Exam 2

Question 1

Which of the following increases as one moves poleward from the tropics?
A) length of the growing season C) seasonal variation in temperature
B) mean annual temperature D) all of the above

Answer 1

C) seasonal variation in temperature

Question 2

The Intertropical Convergence (ITC) is a region of substantial uplift of air heated in contact with the earth’s surface. At any given time of year, where is the ITC located?
A) at the earth’s true equator (0o latitude) B) at the earth’s solar equator

Answer 2

B) at the earth’s solar equator

Question 3

It has sometimes been said that “night is the winter of the tropics”. What is meant by this?
A) Differences between night and day temperatures often exceed differences between mean monthly temperatures of winter and summer.
B) Most locations in the tropics experience sub-freezing temperatures at night, but never during the day.
C) Temperature variation in the tropics is unpredictable.

Answer 3

A) Differences between night and day temperatures often exceed differences between mean monthly temperatures of winter and summer.

Question 4

Your family is planning a holiday trip in late December and early January to the resort city of Cancún, Mexico, located on the Yucatán peninsula at 21o north latitude. Because this trip is during the northern hemisphere winter, your family can count on:
A) relatively dry conditions throughout their vacation.
B) heavy rains throughout their vacation.

Answer 4

A) relatively dry conditions throughout their vacation.

Question 5

High-pressure air masses descending to the earth at approximately 30° north and south of the equator create what conditions at the earth’s surface?
A) arid climate D) constant temperature
B) unusually high precipitation E) all of the above
C) unusually high snowfall

Answer 5

A) arid climate

Question 6

Why are the oceans off the western coasts of the continents highly productive?
A) Upwelling of water from deeper layers carries nutrients to the surface.
B) Sunlight is more intense.
C) Water temperatures are higher.
D) The lack of herbivores leads to higher production.

Answer 6

A) Upwelling of water from deeper layers carries nutrients to the surface.

Question 7

The Atacama-Peruvian Desert lies adjacent to the south Pacific Ocean along the western coast of South America at about 30o south latitude. The Atacama is one of the places receiving the lowest precipitation on earth, and yet it is in close proximity to the ocean. Which of the following is responsible for the desert conditions there?
A) The Atacama is located at about 30o S latitude, where dry, descending air masses predominate.
B) The Atacama is located adjacent to cold, northward-flowing ocean surface currents that tend to strip moisture from moist air masses that flow toward land from the South Pacific Ocean.
C) Both A and B are correct.

Answer 7

C) Both A and B are correct.

Question 8

Please select the correct ranking of three forest biomes from most to least diverse, in terms of number of tree species.
A) boreal forest, temperate seasonal forest, tropical rain forest
B) temperate seasonal forest, tropical rain forest, boreal forest
C) tropical rain forest, boreal forest, temperate seasonal forest
D) boreal forest, tropical rain forest, temperate seasonal forest
E) tropical rain forest, temperate seasonal forest, boreal forest

Answer 8

E) tropical rain forest, temperate seasonal forest, boreal forest

Question 9

Where would you NOT go to see extensive and well-developed examples of the boreal forest (taiga) biome?
A) Canada and Alaska C) southern hemisphere
B) northern Europe D) northern Asia

Answer 9

C) southern hemisphere

Question 10

In Heinrich Walter’s climate diagrams (see text Figure 5.6, above), each 10oC increase in temperature requires a minimum increase of 20 mm of monthly precipitation for there to be sufficient moisture for plant growth (no surplus or deficit). In the diagram above, if the monthly temperature is 10oC, 20 mm of precipitation are required. How much precipitation is required if the monthly temperature is 20oC?
A) 40 mm B) 60 mm C) 80 mm D) 100 mm E) 120 mm

Answer 10

A) 40 mm

Question 11

The terrestrial biome concept emphasizes differences in plant form related to variation in environment. Why has the terrestrial biome concept been difficult to apply to aquatic systems?
A) Aquatic systems lack plants altogether.
B) The environments of aquatic systems vary little from one place to another.
C) Aquatic ecologists have been uninterested in plants.
D) The producers of many aquatic systems are single-celled algae, with little characteristic large-scale structure.

Answer 11

D) The producers of many aquatic systems are single-celled algae, with little characteristic large-scale structure.

Question 12

The distinction between riffles and pools is most appropriate in which of the following aquatic systems?
A) streams
B) rivers
C) lakes
D) estuaries
E) oceans

Answer 12

A) streams

Question 13

Coral reefs are to open oceans as __________.

