Bio Ch 46

Which of the answer choices is a form of nitrogen that can be utilized by plants?

NO3-

What is generally true about biomass and energy as we move from one trophic level to the next?

Not all energy is transferred to the next trophic level

Imagine that scientists have discovered a new planet that is apparently devoid of life but has ice caps located at the poles. These ice caps reveal that the planet's atmospheric O2 levels sharply increased about 1,000,000 years ago but then quickly dropped 50,000 years ago. What could account for these changes in atmospheric O2 levels?

Photosynthetic organisms evolved on the planet 100,000 years ago but went extinct 50,000 years ago.

Trout and amoebas are both heterotrophs and can inhabit similar environments, such as a freshwater pond. However, these organisms are very different when it comes to their shape and size. Why?

Trout and amoebas evolved to utilize different sources of C6H12O6 (or other organic compounds)

A researcher is measuring atmospheric CO2 levels on cloudy and sunny days. He notices that on cloudy days, CO2 levels appear slightly higher than on sunny days. This is an example of:

correlation

The _____ cycle deals with geological processes and carbon reservoirs, some of which have been built up or take place over a period of millennia. In contrast, the _____ cycle involves biological processes that are carried out on a daily and/or seasonal basis.

long-term carbon; short-term carbon

Which of the answer choices is a reservoir of carbon?

organisms soil oceans the atmosphere

Primary consumers obtain carbon, nitrogen, and phosphorus through ingestion of primary producers.

true

Whereas food chains show linear energy transfer between organisms, food webs depict more realistically what occurs in an ecosystem.

true

Your body, your house, and your pets are all considered carbon reservoirs

true

Of the processes involved in the long-term carbon cycle, which introduces CO2 back into the atmosphere?

volcanism

Photosynthesis and respiration affect atmospheric CO2 levels on a _____ timescale, whereas volcanic eruptions affect atmospheric CO2 levels on a _____ timescale

yearly; century

A researcher is measuring Earth's atmospheric CO2 levels, gathering data on CO2 levels in northern and then southern hemispheres. What do you expect that she will find?

Because atmospheric CO2 measurements represent global amounts, measurements in the Northern Hemisphere and Southern Hemisphere will be approximately the same

Recall that during the Paleozoic Era, atmospheric CO2 levels decreased. Why?

Photosynthetic, woody plants first appeared during this period

Which of the statements explains how an oxygen-rich atmosphere became possible on Earth?

Rates of oxygen consumption are lower than rates of photosynthesis.

Which of the statements is true regarding subduction?

The carbon it removes is eventually returned to the atmosphere by volcanism

Recall that photosynthetic rates remain relatively constant in regions near the equator. Imagine that tropical environments persist throughout Earth's northern and southern hemispheres; that is, that Earth's entire climate mirrors that near the equator. If Keeling had collected his atmospheric CO2 data on such an Earth, what would you expect the Keeling Curve to look like?

a straight line sloping upward, indicating that atmospheric CO2 levels would not seasonally oscillate, but would increase over time

A scientist studying a material has determined that 12C, 13C, and 14C occur in the material in a ratio of 1000:10:1. How did he most likely differentiate between these forms of carbon?

by the number of neutrons in 12C, 13C, and 14C

Of the processes involved in the long-term carbon cycle, which removes CO2 from the atmosphere?

chemical weathering

The equation CaSiO3 + CO2 → CaCO3 + SiO2 takes into account which of these processes associated with the long-term carbon cycle?

chemical weathering

Hans Suess's work (and subsequent studies carried out by other researchers) determined that the amount of 13C in Earth's atmosphere has _____ and the amount of 14C in the atmosphere has _____.

decreased; also decreased

Nearly 150 years ago, man-made CO2 was introduced into the atmosphere primarily through _____. Currently, _____ is the main contributing factor to increased levels of human-produced CO2 in the atmosphere.

deforestation; the burning of fossil fuels

In terrestrial ecosystems, nitrogen is returned to the atmosphere by:

denitrifying bacteria

Examining the relationship between primary producers, primary consumers, and secondary consumers is one way to track the flow of _____ through a system.

energy contained in organic compounds

In marine ecosystems, phosphorus is added to the ecosystem primarily from:

erosion of rocks on land

An increased rate of photosynthesis is the most likely explanation as to why atmospheric CO2 levels appear lowest during glacial periods of Earth's history

false

If researchers never evaluated the amount of 14C in the atmosphere, they could still use 13C levels to demonstrate causation between human activities and increased atmospheric CO2.

false

Scientists can gain information about ancient atmospheric CO2 levels through ice core data. CO2 in ice cores is primarily the result of sediments being trapped in glaciers, which scientists can subsequently assess for different carbon isotopes 13C, 12C, and 14C.

false

Which of the answer choices is not considered a photosynthetic organism and, therefore, does not remove atmospheric CO2?

human

Organisms in an ecosystem are linked to their physical environment through the cycling of _____ and the transfer of _____.

nutrients; energy

Which biogeochemical cycle does not include oxidation and reduction reactions that provide energy to microorganisms?

phosphorus

Recall that in the northern hemisphere, atmospheric CO2 levels are highest in early spring and lowest in early fall. What accounts for this seasonal fluctuation in atmospheric CO2 levels?

photosynthesis

Which of the answer choices are not geological processes that drive the long-term carbon cycle?

photosynthesis and respiration

Which of these factors likely contributed to the accumulation of O2 within Earth's atmosphere?

the evolution of cyanobacteria the fact that photosynthesis releases O2 as a product the fact that O2 is also cycled during the carbon cycle the fact that there is a slight "de-coupling" between photosynthesis and respiration

The evolution of biodiversity on the planet can be linked to patterns in the carbon cycle over time.

true

The long-term and short-term carbon cycles are connected by the fact that some of the carbon contained in C6H12O6 (or other organic molecules) in plants is incorporated into sedimentary rocks or oil; carbon in sedimentary rock and oil is not immediately cycled back to the atmosphere

true