21.E: Conservation and Biodiversity (Exercises)
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21.1: Importance of Biodiversity
Biodiversity exists at multiple levels of organization, and is measured in different ways depending on the goals of those taking the measurements. These include numbers of species, genetic diversity, chemical diversity, and ecosystem diversity. The number of described species is estimated to be 1.5 million with about 17,000 new species being described each year. Estimates for the total number of eukaryotic species on Earth vary but are on the order of 10 million.
Multiple Choice
The number of currently described species on the planet is about ________.
A. 17,000
B. 150,000
C. 1.5 million
D. 10 million
- Answer
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C
A secondary plant compound might be used for which of the following?
A. a new crop variety
B. a new drug
C. a soil nutrient
D. a crop pest
- Answer
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B
Pollination is an example of ________.
A. a possible source of new drugs
B. chemical diversity
C. an ecosystem service
D. crop pest control
- Answer
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C
Free Response
Explain how biodiversity loss can impact crop diversity.
- Answer
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Crop plants are derived from wild plants, and genes from wild relatives are frequently brought into crop varieties by plant breeders to add valued characteristics to the crops. If the wild species are lost, then this genetic variation would no longer be available.
Describe two types of compounds from living things that are used as medications.
- Answer
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Secondary plant compounds are toxins produced by plants to kill predators trying to eat them; some of these compounds can be used as drugs. Animal toxins, such as snake venom, can be used as medicine. (Alternate answer: antibiotics are compounds produced by bacteria and fungi which can be used to kill bacteria.)
21.2: Threats to Biodiversity
The core threats to biodiversity are human population growth and unsustainable resource use. To date, the most significant causes of extinction are habitat loss, introduction of exotic species, and overharvesting. Climate change is predicted to be a significant cause of extinction in the coming century. Habitat loss occurs through deforestation, damming of rivers, and other activities. Overharvesting is a threat particularly to aquatic species, but the taking of bush meat in the humid tropics threatens many species in Asia, Africa, and the Americas.
Multiple Choice
Converting a prairie to a farm field is an example of ________.
A. overharvesting
B. habitat loss
C. exotic species
D. climate change
- Answer
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B
Which two extinction risks may be a direct result of the pet trade?
A. climate change and exotic species introduction
B. habitat loss and overharvesting
C. overharvesting and exotic species introduction
D. habitat loss and climate change
- Answer
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C
What kind of ecosystem are exotic species especially threatening to?
A. deserts
B. marine ecosystems
C. islands
D. tropical forests
- Answer
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C
Free Response
Describe the mechanisms by which human population growth and resource use causes increased extinction rates.
- Answer
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Human population growth leads to unsustainable resource use, which causes habitat destruction to build new human settlements, create agricultural fields, and so on. Larger human populations have also led to unsustainable fishing and hunting of wild animal populations. Excessive use of fossil fuels also leads to global warming.
Explain what extinction threats a frog living on a mountainside in Costa Rica might face.
- Answer
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The frog is at risk from global warming shifting its preferred habitat up the mountain. In addition, it will be at risk from exotic species, either as a new predator or through the impact of transmitted diseases such as chytridiomycosis. It is also possible that habitat destruction will threaten the species.
21.3: Preserving Biodiversity
Five mass extinctions with losses of more than 50 percent of extant species are observable in the fossil record. Recent extinctions are recorded in written history and are the basis for one method of estimating contemporary extinction rates. The other method uses measures of habitat loss and species-area relationships. Estimates of contemporary extinction rates vary but are as high as 500 times the background rate, as determined from the fossil record, and are predicted to rise.
Multiple Choice
Certain species of parrot cannot be brought to the United States to be sold as pets. What is the name of the legislation that makes this illegal?
A. Red List
B. Migratory Bird Act
C. CITES
D. Endangered Species Act (ESA)
- Answer
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C
What is the name of the first international agreement on climate change?
A. Red List
B. Montreal Protocol
C. International Union for the Conservation of Nature (IUCN)
D. Kyoto Protocol
- Answer
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D
Free Response
Describe two considerations in conservation preserve design.
- Answer
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Larger preserves will contain more species. Preserves should have a buffer around them to protect species from edge effects. Preserves that are round or square are better than preserves with many thin arms.
Describe what happens to an ecosystem when a keystone species is removed.
- Answer
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Many species will disappear from the ecosystem when a keystone species is removed.