A) tropical rain forests are to deserts B) deserts are to tropical rain forests

Answer 13

A) tropical rain forests are to deserts

Question 14

Many temperate lakes exhibit vertical mixing of surface and deeper waters, called overturn, twice annually. During which seasons does overturn occur?
A) winter and spring C) winter and summer
B) fall and spring D) fall and summer

Answer 14

B) fall and spring

Question 15

Ice skaters get excited when ice begins to form on the surfaces of temperate lakes during winter. At this time, where is the coldest water in the lake?
A) At the bottom, just above the benthic zone.
B) At the top, just below the ice.

Answer 15

B) At the top, just below the ice.

Question 16

Which of the following is an important component of life history?
A) age at maturity B) parity C) fecundity D) longevity E) all of the above

Answer 16

E) all of the above

Question 17

Much of the effort in the study of life histories has been to understand the fitness consequences of changing the allocation of limited time and resources to competing functions.
A) True B) False

Answer 17

A) True

Question 18

A mature female sockeye salmon swims up to 5,000 km from her Pacific Ocean feeding ground to the mouth of a coastal river in British Columbia and then another 1,000 km upstream to her spawning ground. Once there, she lays thousands of eggs in her single reproductive event and promptly dies. The salmon’s reproductive life history is referred to as:
A) semelparous B) iteroparous C) oddparous D) evenparous E) nonparous

Answer 18

A) semelparous

Question 19

A female African elephant produces a single offspring at a time at intervals of several years, caring for her young for an extended period before reproducing again. The elephant’s reproductive life history is referred to as:
A) semelparous B) iteroparous

Answer 19

B) iteroparous

Question 20

Where would you place the elephant (previous question) on the “Slow-Fast Continuum”?
A) Slow (“K”)
B) Fast (“r”)

Answer 20

A) Slow (“K”)

Question 21

“Bet hedging” (spreading reproduction over both good and bad years) has been proposed as an advantage to which of the following life histories?
A) semelparity
B) iteroparity

Answer 21

B) iteroparity

Question 22

Which of the following British biologists first placed the clutch size of birds in an evolutionary context?
A) J.P. Grime B) Charles Darwin C) E.P. Odum D) A.G. Tansley E) David Lack

Answer 22

E) David Lack

Question 23

The average European magpie’s (Pica pica) clutch size of seven eggs was manipulated by Swedish ecologist Gören Hogstedt by adding or removing eggs, to make up clutches of five to nine eggs. What was the most productive clutch size (number of chicks fledged)?
A) five eggs B) six eggs C) seven eggs D) eight eggs E) nine eggs

Answer 23

C) seven eggs

Question 24

Imagine two different genotypes of a particular plant species. Both genotypes have a hermaphroditic phenotype (each plant is functionally male and female). Genotype 1 has an annual phenotype: individuals of this genotype produce offspring (seeds) at the end of the year, then die. Genotype 2 has an immortal phenotype: individuals of this genotype produce offspring (seeds) at the end of each year and live forever. Assume that the only mortality affecting our two hypothetical genotypes is the death of mature annual plants after they reproduce. If each individual of the genotype 1 (annual phenotype) produces 102 seeds, and each individual of genotype 2 (immortal phenotype) produces 100 seeds, which genotype will increase more rapidly in the population?
A) genotype 1 (annual phenotype) B) genotype 2 (immortal phenotype)

Answer 24

A) genotype 1 (annual phenotype)

Question 25

By breeding at an earlier age, an organism will reap the obvious benefit of increased fecundity at that age. Is there any potential cost associated with breeding at an earlier age?
A) Yes, there is a cost: reduced survival to older ages.
B) There is no cost associated with breeding at an earlier age.

Answer 25

A) Yes, there is a cost: reduced survival to older ages.

Question 26

Storm-petrels live 30 to 40 years. Thrushes rarely live beyond 3 to 4 years. Even if you knew nothing more about the life histories of these two species, could you make an educated guess about which species has the longer prereproductive period?
A) Yes, the longer-lived species (storm-petrel) probably has the longer prereproductive period.
B) Yes, the shorter-lived species (thrush) probably has the longer prereproductive period.
C) No, information about maximum age is insufficient background for an educated guess.

