Question 1

What is the primary reason that a modern transmission electron microscope (TEM)can resolve biological structures as small as 2 nm,whereas 200 nm is the limit of resolution for a light microscope?
A)Diffraction of light by a light microscope distorts the image.
B)Contrast is enhanced by staining with atoms of heavy metal.
C)Electron beams have much shorter wavelengths than visible light.
D)TEM is used to visualize very thin sections of cells.

Accepted Answer

The primary reason that a modern transmission electron microscope (TEM) can resolve biological structures as small as 2 nm, whereas 200 nm is the limit of resolution for a light microscope, is that electron beams have much shorter wavelengths than visible light. This allows for much greater resolution and clarity when visualizing structures at a microscopic level.

Question 2

If a treatment were available that would disrupt the nuclear lamina in living cells,what would you expect to be the most likely immediate consequence for the cell?
A)the loss of chromosome function
B)the inability of the nucleus to divide during cell division
C)a change in the shape of the nucleus
D)closure of nuclear pores disrupting transport of materials into and out of the nucleus

Accepted Answer

The nuclear lamina is a network of fibers that lines the inner surface of the nuclear envelope and helps maintain the shape of the nucleus. Disrupting the nuclear lamina would likely cause a change in the shape of the nucleus, making it more irregular and potentially affecting cellular processes that rely on proper nuclear shape and organization. Options A, B, and D are less likely immediate consequences of disrupting the nuclear lamina, although they could potentially occur in the long term as a result of continued disruption of nuclear structure and function.

Question 3

Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules?
A)lipids
B)glycogen
C)proteins
D)cellulose
E)nucleic acids

Accepted Answer

Ribosomes are responsible for protein synthesis, so larger numbers of ribosomes in a cell indicate that the cell is specialized in producing proteins.

Question 4

Cell fractionation is commonly used in biological research to
A)sort cells based on their size and weight.
B)visualize the 3-D structure of cell membranes.
C)isolate organelles to examine their biological functions.
D)examine the distribution of organelles within the cell.

Accepted Answer

Cell fractionation involves breaking down cells and separating different components based on their physical properties such as size, density, and solubility. This enables researchers to isolate organelles such as mitochondria, chloroplasts, and nuclei for further study of their biological functions. Therefore, choice C is the best choice as it accurately describes the purpose of cell fractionation in biological research.

Question 5

Which of the following statements is a plausible description of some aspect of protein secretion from prokaryotic cells?
A)Prokaryotes are unlikely to be able to secrete proteins because they lack an endomembrane system.
B)The mechanism of protein secretion in prokaryotes is probably the same as that in eukaryotes.
C)Proteins that are secreted by prokaryotes may be synthesized on ribosomes that are associated with the cytoplasmic surface of the plasma membrane.
D)In prokaryotes,the ribosomes that are involved in the synthesis of secreted proteins are located outside of the cell.

Accepted Answer

Prokaryotes lack an endomembrane system, which means that they cannot secrete proteins in the same way as eukaryotes. However, proteins that are secreted by prokaryotes may be synthesized on ribosomes associated with the cytoplasmic surface of the plasma membrane, which makes choice C a plausible description. Choice B is incorrect because the mechanism of protein secretion in prokaryotes is different than in eukaryotes. Choice D is incorrect because ribosomes involved in the synthesis of secreted proteins are typically located within the cell, not outside of it.

Question 6

Which structure is the site of the synthesis of proteins destined for export from the cell?
A)smooth ER
B)lysosomes
C)rough ER
D)Golgi vesicles
E)free cytoplasmic ribosomes

Accepted Answer

Proteins destined for export from the cell are synthesized by ribosomes attached to the rough endoplasmic reticulum (ER), which is studded with ribosomes. The rough ER is involved in protein synthesis and modification, and proteins synthesized on the rough ER are often modified, folded, and transported to other cell locations, such as the Golgi apparatus, for further processing and eventual export from the cell.

Question 7

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)scanning electron microscope.
C)transmission electronic microscope.
D)confocal fluorescence microscope.

