Bio 1: Module 2 Launchpad HW Questions
What type of agent would be most likely to disrupt the structures of microvilli? a. Actin depolymerizing agent b. Microtubule disruptors c. Actin polymerizing agent d. Actin cross-linking agent e. Tubulin polymerization inhibitor
a. Actin depolymerizing agent
A unicellular organism adapted to living in salt water is placed in a freshwater tank. What is the likely outcome? a. Water moves into the cell, causing it to burst. b. Water and salt move in opposite directions until the organism can adapt. c. Water moves out of the cell, causing it to shrivel. d. Water moves into the cell until the organism can adapt. e. Water moves out of the cell until the organism can adapt.
a. Water moves into the cell, causing it to burst.
A new protein with a molecular weight of 25,000 Da is discovered and found to reside only in the nucleus. For this to happen, the protein must a. be transported across the nuclear envelope. b. be synthesized by a unique mechanism. c. contain a large number of hydrophobic amino acids. d. exist in a denatured state. e. be made in the nucleolus.
a. be transported across the nuclear envelope.
The overall shape of an animal cell is determined by its a. cytoskeleton. b. endoplasmic reticulum. c. nucleus. d. cytosol. e. cell membrane.
a. cytoskeleton.
Most plant and animal cells are a. large enough to be seen with a light microscope. b. smaller than a chloroplast. c. larger than most fungal cells. d. large enough to be seen with the unaided eye. e. smaller than most bacteria.
a. large enough to be seen with a light microscope.
The cytoskeleton consists of a. microtubules, intermediate filaments, and microfilaments. b. calcified microtubules. c. cilia, flagella, and microfilaments. d. cilia, microtubules, and microfilaments. e. internal cell walls.
a. microtubules, intermediate filaments, and microfilaments.
A large organelle that genetically controls a eukaryotic cell's activities is the a. nucleus b. chloroplast. c. flagellum. d. vacuole. e. centriole.
a. nucleus
Some proteins on the surface of a mammalian cell contain carbohydrates. These proteins are synthesized by _______ and the sugars are added in the _______. a. ribosomes on the rough endoplasmic reticulum; Golgi apparatus b. the Golgi apparatus; rough endoplasmic reticulum c. cytoplasmic ribosomes; smooth endoplasmic reticulum d. mitochondrial ribosomes; smooth endoplasmic reticulum e. cytoplasmic ribosomes; plasma membrane
a. ribosomes on the rough endoplasmic reticulum; Golgi apparatus
It is found that a particular type of cell isolated and growing in culture secretes a much larger amount of protein than human liver cells grown under the same conditions. From this, you hypothesize that these cells must have a large number or amount of a. rough endoplasmic reticulum. b. peptidoglycan. c. smooth endoplasmic reticulum. d. nuclear pores. e. chromosomes.
a. rough endoplasmic reticulum.
Microtubules are composed of a. α- and β-tubulin. b. κ tubules. c. ρ- and σ-myosin. d. κ actinomin. e. δ- and λ-actin.
a. α- and β-tubulin.
A particle of food encounters a series of cellular structures during digestion by an animal cell. In what order does this encounter occur, starting from the exterior of the cell? a. Cell membrane → primary lysosome → secondary lysosome → phagosome b. Cell membrane → phagosome → primary lysosome → secondary lysosome c. Phagosome → secondary lysosome → primary lysosome → cell membrane d. Secondary lysosome → primary lysosome → phagosome → cell membrane e. Phagosome → cell membrane → primary lysosome → secondary lysosome
b. Cell membrane → phagosome → primary lysosome → secondary lysosome
Five statements about cell membranes are given. Which statement can be used to explain the importance of the cell membrane to cell survival? a. The cell membranes of prokaryotes and eukaryotes have the same basic structure. b. Cell membranes are selectively permeable with respect to molecules and ions. c. Cell membranes are composed of a phospholipid bilayer embedded with proteins. d. The cell membrane is so small that it is best viewed with an electron microscope. e. The cell membrane expands or shrinks by the addition or removal of phospholipid molecules.
b. Cell membranes are selectively permeable with respect to molecules and ions.
Which statement about the nuclear envelope is true? a. It contains ribosomes on the inner surface. b. It contains pores for the passage of large molecules. c. It allows proteins to freely pass through. d. It cannot be separated from other subcellular structures by cell fractionation. e. It is composed of a single membrane.
b. It contains pores for the passage of large molecules.
