Question 1

_______ refers to the active process of maintaining a relatively stable internal environment.
A) Motivation
B) Endothermic
C) Homeostasis
D) Negative feedback

Accepted Answer

Homeostasis refers to the active process of maintaining a relatively stable internal environment, such as body temperature or blood sugar levels, to allow cells to function properly. Motivation refers to the drive or impulse to achieve a goal or satisfy a need. Endothermic refers to animals that regulate their body temperature internally, while exothermic animals rely on the environment to regulate their body temperature. Negative feedback is a mechanism in which the body responds to a stimulus by reversing or reducing the stimulus to maintain homeostasis.

Question 2

Endotherms may show a significant departure from their average body temperatures as a consequence of
A) negative feedback.
B) fever.
C) allostasis.
D) thermoregulation.

Accepted Answer

Endotherms may develop a fever in response to infection or illness, leading to a significant departure from their average body temperature.

Question 3

Which example demonstrates ectothermic behavior?
A) A dog panting on a hot day
B) A group of birds roosting together at night
C) A turtle basking on a sunny log
D) A person shivering in a cold house

Accepted Answer

Ectothermic animals, such as turtles, rely on the environment to regulate their body temperature. Basking on a sunny log helps them to warm up and increase their activity levels. Choices A, B, and D all involve endothermic animals, which maintain a stable body temperature through internal processes.

Question 4

One of the selective advantages of endothermy appears to be
A) greater tolerance for high external temperatures.
B) increased capacity to sustain a high level of muscular activity.
C) a reduction energy requirements.
D) a greater differential between the animal's metabolism during rest and during activity.

Accepted Answer

Endothermy allows for increased metabolism and the ability to produce heat internally, which in turn allows for a higher level of sustained muscular activity compared to ectotherms.

Question 5

Lesions to which brain region would impair physiological responses to temperature in endotherms?
A) Preoptic area
B) Brainstem
C) Medial hypothalamus
D) Dorsomedial thalamus

Accepted Answer

The preoptic area of the hypothalamus is responsible for regulating body temperature and plays a critical role in thermoregulation. Lesions to this region would impair the physiological responses to temperature in endotherms.

Question 6

Thermoregulation is considered a negative feedback system because
A) it requires such a great deal of energy.
B) larger temperature changes trigger smaller responses.
C) restoring the desired temperature turns off the response.
D) hot and cold temperatures are the opposite of each other.

Accepted Answer

Negative feedback systems work to maintain the body's internal environment within a narrow range of conditions. Thermoregulation is an example of a negative feedback system. When the body's temperature deviates from the desired range, sensors in the body detect the change and trigger responses to restore the temperature to the set point. Once the temperature returns to the desired range, the response is turned off, demonstrating the negative feedback loop. Therefore, choice C is correct.

Question 7

What is the significance of a set zone, as opposed to a precise set point, in terms of thermoregulation?
A) A set zone allows an animals more precise control over body responses.
B) The wide variety of conditions that animals face makes a tolerance, or set zone, instead of a precise set point, more adaptable.
C) A set zone is more adaptable in environments that are very stable.
D) A set point is more conducive to body regulation than a set zone is.

Accepted Answer

A set zone allows for greater adaptability in changing environments and a wider range of potential conditions that animals may face, compared to a precise set point which may be too rigid and difficult to maintain in constantly changing conditions.

Question 8

Behavioral regulation of body temperature, like moving closer to the fire, is especially affected by lesions of the
A) lateral hypothalamus.
B) preoptic area.
C) ventromedial hypothalamus.
D) amygdala.

Accepted Answer

The lateral hypothalamus is involved in the regulation of body temperature. Lesions of the lateral hypothalamus can lead to a decrease in body temperature, as the animal is no longer able to generate heat to maintain its body temperature.

Question 9

Suppose that your car battery dies, and you find yourself stranded in a winter storm. Which response would not be considered a behavioral mechanism for regulating body temperature while you are waiting for help to arrive?
A) Lowering your breathing rate
B) Building a snow cave
C) Ripping some of the upholstery out of the car and using it as extra insulation under your clothing
D) Huddling in the fetal position

Accepted Answer

Lowering your breathing rate is not a behavioral mechanism for regulating body temperature. It may help regulate metabolism and conserve energy but it does not directly affect body temperature. The other choices all involve physical actions that can help regulate body temperature in a winter storm. Building a snow cave or using upholstery as insulation can provide shelter and warmth, while huddling in the fetal position reduces surface area exposure to the cold.

Question 10

Which response is not a physiological response of the mammalian thermoregulatory system?
A) Increased thyroid activity
B) Constriction of cutaneous blood vessels
C) Sweating
D) Lying in the shade

Accepted Answer

Lying in the shade is a behavioral response and not a physiological response of the mammalian thermoregulatory system. Physiological responses involve changes in the body's internal processes, such as increasing thyroid activity to increase metabolic rate, constricting cutaneous blood vessels to conserve heat, or sweating to release heat through evaporation. Lying in the shade is a behavioral response that removes the animal from direct sunlight and reduces heat gain, but it does not involve any internal processes.

Question 11

In mammals, the saltiness of the _______ environment _______.
A) intracellular; is similar to that of seawater
B) intracellular; is saltier than that of seawater
C) extracellular; is similar across species
D) extracellular; varies widely among species

Accepted Answer

The saltiness of the extracellular environment in mammals is maintained within a relatively narrow range and is similar across different species, ensuring proper cellular function and homeostasis.

