Physiology Sg-5

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1. Connective tissue cells include

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bone cells.
blood cells

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2. Epithelial cells

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form boundaries between body compartments

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3. The internal environment

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is regulated to remain relatively constant by the specialized activities of many of the body's cells.

C. is the medium for exchange of nutrients and wastes for the body's cells

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4. Homeostasis

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refers to maintaining a stable internal environment.

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5. Feedforward regulatory processes

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work in anticipation of changes in regulated variables

work in conjunction with negative feedback processes

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6. The hormone insulin enhances the transport of glucose into most of the body's cells. Its secretion is controlled by a negative-feedback system between the concentration of glucose in the blood and the cells that secrete insulin. Which of the following statements is most likely to be correct?

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An increase in blood glucose concentration will stimulate insulin secretion, which will in turn lower the blood glucose concentration.

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7. A covalent bond between two atoms

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is formed when each atom shares one of its outer-orbit electrons with the other atom.

is the strongest of the chemical bonds.

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8. Free radicals

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react rapidly with other atoms.

include hydroxyl radical and nitric oxide

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9. Consider the adage familiar to anyone who has observed oil spills in the ocean or has made a salad dressing: “Oil and water do not mix.” Which of the following helps explain this observation

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Oil is hydrophobic.

Oil is nonpolar.

Oil is composed largely of carbon and hydrogen.

Water is hydrophilic.

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10. A major function of plasma membranes is

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to regulate the passage of molecules into and out of the cell.

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11. Functions of agranular endoplasmic reticulum include

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synthesis of steroids.

storage of intracellular calcium ion.

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12. The organelles that digest engulfed bacteria and cell debris are the

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lysosomes

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13. Functions of the Golgi apparatus include

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modifying proteins synthesized on ribosomes associated with granular endoplasmic reticulum.

allowing the distribution of modified proteins throughout the cell in vesicles

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14. A gene

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contains information necessary for the synthesis of carbohydrates.

is a sequence of nucleotides in DNA.

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15. The genetic code

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is the same for all cells.

is the same for all organisms

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16. Nucleolus

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Site(s) of assembly of ribosome components.

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17. Nuclear pores

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Allows passage of large molecules between nucleus and cytoplasm

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18. Nuclear envelope

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Double membrane.

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19. Chromatin

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Composed of DNA and protein.

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20. Ribosomes

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Site(s) of protein synthesis

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21. Which of the following statements regarding the structure and function of cell membranes is correct?

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The phospholipid bilayer is arranged so that the hydrophilic heads of the phospholipid molecule face the extra- and intracellular fluids.

Some proteins integrated into the membrane function as channels associated with transport of ions through the membrane.

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22. The net flux of a penetrating solute into a cell will increase if the

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permeability constant for that solute increases.

concentration of that solute in the extracellular fluid increases.

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23. Which of the following statements regarding the movement of molecules across cell membranes is correct?

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The diffusion of molecules across a cell membrane occurs at a rate that is influenced by the surface area of the membrane and the magnitude of the concentration difference across it.

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24. “Osmosis” refers to the movement of across semi-permeable membranes.

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water

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25. If a cell is placed in a hyperosmotic solution, it

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may swell, shrink, or stay the same size, depending upon the concentration of penetrating and nonpenetrating solutes in the solution.

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26. Which of the following statements regarding endocytosis and exocytosis is correct?

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Endocytosis is a method by which large molecules may be brought into a cell.

Exocytosis is a method by which large molecules may be secreted from a cell.

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27. Exocrine glands differ from endocrine glands in that the former

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are formed from infoldings of embryonic epithelium whereas the latter are not.

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28. A ligand is a molecule that binds to

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a protein by noncovalent bonds.

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29. The affinity of a ligand for its binding site is determined by

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the number and position of mutually attracting electrical charges.

the number and position of mutually attracting hydrophobic surfaces.

the presence or absence of interfering or hindrance determinants

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30. The term “metabolism”

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refers to all the chemical reactions that occur in the body.

includes the synthesis of complex molecules from simpler molecules.

includes the breakdown of complex molecules into simpler molecules.

includes anabolism and catabolism.

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31. With regard to chemical reaction rates, which of the following statements is true?

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Increasing the concentration of the reactants will increase the reaction rate.

Increasing the temperature will increase the reaction rate

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32. A catalyst for a chemical reaction

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lowers the activation energy of the reaction.

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33. Enzymes

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are catalysts in chemical reactions.

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34. ATP

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represents the energy “currency” of all cells.

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35. The site where most of the ATP is generated in a cell is the

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mitochondria.

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36. Which of the following metabolic pathways does not require oxygen?

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Glycolysis

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37. The reactions of the Krebs cycle

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generate ATP directly by substrate phosphorylation

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38. Fatty acid catabolism

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is initiated by the binding of a molecule of coenzyme A.

proceeds by a process called beta-oxidation.

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39. Fatty acid synthesis

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takes place in the cytosol of cells.

results in molecules with an even number of carbon atoms only.

requires more energy than is produced by the catabolism of the same fatty acid

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40. Which of the following questions about G proteins is not correct? G proteins may

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act as second messengers

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41. Second messengers

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act in the cell cytoplasm.

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42. A given neuron can

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receive information from more than one other neuron.

transmit information to more than one other neuron

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43. An increase in the extracellular concentration of K+ above normal would result in

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an increase in intracellular K+.

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44. Action potentials are said to be “all-or-none” in character because

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the amplitude of an action potential generated in any given neuron is the same, regardless of the stimulus strength.

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45. Which of the following statements about the refractory period of a membrane is true?

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The absolute refractory period refers to the period of time during which another action potential cannot be initiated in that part of the membrane that has just undergone an action potential, no matter how great the strength of the stimulus.

The relative refractory period refers to the period of time during which another action potential can be initiated in that part of the membrane that has just undergone an action potential, if the stimulus is strong enough.

The refractory period prevents the action potential from spreading back over the part of the membrane that just underwent an action potential.

The refractory period places an upper limit on the frequency with which a nerve cell can conduct action potentials.

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46. Exocytosis of neurotransmitter into the synaptic cleft is triggered by an influx of ______ in response to the arrival of an action potential in the axon terminal.

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Ca2+

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47. An inhibitory postsynaptic potential

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is produced by an increased permeability to Cl- and/or K+.

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48. Temporal summation on a postsynaptic membrane

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refers only to addition of EPSPs.

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49. The significance of the initial segment of axons is that

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its threshold potential is lower than that of the cell body and dendrites.

synapses close to it are more effective in influencing whether an action potential will be generated in that axon than are synapses farther away from the initial segment

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50. The portion of the peripheral nervous system that is composed of nerve fibers that innervate skeletal muscle is the

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somatic motor nervous system.