Question 1

An elephant and a mouse are both running in full sunlight, and both overheat by the same amount above their normal body temperatures. When they move into the shade and rest, which animal will cool down faster?

Accepted Answer

The mouse will cool down faster because it has the lower surface area/volume ratio, meaning it has a larger surface area relative to its body size, which allows for greater heat loss through radiation and convection.

Question 2

What is the stratified epithelium composed of?

Accepted Answer

Stratified epithelium is composed of multiple layers of cells stacked from the basolateral side to the apical side.

Question 3

Which of the following is a true statement about body size and physiology?

Accepted Answer

This is known as the surface-area-to-volume ratio principle. As an animal's size increases, its surface area increases as a squared function while its volume (and therefore mass) increases cubically. This creates different physiological challenges for small and large animals, such as heat regulation, nutrient and gas exchange, and structural support. Choice A is false as an animal's nutrient use and waste production are directly proportional to its volume. Choice B is partially true as waste production increases proportionally with volume, but not necessarily twice as volume doubles. Choice D is false as larger animals require more food, oxygen, and produce more waste and heat than smaller animals.

Question 4

You begin exercising vigorously. This will, in a short time, cause your blood pH to begin dropping due to the release of carbon dioxide into your bloodstream. Which component of your homeostatic feedback system is responsible for deciding if your blood pH is far enough from normal that a response is necessary?

Accepted Answer

The integrator, which is typically the brain or a specific gland, is responsible for comparing the sensor's input (in this case, the pH levels) to the desired set point and determining if a response is necessary.

Question 5

Which one of the following is not a good strategy for increasing the surface area relative to the volume?

Accepted Answer

Enlarging and making an object more spherical decreases the surface area relative to the volume, as a sphere has the smallest surface area for a given volume compared to other shapes. This is contrary to increasing surface area relative to volume, which is achieved by making structures flatter, increasing folding, or increasing branching, as these strategies increase the surface area without a proportional increase in volume.

Question 6

Epithelial cells have multiple functions. They may have different structures on one of their surfaces compared to their opposite surface. What property of these cells allows them to undergo these various functions?

Accepted Answer

Epithelial cells are polar, meaning they have distinct structural and functional differences between their top (apical) and bottom (basolateral) surfaces. This polarity is reflected in the presence of an apical membrane and a basolateral membrane, which have different proteins and functions, enabling the cells to perform various roles such as absorption, secretion, and protection.

Question 7

Epithelial tissues have polarity, with an apical side that faces the environment and a basolateral side that faces the interior of the animal. Because of the harsh environmental exposure on the apical side, epithelial cells have a short life span of 2- 6 days. Which of the following is the most likely reason that the tissue as a whole does not wear away, despite the short life spans of the cells?

Accepted Answer

Epithelial tissue has a high rate of cell turnover due to the harsh environmental exposure on the apical side. However, the tissue as a whole does not wear away because the tissue has cells that actively undergo mitosis and cytokinesis to replace the lost cells. This process helps to maintain the integrity and function of the tissue.

Question 8

You discover a new species of bacteria that grows in aquatic environments with high salt levels. While studying these bacteria, you note that their internal environment is similar to the salt concentrations in their surroundings. You also discover that the internal salt concentrations of the bacteria change as the salt concentration in their environment changes. The new species can tolerate small changes in this way, but dies from large changes because it has no mechanism for altering its own internal salt levels. What type of homeostatic mechanism is this species using to regulate its internal salt levels?

Accepted Answer

The species is using a mechanism called conformation, where its internal salt concentrations change to match the salt concentrations of its environment. It does not have the ability to actively regulate or assimilate salt, nor does it integrate its internal salt levels with external cues.

Question 9

Wading birds in northern climates are able to walk in pools of water on ice without dying of hypothermia because they have countercurrent heat exchangers in their legs. These exchangers allow heat in warm blood going to the feet to be transferred to cool blood returning from the feet. Why are such countercurrent heat exchangers so efficient at conserving heat?

Accepted Answer

Countercurrent heat exchange is efficient at conserving heat because it maintains a constant gradient between the two currents, even as one current cools and the other heats, and there is a large temperature differential from one end of each current to the other. However, blood in the arteries and veins do flow in opposite directions, which increases the efficiency of heat transfer but also creates frictional losses, so choice C is not correct.

Question 10

How do the epithelial tissues covering organisms contribute to the maintenance of homeostasis?

Accepted Answer

Epithelial tissues covering organisms contribute to the maintenance of homeostasis by acting as a barrier to create an internal environment different from the external environment, regulating the exchange of ions between the body and the environment, and helping to prevent water loss from the body in a terrestrial environment. Therefore, all of the above options apply.

