38. Animal Form and Function

Thermoregulation

Textbook Question
The dinosaur Apatosaurus (Brontosaurus) is one of the largest terrestrial animals that ever lived—over 20 m in length and weighing over 20 metric tons. Is it more likely that Apatosaurus was homeothermic or poikilothermic? Explain.
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Textbook Question
The mosquito-borne Zika virus (ZIKV) is one of the most feared viruses for pregnant women. Recent statistics justify this fear: Infants born to mothers infected with ZIKV during pregnancy face a risk of up to 42 percent of developing birth defects, including microcephaly (an abnormally small head and decreased brain volume).
What do we know about how ZIKV causes damage to the developing brain?
ZIKV is a Baltimore class IV virus. Based on this classification, what do you know about the structure of its genome?
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Textbook Question
After a long, hot run together, your friend tells you that you should dunk your head into a cooler of water to lower your body temperature more rapidly, rather than sitting and waiting to cool down. What do you think? Form a hypothesis about how the ice-cold water might affect the rate at which your body temperature returns to normal. How could you test your hypothesis?
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Textbook Question
You are in a room of empty chairs. As the chairs fill with people, you become hotter and hotter. A ceiling fan is turned on, and you feel cooler. You gained heat by _________ and lost heat to the environment by _________ .
a. Conduction … convection
b. Radiation … convection
c. Radiation … conduction
d. Convection … radiation
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Textbook Question
Can ectotherms have stable body temperatures? Explain.
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Textbook Question
Some diuretics are on a list of substances that the International Olympic Committee has banned for use by athletes. What do diuretics do? Propose an explanation for how diuretic use could be an unfair advantage for a competitor in a sport like wrestling, in which weight classes are part of the competition.
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Textbook Question
You are studying a large tropical reptile that has a high and relatively stable body temperature. How would you determine whether this animal is an endotherm or an ectotherm?
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Textbook Question
Dolphins have an insulating layer of blubber that protects them from cold water, but their flippers are not insulated. Propose a hypothesis to explain why dolphin flippers do not freeze. Describe an experiment you could do to test your hypothesis. (You may assume you have equipment for measuring temperatures in dolphin flippers.) What results would you expect if your hypothesis is correct?
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Textbook Question
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 living at lower latitudes. Suggest an evolutionary hypothesis to explain this observation.
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Open Question
a. Consider three spheres with radii of 1 cm, 5 cm, and 10 cm. Based on what you read in the chapter, predict which sphere will have the highest surface area to volume ratio, and which sphere will have the lowest.
b. Next, calculate the surface area and the volume of each sphere. (Surface area of a sphere=4𝜋𝑟2; volume of a sphere=(4/3)𝜋𝑟3.) Plot the results on a graph with radius on the 𝑥-axis and surface area and volume on the 𝑦-axis.
c. Which sphere has the highest surface area to volume ratio? The lowest? Explain how the graph shows the relationship between size and surface area to volume ratio.
d. Now imagine that these spheres represent a small, medium, and large endothermic animal. Which animal would lose heat most rapidly? Explain using the surface area to volume ratio.
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