Chapter 42 Homework

9 September 2022
4.7 (114 reviews)
32 test answers

Unlock all answers in this set

Unlock answers (28)
question
The energy for nearly every organism in nearly every ecosystem ultimately comes from _____.
answer
the sun
question
The law of conservation of mass states that matter cannot be created, yet matter is sometimes gained or lost to an ecosystem. What is the reason for this seeming contradiction?
answer
Ecosystems are open systems; therefore, matter can be moved in/out of an ecosystem from/to another ecosystem.
question
If the sun were to suddenly stop providing energy to Earth, most ecosystems would vanish. Which of the following ecosystems would likely survive the longest after this hypothetical disaster?
answer
deep-sea hydrothermal vent community
question
As big as it is, the ocean is nutrient-limited. If you wanted to investigate this, one reasonable approach would be to
answer
experimentally enrich some areas of the ocean and compare their productivity to that of untreated areas.
question
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.
question
A 3-hectare lake in the American Midwest suddenly has succumbed to an algal bloom. What is the likely cause of eutrophication in this lake?
answer
nutrient-rich runoff
question
How is net ecosystem production (NEP) typically estimated in ecosystems?
answer
the net flux of CO2 and O2 in or out of an ecosystem
question
What name is given to the process by which detritivores return carbon to the atmosphere?
answer
decomposition
question
Which of these removes carbon from the atmosphere?
answer
algae
question
Detritus is composed of _____.
answer
dead organic matter and excreted wastes
question
Which of the following statements about the movement of nutrients through an ecosystem is true?
answer
Carbon cycles between the atmosphere and living biomass.
question
True or false? Local biogeochemical cycles are isolated within their particular ecosystem and all ions and molecules remain in that ecosystem permanently.
answer
False
question
Which area is not one of the three major reservoirs of the global carbon cycle?
answer
Sedimentary rock
question
True or false? In the global carbon cycle, rivers link the terrestrial and marine reservoirs of carbon, whereas carbon exchange between the atmosphere and the ocean is achieved by active transport.
answer
False
question
How does carbon move from the biota to the atmosphere?
answer
Carbon dioxide is released during cellular respiration.
question
How have humans altered the global carbon cycle?
answer
Carbon inputs into the atmosphere have risen.
question
How do greenhouse gases contribute to global warming?
answer
They prevent infrared light from leaving Earth's atmosphere.
question
Nitrifying bacteria convert _____ to _____.
answer
ammonium, nitrites
question
_____ removes nitrogen from the atmosphere.
answer
Nitrogen fixation
question
Denitrifying bacteria convert _____ to _____.
answer
nitrates, nitrogen gas
question
Which one of these is a nitrate?
answer
NO3-
question
Which one of these is a nitrite?
answer
NO2-
question
_____ are secondary consumers.
answer
Carnivores
question
Approximately _____% of the energy at one trophic level is passed on to the next highest trophic level.
answer
5-10
question
10,000 kcal of producer could support approximately _____ kcal of tertiary consumer.
answer
10
question
The amount of chemical energy in a consumer's food that is converted to its own new biomass during a given time period is known as which of the following?
answer
secondary production
question
Which statement best describes what ultimately happens to the chemical energy that is not converted to new biomass in the process of energy transfer between trophic levels in an ecosystem?
answer
It is eliminated as feces or is dissipated into space as heat in accordance with the second law of thermodynamics.
question
Biogeochemical cycles are crucial to ecosystem function because _____.
answer
nutrients and other life-sustaining molecules are in limited supply and must be continually recycled
question
Which of the following locations is the main reservoir for nitrogen in Earth's nitrogen cycle?
answer
atmosphere
question
Why do logged tropical rain forests typically have nutrient-poor soils?
answer
Most of the nutrients in the ecosystem are removed in the harvested timber.
question
What is the goal of restoration ecology?
answer
to speed up the restoration of a degraded ecosystem
question
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 degraded soils is an example of
answer
biological augmentation