize.
c
If a cell has completed the first meiotic division and is just beginning meiosis II, which of the following is an appropriate description of its contents? A) It has one-fourth the DNA and one-half the chromosomes as the originating cell. B) It is identical in content to another cell from the same meiosis. C) It has half the amount of DNA as the cell that began meiosis. D) It has half the chromosomes but twice the DNA of the originating cell. E) It has the same number of chromosomes but each of them has different alleles than another cell from the same meiosis.
c
In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short? A) 1/4 B) 1 C) 0 D) 1/2 E) 1/6
c
The MPF protein complex turns itself off by A) activating an enzyme that stimulates cyclin. B) exiting the cell. C) activating a process that destroys cyclin components. D) activating the anaphase-promoting complex. E) binding to chromatin.
c
What is a cleavage furrow? A) a ring of vesicles forming a cell plate B) the separation of divided prokaryotes C) a groove in the plasma membrane between daughter nuclei D) the metaphase plate where chromosomes attach to the spindle E) the space that is created between two chromatids during anaphase
c
What kinds of molecules pass through a cell membrane most easily? A) large and hydrophobic B) ionic C) small and hydrophobic D) monosaccharides such as glucose E) large polar
c
Which of the following is a protein synthesized at specific times during the cell cycle that associates with a kinase to form a catalytically active complex? A) MPF B) Cdk C) cyclin D) protein kinase E) PDGF
c
Which of the following is a true statement about sexual vs. asexual reproduction? A) Asexual reproduction produces only haploid offspring. B) In asexual reproduction, offspring are produced by fertilization without meiosis. C) In sexual reproduction, individuals transmit 50% of their genes to each of their offspring. D) Sexual reproduction requires that parents be diploid. E) Asexual reproduction, but not sexual reproduction, is characteristic of plants and fungi.
c
Which of the following is most likely true of a protein that cotransports glucose and sodium ions into the intestinal cells of an animal? A) Glucose entering the cell along its concentration gradient provides energy for uptake of sodium ions against the electrochemical gradient. B) Sodium ions can move down their electrochemical gradient through the cotransporter whether or not glucose is present outside the cell. C) A substance that blocks sodium ions from binding to the cotransport protein will also block the transport of glucose. D) The cotransporter can also transport potassium ions. E) The sodium ions are moving down their electrochemical gradient while glucose is moving up.
c
Which of the following is one of the ways that the membranes of winter wheat are able to remain fluid when it is extremely cold? A) by increasing the percentage of cholesterol molecules in the membrane B) by using active transport C) by increasing the percentage of unsaturated phospholipids in the membrane D) by decreasing the number of hydrophobic proteins in the membrane E) by cotransport of glucose and hydrogen
c
Which of the following statements about the cytoskeleton is true? A) The dynamic aspect of cytoskeletal function is made possible by the assembly and disassembly of a large variety of proteins into complex aggregates. B) Chemicals that block the assembly of the cytoskeleton would cause little effect on the cell's response to external signals and stimuli. C) Movement of cilia and flagella is the result of motor proteins causing microtubules to move relative to each other. D) Transport vesicles among the membranes of the endomembrane system produce the cytoskeleton. E) Microfilaments are structurally rigid and resist compression, whereas microtubules resist tension (stretching).
c
What is the reason that a modern electron microscope (TEM) can resolve biological images to the subnanometer level, as opposed to tens of nanometers achievable for the best super-resolution light microscope? A) The electron microscope has a much greater ratio of image size to real size. B) Contrast is enhanced by staining with atoms of heavy metal. C) The focal length of the electron microscope is significantly longer. D) Electron beams have much shorter wavelengths than visible light. E) The electron microscope cannot image whole cells at one time.
d
Which of the following best describes how chromosomes move toward the poles of the spindle during mitosis? A) The chromosomes are "reeled in" by the contraction of spindle microtubules. B) Motor proteins of the kinetochores move the chromosomes along the spindle microtubules. C) Nonkinetochore spindle fibers serve to push chromosomes in the direction of the poles. D) The chromosomes are "reeled in" by the contraction of spindle microtubules, and motor proteins of the kinetochores move the chromosomes along the spindle microtubules. E) The chromosomes are "reeled in" by the contraction of spindle microtubules, motor proteins of the kinetochores move the chromosomes along the spindle microtubules, and nonkinetochore spindle fibers serve to push chromosomes in the direction of the poles.
