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01:43Which of these is a consequence of biological magnification?
a. Toxic chemicals in the environment pose greater risk to top-level predators than to primary consumers.
b. Populations of top-level predators are generally smaller than populations of primary consumers.
c. The biomass of producers in an ecosystem is generally higher than the biomass of primary consumers.
d. Only a small portion of the energy captured by producers is transferred to consumers.
The main cause of the increase in the amount of CO₂ in Earth's atmosphere over the past 150 years is
a. Increased worldwide primary production
b. Increased worldwide standing crop
c. An increase in the amount of infrared radiation absorbed by the atmosphere
d. The burning of larger amounts of wood and fossil fuels
What is the single greatest threat to biodiversity?
a. Overharvesting of commercially important species
b. Habitat alteration, fragmentation, and destruction
c. Introduced species that compete with native species
d. Novel pathogens
Of the following statements about protected areas that have been established to preserve biodiversity, which one is not correct?
a. About 25% of Earth's land area is now protected.
b. National parks are one of many types of protected areas.
c. Management of a protected area should be coordinated with management of the land surrounding the area.
d. It is especially important to protect biodiversity hot spots.