The cytoskeleton is composed of three major components, each with distinct functions. Which represents the correct order of these components, from smallest to largest size? a. Microtubules, intermediate filaments, microfilaments b. Microfilaments, intermediate filaments, microtubules c. Microtubules, microfilaments, intermediate filaments d. Intermediate filaments, microtubules, microfilaments e. Intermediate filaments, microfilaments, microtubules
b. Microfilaments, intermediate filaments, microtubules
Proteins produced by ribosomes pass through several cellular structures before reaching their targeted destinations. Which sequence represents the structures, in the correct order, that will be encountered by a newly synthesized protein targeted for outside the cell? a. SER → cis-Golgi → vesicle → medial-Golgi → trans-Golgi → vesicle → cell membrane b. RER → vesicle → cis-Golgi → medial-Golgi → trans-Golgi → vesicle → cell membrane c. Nuclear membrane → RER → vesicle → trans-Golgi → cis-Golgi → phagosome → cell membrane d. SER → vesicle → trans-Golgi → medial-Golgi → cis-Golgi → vesicle → cell membrane e. RER → vesicle → trans-Golgi → medial-Golgi → cis-Golgi → lysosome → cell membrane
b. RER → vesicle → cis-Golgi → medial-Golgi → trans-Golgi → vesicle → cell membrane
Which is a difference between a prokaryotic and a eukaryotic cell? a. A prokaryotic cell does not use DNA as its genetic material. b. The DNA in a prokaryotic cell is not enclosed in a membrane-bound nucleus. c. A prokaryotic cell is not enclosed by a cell membrane, and a eukaryotic cell is enclosed. d. A prokaryotic cell does not use ribosomes for protein synthesis, whereas a eukaryotic cell does. e. Cellular processes in a prokaryotic cell are compartmentalized, whereas compartmentalization is absent in a eukaryotic cell.
b. The DNA in a prokaryotic cell is not enclosed in a membrane-bound nucleus.
If the DNA encoding a nuclear signal sequence were placed in the gene for a cytoplasmic protein, the protein would a. be directed to the cytoplasm. b. be directed to the nucleus. c. stay in the endoplasmic reticulum. d. be modified in the Golgi. e. be directed to the lysosomes.
b. be directed to the nucleus.
Rough endoplasmic reticulum and smooth endoplasmic reticulum differ a. only in terms of the presence (in RER) or absence (in SER) of ribosomes. b. in their function, and also in terms of the presence (in RER) or absence (in SER) of ribosomes. c. only in terms of their microscopic appearance. d. in terms of their evolutionary origins. e. only in their function.
b. in their function, and also in terms of the presence (in RER) or absence (in SER) of ribosomes.
In protein synthesis, the endoplasmic reticulum a. is the site where all ribosomes bind. b. is the site of completion of translation of membrane-bound and exported proteins. c. produces tRNAs. d. is the site where mRNA attaches. e. brings together mRNA and tRNA.
b. is the site of completion of translation of membrane-bound and exported proteins.
A ribosome is a cell structure but is not considered an organelle because it a. is present in prokaryotes. b. lacks a membrane. c. is not made up of proteins. d. does not produce its own energy. e. does not contain its own genetic material.
b. lacks a membrane.
The plasma membrane of the bacterium Pseudomonas syringae is able to remain fluid when it is extremely cold. The bacterium most likely accomplishes this by a. decreasing the number of hydrophobic proteins present. b. replacing saturated fatty acids with unsaturated fatty acids. c. using fatty acids with longer tails. d. increasing the number of cholesterol molecules present. e. closing protein channels.
b. replacing saturated fatty acids with unsaturated fatty acids.
Which structure is involved with maintaining the position of the organelles within a cell? a. Endoplasmic reticulum b. Mitochondrion c. Intermediate filament d. Ribosome e. Golgi apparatus
c. Intermediate filament
Which protein is not part of the structure of a cilium? a. α-tubulin b. β-tubulin c. Keratin d. Dynein e. Nexin
c. Keratin
Which technique would be best suited to a study of normal cell migration during embryonic development? a. Cell fractionation b. Experimentation on mutants c. Light microscopy d. Electron microscopy e. Direct visual observation
c. Light microscopy
Microvilli are supported by a network of which type of structure? a. Microtubules b. Intermediate filaments c. Microfilaments d. Myosin e. Chromatin
c. Microfilaments
If the organelles of an animal cell were separated by centrifugation, which organelles would require the least centrifugal force to settle to the bottom of the centrifuge tube? a. Mitochondria b. Chloroplasts c. Nuclei d. Lysosomes e. Golgi apparatus
c. Nuclei
Areas A and B are separated by a membrane that is permeable to a substance X. Which set of conditions will result in the greatest rate of diffusion of X into area A? a. The concentration of X in A is 1 M; the concentration of X in B is 500 mM. b. The concentration of X in A is 200 mM; the concentration of X in B is 250 mM. c. The concentration of X in A is 10 mM; the concentration of X in B is 2 M. d. The concentration of X in A is 50 mM; the concentration of X in B is 60 mM. e. The concentration of X in A is 5 mM; the concentration of X in B is 1 μM.
c. The concentration of X in A is 10 mM; the concentration of X in B is 2 M.
