General Bio 2 - Ch 46

Which of the statements is true regarding atmospheric CO2 levels during the last 400,000 years?

Atmospheric CO2 levels fluctuate periodically, with the highest levels occurring during interglacial periods.

Imagine that a researcher has discovered a leaf fossil from the Cambrian Period that is 500 million years old. He notices that the leaf had very few stomata compared to present-day leaves. What does this tell the researcher about atmospheric CO2 levels during the Cambrian Period?

Atmospheric CO2 levels were higher during the Cambrian Period than today.

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.

Which of the statements is true regarding chemical weathering?

It contributes to the accumulation of CaCO3 in oceans.

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

NO3-

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.

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

Rates of oxygen consumption are lower than rates of photosynthesis.

A botanist is comparing the metabolic pathways for photosynthesis in cyanobacteria and redwood trees. What do you expect that she 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).

Which of the answer choices would not be expected to affect primary production?

biomass of primary consumers

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

Which group in a food web is responsible for returning inorganic compounds back to the environment?

decomposers

A community of organisms and the physical environment it occupies are known together as a(n):

ecosystem.

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

erosion of rocks on land.

Currently, atmospheric CO2 levels are the highest they have ever been in Earth's 4.6 billion-year history.

false

Glacial ice core data can provide scientists with information about atmospheric CO2 levels for the last 500 million years 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

Photosynthesis and respiration were the main causes of fluctuations in atmospheric CO2 levels over the last 500 million years.

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

The rate of exchange of carbon between the atmosphere and the oceans represents a carbon:

flux.

A _____ takes into account the diverse interactions between primary producers, consumers, and decomposers. It depicts the flow of carbon through an environment as interdependent of primary producers, consumers, and decomposers.

food web

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

food web.

To some extent, Earth's surface reflects solar radiation (in the form of heat), which is subsequently absorbed by certain _____ gases in the atmosphere, such as methane and CO2.

greenhouse

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 carbon and nitrogen cycles are related to one another because:

microorganisms have important roles in the cycling of each. both are required to make the primary biological molecules (carbohydrates, fats, proteins, and sugars). both are liberated into the environment when organisms decompose.

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

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

photosynthesis and respiration

The equation 6CO2 + 6H2O → C6H12O6 + 6O2 represents the process of:

photosynthesis.

The movement of Earth's crust, plate tectonics, contributes to the long-term carbon cycle through all of the answer choices except:

photosynthesis.

A heterotrophic organism that consumes primary consumers is called a(n):

predator.

Which of these organisms can incorporate atmospheric carbon directly into C6H12O6, thereby playing a major role in a food web?

primary producers

Cyanobacteria, milkweed plants, and oak trees are all considered:

primary producers.

The rate of respiration _____ throughout the year.

remains more or less constant

Energy flow through ecosystems can be depicted using a(n):

trophic pyramid

Most phosphorus on the planet is found in living organisms.

true

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

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