A 3-hectare lake in the American Midwest suddenly has succumbed an algal bloom. What is the likely
cause of eutrophication in freshwater ecosystems, such as this one? - ANSWER Nutritional
runoff
A cow's herbivorous diet indicates that it is a(n) - ANSWER Primary consumer
Approximately how many kg of carnivore biomass can be supported by a field plot containing 1,000
kg of plant material? - ANSWER 10
Aquatic ecosystems are most likely to be limited by which of the following nutrients? -
ANSWER Carbon
Aquatic primary productivity is most limited by which of the following? - ANSWER Light &
nutrients
Consider the food chain grass -> grasshopper -> mouse -> snake -> hawk. How much of the chemical
energy fixed by photosynthesis of the grass (100%) is available to the hawk? -
ANSWER 0.01%
Corn production in many states of the Midwest is limited by nitrogen levels in the soil. Some farmers
reduce the need to apply expensive anhydrous ammonia to their fields by rotating corn crops with
nitrogen-fixing soybean crops. Using soybeans to add nitrogen to soils is an example of -
ANSWER Biological augmentation
For most terrestrial ecosystems, pyramids composed of species abundances, biomass, and energy
are similar in that they have a broad base and a narrow top. The primary reason for this pattern is
that - ANSWER At each step, energy is lost from the system as a result of keeping the
organisms alive
How do the Taylor Glacier bacteria produce their energy? - ANSWER Chemoautorophism
How does inefficient transfer of energy among trophic levels result in the typically high
endangerment status of many top-level predators? - ANSWER Top-level predators are
destined to have small populations that are sparesly distributed
How does phosphorus normally enter ecosystems? - ANSWER Rock weathering
How is it that satellites can detect differences in primary productivity on Earth? -
ANSWER Satellites detect differences by comparing the wavelengths of light captured &
reflected by photoautotrophs to the amount of light reaching
How is it that the open ocean produces the highest net primary productivity of Earth's ecosystems,
yet net primary productivity per square meter is relatively low? - ANSWER Oceans have the
largest area of all the ecosystems on Earth
How is net ecosystem production (NEP) typically estimated in ecosystems? - ANSWER The
net flux of CO2 or O2 in and out of an ecosystem
If the flow of energy in an arctic ecosystem goes through a simple food chain, perhaps involving
humans, starting from phytoplankton to zooplankton to fish to seals to polar bears, then which of the
following could be true? - ANSWER The fish can potentially provide more food or humans
than the seal meat can