Question 11

A researcher is setting up an experiment to measure basal metabolic rate in prairie voles a small mouse- like mammal). Which of the following would be the best set of conditions for the voles immediately before and during the measurement?

Accepted Answer

Basal metabolic rate is the rate of energy expenditure at rest. To get an accurate measurement, the voles should not be stressed and should be in a relaxed state. House them with plenty of food and water to avoid stress and measure their BMR in a room that is the same temperature as where they were housed to avoid any temperature stress. The voles should also be fasted for a few hours before the measurement to ensure that their digestive processes do not affect the BMR. Therefore, Option D is the best choice.

Question 12

A woman standing and watching the stars on a cool, calm night will lose most of her body heat by which mechanism?

Accepted Answer

The woman will lose most of her body heat by radiation, as she is standing still and not in contact with any other objects. Convection and conduction require contact with other objects or fluids, and evaporation requires the presence of moisture on the skin.

Question 13

Natural selection involves energetic trade- offs between which of the following?

Accepted Answer

Natural selection involves a trade-off between producing high survival rates of offspring and the cost of parental care. If parents invest a lot of energy and resources in caring for their offspring, the survival rates of the offspring increase, but the parents will have fewer resources available for producing more offspring. If parents produce many offspring, they may not be able to provide enough care for all of them, which may decrease the survival rates of the offspring. Therefore, there is a balance between parental investment and reproductive success.

Question 14

Some animals have no gills when young, but then develop gills that grow larger as the animal grows larger. What is the reason for this trend?

Accepted Answer

The development of gills that grow larger as the animal grows larger could be due to the fact that when young, these animals have more surface area relative to their volume, which allows for efficient transport of oxygen through diffusion. However, as they grow larger, their volume increases faster than their surface area, making it more difficult to obtain sufficient oxygen through diffusion alone. Development of gills helps to increase the surface area available for oxygen exchange, enabling the larger body to be adequately supplied with oxygen.

Question 15

A behavioural physiologist is studying the homeostatic control of blood pH. In a trial, a lizard runs on a treadmill for a set amount of time and the blood pH is measured. The blood pH drops as carbon dioxide is released into the bloodstream. Which component of the homeostatic feedback system is responsible for determining whether the blood pH is far enough from normal that a response is necessary?

Accepted Answer

The integrator in a homeostatic feedback system is responsible for determining whether the variable (in this case, blood pH) has deviated from its set point enough to warrant a response. It receives information from sensors that monitor changes in conditions and then determines the appropriate response to bring the condition back to its normal state.

Question 16

Your professor announces he has discovered a new species of bird that feeds mostly on worms and soft- bodied insects picked up from the ground and off of leaves. Based on this information, what shape of beak would you predict for this bird?

Accepted Answer

Birds that feed mostly on worms and soft-bodied insects typically have long and narrow beaks, resembling tweezers, to pick up their prey from the ground or off leaves efficiently.

Question 17

Salmon are born in freshwater environments and then migrate to the sea. Near the end of their lives, they return to the freshwater stream where they were born to spawn. In freshwater, water constantly diffuses into the body and ions are lost from the body. In salt water, body water diffuses out of the body and excess ions are gained from the water. A salmon's gills have special cells to pump salt in or out of the body to maintain homeostasis. In response to the salmon's moves between freshwater and salt water, some cells in the gills are produced and others are destroyed. These changes made in the cells of the gills during the lifetime of an individual salmon are an example of which of the following?

Accepted Answer

The changes in the gill cells of salmon as they move between freshwater and saltwater environments to maintain homeostasis are an example of acclimatization. This is because acclimatization refers to the physiological adjustments organisms make in response to changes in their environment, which is exactly what the salmon are doing to survive in both freshwater and saltwater.

Question 18

Which class of tissue has many different types and functions in humans dictated by the unique extracellular matrix surrounding that tissue?

Accepted Answer

Connective tissue has a wide range of types and functions in humans due to the unique extracellular matrix that surrounds that tissue. Different types of connective tissue include bone, cartilage, adipose, and blood.

Question 19

What does the large surface area in the small intestine directly facilitate?

Accepted Answer

The large surface area in the small intestine directly facilitates absorption of nutrients from digested food into the bloodstream.

Question 20

Which of the following is not a function of an effector in the homeostatic regulation of temperature in mammals?

Accepted Answer

Comparing sensory input to the set point is not a function of an effector, but rather a function of the integrator (such as the hypothalamus) in the homeostatic regulation of temperature in mammals. Effector functions involve directly changing physiological processes to maintain the set point, such as constricting blood vessels or stimulating sweat glands.

Quiz 39: Animal Form and Function