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Ecology and the environment
6 MDCAT Biology questions with answers and explanations.
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Primary succession begins on:
- 1 Fertile farm soil
- 2 Bare rock with no soil
- 3 A forest after a fire
- 4 An abandoned field
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Correct answer: Bare rock with no soil
Primary succession starts where no soil exists, for example on bare rock, and pioneer species such as lichens come first.
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Which process returns nitrogen from the soil to the atmosphere?
- 1 Nitrification
- 2 Denitrification
- 3 Ammonification
- 4 Nitrogen fixation
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Correct answer: Denitrification
Denitrifying bacteria convert nitrates into nitrogen gas.
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A relationship in which both organisms benefit is called:
- 1 Parasitism
- 2 Mutualism
- 3 Competition
- 4 Predation
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Correct answer: Mutualism
In mutualism, both partners gain, as with a legume and its root nodule bacteria.
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Which biome has permanently frozen soil called permafrost?
- 1 Savanna
- 2 Tundra
- 3 Desert
- 4 Tropical rainforest
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A population with unlimited resources grows with a:
- 1 Sigmoid curve
- 2 J-shaped (exponential) curve
- 3 Flat line
- 4 Falling curve
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Correct answer: J-shaped (exponential) curve
Without limits, a population grows exponentially, giving a J-shaped curve.
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Which group of chemicals is mainly responsible for damaging the ozone layer?
- 1 Chlorofluorocarbons (CFCs)
- 2 Carbon dioxide
- 3 Nitrogen
- 4 Methane
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Correct answer: Chlorofluorocarbons (CFCs)
CFCs release chlorine atoms in the stratosphere, and these break down ozone.