38. Animal Form and Function

What are three attributes of mitochondria and chloroplasts that suggest they were once free-living bacteria?

Which of these examples best describes the concept that form facilitates function?a. Crickets must balance their resources between spermatophore production and immune defenses.b. A desert jackrabbit has large ears that help eliminate excess heat.c. An Antarctic fish maintains homeostasis by conforming to the stable, external temperature.d. Honeybees will swarm around a predatory wasp and contract their flight muscles to generate a lethal ball of heat.

Consider the energy budgets for a human, an elephant, a penguin, a mouse, and a snake. The would have the highest total annual energy expenditure, and the would have the highest energy expenditure per unit mass.a. elephant; mouseb. elephant; humanc. mouse; snaked. penguin; mouse

The cells of an ant and an elephant are, on average, the same small size; an elephant just has more of them. What is the main advantage of small cell size? (Explain your reasoning.)a. A small cell has a larger plasma membrane surface area than does a large cell.b. Small cells can better take up sufficient nutrients and oxygen to service their cell volume.c. It takes less energy to make an organism out of small cells.d. Small cells require less oxygen than do large cells.

Which of the following statements regarding surface area and volume in animals are correct? Select True or False for each statement.T/FAs an animal grows, its volume increases more rapidly than its surface area.T/FA chihuahua has a higher surface area to volume ratio than a great dane.T/FAnimals with high surface area to volume ratios heat and cool more slowly than animals with lower surface area to volume ratios.T/FAs an animal's volume increases, its total surface area decreases.

Compared with a smaller cell, a larger cell of the same shape hasa. less surface area.b. less surface area per unit of volume.c. the same surface-area-to-volume ratio.d. a smaller cytoplasm-to-nucleus ratio.

Negative-feedback mechanisms are a. most often involved in maintaining homeostasis. b. analogous to a furnace that produces heat. c. found only in birds and mammals. d. all of the above

Which of the following cell structures would you expect to be most important in the growth of bacteria on the surface of your teeth?a. cell wallb. fimbriaec. flagellad. cilia

Describe ways in which the bodies of complex animals are structured for exchanging materials with the environment. Do all animals share such features?

DRAW IT Draw a model of the control circuit(s) required for driving an automobile at a fairly constant speed over a hilly road. Indicate each feature that represents a sensor, stimulus, or response.

The eukaryotic cytoskeleton is a highly dynamic network of filaments and motor proteins. Which of the following correctly describe activities of these cytoskeletal components? Select True or False for each statement.T/FMyosin motors walk toward the plus ends of intermediate filaments.T/FDynein motors are responsible for the whip-like movement of eukaryotic flagella.T/FKinesin motors move vesicles along tracks toward the microtubule-organizing center.T/FActin filaments are required for cytoplasmic streaming.

Suppose a cell is placed in a solution with a high concentration of potassium and no sodium. How would the cellular sodium–potassium pump function in this environment?a. It would stop moving ions across the membrane.b. It would continue using ATP to pump sodium out of the cell and potassium into the cell.c. It would move sodium and potassium ions across the membrane, but no ATP would be used.d. It would reverse the direction of sodium and potassium ions to move them against their gradients.

George Palade's research group used the pulse–chase assay to elucidate the secretory pathway in pancreatic cells. If they had instead performed this assay on muscle cells, where would you expect the labeled proteins to end up during the chase? (Muscle cells consist primarily of actin and myosin filaments and have high energy demands for muscle contraction.)

Examine the experimental chamber in Figure 6.8a. Explain what would occur by osmosis if you added a 1-M solution of sodium chloride on the left side and an equal volume of a 1.5 M solution of potassium ions on the right. How might the addition of the CFTR protein to the lipid bilayer impact the direction of water movement?