16.5–16.6: Extinction reduces biodiversity.

An extinction occurs when all individuals in a species have died.

Question 16.17

A habitat with _______ disturbance is expected to have the greatest species richness.

  • a) a great deal of
  • b) an intermediate amount of
  • c) predictable
  • d) very little
  • e) sporadic

Question 16.18

What bird, once the most abundant in North America, was hunted to extinction by shooting and trapping during the 1800s?

  • a) California condor
  • b) blue-footed booby
  • c) dodo
  • d) passenger pigeon
  • e) great auk

Question 16.19

How many species do biologists estimate to be currently existing on earth?

  • a) fewer than 1 million
  • b) between 3 million and 5 million
  • c) more than 1 billion
  • d) between 5 million and 100 million
  • e) between 1 million and 2 million

Question 16.20

Which of the following is currently the leading cause of extinction?

  • a) pollution
  • b) habitat loss
  • c) disease
  • d) exotic species
  • e) overexploitation

Question 16.21

Currently, the major threat to most large land mammals is:

  • a) invasive species.
  • b) loss of genetic variation.
  • c) overexploitation.
  • d) habitat loss.
  • e) mutation.

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