d
Which of the following is (are) required for motor proteins to function in the movement of chromosomes toward the poles of the mitotic spindle? A) intact centromeres B) an MTOC (microtubule organizing center) C) a kinetochore attached to the metaphase plate D) ATP as an energy source E) synthesis of cohesin
d
Which of the following is a function of those spindle microtubules that do not attach to kinetochores? A) maintaining an appropriate spacing among the moving chromosomes B) producing a cleavage furrow when telophase is complete C) providing the ATP needed by the fibers attached to kinetochores D) maintaining the region of overlap of microtubules in the cell's center E) pulling the poles of the spindles closer to one another
d
Which of the following is a major cause of the size limits for certain types of cells? A) the difference in plasma membranes between prokaryotes and eukaryotes B) evolutionary progression in cell size; more primitive cells have smaller sizes C) limitation on the strength and integrity of the plasma membrane as cell size increases D) the need for a surface area of sufficient area to support the cell's metabolic needs E) rigid cell walls that limit cell size expansion
d
Which of the following is a protein synthesized at specific times during the cell cycle that associates with a kinase to form a catalytically active complex? A) PDGF B) MPF C) protein kinase D) cyclin E) Cdk
d
Which of the following proteins are involved in binary fission as well as eukaryotic mitotic division? A) cyclins B) Cdks C) MPF D) actin and tubulin E) cohesins
d
A mutation results in a cell that no longer produces a normal protein kinase for the M phase checkpoint. Which of the following would likely be the immediate result of this mutation? A) The cell would prematurely enter anaphase. B) The cell would never leave metaphase. C) The cell would never enter metaphase. D) The cell would never enter prophase. E) The cell would undergo normal mitosis, but fail to enter the next G1 phase.
e
All cell cycle checkpoints are similar in which way? A) They activate or inactivate other proteins. B) They utilize the same Cdks. C) They each have only one cyclin/Cdk complex. D) They respond to the same cyclins. E) They give the go-ahead signal to progress to the next checkpoint.
e
At which phase are centrioles beginning to move apart in animal cells? A) telophase B) anaphase C) prometaphase D) metaphase E) prophase
e
In general, a signal transmitted via phosphorylation of a series of proteins A) requires binding of a hormone to a cytosol receptor. B) allows target cells to change their shape and therefore their activity. C) requires phosphorylase activity. D) cannot occur in yeasts because they lack protein phosphatases. E) brings a conformational change to each protein.
e
In order for a protein to be an integral membrane protein it would have to be A) completely covered with phospholipids. B) hydrophilic. C) exposed on only one surface of the membrane. D) hydrophobic. E) amphipathic, with at least one hydrophobic region.
e
Proteins that are involved in the regulation of the cell cycle, and that show fluctuations in concentration during the cell cycle, are called A) ATPases. B) kinetochores. C) kinases. D) proton pumps. E) cyclins.
e
The cell walls of bacteria, fungi, and plant cells and the extracellular matrix of animal cells are all external to the plasma membrane. Which of the following is a characteristic common to all of these extracellular structures? A) They must block water and small molecules in order to regulate the exchange of matter and energy with their environment. B) They must provide a rigid structure that maintains an appropriate ratio of cell surface area to volume. C) They must permit information transfer between the cell's cytoplasm and the nucleus. D) They are composed of a mixture of lipids and carbohydrates. E) They are constructed of polymers that are synthesized in the cytoplasm and then transported out of the cell.
e
The cyclin component of MPF is destroyed toward the end of which phase? A) G0 B) G1 C) S D) G2 E) M
e
Vinblastine, a drug that inhibits microtubule polymerization, is used to treat some forms of cancer. Cancer cells given vinblastine would be unable to A) extend pseudopods. B) maintain the shape of the nucleus. C) form cleavage furrows during cell division. D) migrate by amoeboid movement. E) separate chromosomes during cell division.
e
Which of the following is a protein maintained at constant levels throughout the cell cycle that requires cyclin to become catalytically active? A) PDGF B) MPF C) protein kinase D) cyclin E) Cdk
e
Which of the following is true concerning cancer cells? A) They do not exhibit density-dependent inhibition when growing in culture. B) When they stop dividing, they do so at random points in the cell cycle. C) They are not subject to cell cycle controls. D) When they stop dividing, they do so at random points in the cell cycle, and they are not subject to cell cycle controls. E) When they stop dividing, they do so at random points in the cell cycle; they are not subject to cell cycle controls; and they do not exhibit density-dependent inhibition when growing in culture.
e