Biology Ch. 7

If a red blood cell is placed in a salt solution and bursts, what is the tonicity of the solution relative to the interior of the cell? A. Hypotonic B. Isotonic C. Hypertonic D. Osmotic

A

To what does the term "ligand" refer in cell biology? A. any small molecule that can bind in a specific manner to a larger one B. the target cell of a signal molecule C. the bond that forms between a signaling molecule and its receptor D. the change in shape that occurs when a signaling molecule binds to its receptor E. a molecule that can occupy a receptor site while not activating the receptor

A

Which of the following is a substance that acts at a long distance from the site at which it is secreted? A. hormone B. neurotransmitter C. synaptic signal D. paracrine signal E. local regulator

A

Which of the following statements about a typical plasma membrane is correct? A. The two sides of the plasma membrane have different lipid and protein composition. B. The plasma membrane is a covalently linked network of phospholipids and proteins that controls the movement of solutes into and out of a cell. C. Phospholipids are the primary component that determines which solutes can cross the plasma membrane. D. The hydrophilic interior of the membrane is composed primarily of the fatty acid tails of the phospholipids. E. Carbohydrates on the membrane surface are important in determining the overall bilayer structure.

A

A(n) _____ is an example of a signal molecule that can bind to an intracellular receptor and thereby cause a gene to be turned on or off. A. carbohydrate B. steroid C. ion D. nucleic acid E. protein

B

Active and passive transport of solutes across a membrane typically differ in which of the following ways? A. Active transport is usually down the concentration gradient of the solute, whereas passive transport is always against the concentration gradient of the solute. B. Active transport always involves the utilization of cellular energy, whereas passive transport does not require cellular energy. C. Active transport is always faster than passive transport. D. Active transport uses protein carriers, whereas passive transport uses carbohydrate carriers. E. Active transport is used for ions, passive transport is used for uncharged solutes.

B

How can a lipid be distinguished from a sugar? A. Lipids are mostly saturated. B. Lipids are mostly nonpolar. C. A lipid is made up of only hydrocarbons. D. A lipid dissolves in water.

B

In facilitated diffusion, what is the role of the transport protein? A. Transport proteins provide a low-resistance channel for water molecules to cross the membrane. B. Transport proteins provide a hydrophilic route for the solute to cross the membrane. C. Transport proteins provide a protein site for ATP hydrolysis, which facilitates the movement of a solute across a membrane. D. Transport proteins provide the energy for diffusion of the solute. E. Transport proteins organize the phospholipids to allow the solute to cross the membrane.

B

The permeability of a biological membrane to a specific polar solute may depend on which of the following? A. the amount of cholesterol in the membrane B. the types of transport proteins in the membrane C. the phospholipid composition of the membrane D. the presence of unsaturated fatty acids in the membrane E. the types of polysaccharides present in the membrane

B

What property of dishwashing liquid (detergent) makes it useful to wash grease from pans? A. Solubility in water B. Amphipathic nature C. Hydrophobic nature D. Permeability

B

Which of the following factors does not affect membrane permeability? A. The saturation of hydrocarbon tails in membrane phospholipids B. The polarity of membrane phospholipids C. The amount of cholesterol in the membrane D. Temperature

B

Which of the following statements about osmosis is correct? A. If a cell is placed in an isotonic solution, more water will enter the cell than leaves the cell. B. The presence of aquaporins (proteins that form water channels in the membrane) should speed up the process of osmosis. C. Osmosis is the diffusion of water from a region of lower water concentration to a region of higher water concentration. D. Osmotic movement of water into a cell would likely occur if the cell accumulates water from its environment. E. If a solution outside the cell is hypertonic compared to the cytoplasm, water will move into the cell by osmosis.