How might a researcher study the presence of a specific protein in cells from different tissues of the body? a. Use scanning electron microscopy to search for the protein in the three-dimensional surfaces of whole cells. b. Observe the protein in living cells, using light microscopy techniques that preserve cells in the living state. c. Treat cells with a dye that selectively binds to the protein of interest, and look for evidence of this dye in cells, using light microscopy. d. Slice cells into thin sections, use electron microscopy to take many images of structures inside the cells, and search for the protein in the images. e. Use a general protein stain to treat cells before preparing them for bright-field microscopy, and then search for evidence of this dye in the samples.
c. Treat cells with a dye that selectively binds to the protein of interest, and look for evidence of this dye in cells, using light microscopy.
A cultured cell line appears to be having trouble surviving. Upon closer examination, you find that the cells do not appear to have normal chromosome separation. Based on this observation, you decide to check for the presence of a mutated protein. You will be sure to analyze the gene for which protein? a. Actin b. Myosin c. Tubulin d. Nexin e. Melanin
c. Tubulin
The speed and direction of ions as they move through channels in the cell membrane are determined by the a. ability of the ions to bind water. b. size and charge of the ions. c. concentration gradient. d. number of channel proteins present. e. thickness of the cell membrane.
c. concentration gradient.
Hair and some intermediate filaments are composed of a. collagen. b. proteoglycans. c. keratin. d. microfilaments. e. microtubules.
c. keratin.
The membranes of the endoplasmic reticulum are continuous with the membranes of the a. mitochondria. b. nucleolus. c. nuclear envelope. d. cell membrane. e. Golgi apparatus.
c. nuclear envelope.
Proteins that are transported in vesicles are made by a. the smooth endoplasmic reticulum. b. ribosomes within the mitochondrion. c. ribosomes on the rough endoplasmic reticulum. d. ribosomes within chloroplasts. e. the Golgi apparatus.
c. ribosomes on the rough endoplasmic reticulum.
Which statement about microfilaments and microtubules is false? a. Both help maintain and support cellular structures. b. Both are components of the cytoskeleton. c. Both are involved in movement of cells. d. Both are made of the same protein monomers. e. Both have a plus end and a minus end.
d. Both are made of the same protein monomers.
What is the difference between "free" and "attached" ribosomes? a. Free ribosomes produce proteins that are exported from the cell, whereas attached ribosomes make proteins for mitochondria and chloroplasts. b. Free ribosomes function in protein synthesis, whereas attached ribosomes function in protein modification. c. Free ribosomes are found in prokaryotes, whereas attached ribosomes are found in eukaryotes. d. Free ribosomes are in the cytoplasm, whereas attached ribosomes are anchored to the endoplasmic reticulum. e. Free ribosomes produce proteins in the nucleus, whereas attached ribosomes produce proteins in the cytoplasm.
d. Free ribosomes are in the cytoplasm, whereas attached ribosomes are anchored to the endoplasmic reticulum.
Suppose that a new drug shows promise in treating cancer because it can enter cells by simple diffusion. Which statement about the drug is false? a. Diffusion of the drug molecules is a random process. b. Diffusion of the drug continues until its concentrations across membranes are in equilibrium. c. The drug molecules move from areas of higher concentration to areas of lower concentration. d. It depends on a specific carrier protein to enter the cells. e. The rate of its diffusion is affected by temperature.
d. It depends on a specific carrier protein to enter the cells.
The hydrophilic regions of a membrane protein would most likely be found a. only in cell membranes. b. in the interior of the membrane. c. either on the surface or inserted into the interior of the membrane. d. exposed on the surface of the membrane. e. associated with the fatty acid region of the lipids.
d. exposed on the surface of the membrane.
The addition of sugar residues to the protein after translation is called a. proteolysis. b. exonuclease digestion. c. sucrosis. d. glycosylation. e. phosphorylation.
d. glycosylation.
A protein that is destined to be secreted from the cell a. is targeted directly to lysosomes. b. is made solely by ribosomes free in the cytosol. c. has a signal sequence that targets it to the plasma membrane. d. has a signal sequence that targets its translation into the lumen of the RER. e. is targeted to the RER as a soluble protein.
d. has a signal sequence that targets its translation into the lumen of the RER.
