16.7–16.11: Human activities can have disruptive environmental impacts.

Disruptions of ecosystems can be disastrous.

Question 16.22

Exotic species can disrupt ecosystems because:

  • a) they frequently have no predators in their new habitat and grow unchecked.
  • b) they are favored by ecotourists.
  • c) they have no natural prey items and so must rely on humans for their survival.
  • d) they have better dispersal capability than endemic species.
  • e) All of the above are correct.

Question 16.23

Even though there is a carbon cycle, carbon dioxide levels around the world seem to be rising. Which of the following best explains why this is so?

  • a) Animals give off carbon dioxide during their normal metabolism.
  • b) As the atmosphere heats up, it can contain more carbon dioxide.
  • c) The destruction of coral reefs leads to increased levels of carbon dioxide.
  • d) More carbon dioxide is being given off by ocean waters as they heat up.
  • e) The burning of fossil fuels releases more carbon dioxide into the atmosphere.

Question 16.24

Increased exposure to short-wavelength ultraviolet radiation resulting from depletion of stratospheric ozone:

  • a) increases the acidification of lakes and streams.
  • b) reduces the rate of photosynthesis by plants.
  • c) has lowered the average daily temperature on the earth’s surface by 4% per decade.
  • d) increases the rate of photosynthesis by plants.
  • e) has raised the average daily temperature on the earth’s surface by 4% per decade.

Question 16.25

A charismatic species that can engender significant public support for conservation of other species and the ecosystem they all inhabit is called:

  • a) an indicator species.
  • b) a keystone species.
  • c) a flagship species.
  • d) a phylogenetic species.
  • e) an endangered species.

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