Question 12

The body fluid compartments change with _______ upon severe water loss.
A) increased blood pressure and increased plasma volume
B) decreased blood pressure and no change in plasma volume
C) decreased blood pressure and decreased plasma volume
D) increased blood pressure and decreased plasma volume

Accepted Answer

Severe water loss will lead to dehydration, which causes a decrease in blood pressure and a decrease in plasma volume due to fluid shifts from the intravascular to the interstitial spaces.

Question 13

A(n) _______ solution is a solution with the same concentration as physiological saline.
A) isotonic
B) hypertonic
C) hypotonic
D) neotonic

Accepted Answer

An isotonic solution has the same concentration of solutes as the fluid inside the cell or organism, such as physiological saline. Hypertonic solutions have a higher concentration of solutes and hypotonic solutions have a lower concentration of solutes. Neotonic is not a scientific term.

Question 14

Which statement correctly describes osmotic pressure?
A) The tendency of a solvent to move across a membrane in order to equalize the concentration of solute on both sides of the membrane
B) The spontaneous spread of solute molecules through a solvent
C) The force of solute against a cell membrane
D) The tendency of a solvent to sink due to higher density.

Accepted Answer

Osmotic pressure is the pressure exerted by a solvent in a solution with a higher concentration of solute, to move across a semipermeable membrane to an area with lower concentration of solute in order to equalize the concentration on both sides of the membrane.

Question 15

When a cell comes into contact with pure water it
A) shrinks.
B) swells.
C) does not change.
D) immediately dies.

Accepted Answer

When a cell comes into contact with pure water, water molecules move into the cell via osmosis, causing the cell to swell. This is because the concentration of solutes inside the cell is higher than the concentration of solutes outside the cell. If the cell continues to take in water, it may burst or undergo lysis.

Question 16

The receptors that detect drops in extracellular volume are located in the
A) hypothalamus.
B) kidneys.
C) ventricular system.
D) vascular system.

Accepted Answer

The vascular system contains baroreceptors that detect changes in blood pressure and volume, signaling the body to adjust fluid balance accordingly.

Question 17

When an animal loses a lot of blood, there is a tendency of baroreceptors to signal
A) grooming.
B) fatigue.
C) temperature increase.
D) thirst.

Accepted Answer

When an animal loses blood, it can lead to dehydration which triggers thirst. This is especially important to maintain fluid balance and prevent further decrease in blood volume. Therefore, the baroreceptors will signal thirst.

Question 18

Which circumventricular organ contains osmosensory neurons?
A) Subfornical organ
B) Organum vasculosum of the lamina terminalis (OVLT)
C) Periventricular organ
D) Area postrema

Accepted Answer

The organum vasculosum of the lamina terminalis (OVLT) contains osmosensory neurons, which detect changes in osmotic pressure in the blood and help regulate fluid homeostasis. The other circumventricular organs listed (subfornical organ, periventricular organ, and area postrema) have other functions such as regulating hormone release or detecting toxins in the blood.

Question 19

The brain responds to hypovolemia by triggering both thirst and hunger for
A) protein.
B) carbohydrates.
C) sugar.
D) salt.

Accepted Answer

When the body experiences hypovolemia (low blood volume), it typically triggers a craving for salt (sodium). This is because sodium helps to retain water in the body and increase blood volume. While thirst is also a common response to hypovolemia, hunger for specific macronutrients like protein, carbohydrates, or sugar is not typically associated with this condition.

Question 20

The two main kinds of thirst are _______ thirst and _______ thirst.
A) osmotic; hypervolemic
B) isotonic; isovolemic
C) osmotic; hypovolemic
D) hypotonic; hypervolemic

Accepted Answer

Osmotic thirst is caused by an increase in the concentration of solutes in the extracellular fluid, which triggers the thirst mechanism in response to the osmotic pressure. Hypovolemic thirst is caused by low blood volume and blood pressure, which triggers the thirst mechanism in response to decreased blood pressure. The other options are incorrect because isotonic and hypotonic do not accurately describe the causes of thirst, and hypervolemic does not describe a type of thirst at all.

Quiz 10: Homeostasis: Active Regulation of the Internal Environment

_______ refers to the active process of maintaining a relatively stable internal environment.

Endotherms may show a significant departure from their average body temperatures as a consequence of

Which example demonstrates ectothermic behavior?

One of the selective advantages of endothermy appears to be

Lesions to which brain region would impair physiological responses to temperature in endotherms?

Thermoregulation is considered a negative feedback system because

What is the significance of a set zone, as opposed to a precise set point, in terms of thermoregulation?

Behavioral regulation of body temperature, like moving closer to the fire, is especially affected by lesions of the

Suppose that your car battery dies, and you find yourself stranded in a winter storm. Which response would not be considered a behavioral mechanism for regulating body temperature while you are waiting for help to arrive?

Which response is not a physiological response of the mammalian thermoregulatory system?

In mammals, the saltiness of the _ environment _.

The body fluid compartments change with _______ upon severe water loss.

A(n) _______ solution is a solution with the same concentration as physiological saline.

Which statement correctly describes osmotic pressure?

When a cell comes into contact with pure water it

The receptors that detect drops in extracellular volume are located in the

When an animal loses a lot of blood, there is a tendency of baroreceptors to signal

Which circumventricular organ contains osmosensory neurons?

The brain responds to hypovolemia by triggering both thirst and hunger for

The two main kinds of thirst are _ thirst and _ thirst.