Proteins packaged by the Golgi apparatus are delivered to the correct location by means of a. the control provided by the nucleus. b. the general flow of vesicles within the cell. c. motor proteins that direct the Golgi apparatus. d. identifying proteins embedded in the vesicle membrane. e. microfilaments.
d. identifying proteins embedded in the vesicle membrane.
If a cell has an increased need for a particular molecule already present in a higher concentration within the cell than in the extracellular fluid, the cell might use active transport, which usually moves molecules a. in the same direction as diffusion moves them. b. in a direction that tends to bring about equilibrium. c. from inside to outside the cell. d. in a direction opposite to the one in which diffusion moves them. e. toward higher pH.
d. in a direction opposite to the one in which diffusion moves them.
Membrane-bound organelles are present in eukaryotes but not in prokaryotes. These structures a. decrease the flow of materials into and out of the eukaryotic cell. b. regulate the flow of traffic inside the eukaryotic cell. c. provide a means of cellular reproduction in eukaryotes. d. increase the efficiency of cellular activities in eukaryotes. e. provide structural support for the eukaryotic cell.
d. increase the efficiency of cellular activities in eukaryotes.
Steroids are synthesized by a. the Golgi apparatus. b. chloroplasts. c. lysosomes. d. smooth endoplasmic reticulum. e. mitochondria.
d. smooth endoplasmic reticulum.
Microtubules are made of a. polysaccharides, and they function in locomotion. b. actin, and they function to change cell shape. c. actin, and they function in locomotion. d. tubulin, and they are essential in chromosome movement during mitosis. e. tubulin, and they are found in microvilli.
d. tubulin, and they are essential in chromosome movement during mitosis.
You are monitoring the diffusion of a molecule across a membrane. Of the options listed below, the fastest rate of diffusion would result from an internal concentration of _______ μM and an external concentration of _______ μM. a. 50; 50 b. 100; 120 c. 50; 40 d. 35; 40 e. 5; 60
e. 5; 60
A patient is admitted to the hospital for dehydration and malnutrition. On close observation of the intestine, it appears that the cells lining the intestine have fully formed microvilli. However, these microvilli are not uniformly standing upright and protruding into the lumen of the intestine, but are lying down so that full exposure to the contents of the intestine cannot be obtained. The doctors conclude that the patient may have a defect in what cellular component? a. Myosin b. Microfibers c. Intermediate filaments d. Tubulin e. Actin
e. Actin
Cytoskeletal components with a 7 nm diameter are discovered in the cultured cells of an animal. Which would be a good experiment to check your hypothesis about the identity of these cytoskeletal components? a. Include a keratin digestion component in the culture, and confirm loss of the structure. b. Expose the cells to a substance that binds myosin proteins, and see if the cell is still able to make the structures. c. Add a dynein inhibitor, and see whether the structures disappear. d. Inject a tubulin binding protein, and see whether the cell is able to maintain the structures. e. Incubate the cells in a substance that will depolymerize actin, and observe whether the structure collapses.
e. Incubate the cells in a substance that will depolymerize actin, and observe whether the structure collapses.
A cancer drug is being tested, and it is found that although the cancer cells can divide, the nuclear envelope cannot re-form. It is determined that a protein substance is sequestered so that it cannot be polymerized into the necessary structure. What is the most likely protein target of the drug? a. α-tubulin b. Actin c. β-tubulin d. Keratin e. Lamin
e. Lamin
Lysosomes are important to eukaryotic cells because they contain a. their own DNA molecules. b. cell waste materials. c. starch molecules for energy storage. d. photosynthetic pigments. e. digestive enzymes.
e. digestive enzymes
Ribosomes are not visible under a light microscope, but they can be seen with an electron microscope because a. electrons have such high energy that they pass through biological samples. b. electron beams have more energy than light beams. c. electron microscopes can be used to observe living cells. d. electron microscopes focus light with magnets. e. electron microscopes have more resolving power than light microscopes.
e. electron microscopes have more resolving power than light microscopes.
In a biological membrane, the phospholipids are arranged with the fatty acid chains facing the interior of the membrane. As a result, the interior of the membrane is a. hydrophilic. b. filled with water. c. charged. d. polar. e. hydrophobic.
e. hydrophobic.
A general function of all cellular membranes is to a. support the cell and determine its shape. b. produce energy for the cell. c. produce proteins for the cell. d. move the cell. e. regulate which materials can enter or leave the cell.
e. regulate which materials can enter or leave the cell.
One benefit of scanning electron microscopy is that it enables researchers a. to observe cells dividing. b. to sequence DNA molecules. c. to follow metabolic reactions inside cells. d. to determine the age of a cell. e. to visualize 3-D topography of a cell or tissue sample.
e. to visualize 3-D topography of a cell or tissue sample.
