Chapter 46 LearningCurve

Following the 10% rule for energy moving through a trophic pyramid, an increase of 10% at the level of primary producer would increase the biomass supported in the secondary producer trophic level by:

0.1%

If all volcanic activity were to stop tomorrow, there would be a _____ reduction in carbon flux into the atmosphere.

99%

The carbon and nitrogen cycles are related to one another because:

All of these choices are correct. (Microorganisms have important roles in the cycling of each. Both are liberated into the environment when organisms decompose. Both are required to make the primary biological molecules (carbohydrates, fats, proteins, and sugars).)

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

All of these choices are correct. (The evolution of cyanobacteria. 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 fact that photosynthesis releases O2 as a product.)

Which of the statements is true regarding the carbon cycle?

All of these choices are correct. (It evolved before plants appeared on Earth. It cycles both carbon and H2O. It was based on microbes during the early stages of Earth's history. It involves both long- and short-term processes.)

Researchers are measuring Earth's atmospheric CO2 levels, gathering data on CO2 levels in northern and then southern hemispheres. What do you expect that they will find?

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

Why does the burning of fossil fuels have such a large impact on atmospheric carbon concentrations?

Burning fossil fuels results in the release of carbon held in sinks for over 350 million years, and there is no other reservoir capable of holding that amount of carbon.

The majority of carbon stored in abiotic reservoirs is in the form of:

CaCO3.

Consider the graph shown. Studies using isotopic CO2 ratios have shown that the ratio of 13C /12C in the atmosphere has declined. What would it indicate if the ratio of 13C /12C had remained constant? [I will not pay money to add a picture of the graph]

Detecting an increase in CO2 emissions from the burning of fossil fuels would be less likely.

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 all of the tertiary consumers were removed from an environment, the associated food web, and thus the carbon cycle, would collapse.

False

Most phosphorus on the planet is found in living organisms.

False

The diverse array of photosynthetic plants and microbes is the result of different sources of CO2 and has little to do with environmental conditions.

False

Why are CO2 levels higher during interglacial periods?

Lower ice levels cause CO2 trapped in air bubbles to be released, raising temperatures.

Marine trophic pyramids are inverted in terms of biomass but not energy. Which statement best reflects why this is the case?

Organisms at the bottom of the trophic pyramid have high rates of primary production and replenish biomass eaten by primary consumers with high reproductive rates.

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.

Carbon moves through ecosystems on both short- and long-term scales. Which of the statements best describes the movement of carbon through short-term time scales of the food chain?

Primary producers fix atmospheric carbon into compounds that will be oxidized by secondary consumers.

The higher the level of biodiversity of a region, the greater its:

Primary productivity

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

Rates of oxygen consumption are lower than rates of photosynthesis.

If we were able to restore the forests in the Northern Hemisphere that have been clear-cut in the past 300 years, what changes to the data shown in the graph would you expect? [I will not pay money to add a picture of the graph]

The year-to-year oscillation in CO2 levels would be more pronounced in that more CO2 could be absorbed each season.

Consider the levels of atmospheric CO2 shown in the graph. [I will not pay money to add a graph] Why isn't the point for CO2 concentration the same for April 2015 and April 2016?

There is a continual rise from one year to the next in CO2 levels on the planet.

As shown in the graph, we see decreases in CO2 that follow an annual pattern. This pattern is attributed to seasonal fluctuations in photosynthesis from large forests in the Northern Hemisphere. There are no large deciduous temperate forests in the Southern Hemisphere. How would you predict the CO2 concentration figure to change if there were deciduous temperate forests in the Southern Hemisphere as well ? [I will not pay money to add a picture of the graph]

There would still be an increase year over year, but the magnitude of change in CO2 levels would be greater.

Botanists are comparing the metabolic pathways for photosynthesis in cyanobacteria and redwood trees. What do you expect that they will find?

These two pathways will actually be quite similar, though subtle differences may exist.

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).

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

True

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

True

Autotrophs in marine environments are carbon sinks and contribute to the short-term carbon cycle. When the outer shells of these organisms fall to the ocean floor through sedimentation, these same autotrophs contribute to the long-term carbon cycle. Plant diversity in terrestrial environments contributes to the short-term carbon cycle through photosynthesis. Plants contribute to the long-term carbon cycle:

by decaying in soils.

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

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

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

chemical weathering

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.

Nutrient cycling through ecosystems can be depicted using a(n):

food web.

You would expect to see the lowest rates of primary productivity:

in the open ocean.

Which of these relationships best depicts the amount of carbon stored in the atmosphere, sedimentary rocks, living organisms, and soil?

living organisms < the atmosphere < soil < sedimentary rocks

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

An examination of geologic processes that drive the long-term carbon cycle shows that:

more carbon is moved from the atmosphere into geologic reservoirs than is released from geologic reservoirs into the atmosphere.

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

nutrients; energy

By eating primary producers, primary consumers are able to obtain _____ for making nucleic acids.

phosphorous

Consider the figure shown. Which organism would have the least effect if removed from the food web? [I will not pay money to add a picture of the food web]

raccoon

The Olympic Mountain Range is an actively growing mountain range, where two tectonic plates are continuing to move each other, exposing more sedimentary rock. This movement of one tectonic plate contributing to the growth of the mountain chain will primarily:

return carbon to the ocean through weathering.

Phosphorous that is incorporated into primary producers returns to geologic reservoirs through the process of:

sedimentation.

Many organisms make up a food web. If snakes are removed from the food web, then: [I will not pay money to add a picture of the food web]

tertiary consumer population sizes will decrease.

Atmospheric carbon dioxide levels began decreasing approximately 580 million years ago. This coincides with:

the appearance of the first animals in marine environments.