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When biologists wish to study the internal ultrastructure of cells, they can achieve the finest resolution by using
A) a phase-contrast light microscope.
B) a scanning electron microscope.
C) a transmission electronic microscope.
D) a confocal fluorescence microscope.
E) a super-resolution fluorescence microscope.
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) light microscopy provides higher contrast than electron microscopy.
E) specimen preparation for light microcopy does not produce artifacts.
A primary objective of cell fractionation is to
A) view the structure of cell membranes.
B) sort cells based on their size and weight.
C) determine the size of various organelles.
D) separate the major organelles so that their particular functions can be determined.
E) separate lipid-soluble from water-soluble molecules.
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 presence or absence of nucleic acids in the component.
E) the presence or absence of lipids in the component.
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
Green fluorescent protein (GFP) can be used to fluorescently label a specific protein in cells by genetically engineering cells to synthesize the target protein fused to GFP. What is the advantage of using GFP fusions to visualize specific proteins, instead of staining cells with fluorescently labeled probes that bind to the target protein?
A) GFP fusions enable one to track changes in the location of the protein in living cells; staining usually requires preserved cells.
B) GFP fusions enable higher resolution than staining with fluorescent probes.
C) GFP permits the position of the protein in the cell more precisely than fluorescent probes.
D) GFP permits visualization of protein-protein interactions; fluorescent probes do not.
E) GFP fusions are not subject to artifacts; fluorescent probes may introduce background artifacts.
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 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 a much greater ratio of image size to real size.
E) The electron microscope cannot image whole cells at one time.
What technique would be most appropriate to use to observe the movements of condensed chromosomes during cell division?
A) light microscopy
B) scanning electron microscopy
C) transmission electron microscopy
D) confocal fluorescence microscopy
E) super-resolution fluorescence microscopy
All of the following are part of a prokaryotic cell except
B) a cell wall.
C) a plasma membrane.
E) an endoplasmic reticulum.
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, whereas plant cells are elongated.
E) plant cells can have lower surface-to-volume ratios than animal cells because plant cells synthesize their own nutrients.
A mycoplasma is an organism with a diameter between 0.1 and 1.0 µm. What does the organism's 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.
Which of the following is a major cause of the size limits for certain types of cells?
A) limitation on the strength and integrity of the plasma membrane as cell size increases
B) the difference in plasma membranes between prokaryotes and eukaryotes
C) evolutionary progression in cell size; more primitive cells have smaller sizes
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
Which of the following statements concerning bacteria and archaea cells is correct?
A) Archaea cells contain small membrane-enclosed organelles; bacteria do not.
B) Archaea cells contain a membrane-bound nucleus; bacteria do not.
C) DNA is present in both archaea cells and bacteria cells.
D) DNA is present in the mitochondria of both bacteria and archaea cells.
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) anaerobic archaea taking up residence inside a larger bacterial host cell to escape toxic oxygen–the anaerobic bacterium evolved into chloroplasts.
C) an endosymbiotic fungal cell evolved into the nucleus.
D) acquisition of an endomembrane system, and subsequent evolution of mitochondria from a portion of the Golgi.
Prokaryotes are classified as belonging to two different domains. What are the domains?
A) Bacteria and Eukarya
B) Bacteria and Archaea
C) Archaea and Protista
D) Bacteria and Protista
E) Bacteria and Fungi
If radioactive deoxythymidine triphosphate (dTTP) is added to a culture of rapidly growing bacterial cells, where in the cell would you expect to find the greatest concentration of radioactivity?
C) endoplasmic reticulum
Which organelle or structure is absent in plant cells?
B) Golgi vesicles
Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules?
E) nucleic acids
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 nucleus to divide during cell division
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
Recent evidence shows that when chromosomes decondense during interphase, their DNA molecules do not intermingle. Instead, they occupy distinct territories within the nucleus. Considering the structure and location of the following structures, which is most likely to be involved in chromosome location?
A) nuclear pores
B) the nucleolus
D) the nuclear lamina
E) the nuclear matrix
A cell with a predominance of free ribosomes is most likely
A) producing primarily proteins for secretion.
B) producing primarily cytoplasmic proteins.
C) constructing an extensive cell wall or extracellular matrix.
D) digesting large food particles.
E) enlarging its vacuole.
Which type of organelle or structure is primarily involved in the synthesis of oils, phospholipids, and steroids?
C) smooth endoplasmic reticulum
E) contractile vacuole
Which structure is the site of the synthesis of proteins that may be exported from the cell?
A) rough ER
D) Golgi vesicles
E) free cytoplasmic ribosomes
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.
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 separated from the endoplasmic reticulum.
D) small vesicles from the Golgi fuse with the nuclear envelope.
E) nuclear pore complexes contain proteins.
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