Question 1

Which of the following best explains why small mammals, such as shrews, have higher mass-specific metabolic rates than large mammals, such as elephants?

Accepted Answer

Small mammals have a higher surface area-to-volume ratio, leading to greater heat loss and a need for higher metabolic rates to maintain body temperature.

Question 2

Given the equation for basal metabolic rate (BMR) as $$MR = aM^b$$, what does the exponent $$b$$ represent in the context of animal physiology?

Accepted Answer

The scaling relationship between body mass and metabolic rate across species.

Question 3

If a cube has a side length of 3 cm, what is its surface area to volume ratio?

Accepted Answer

$$2:1$$

Question 4

Why does volume increase more rapidly than surface area as an animal grows larger?

Accepted Answer

Because volume scales with the cube of length ($$l^3) $$while surface area scales with the square of length ($$l^2).$$

Question 5

A mouse has a mass-specific oxygen consumption rate of $$1.65 \ \mathrm{ml} \ g$$^{-1}$$ \ h$$^{-1}$$, while an elephant has 0.07$$ \ \mathrm{ml} \ $$g^{-1}$$ \ $$h^{-1}. $$What does this indicate about their relative metabolic demands?

Accepted Answer

The mouse requires much more energy per gram of tissue than the elephant.

Question 6

If the relationship between metabolic rate and mass is $$MR = aM$$^{0.75}$$, what happens to the mass-specific metabolic rate (MR/$$Mass$$) as mass increases?

Accepted Answer

It decreases, because $$MR/Mass = aM$$^{-0.25}$$.

Question 7

Which of the following is a direct consequence of the decrease in surface area-to-volume ratio as animals increase in size?

Accepted Answer

Larger animals lose heat more slowly relative to their volume.

Question 8

A researcher plots the log of metabolic rate ($$\log MR) $$against the log of body mass ($$\log M) $$for several mammal species and finds a straight line. What does the slope of this line represent?

Accepted Answer

The scaling exponent $$b in $$the equation $$MR = aM^b.$$

Question 9

Which of the following best describes why an elephant, despite being much larger than a mouse, has a lower mass-specific metabolic rate?

Accepted Answer

Larger animals have a lower surface area-to-volume ratio, reducing the rate of heat loss and thus requiring a lower metabolic rate per gram.

Question 10

If a blue whale has a mass of $$100,000 \ \mathrm{kg}$$ and a mass-specific oxygen consumption of $$0.04 \ \mathrm{ml} \ g$$^{-1}$$ \ h$$^{-1}$$, what is the total oxygen consumption per hour?

Accepted Answer

$$4,000,000 \ \mathrm{ml} \ h$$^{-1}$$

Question 11

Which of the following physiological traits is predicted to scale with body mass in a similar way to metabolic rate?

Accepted Answer

Heart rate

Question 12

A cube with a side length of 2 cm has a surface area of $$24 \ \mathrm{cm}^2$$ and a volume of $$8 \ \mathrm{cm}^3. $$What is its surface area-to-volume ratio?

Accepted Answer

$$3:1$$

Question 13

If two animals have the same total metabolic rate but different body masses, which animal will have the higher mass-specific metabolic rate?

Accepted Answer

The smaller animal

Question 14

Which of the following statements about the relationship between body size and lifetime number of offspring is most accurate?

Accepted Answer

Larger animals tend to have fewer offspring over their lifetime compared to smaller animals.

Question 15

A rat has a mass of $$0.29 \ \mathrm{kg}$$ and a mass-specific oxygen consumption of $$0.87 \ \mathrm{ml} \ g$$^{-1}$$ \ h$$^{-1}$$. What is its total oxygen consumption per hour?

Accepted Answer

$$252.3 \ \mathrm{ml} \ h$$^{-1}$$

Question 16

Which of the following best explains why the relationship between metabolic rate and body mass is not directly proportional?

Accepted Answer

Metabolic rate increases with mass, but at a slower rate than mass itself, due to constraints such as surface area-to-volume ratio.

Question 17

If the surface area of a cube is given by $$6l^2$$ and the volume by $$l^3$$, what happens to the surface area-to-volume ratio as $$l$$ increases?

Accepted Answer

It decreases, because $$\frac{6l^2$}{l^3$} = \frac{6}{l}.$$

Question 18

Which of the following is a likely consequence for a small mammal if its metabolic rate were to decrease to the level of a large mammal (per gram of tissue)?

Accepted Answer

It would have difficulty maintaining its body temperature and could become hypothermic.

Question 19

Which of the following best describes the relationship between heart rate and body size in mammals?

Accepted Answer

Heart rate decreases as body size increases.

Body Size and Metabolic Scaling in Animals: Surface Area, Volume, and Energy Use

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