Q: Which of the following equations accurately represents the change in population size over time?

$$\Delta N = (\text{Births} + \text{Immigrants}) - (\text{Deaths} + \text{Emigrants})$$

Question 1

Which of the following best describes the difference between an organism's environment, habitat, and niche?

Accepted Answer

Environment refers to all external biotic and abiotic factors, habitat is the specific place where an organism lives and reproduces, and niche is the ecological role a species performs in its habitat.

Question 2

Which of the following is an example of an abiotic factor influencing an ecological interaction?

Accepted Answer

A drought reducing the water available to a population of frogs.

Question 3

Which level of ecological study would focus on how the distribution of capybaras is affected by the presence of caiman predators in a wetland ecosystem?

Accepted Answer

Community ecology

Question 4

A researcher is interested in how the flow of energy and nutrients is affected by both living and non-living components in a forest. Which level of ecological study is this?

Accepted Answer

Ecosystem ecology

Question 5

Which of the following scenarios best illustrates the concept of a 'niche'?

Accepted Answer

A bee pollinating flowers, thereby aiding plant reproduction and obtaining nectar for food.

Question 6

Which of the following is NOT a biotic factor?

Accepted Answer

Soil pH

Question 7

Suppose a population of rabbits in a forest has an initial population of 500. Over the course of one year, 200 new rabbits are born, and 150 rabbits die. Additionally, 20 rabbits emigrate out of the forest and 50 rabbits immigrate into the forest. What is the population size at the end of the year?

Accepted Answer

580 rabbits

Question 8

Which of the following equations accurately represents the change in population size over time?

Accepted Answer

$$\Delta N = (	ext{Births} + 	ext{Immigrants}) - (	ext{Deaths} + 	ext{Emigrants})$$

Question 9

A population of 200 fish in an isolated pond experiences a per capita birth rate ($$b) of 0.3 $$and a per capita death rate ($$d) of 0.1 in a $$month. What is the population growth rate ($$\Delta N) $$and the intrinsic rate of increase ($$r$$)?

Accepted Answer

$$\Delta N = 40$$ fish/month; $$r = 0.2$$ fish/month/fish

Question 10

Which of the following is a density-independent factor that limits a population’s growth?

Accepted Answer

Drought

Question 11

If a bacterial population starts with 100 cells and has a per capita population growth rate $$r of 0.1 $$cells per hour per cell, what would be the population size after 5 hours? (Use the exponential growth equation: $$N_t = N_0$ e$$^{rt}$$)

Accepted Answer

165 individuals

Question 12

A population of spotted hyenas in a South African National Park currently has 87 individuals. The carrying capacity for spotted hyenas in the park is estimated to be 125 hyenas & the intrinsic growth rate ($$r) is 0.25 $$hyenas/year/hyena. What is the instantaneous rate of population growth of the spotted hyena population? (Use the logistic growth equation: $$\frac{dN}{dt} = rN(1-\frac{N}{K}))$$

Accepted Answer

7 hyenas/year

Question 13

Which of the following statements about r- and K-selection is true?

Accepted Answer

K-selected organisms tend to exhibit iteroparity so they can better care for their offspring.

Question 14

Which of the following is an example of direct, asymmetric competition?

Accepted Answer

A large bear chases away a fox from a deer carcass, then comes back to eat the whole deer for itself.

Question 15

Which of the following best describes the relationship between two species if removal of species A reduces the fitness of species B, but removal of species B has no significant impact on species A?

Accepted Answer

Commensalism, where species B benefits while species A is unaffected.

Question 16

Some stick insects can change color to blend in with their surroundings. This is an example of:

Accepted Answer

Cryptic coloration

Question 17

Which of the following is an example of a parasitoid?

Accepted Answer

A wasp that lays its eggs in a caterpillar; the larvae then eat the caterpillar when they hatch.

Question 18

If a forest contains 47,000 kg of plant material, how many kg of tertiary consumers can it support? (Assume ~10% energy transfer between trophic levels.)

Accepted Answer

47 kg

Question 19

Which of the following could be characterized as top-down control in a community?

Accepted Answer

Otters keeping the sea urchin population down by consuming them.

Ecology and Population Biology: Structured Study Notes

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