In a commensal relationship: a) one species pollinates the other. b) neither species benefits or is harmed, but the community itself benefits. c) one species provides nutrients, usually cellulose, for the other. d) one species benefits while the other neither benefits nor is harmed. e) the loser has reduced reproductive output.
1. Describe a feature of tigers that renders their species susceptible to extinction. 2. What is the chief reason for the loss and impending loss of so many species? 3. Why are ecosystem disturbances that involve the loss of species considered so devastating?
Madagascar is unusually important to conservation because it: a) has more species per unit area than any other place on earth. b) is the fourth largest island in the world. c) is home to more endangered species than any other country. d) has a higher percentage of endemic plants and animals than any comparably sized […]
1. Describe two reasons why we should be concerned about exotic species 2. Why are carbon dioxide and methane called greenhouse gases? 3. Which gases are produced when fossil fuels are burned?
. Earths largest terrestrial ecosystems, the biomes, are defined primarily by: a) the average rainfall. b) the average temperature. c) the seasonal variability in temperature. d) the seasonal variability in rainfall. e) All of the above.
1. . Explain how natural selection weeds out alleles that cause sickness and death early in life. 2. Why do some species have individuals with very long lives, while others do not? How could the life span of any species be extended?
1. Which feature of colonizers is crucial in the earliest stages of primary succession? 2. . Biodiversity is considered important because of: a) the direct economic benefits to humans, such as medicines and food. b) the symbolic value that elements of the natural world can provide. c) the aesthetic value it holds. d) its potential […]
Which of the following statements about an organisms niche is incorrect? a) It encompasses the space the organism requires. b) It includes the type and amount of food the organism consumes. c) It is not always fully exploited. d) It may be occupied by two species, as long as they are not competitors. e) It […]
1. Describe the two elements of an organisms physical or abiotic environment 2. . What changes in climate occur on moving from the equator toward the Poles? Which two aspects of weather determine the type of biome found at any location?
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 […]
