Question 1

The most inclusive level of biological organization is
A) ecosystems.
B) biomes.
C) the biosphere.
D) communities.
E) ecotypes.

Accepted Answer

The biosphere encompasses all ecosystems and thus all spheres where living organisms are found.

Question 2

As humans continue to use fossil fuels as a primary source of energy, the amount of carbon entering the atmosphere from fossil fuel combustion will continue to increase dramatically. What is the effect of large-scale deforestation on the carbon in the atmosphere?
A) Because trees are a major sink for atmospheric carbon, fewer trees will result in less carbon being removed from the atmosphere for photosynthesis.
B) As trees are removed, there is more room for carbon to enter the soil directly and be used by other plants.
C) The large-scale removal of forests does not have any real effect on atmospheric carbon, because carbon dioxide is not stored in trees.
D) Because trees produce carbon dioxide, the amount of carbon in the atmosphere will decrease with their wide-scale removal.

Accepted Answer

Plants remove carbon dioxide from the atmosphere in order to conduct photosynthesis. As forests are removed, this sink, or storage area, for carbon is taken away, resulting in less carbon dioxide being removed from the atmosphere.

Question 3

The greenhouse effect
A) will lead to decreased sea levels.
B) decreases the amount of carbon dioxide in the air.
C) increases the amount of carbon dioxide in the air.
D) is caused by gases such as carbon dioxide trapping heat in the Earth's atmosphere.
E) is due to gases forming a barrier around the Earth and insulating the Earth from the sun's rays.

Accepted Answer

As carbon dioxide and other gases continue to increase in the atmosphere, these gases absorb and reradiate heat back to the Earth leading to a rise in overall temperature across the Earth.

Question 4

What is the main reason that the tundra does not have large plants?
A) The seeds of large plants were never dispersed into these regions.
B) The amount of sunlight is not great enough for large plants to survive.
C) The amount of rainfall is not enough for large plants to survive.
D) The other species of plants have outcompeted them for resources.
E) The permafrost persists, even during the summer.

Accepted Answer

Permafrost is a layer of permanently frozen ground found within the tundra. Even during the summer months and the short growing season, this layer of ground will remain frozen. It is the frozen ground that is the greatest limiting factor for the growth of large plants. They cannot establish a root system deep enough into the ground to support them.

Question 5

Biomes are defined by
A) their size.
B) types of animals.
C) communities.
D) temperature and rainfall.
E) plants, animals, and inorganic matter.

Accepted Answer

Temperature and rainfall account for the regional climate and different organisms are adapted to live in different climates.

Question 6

How does climate change effect Earth's oceans? A) The pH level of the ocean will shift to a more acidic environment, leading to stress and the possible extinction of many species of shellfish and corals. B) The pH level of the ocean will shift to a more basic environment, leading to a decrease in overall productivity. C) As levels of carbon in the atmosphere increase, the amount of carbon in the ocean decreases proportionately. D) Excess carbon in the atmosphere is absorbed by the ocean, which directly increases ocean temperature. As E) the CO₂ levels in the atmosphere increase, so do the levels in the ocean, leading to ocean acidification.

Accepted Answer

As the CO2 levels in the atmosphere increase, so do the levels in the ocean, leading to ocean acidification.

Question 7

All of the following are reservoirs except
A) oil.
B) calcium carbonate.
C) coal.
D) natural gas.
E) bicarbonate.

Accepted Answer

Bicarbonate is formed when carbon dioxide from the air combines with water. This is an immediate source of carbon for aquatic organisms, not a reservoir.

Question 8

Which two terrestrial biomes are the most similar with regards to rainfall?
A) desert & taiga
B) rainforest & desert
C) desert & temperate forest
D) temperate grasslands & desert
E) temperate forests & rainforests

Accepted Answer

In regards to rainfall, the tundra has minimal to moderate; the taiga, temperate forests, and tropical grasslands savanna) all have moderate; temperate grasslands and deserts have low; and tropical rainforests have the highest amount of rainfall.

Question 9

To increase her tomato yield, an organic gardener plants legumes alongside her tomato bushes rather than using fertilizers. Why did she plant legumes?
A) Legumes have root nodules with nitrogen-fixing bacteria.
B) Legumes convert ammonium to nitrates.
C) Root nodules on legumes have denitrifying bacteria.
D) Legumes are an immediate source of phosphorus and nitrogen.
E) Root nodules on legumes produce nitrifying bacteria.

Accepted Answer

Legumes have nodules with nitrogen-fixing bacteria and this increases the nitrogen content of the soil.

