Question 1

Which of the following scenarios illustrates the physiological response of acclimatization?
A) Desert- dwelling plants such as the cactus have developed long root systems to ensure that they get enough water.
B) A dog sheds its thick winter fur for a lighter coat of fur when the temperature warms in the spring and summer.
C) Genetic changes have occurred in populations that have lived high in the Alps for many generations that allow individuals in these populations to cope with an environment with low oxygen.

Accepted Answer

Acclimatization refers to the physiological adjustments organisms make in response to changes in their environment, such as temperature changes. The dog shedding its thick winter fur for a lighter coat in response to warmer temperatures is an example of an acclimatization response. Choices A and C describe adaptations, which are long-term evolutionary changes, rather than immediate physiological responses.

Question 2

Scientists have performed studies to show that having a fever is adaptive. Which of the following observations in an ectotherm would be consistent with this conclusion?
A) An ectotherm with a fever will tend to stay warm by covering with a blanket.
B) An ectotherm with a fever will seek out cooler environments, like a tub of cool water.
C) An ectotherm will develop a fever after an infectious organism has been destroyed in order to speed healing.
D) An ectotherm with a fever will tend to decrease overall activity levels in order to keep from overheating.

Accepted Answer

Ectotherms rely on external sources of heat to regulate their body temperature. If having a fever is adaptive, an ectotherm with a fever would seek out warmer environments to increase their body temperature, similar to covering with a blanket, to enhance immune function.

Question 3

You are a doctor and you are given the files of two patients who are identical twin brothers: Patient #1: 25 year old male, 30% muscle mass, 70% fat content, 37 degrees C internal temperature Patient #2: 25 year old male, 70 % muscle mass, 30% fat content, 37 degrees C internal temperature
If you are told that both patients are equally active and are completely healthy, which of the following assumptions can we make regarding the metabolic rates of the brothers?
A) Patient # 1 likely has a lower metabolic rate than Patient # 2.
B) Patient # 1 and Patient # 2 likely have the same metabolic rate.
C) Patient # 1 likely has a higher metabolic rate than Patient # 2.

Accepted Answer

Muscle tissue is more metabolically active than fat tissue, meaning it burns more calories at rest. Therefore, Patient #2, with a higher muscle mass (70%), is likely to have a higher metabolic rate than Patient #1, who has a higher fat content (70%).

Question 4

Which term best describes an animal that, although generating a significant amount of heat through metabolism, nonetheless does not maintain a constant body temperature?
A) heterothermic endotherm
B) homeothermic endotherm
C) heterothermic ectotherm
D) homeothermic ectotherm

Accepted Answer

Heterothermic endotherms are animals that generate heat through metabolism but can allow their body temperature to vary, unlike homeothermic endotherms that maintain a constant body temperature.

Question 5

Which of the following is an example of a structure that has an increased surface area for absorption?
A) an earthworm's segmented body
B) a cheetah's large nostrils
C) a human's lungs with many thin- walled alveoli
D) a cow's digestive tract consisting of 3 stomachs

Accepted Answer

The human lungs with many thin-walled alveoli have an increased surface area for absorption. This allows for efficient exchange of gases during respiration, including the absorption of oxygen into the bloodstream. The other choices do not necessarily involve absorption, and even if they do (such as the cow's digestive tract), they do not have an increased surface area for absorption.

Question 6

Use the following information when answering the question below.
The crucian carp Carassius carassius) is a Northern European freshwater fish often inhabiting ponds that become hypoxic hav reduced oxygen levels) and even anoxic have no oxygen) when the surface freezes during the winter. Surprisingly, when oxygen levels are normal, these fish lack the lamellae that provide a large surface area for gas exchange between water and blood: their gills are smooth. Yet when the level of oxygen in the water falls, the gill morphology undergoes a change:
packing cells stop dividing and programmed cell death is induced, exposing gill lamellae that were buried in other tissue. With lamellae exposed, the gills have increased surface area for gas exchange. These changes in gill lamellar profile are reversible: investigators observed that the gills return to their normal structure within 7 days after returning the fish to
well- oxygenated water. Jørund Sollid, Paula De Angelis, Kristian Gundersen, and Göran E. Nilsson. 2003. Hypoxia induces adaptive and reversible gross morphological changes in crucian carp gills. Journal of Experimental Biology 206:3667- 73.)
-Gills serve multiple functions in fish in addition to gas exchange. Given the large surface area of gills with lamellae, what is the most likely explanation for why crucian carp cover protruding lamellae in their gills when levels of oxygen are normal?
A) to prevent loss of heat to the surrounding water
B) to prevent protein loss to the surrounding water
C) to prevent loss of ions to the surrounding water
D) to prevent loss of oxygen to the surrounding water

Accepted Answer

The large surface area of gills with lamellae would facilitate not only gas exchange but also the exchange of ions between the fish and its environment. When oxygen levels are normal, covering the lamellae reduces unnecessary ion loss to the surrounding water, maintaining the fish's ion balance.

