Species Distribution & Change

Question 1

In the central plains, summers have become about 3 °C hotter over the last two decades and farmers have started using a powerful herbicide that kills much of the native grass. Which statement correctly describes two different ways these environmental changes could affect the distribution of the prairie fence lizard?

Accepted Answer

The lizard may move its range northward to stay in cooler areas, and the loss of grass cover could cause local extinctions at the southern edge of its current range.

Answer

The lizard will expand its range equally northward and southward because warmer temperatures help it grow faster.

Answer

The lizard will become an invasive species in nearby coastal marshes because the herbicide makes it more aggressive.

Answer

The lizard will change its diet to eat more insects, which will keep its range the same but increase its population size.

Question 2

A scientist measured three components of a small pond ecosystem before and after adding a fertilizer that increased the nitrogen concentration in the water. The data are: - Algal biomass: 10 g → 30 g - Zooplankton density: 200 individuals/L → 80 individuals/L - Fish population: 15 individuals → 15 individuals Which statement is best supported by these observations?

Accepted Answer

The increase in nitrogen led to a rise in algal biomass, which was accompanied by a decline in zooplankton density, suggesting that the algal bloom negatively impacted the zooplankton population.

Answer

The decrease in zooplankton caused the increase in algae, showing that zooplankton control algal growth.

Answer

Because the fish population did not change, the added nitrogen had no effect on any organism in the pond.

Answer

The rise in algal biomass should have increased zooplankton numbers because zooplankton eat algae, so the observed decline must be due to a counting mistake.

Question 3

A farmer clears a part of a forest to plant crops, removing much of the shade and moisture that a local shade‑loving frog species depends on. Which of the following is the most likely effect on the distribution of that frog species?

Accepted Answer

The frogs will move to cooler, wetter areas nearby.

Answer

The frogs will stay in the same area but become more active during the day.

Answer

The frogs will increase in number in the cleared area.

Answer

The frogs will migrate to a different continent.

Try three questions

A farmer clears a part of a forest to plant crops, removing much of the shade and moisture that a local shade‑loving frog species depends on. Which of the following is the most likely effect on the distribution of that frog species?

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