Answer 26

A) Yes, the longer-lived species (storm-petrel) probably has the longer prereproductive period

Question 27

In class, we performed a “thought experiment” involving two fish genotypes, each with a distinctive phenotype (see Table 7.3 above). For fish living a fairly long time (6 or more years), what would you predict to be the better strategy (in terms of lifetime reproductive output) of allocating resources to growth and fecundity?
A) slow growth and high fecundity
B) rapid growth and low fecundity

Answer 27

B) rapid growth and low fecundity

Question 28

Dr. Hoffmann from the Department of Plant Biology showed that a genotype exhibiting a semelparous life history could outperform (in terms of lifetime reproductive output) either of the iteroparous genotypes described in the question above. What was the semelparous life history that Dr. Hoffmann described?
A) a fish that puts all its resources into reproduction at the end of its first year of life and dies
B) a fish that puts all its resources into reproduction at the end of its sixth year of life and dies

Answer 28

B) a fish that puts all its resources into reproduction at the end of its sixth year of life and dies

Question 29

The widespread occurrence of sexual reproduction in the biological world is actually surprising, given the attendant costs. Each of the following describes one of these costs, with one exception. The exception describes a benefit of sex - which one is it?
A) When organisms reproduce sexually, each parent contributes one half of the genes of each of its offspring.
B) The shuffling of genes that occurs during sexual reproduction results in the production of genetically varied offspring that may have defenses to which the parents’ pathogens are not well adapted.
C) Because all individuals in asexually reproducing populations produce offspring, such populations increase in size at approximately twice the rate of sexually reproducing populations.
D) Mating behaviors can be risky and expensive, facilitating spread of diseases, increasing exposure to predation, and taking time away from feeding and other maintenance activities.

Answer 29

B) The shuffling of genes that occurs during sexual reproduction results in the production of genetically varied offspring that may have defenses to which the parents’ pathogens are not well adapted.

Question 30

In the previous question, item A states: “When organisms reproduce sexually, each parent contributes one half of the genes of each of its offspring.” What name do we apply to this situation?
A) cost associated with maintaining breeding territories
B) cost of maintaining sexual machinery (i.e., gonads)
C) twofold cost of meiosis

Answer 30

C) twofold cost of meiosis

Question 31

What is the key evolutionary concept underlying the Red Queen hypothesis?
A) Through sex and genetic recombination, hosts present a moving target for evolving pathogens.
B) Through sex and genetic recombination, hosts prevent evolution of pathogens.
C) Through sex and genetic recombination, hosts are able to stop evolving and still maintain high fitness.
D) All of the above are true.

Answer 31

A) Through sex and genetic recombination, hosts present a moving target for evolving pathogens.

Question 32

Many organisms exhibit a 50:50 sex ratio, which is the most common ratio observed in nature. What kind of selection tends to maintain such a balanced sex ratio?
A) directional selection
B) sexual selection
C) frequency-dependent selection

Answer 32

C) frequency-dependent selection

Question 33

In a famous study of the US census data from 1790 to 1910, Raymond Pearl and Lowell Reed applied the logistic model of population growth to model dN/dt (the instantaneous change in population size with respect to time). Which of the following formulae did they choose?
A) dN/dt = rN
B) N(t) = N(0)ert
C) dN/dt = r0N(1 – (N/K))
D) N(t) = N(0)λt
E) N(t+1) = N(t)λ

Answer 33

C) dN/dt = r0N(1 – (N/K))

Question 34

When a population grows according to the logistic model, at what population size does dN/dt equal zero?
A) N = K B) N = K/2 C) N = r0 D) N = ∞

Answer 34

A) N = K

Question 35

Population growth rates sometimes increase with increasing population density (in contrast to the expectations of logistic growth), especially at low population densities. We refer to this kind of population response (seen, for example, in certain fish stocks and plant populations) as __________.
A) positive density dependence (the Allee effect)
B) negative density dependence
C) juvenile recruitment
D) self-thinning

Answer 35

A) positive density dependence (the Allee effect)

Question 36

China often captures the headlines when human population is under discussion. Currently the world’s most populous country, China (in mid-2013, according to the Population Reference Bureau, or PRB) had 1.357 billion people. The PRB found that, again in mid-2013, the Chinese population was experiencing a birth rate of 12 births per thousand persons, and a death rate of 7 deaths per thousand persons. Data of the type presented in the preceding sentence are referred to as crude birth and death rates, and they can be directly converted to the parameters B (0.012) and D (0.007), respectively, used in the geometric growth model. It is also true that λ = 1 + (B – D).
Now, please calculate the value of λ (geometric population growth rate, or multiplication rate per year) for the Chinese population in mid-2013.
A) 0.005
B) 1.005
C) 1.012
D) 0.019
E) 1.019

Answer 36

B) 1.005

Question 37

As mentioned above, the Chinese population in mid-2013 was estimated by the PRB at 1.357 billion. Assuming conditions of geometric growth at the current growth rate (from question 36), predict the size of the Chinese population exactly one year later, in mid-2014 (rounding off to the same number of decimal places as the mid-2013 estimate):
A) 1.338 billion
B) 1.345 billion
C) 1.354 billion
D) 1.364 billion