Question 7

Which of the following is an example of negative feedback?
A) During birthing contractions, the hormone oxytocin is released and acts to stimulate further contractions.
B) When blood glucose concentration increases, the pancreas produces and releases the hormone insulin. Insulin acts to decrease blood glucose. As blood glucose decreases, the rate of production and release of insulin decreases.
C) When a baby is nursing, suckling leads to the production of more milk and a subsequent increase in the secretion of prolactin, which in turn stimulates lactation.
D) After a blood vessel is damaged, signals are released by the damaged tissues that activate platelets in the blood. These activated platelets release chemicals that activate more platelets.

Accepted Answer

Negative feedbacks involve a response that works to counteract a stimulus or disturbance, in order to maintain or restore a stable state or set point. In option B, blood glucose concentration is the stimulus, and insulin release is the response that works to decrease glucose concentration. As glucose concentration decreases, the rate of insulin production and release is also reduced, thus providing negative feedback to prevent excessive lowering of blood glucose. Option A, C, and D describe positive feedback mechanisms, which involve a response that amplifies or reinforces a stimulus or deviation from a set point, leading to an enhanced or accelerated change in the same direction.

Question 8

Which of the following statements comparing endotherms and ectotherms is FALSE?
A) Mitochondrial density and enzyme activity are 3- 4 times higher in the cells of endotherms than in the cells of ectotherms of similar size.
B) Ectotherms can use more of their energy intake for reproduction than endotherms can.
C) Endotherms and ectotherms have about the same mass- specific metabolic rate.
D) Both endotherms and ectotherms exchange heat with the environment through convection, conduction, radiation, and evaporation.
E) B, C, and D are all false.

Accepted Answer

Endotherms have a higher mass-specific metabolic rate than ectotherms due to their need to maintain their internal body temperature.

Question 9

Structure- function correlations exist throughout nature at all levels of organization, from the cellular level to systems level. Keeping this in mind, you visualize a cell under a microscope and it contains a lot of rough endoplasmic reticulum. What might you hypothesize the primary function of the cell to be?
A) participation in the immune response
B) energy storage
C) hormone protein) synthesis and release
D) conduction of electrical signals

Accepted Answer

The answer of Structure- function correlations exist throughout nature at...

Question 10

Which of the following explanations for brown adipose tissue explains why infant humans and some small mammals have this tissue type?
A) This tissue stores more heat than other types of fat because of its darker colour.
B) This tissue can convert ATP into heat energy instead of using it for muscle contraction and other energy- requiring processes.
C) This tissue allows for the conversion of fats directly into heat without the production of ATP.
D) This tissue type has less water than other adipose tissues and thus has less evaporative cooling.

Accepted Answer

Brown adipose tissue is specialized for non-shivering thermogenesis, where it converts fats directly into heat without producing ATP, helping infants and small mammals maintain body temperature.

Question 11

Many types of ectothermic animals can be seen lying out in the sun on a warm, sunny day. What is the primary mechanism by which the animal warms itself during this activity?
A) conduction
B) radiation
C) evaporation
D) convection

Accepted Answer

Ectothermic animals warm themselves primarily through radiation, which involves absorbing heat from the sun's rays. Conduction and convection refer to heat transfer through direct contact with a warm surface or a moving fluid, respectively, which may play a role in warming the animal but are not the primary mechanism. Evaporation is a cooling mechanism rather than a warming mechanism.

Question 12

Natural selection has contributed to the wide variety of beak morphologies exhibited by the Galápagos Island finches. A correlation exists whereby beak morphology suggests the primary food source of the finch. Which physiological response listed below best describes the variety of beak morphologies seen in these finches?
A) acclimation
B) acclimatization
C) adaptation

Accepted Answer

The variety of beak morphologies seen in Galápagos Island finches is best described as an adaptation, as natural selection has favored the development of different beak structures in response to different food sources.