Question 10

What is the source of carbon for most aquatic organisms?
A) carbon dioxide
B) calcium carbonate
C) bicarbonate ions
D) carbon monoxide
E) fossil fuels

Accepted Answer

Carbon dioxide in the air combines with water to produce biocarbonate.

Question 11

Which ecosystem makes up approximately 70% of the Earth's surface?
A) aquatic; marine
B) aquatic; fresh water
C) aquatic; coral reefs
D) terrestrial; tundra
E) terrestrial; rainforest

Accepted Answer

Aquatic ecosystems are divided into those composed of fresh water and those composed of salt water marine ecosystems). The ocean, a marine ecosystem, covers 70% of the Earth's surface. Two types of freshwater ecosystems are those with standing water, such as lakes and ponds, and those with running water, such as rivers and streams.

Question 12

In aquatic ecosystems, primary productivity is most dependent on
A) organic nutrients.
B) species richness and diversity.
C) the type of soil.
D) the rate of photosynthesis.
E) inorganic nutrients.

Accepted Answer

Inorganic nutrients are often limiting factors for growth. Estuaries and marshes have many decomposers which convert organic nutrients to inorganic compounds, which are needed for growth.

Question 13

What process is occurring in Box C?
A) nitrification
B) decomposition
C) denitrification
D) nitrogen fixing
E) nitrogen incorporation

Accepted Answer

When nitrogen gas is transformed into ammonium, this is known as nitrogen fixing or nitrogen fixation.

Question 14

Water is a major limiting factor in which of the following biomes?
A) temperate grasslands
B) tundra
C) savannah
D) tropical rainforest
E) coral reef

Accepted Answer

In the tundra, much of the water is frozen so it is unavailable to plants.

Question 15

Which of the following terrestrial ecosystems has the highest rate of primary productivity?
A) marsh
B) tropical rainforest
C) temperate rainforest
D) prairie
E) tundra

Accepted Answer

Tropical rainforests have high rates of rainfall and warm temperatures. The result is an abundance of aboveground vegetation and higher primary productivity.

Question 16

What is the first step in energy flow through an ecosystem?
A) Producers absorb solar energy.
B) Producers are eaten by the herbivores.
C) Decomposers break down the organic matter and make it available for the producers.
D) Top-level carnivores eat the herbivores or omnivores within the ecosystem.
E) Producers absorb nutrients from the soil.

Accepted Answer

Energy flow through an ecosystem begins when producers absorb solar energy. Chemical cycling then begins when producers take in inorganic nutrients from the physical environment.

Question 17

When an animal respires, the carbon in the carbon dioxide that it breathes out comes indirectly from
A) the air that the organism breaths in.
B) dead and decaying plant matter.
C) fossil fuels.
D) photosynthesis.
E) carbon fixation.

Accepted Answer

When plants photosynthesize, they take carbon dioxide from the atmosphere and build organic molecules such as glucose. When an animal eats either plants or animals, the carbohydrates are broken down and carbon dioxide is released as a waste product. These carbohydrates were originally produced via photosynthesis by producers.

Question 18

What is the main reason that the tundra does not have large plants?
A) The seeds of large plants were never dispersed into these regions.
B) The amount of sunlight is not great enough for large plants to survive.
C) The amount of rainfall is not enough for large plants to survive.
D) The other species of plants have outcompeted them for resources.
E) The permafrost persists, even during the summer.

Accepted Answer

Permafrost is a layer of permanently frozen ground found within the tundra. Even during the summer months and the short growing season, this layer of ground will remain frozen. It is the frozen ground that is the greatest limiting factor for the growth of large plants. They cannot establish a root system deep enough into the ground to support them.

Quiz 31: Communities and Ecosystems

The most inclusive level of biological organization is

As humans continue to use fossil fuels as a primary source of energy, the amount of carbon entering the atmosphere from fossil fuel combustion will continue to increase dramatically. What is the effect of large-scale deforestation on the carbon in the atmosphere?

The greenhouse effect

What is the main reason that the tundra does not have large plants?

Biomes are defined by

How does climate change effect Earth's oceans?

All of the following are reservoirs except

Which two terrestrial biomes are the most similar with regards to rainfall?

To increase her tomato yield, an organic gardener plants legumes alongside her tomato bushes rather than using fertilizers. Why did she plant legumes?

What is the source of carbon for most aquatic organisms?

Which ecosystem makes up approximately 70% of the Earth's surface?

In aquatic ecosystems, primary productivity is most dependent on

What process is occurring in Box C?

Water is a major limiting factor in which of the following biomes?

Which of the following terrestrial ecosystems has the highest rate of primary productivity?

What is the first step in energy flow through an ecosystem?

When an animal respires, the carbon in the carbon dioxide that it breathes out comes indirectly from

What is the main reason that the tundra does not have large plants?