USABO - USA Biology Olympiad Population Ecology and Dynamics Questions and Answers

Question 1

An age-structure diagram for a developing country shows a classic pyramid shape, with a very broad base that narrows progressively toward the top.
Which of the following is the most accurate long-term prediction for this population, assuming current trends continue?

Accepted Answer

The population will experience rapid growth due to a large proportion of individuals in pre-reproductive and reproductive age groups.

Answer

The population size will remain stable as the high birth rate is offset by a high death rate in older age groups.

Answer

The population will begin to decline as the large younger generation moves into post-reproductive years.

Answer

The population will experience a 'boom and bust' cycle due to density-independent factors.

Question 2

A species of marine invertebrate releases millions of eggs into the water, of which very few survive to maturity. However, those that do survive the initial larval stages have a high probability of living for a long time. Which type of survivorship curve would this species most likely exhibit?

Accepted Answer

Type III

Answer

Type I

Answer

Type II

Answer

A combination of Type I and Type II

Question 3

In the logistic growth model, represented by the equation dN/dt = rN((K-N)/K), what happens to the population growth rate (dN/dt) as the population size (N) approaches the carrying capacity (K)?

Accepted Answer

The growth rate approaches zero.

Answer

The growth rate increases exponentially.

Answer

The growth rate becomes negative.

Answer

The growth rate remains constant at the maximum rate (r).

Question 4

Which of the following describes a key characteristic of a K-selected species compared to an r-selected species?

Accepted Answer

Extensive parental care and few offspring

Answer

Early age of first reproduction

Answer

High intrinsic rate of increase (r)

Answer

Short lifespan and small body size

Question 5

A sudden, severe frost kills a large portion of a monarch butterfly population overwintering in Mexico. This event is an example of:

Accepted Answer

A density-independent limiting factor.

Answer

A density-dependent limiting factor.

Answer

A K-selection pressure.

Answer

Intraspecific competition.

Question 6

A conservation biologist is studying several fragmented populations of a rare orchid. She observes that one large, thriving population (Population A) frequently provides seeds that colonize smaller, less stable habitat patches where the orchid populations would otherwise go extinct. In metapopulation theory, what are Population A and the smaller patches called, respectively?

Accepted Answer

Source population and sink populations

Answer

Founder population and satellite populations

Answer

Core population and peripheral populations

Answer

Keystone population and indicator populations

An age-structure diagram for a developing country shows a classic pyramid shape, with a very broad base that narrows progressively toward the top.Which of the following is the most accurate long-term prediction for this population, assuming current trends continue?

An age-structure diagram for a developing country shows a classic pyramid shape, with a very broad base that narrows progressively toward the top.
Which of the following is the most accurate long-term prediction for this population, assuming current trends continue?