Question 13

Torpor has evolved in several high- latitude species even though it is energetically expensive. Why does this adaptation require a large energy input for those species that utilize this function?
A) During torpor, animals undergo excessive shivering to maintain their body temperature.
B) Animals in torpor lower their body temperature dramatically and require a great deal of energy to bring the body temperature back up to normal.
C) It takes a great deal of energy to stay alive when the body temperature drops to near ambient levels.
D) These animals expend a great deal of metabolic energy to maintain their body temperature as the ambient temperatures drop.

Accepted Answer

Torpor involves lowering the body temperature, which requires energy to bring it back up to normal.

Question 14

Which principle of heat exchange is the most important explanation for why birds look larger in colder weather because they fluff their feathers?
A) Fluffing creates a pocket of air near the bird that acts as insulation.
B) Fluffing decreases the surface area/volume ratio, thus decreasing the amount of heat lost to the environment.
C) Fluffing feathers results in less cooling by radiation since feathers emit less infrared radiation than other tissues do.
D) Fluffing decreases the amount of heat lost by conduction when the bird makes contact with cold objects in its environment.

Accepted Answer

Fluffing creates a pocket of air near the bird that acts as insulation, which is a key principle of heat exchange. This trapped air acts as an insulating layer, reducing the amount of heat lost from the bird's body to the cold environment.

Question 15

What is the main reason that a person sitting on the beach with an air temperature of 15°C loses heat less rapidly than when immersed in lake water at 15°C?
A) Metabolic heat production is greater in air than in water.
B) Air is a poor insulator.
C) Water conducts heat more efficiently than air does.
D) Water evaporates, and heat is lost to evaporation.

Accepted Answer

Water conducts heat more efficiently than air does, meaning that heat is transferred away from the body more quickly when immersed in water compared to sitting in air.

Question 16

After you eat a meal, blood glucose concentration increases. Insulin is released from the pancreas to restore blood glucose concentration by facilitating the uptake of glucose by cells and stimulating the conversion of glucose to glycogen. What homeostatic mechanism is this an example of?
A) negative feedback
B) positive feedback
C) feedback inhibition
D) neutralizing feedback

Accepted Answer

This is an example of negative feedback, where a change in a variable (increase in blood glucose concentration) triggers a response that opposes the change and restores the variable to its set point (insulin release to facilitate uptake of glucose by cells and convert glucose to glycogen).

Question 17

Multicellular organisms are limited by size and, thus, ways to increase surface area of a structure are often advantageous. Which of the following pairs of words best describes ways to increase the surface area of a structure?
A) shortening and flattening
B) flattening and converging
C) shortening and converging
D) folding and branching

Accepted Answer

Folding and branching both create a more complex structure that increases the amount of surface area within a limited space. Shortening and flattening or converging would both decrease surface area, so they are not the best choices.

Quiz 39: Animal Form and Function

Which of the following scenarios illustrates the physiological response of acclimatization?

Scientists have performed studies to show that having a fever is adaptive. Which of the following observations in an ectotherm would be consistent with this conclusion?

Which term best describes an animal that, although generating a significant amount of heat through metabolism, nonetheless does not maintain a constant body temperature?

Which of the following is an example of a structure that has an increased surface area for absorption?

Which of the following is an example of negative feedback?

Which of the following statements comparing endotherms and ectotherms is FALSE?

Which of the following explanations for brown adipose tissue explains why infant humans and some small mammals have this tissue type?

Many types of ectothermic animals can be seen lying out in the sun on a warm, sunny day. What is the primary mechanism by which the animal warms itself during this activity?

Torpor has evolved in several high- latitude species even though it is energetically expensive. Why does this adaptation require a large energy input for those species that utilize this function?

Which principle of heat exchange is the most important explanation for why birds look larger in colder weather because they fluff their feathers?

What is the main reason that a person sitting on the beach with an air temperature of 15°C loses heat less rapidly than when immersed in lake water at 15°C?

After you eat a meal, blood glucose concentration increases. Insulin is released from the pancreas to restore blood glucose concentration by facilitating the uptake of glucose by cells and stimulating the conversion of glucose to glycogen. What homeostatic mechanism is this an example of?

Multicellular organisms are limited by size and, thus, ways to increase surface area of a structure are often advantageous. Which of the following pairs of words best describes ways to increase the surface area of a structure?