Basic Principles of Animal Form and Function

What properties do all types of epithelia share?

Consider the idealized animal in Figure 40.4. At which sites must oxygen cross a plasma membrane in traveling from the external environment to the cytoplasm of a body cell?

Suppose you are standing at the edge of a cliff and suddenly slip, barely managing to keep your balance and avoid falling. As your heart races, you feel a burst of energy, due in part to a surge of blood into dilated (widened) vessels in your muscles and an upward spike in the level of glucose in your blood. Why might you expect that this “fight-or-flight” response requires both the nervous and endocrine systems?

How does negative feedback in thermoregulation differ from feedback inhibition in an enzyme-catalyzed biosynthetic process (see Figure 8.21)

If you were deciding where to put the thermostat in a house, what factors would govern your decision? How do these factors relate to the fact that many homeostatic control sensors in humans are located in the brain?

Like animals, cyanobacteria have a circadian rhythm. By analyzing the genes that maintain biological clocks, scientists concluded that the 24-hour rhythms of humans and cyanobacteria reflect convergent evolution (see Concept 26.2). What evidence would have supported this conclusion? Explain.

What mode of heat exchange is involved in “wind chill,” when moving air feels colder than still air at the same temperature? Explain.

Flowers differ in how much sunlight they absorb. Why might this matter to a hummingbird seeking nectar on a cool morning?

Why is shivering likely during the onset of a fever?

You can estimate the contribution of each wedge in a pie chart by remembering that the entire circle represents 100%, half is 50%, and so on. What percent of the mouse's energy budget goes to basal metabolism? What percent of the penguin's budget is for activity?

Without considering the sizes of the wedges, how do the three pie charts differ in which functions they include? Explain these differences.

Does the penguin or the mouse expend a greater proportion of its energy budget on thermoregulation? Why?

Now look at the total annual energy expenditures for each animal. How much more energy does the penguin expend each year compared to the similarly sized python?

Which animal expends the most kilocalories per year on thermoregulation?

If you monitored energy allocation in the penguin for just a few months instead of an entire year, you might find the growth category to be a significant part of the pie chart. Given that adult penguins don’t grow from year to year, how would you explain this finding?

If a mouse and a small lizard of the same mass (both at rest) were placed in experimental chambers under identical environmental conditions, which animal would consume oxygen at a higher rate? Explain.

Which animal must eat a larger proportion of its weight in food each day: a house cat or an African lion caged in a zoo? Explain.

Suppose the animals at a zoo were resting comfortably and remained at rest while the nighttime air temperature dropped. If the temperature change were sufficient to cause a change in metabolic rate, what changes would you expect for an alligator and a lion?

The body tissue that consists largely of material located outside of cells is

(A) epithelial tissue.

(B) connective tissue.

(C) muscle tissue.

(D) nervous tissue. 

Compared with a smaller cell, a larger cell of the same shape has 

(A) 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.

Which of the following would increase the rate of heat exchange between an animal and its environment?

(A) feathers or fur.

(B) vasoconstriction.

(C) wind blowing across the body surface.

(D) countercurrent heat exchanger.

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; mouse 

(B) elephant; human 

(C) mouse; snake 

(D) penguin; mouse 

An animal's inputs of energy and materials would exceed its outputs 

(A) if the animal is an endotherm, which must always take in more energy because of its high metabolic rate. 

(B) if it is actively foraging for food. 

(C) if it is growing and increasing its mass. 

(D) never; due to homeostasis, these energy and material budgets always balance.

You are studying a large tropical reptile that has a high and relatively stable body temperature. How do you determine whether this animal is an endotherm or an ectotherm? 

(A) You know from its high and stable body temperature that it must be an endotherm.

(B) You subject this reptile to various temperatures in the lab and find that its body temperature and metabolic rate change with the ambient temperature. You conclude that it is an ectotherm.

(C) You note that its environment has a high and stable temperature. Because its body temperature matches the environmental temperature, you conclude that it is an ectotherm.

(D) You measure the metabolic rate of the reptile, and because it is higher than that of a related species that live in temperate forests, you conclude that this reptile is an endotherm, and its relative is an ectotherm.

Which of the following animals uses the largest percentage of its energy budget for homeostatic regulation?

(A) marine jelly (an invertebrate) 

(B) snake in a temperate forest 

(C) desert insect.

(D) desert bird.

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.

In 1847, the German biologist Christian Bergmann noted that mammals and birds living at higher latitudes (farther from the equator) are on average larger and bulkier than related species found at lower latitudes. Suggest an evolutionary hypothesis to explain this observation.

Eastern tent caterpillars (Malacosoma americanum) live in large groups in silk nests resembling tents, which they build in trees. They are among the first insects to be active in early spring when the daily temperature fluctuates from freezing to very hot. Over the course of a day, they display striking differences in behavior: Early in the morning, they rest in a tightly packed group on the tent's east-facing surface. In midafternoon, they are on its undersurface, each caterpillar hanging by a few of its legs. Propose a hypothesis to explain this behavior. How could you test it? 

Medical researchers are investigating artificial substitutes for various human tissues. Why might artificial blood or skin be useful? What characteristics would these substitutes need in order to function well in the body? Why do real tissues work better? Why not use the real tissues if they work better? What other artificial tissues might be useful? What problems do you anticipate in developing and applying them?

In a short essay (about 100–150 words) focusing on energy transfer and transformation, discuss the advantages and disadvantages of hibernation. 

These macaques (Macaca fuscata) are partially immersed in a hot spring in a snowy region of Japan. What are some ways that form, function, and behavior contribute to homeostasis for these animals?