Accepted Answer

The transmission electron microscope (TEM) is the best choice when biologists wish to study the internal ultrastructure of cells with the finest resolution. The TEM uses a beam of electrons that pass through a thin specimen, allowing for high magnification and resolution of internal structures. The other options - phase-contrast light microscope, scanning electron microscope, and confocal fluorescence microscope - are also useful for studying cells, but they do not have the same level of resolution as the TEM when it comes to studying internal structures.

Question 8

Which of the following structures will be found in nearly all eukaryotic cells?
A)cell wall
B)mitochondria
C)chloroplast
D)nucleoid
E)flagella

Accepted Answer

Mitochondria are found in nearly all eukaryotic cells and are the site of cellular respiration, producing energy in the form of ATP. However, not all eukaryotic cells have a cell wall, chloroplasts, a nucleoid (this is a structure found in prokaryotic cells), or flagella.

Question 9

The total volume of plant cells is often significantly greater than the total 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 occupies much of the volume of the cell.
D)animal cells are spherical,whereas plant cells are elongated.

Accepted Answer

Plant cells have a large central vacuole that occupies much of the volume of the cell. This vacuole is used for storage of nutrients, waste products, and water, and can take up as much as 90% of the total volume of the cell. Animal cells, on the other hand, have smaller vacuoles or none at all, resulting in a smaller overall cell volume.

Question 10

Proteins that will be exported from the cell are synthesized by which of the following cellular components?
A)smooth ER
B)lysosomes
C)rough ER
D)Golgi vesicles
E)free cytoplasmic ribosomes

Accepted Answer

Proteins destined for export are synthesized by ribosomes on the rough endoplasmic reticulum (rough ER), where they enter the ER lumen for processing and modification before being transported to their final destinations.

Question 11

Prokaryotes are classified as belonging to two different domains.What are the domains?
A)Bacteria and Eukaryotes
B)Bacteria and Protists
C)Bacteria and Fungi
D)Bacteria and Archaea

Accepted Answer

Prokaryotes are classified into two different domains: Bacteria and Archaea. Eukaryotes belong to a different domain altogether. Protists, fungi, and other eukaryotes are not considered prokaryotes since they have a membrane-bound nucleus and organelles, which are lacking in prokaryotes. Therefore, the correct answer is D.

Question 12

A researcher disrupts cells and separates subcellular components using centrifugation.What is the primary factor that determines whether a specific cellular component remains in the liquid solution or ends up in the pellet?
A)the relative size and weight of the component
B)the relative solubility of the component
C)how hydrophobic the component is
D)the carbohydrate composition of the component

Accepted Answer

The primary factor that determines whether a specific cellular component remains in the liquid solution or ends up in the pellet is the relative size and weight of the component. This is because centrifugation separates components based on their density, and the larger and denser components will sediment to the bottom of the tube and form a pellet.

Question 13

A researcher disrupts cells and separates subcellular components using centrifugation.Which of the following correctly lists the order in which cellular components will pellet when disrupted cell mixtures are centrifuged at increasingly higher speeds?
A)ribosomes,nuclei,mitochondria
B)chloroplasts,ribosomes,pieces of membrane
C)nucleus,ribosomes,chloroplasts
D)nucleus,mitochondria,ribosomes

Accepted Answer

When disrupted cell mixtures are centrifuged at increasingly higher speeds, the larger and denser components will pellet first, followed by smaller and less dense components. In general, the order of pelleting is nuclei > mitochondria > ribosomes. Therefore, choice D is the correct order of pelleting: nucleus first, followed by mitochondria, and then ribosomes. Choice A is incorrect because ribosomes are much smaller and less dense than nuclei and mitochondria, and would not pellet before them. Choice B is incorrect because chloroplasts are only present in plant cells and would not be present in all cell types. Choice C is incorrect because chloroplasts would not pellet before ribosomes, and because nuclei are larger and denser than ribosomes and would pellet first.

Question 14

A cell with an abundance of free ribosomes is most likely carrying out which of the following processes?
A)producing primarily proteins for secretion
B)producing primarily cytoplasmic proteins
C)producing primarily cell wall or extracellular matrix components
D)producing primarily an abundance of new membranes
E)producing primarily vacuole contents

Accepted Answer

Free ribosomes produce proteins that function within the cytosol, so a cell with an abundance of free ribosomes is most likely producing cytoplasmic proteins.