B

Dioxin, produced as a by-product of various industrial chemical processes, is suspected of contributing to the development of cancer and birth defects in animals and humans. It apparently acts by entering cells by simple diffusion and binding to proteins in the cytoplasm, then altering the pattern of gene expression. Which of the following are likely to be the cytoplasmic proteins to which dioxin binds? A. nucleosomes B. growth factor receptors C. transcription factors D. enhancers E. DNA polymerases

C

If the concentration of phosphate in the cytosol is 2.0 mM and the concentration of phosphate in the surrounding fluid is 0.1 mM, how could the cell increase the concentration of phosphate in the cytosol? A. passive transport B. diffusion C. active transport D. osmosis E. facilitated diffusion

C

What is the function of tyrosine-kinase receptors? A. enzymatic degrading of GTP to GDP B. allowing specific ions to enter the cell after ligand binding C. enzymatic phosphorylation of tyrosine in the receptor protein D. binding to nonpolar signaling molecules such as nitric oxide or the steroid hormones E. enzymatic hydrolyzing of the signaling molecule shortly after its arrival

C

Which of these extracellular signal molecules could diffuse through a plasma membrane and bind to an intracellular receptor? A. glucose B. cellulose C. estrogen D. starch E. glycerol

C

Thyroid hormones bind to _____ receptors. A. G-protein-linked B. plasma membrane ion-channel C. steroid D. intracellular E. tyrosine-kinase

D

Which of the following best describes the structure of a biological membrane? A. a fluid structure in which phospholipids and proteins move freely between sides of the membrane B. a mixture of covalently linked phospholipids and proteins that determines which solutes can cross the membrane and which cannot C. two layers of phospholipids (with opposite orientations of the phospholipids in each layer) with each layer covered on the outside with proteins D. two layers of phospholipids with proteins either crossing the layers or on the surface of the layers E. two layers of phospholipids with proteins embedded between the two layers

D

Which of the following particles could diffuse easily through a cell membrane? A. Hydrogen ion (H+) B. Glucose C. Sodium ion (Na+) D. Oxygen (O2)

D

The movement of glucose into a cell against a concentration gradient is most likely to be accomplished by which of the following? A. facilitated diffusion of the glucose using a carrier protein B. passive diffusion of the glucose through the lipid bilayer C. movement of glucose into the cell through a glucose channel D. receptor-mediated endocytosis E. cotransport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis

E

Which of the following correctly describes some aspect of exocytosis or endocytosis? A. The inner surface of a transport vesicle that fuses with or buds from the plasma membrane is most closely related to the inner surface of the plasma membrane. B. These two processes require the participation of mitochondria. C. Endocytosis and exocytosis involve passive transport. D. Both processes provide a mechanism for exchanging membrane-impermeable molecules between the organelles and the cytosol. E. Exocytosis and endocytosis change the surface area of the plasma membrane.

E

Which of the following is least likely to be important in holding the components of a biological membrane together? A. hydrophobic interactions among the fatty acid tails of phospholipids on the same side of the membrane B. hydrophobic interactions between the phospholipid tails and the surface of integral membrane proteins buried in the membrane C. polar interactions among the phospholipid head groups on the same surface of the membrane D. hydrophobic interactions among the fatty acid tails of phospholipids on opposite sides of the membrane E. covalent interactions between the phospholipid and protein components of the membrane

E

Which of the following provides molecular evidence that signal transduction pathways evolved early in the history of life? A. Simple forms of life, such as prokaryotic cells, utilize cell signaling. B. Receptor molecules have been identified in preparations of fossilized organisms billions of years old. C. Cell signaling is observed in organisms that do not utilize sexual reproduction. D. The pathways in primitive organisms, such as bacteria, are short, whereas those in advanced forms, such as mammals, are long. E. The molecular details of cell signaling are quite similar in organisms whose last common ancestor was a billion years ago.

E

True or false? Osmosis is a type of diffusion.

TRUE

True or false? The water-soluble portion of a phospholipid is the polar head, which generally consists of a glycerol molecule linked to a phosphate group

TRUE