Answer Key for Bio272b Midterm

 

Section A: True or false questions (1/2 mark each = 10 marks).  There is no deduction for wrong answers. Please mark A for true and B for false.

 

 

Q:

statement

t

f

1

Pleiotropy means that a single trait may be governed by many genes (pleiotropy means that a single gene may affect many traits)

 

B

2

The main advantage of the doubly-labelled water technique for measuring metabolic rate is that it can be used on free-living animals

A

 

3

The same genotype may produce different phenotypes under different environmental conditions

A

 

4

Convergent evolution occurs when closely related organisms exhibit similar traits (unrelated organisms exhibiting similar traits is convergent evolution  )

 

B

5

Large animals are more likely to be regulators than small animals

A

 

6

True BMR is difficult to measure

A

 

7

The peripheral limitation hypothesis suggests that metabolic rate is limited by the ability of the gut to process nutrients (this is the central limitation hypothesis)

 

B

8

In general, an animal moved from warm to cold temperatures acclimates faster than a similar animal moved from cold to warm temperatures (opposite: generally faster acclimation from cold → warm than warm→ cold)

 

B

9

Atmospheric O2 levels were greater in the Carboniferous than they are today

A

 

10

A closed circulatory system permits a larger body size than an open circulatory system

A

 

11

In endotherms, resting metabolic rate can be independent of ambient temperature  (thermoneutral zone)

A

 

12

Water boils at > 100° C at high altitude (> 100° C)

 

B

13

The solubility constant (a) of a particular gas depends on the partial pressure of that gas (solubility constant varies with temp, not partial pressure)

 

B

14

One thousand 20g mice require more energy than one 20kg dog

A

 

15

In humans, gas exchange cannot occur if atmospheric pressure is equal to vapor pressure at 37°C

A

 

16

Some fast-swimming fish do not have lamellar gills (do not have buccal pump, but still have lamellar gills)

 

B

17

Warm water contains less O2 than cold water, but warm water contains more CO2 than cold water (both gases are less soluble in warm than in cold water)

 

B

18

Gas exchange at a body surface is limited to small, sessile invertebrates (also amphibians, eels etc.)

 

B

19

Lethal temperatures vary more among ectotherms than among endotherms

A

 

20

On land, fish gills stick together because O2 levels in air are too high (stick together because of their densely packed structure)

 

B

 

 

Section B: Multiple Choice.  1 mark each = 7 marks

 

 

21.  At 10°C, a fish consumes oxygen at a rate of 10 mlO2h-1.  When moved to 20°C, its oxygen consumption increases to 20 mlO2h-1.  After 24h, it’s oxygen consumption declines to 7 mlO2h-1.   Which of the following statements is true?

 

A:   Q10 = 2

B:   After 24h, the fish shows partial compensation

C:   After 24h, the fish shows overcompensation

D:   The fish is unable to acclimate to 20°C

E:    Both A and C

 

(over a change of 10°C,  20 mlO2h-1/10 mlO2h-1 = 2; after 24h, MR is less than at beginning of expt = overcompensation)

 

22.  Consider 2 closely related species of birds, one weighing 20g and the other weighing 40g.  Which of the following statements is probably false?

 

A:   daily food consumption (as a  percentage of body mass) is greater in the 20g bird  than in the 40g bird

B:   the 40g bird can probably last longer without eating

C:   lung volume is the same in the two species

D:   body temperature is the same in the two species

 

(ratio of lung vol: body mass is same (isometric), but absolute lung volume is greater in the larger bird)

 

 

23.   Over the range of temperatures that an ectotherm normally functions in, its metabolic rate:

 

A:   typically increases as a multiple of 2 to 3 with every 10°C increase in

            temperature

B:   typically increases by an exponent of 2 or 3 with every 10°C increase in

            temperature

C:   will not change with temperature, at least before it becomes acclimatized

D:   will not change with temperature, at least within the thermoneutral zone

 

(Q10)

24.  In passerine (perching) birds, metabolic rate (mlO2h-1) = 7.5 Mb0.72 .  (Mb = body mass in grams).  In non-passerine birds, metabolic rate (mlO2h-1) = 4.6 Mb0.72 .  Which of the following statements is false?

 

A:  In both groups of birds, a 30 g bird has a higher metabolic rate than a 20g bird

B:  In both groups of birds, mass-specific metabolic rate scales with body mass

            with a slope of  -0.28

C:  At a given body size, metabolic rate of non-passerines is about 40% lower than that of a passerine

D:  The ratio of MR(passerine) to MR(non-passerine) decreases with increasing body mass.

 

(because the scaling exponent (b) is the same for both groups, the slopes are the same, but intercepts are different; therefore the ratio of MRp to MRnp is the same over the range of body masses)

 

25.  Not all traits are adaptive.  Which of the following statements is false regarding the presence of non-adaptive traits?

 

A:  A non-adaptive trait  may be selectively neutral

B:  A non-adaptive trait may be retained because it may later become useful

C:  A non-adaptive trait may be genetically linked to a trait under selection

D:  A non-adaptive trait may be fixed ancestrally in the lineage

 

(natural selection can’t see into the future; acts at each generation)

 

26:  Which of the following statements is false regarding the schematic diagram below?

 

A:   [O2] of water is greater at (1) than (2)

B:   [O2] of blood is greater at (1) than (2)

C:   [O2] of water at (1) and (2) depends on whether flow is incurrent or excurrent

D:   [O2] of water is greater than [O2] of blood  at both (1) and (2)

 

(in countercurrent exchange, flow is unidirectional (no incurrent or excurrent))

 

27.  If a mammal has a RMR of 4.5 kJ/g-1/d-1, a reasonable estimate of it’s maximum sustained metabolic rate would be:

 

A:   22.5 kJ/g-1/d-1

B:   9 kJ/g-1/d-1

C:   51 kJ/g-1/d-1

D:   75  kJ/g-1/d-1                         

 

( maximum sustainable metabolic rate is usually 4-7 X BMR; 22.5 = 5X BMR)

 

Match the elements in Column A with those in Column B. 

(½ mark each = 3 marks)

 

Column A

Column B

28.  After 2 weeks at high altitude, a human shows increased ventilation rate, increased heart rate and increased hematocrit ___E__________

 

A: compensation

B: adaptation

C: preadaptation

D: developmental

    plasticity

E: acclimatization

29.  Some frogs are freeze tolerant because they are able to withstand dessication ____C______________

 

30.  Some insect larvae enter diapause if environmental conditions are poor ___D__________

 

31.  An arctic fox has a lower critical

temperature of -40° C ___B________________

 

32.  Goldfish acclimatized to low ambient temperatures alter the expression of heavy and light myosin chains in muscle ____A___________________

 

33.  Water flow over lamellar gills is

unidirectional  ____B________________