Answer 37

D) 1.364 billion

Question 38

Again assuming conditions of geometric population growth at the current growth rate (from question 36), what would you predict the size of the Chinese population to be in mid-2050, given its size of 1.357 billion in mid-2013 (rounding off to the same number of decimal places as the mid-2013 estimate)?
A) 1.221 billion
B) 1.338 billion
C) 1.632 billion
D) 1.717 billion
E) 53.520 billion

Answer 38

C) 1.632 billion

Question 39

According to the PRB, the best estimate of China’s human population in mid-2050 is 1.437 billion. Given your estimate of China’s population in mid-2050 (previous question), what would you conclude about the current geometric growth rate (the one you estimated in Question 36)?
A) The current geometric growth rate will be sustained through mid-2050.
B) The current geometric growth rate will increase between mid-2013 and mid-2050.
C) The current geometric growth rate will decrease between mid-2013 and mid-2050.

Answer 39

C) The current geometric growth rate will decrease between mid-2013 and mid-2050.

Question 40

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Answer 40

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Question 41

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Answer 41

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Question 42

The PRB estimates that the human population of India in mid-2013 was 1.277 billion, less than China’s mid-2013 population of 1.357 billion. As we’ve just seen (previous question), the PRB expects China’s mid-2050 population to be 1.437 billion. However, the PRB expects India’s mid-2050 population to exceed China’s, soaring to 1.748 billion! For this to happen, what must be true of the geometric growth rates of these two countries between mid-2013 and mid-2050?
A) λIndia = λChina B) λIndia > λChina C) λIndia

Answer 42

B) λIndia > λChina

Question 43

Because human populations grow continuously, demographers typically prefer to work with the exponential growth model, which uses “little r” as its key parameter. Please calculate the value of r for the Chinese population in mid-2013 (please round to three decimal places). Please use your value of λ from Question 36 to answer this question!
A) -5.298
B) 0.005
C) 0.012
D) –3.963
E) 0.019

Answer 43

B) 0.005

Question 44

Using your estimate of r for the Chinese population in mid-2013 (previous question), what would be the expected doubling time of the population in years?
A) 139 years
B) 58 years
C) 36 years

Answer 44

A) 139 years

Question 45

In the preceding questions, we have worked with both geometric (estimating λ) and exponential (estimating r) population growth models. We’ve seen in class that there are exact economic analogies to these two models. In particular, which kind of interest rate is most closely related to λ?
A) APR (annual percentage rate, also known as APY, annual percentage yield)
B) daily compounding rate

Answer 45

A) APR (annual percentage rate, also known as APY, annual percentage yield)

Question 46

A grasshopper population in the insecticide-free part of our soybean field at the Central Crops Research Station is determined to be following the predictions of the exponential population model. It is determined to have a “little r” of -0.872. What is its corresponding value of λ?
A) greater than 1
B) 1
C) less than 1, but greater than 0
D) 0
E) less than 0

Answer 46

C) less than 1, but greater than 0

Question 47

According to what we’ve learned about populations, a single _________ population has a much lower likelihood of undergoing stochastic extinction than a single __________ one.
A) small, large
B) large, small

Answer 47

B) large, small

Question 48

If you were asked to choose to protect only one from among the following metapopulations of a rare species, which would you select to ensure the smallest likelihood of stochastic extinction?
A) 8 small patches that are far apart
B) 8 small patches that are close to one another
C) 8 large patches that are far apart
D) 8 large patches that are close to one another

Answer 48

D) 8 large patches that are close to one another

Question 49

What is the purpose of the equation dP/dt = cP(1 - P)eP?
A) it models logistic growth of a single population
B) it models the exponential growth of a population or savings account
C) it models patch occupancy dynamics of a metapopulation
D) no way to tell - it has not yet been covered in PB 360

Answer 49

C) it models patch occupancy dynamics of a metapopulation

Question 50

We manipulated the graph above in our SimUText chapter on metapopulations. What was the purpose of this graph?
A) It shows how balanced rates of colonization and extinction rates result in an equilibrium patch occupancy rate.
B) It shows why metapopulations models are unsuited for use in conservation ecology.
C) It shows how “little r” and “λ” are related.
D) It shows how supply and demand affect the pricing of a commodity.

Answer 50

A) It shows how balanced rates of colonization and extinction rates result in an equilibrium patch occupancy rate.

Question 51

Deep sea vents are openings in the sea floor where hot water and nutrients spew out. They have a rich community of species. However, individual vents often become plugged up, while new vents can appear in far flung parts of the ocean. You would expect to find that species who specialize at living around these vents are especially good at:
A) dispersal
B) intrinsic growth
C) local extinctions
D) patch occupancy

Answer 51

A) dispersal