IB Biology Exam Prep - Question List

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141.
When existing species in a habitat alter environmental conditions in such a way that they inhibit their own reproduction in relation to other species, which of the following events is likely to occur?
  1. Density independent selection.
  2. Habitat fragmentation.
  3. Boom and bust population cycles.
  4. Secondary succession.
142.
There is less biomass at higher trophic levels of an ecosystem because at the higher trophic levels:
  1. Biodiversity is lower.
  2. Less energy is available.
  3. Decomposers are dominant.
  4. Toxic compounds accumulate.
143.
The phosphorus cycle differs from the carbon and nitrogen cycles in that phosphorus is:
  1. In the same chemical form throughout its cycle.
  2. Not produced as a result of human activities.
  3. Not in a gas phase during any part of its cycle.
  4. Rarely a limiting factor in ecosystems.
144.
Which of the following statements about the carbon cycle is accurate?
  1. Decomposers and other heterotrophs absorb carbon dioxide from the atmosphere during respiration.
  2. Historically, calcium carbonate from dead organisms has been a primary reservoir of carbon stored in ocean sediments.
  3. The main source of carbon dioxide returning to the atmosphere is the respiration of terrestrial consumers from the higher trophic levels.
  4. More carbon dioxide is absorbed by an acre of living trees in a year than is released by an acre of trees burning during a fire.
145.
The use of phosphate-free detergents has been very effective in cleaning up lakes and rivers. This is because in freshwater ecosystems phosphorus:
  1. Presents osmoregulatory difficulties for zooplankton.
  2. Lowers the pH as a result of increased carbon dioxide levels.
  3. Accumulates in the brown fatty tissues of fish.
  4. Is the limiting nutrient for algal growth.

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