Question 15

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)lysosomes

Accepted Answer

Smooth ER is primarily involved in detoxification of drugs and poisons, and it is abundant in liver cells.

Question 16

The smallest cell structures that would most likely be visible with a standard (not super-resolution)research-grade light microscope are
A)microtubules.
B)chloroplasts.
C)ribosomes.
D)nuclear pores.

Accepted Answer

Chloroplasts, being relatively large organelles found in plant cells, are visible under a standard light microscope, typically ranging in size from 1 to 10 micrometers. Other structures listed are too small to be resolved clearly with conventional light microscopy.

Question 17

One advantage of light microscopy over transmission electron microscopy is that
A)specimen preparation for light microcopy does not produce artifacts.
B)light microscopy provides for higher resolving power than transmission electron microscopy.
C)light microscopy provides for higher magnification than transmission electron microscopy.
D)light microscopy allows you to view dynamic processes in living cells.

Accepted Answer

One advantage of light microscopy is that it allows viewing of dynamic processes in living cells, which is not possible with electron microscopy. Specimen preparation for light microscopy does produce artifacts, and transmission electron microscopy provides for higher resolving power and magnification than light microscopy.

Question 18

What technique would be most appropriate to use to observe the movements of condensed chromosomes during cell division?
A)standard light microscopy
B)a hand lens (magnifying glass)
C)transmission electron microscopy
D)scanning electron microscopy

Accepted Answer

Standard light microscopy is suitable for observing the movements of condensed chromosomes during cell division because it allows for the visualization of live cells and dynamic processes.

Question 19

Which of the following statements concerning cells of bacteria and archaea is correct?
A)Archaea contain small membrane-enclosed organelles;bacteria do not.
B)Archaea contain a membrane-bound nucleus;bacteria do not.
C)Chromosomes in both archaea and bacteria contain DNA.
D)Mitochondria are present in some bacteria and all archaea.

Accepted Answer

Both archaea and bacteria have chromosomes which contain DNA. The other choices are incorrect as they contain untrue statements.

Question 20

Which of the following molecules or structures may be found in eukaryotic cells but not in bacteria?
A)DNA
B)flagella
C)plasma membrane
D)ribosomes
E)endoplasmic reticulum

Accepted Answer

Eukaryotic cells have a complex structure including organelles such as the endoplasmic reticulum, which is not found in bacteria. Bacteria, being prokaryotes, lack membrane-bound organelles.

Quiz 4: A Tour of the Cell

What is the primary reason that a modern transmission electron microscope (TEM) can resolve biological structures as small as 2 nm,whereas 200 nm is the limit of resolution for a light microscope?

If a treatment were available that would disrupt the nuclear lamina in living cells,what would you expect to be the most likely immediate consequence for the cell?

Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules?

Cell fractionation is commonly used in biological research to

Which of the following statements is a plausible description of some aspect of protein secretion from prokaryotic cells?

Which structure is the site of the synthesis of proteins destined for export from the cell?

When biologists wish to study the internal ultrastructure of cells,they can achieve the finest resolution by using a

Which of the following structures will be found in nearly all eukaryotic cells?

The total volume of plant cells is often significantly greater than the total volume in animal cells.The most reasonable explanation for this observation is that

Proteins that will be exported from the cell are synthesized by which of the following cellular components?

Prokaryotes are classified as belonging to two different domains.What are the domains?

A researcher disrupts cells and separates subcellular components using centrifugation.What is the primary factor that determines whether a specific cellular component remains in the liquid solution or ends up in the pellet?

A researcher disrupts cells and separates subcellular components using centrifugation.Which of the following correctly lists the order in which cellular components will pellet when disrupted cell mixtures are centrifuged at increasingly higher speeds?

A cell with an abundance of free ribosomes is most likely carrying out which of the following processes?

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?

The smallest cell structures that would most likely be visible with a standard (not super-resolution) research-grade light microscope are

One advantage of light microscopy over transmission electron microscopy is that

What technique would be most appropriate to use to observe the movements of condensed chromosomes during cell division?

Which of the following statements concerning cells of bacteria and archaea is correct?

Which of the following molecules or structures may be found in eukaryotic cells but not in bacteria?