Question 1

Water-soluble wastes are not a significant pollution problem because liquid water cannot dissolve as many compounds as most other liquids.

Accepted Answer

Water-soluble wastes can still be a significant pollution problem because water can dissolve many different types of compounds, including harmful chemicals and pollutants. These can then spread through waterways and contaminate the environment.

Question 2

Human activities affect the phosphorus cycle by greatly increasing the amount of phosphorus stored in the earth, reducing the amount available for plant growth.

Accepted Answer

Human activities, such as the use of fertilizers and detergents, actually increase the amount of phosphorus in the soil and water bodies, which can lead to eutrophication and harm aquatic ecosystems, rather than reducing the amount available for plant growth.

Question 3

Only about 0.024% of the earth's vast water supply is available to humans and other species as liquid freshwater.

Accepted Answer

This statement is true. Approximately 97.5% of the earth's water is saltwater in oceans and seas, and only about 2.5% is freshwater. However, two-thirds of that freshwater is locked up in ice caps and glaciers, leaving only about 0.024% of the earth's water supply as liquid freshwater available for human use and consumption.

Question 4

Plants, but not animals, carry out photosynthesis while animals, but not plants, carry out aerobic respiration.

Accepted Answer

Both plants and animals carry out aerobic respiration, but only plants carry out photosynthesis.

Question 5

Plants utilize a portion of their gross primary productivity (GPP) for respiration.

Accepted Answer

Plants do use a portion of their GPP for respiration, which is necessary for the plant's metabolism and growth. The remaining portion of GPP is used for growth and reproduction.

Question 6

Water has the ability to filter out wavelengths of the sun's ultraviolet radiation that would harm some aquatic organisms.

Accepted Answer

Water has the ability to absorb and filter out certain wavelengths of UV radiation, providing protection for some aquatic organisms.

Question 7

Water exists as a liquid over a wide range of temperatures because of the lack of attractive forces between its molecules.

Accepted Answer

Water exists as a liquid over a wide range of temperatures because of the strong hydrogen bonds between its molecules, not the lack of attractive forces.

Question 8

If an ecologist spent a summer recording the behavior of grasshoppers in a meadow, the work would be considered laboratory research.

Accepted Answer

The research would be considered field research, as it is being conducted in the natural environment of the grasshoppers, rather than in a laboratory setting.

Question 9

Human activities affect the hydrologic cycle by making changes to the land surface that reduce infiltration and increase runoff.

Accepted Answer

Human activities such as urbanization, deforestation, and agriculture alter the natural landscape and cause increased runoff by reducing the amount of water that can infiltrate into the ground. This can lead to issues such as erosion, flooding, and water pollution.

Question 10

Aerobic respiration is the process by which cells use oxygen to produce energy that they can use to fuel life processes.

Accepted Answer

Aerobic respiration is a well-known metabolic process that takes place in cells, where glucose and oxygen are used to create ATP, which is subsequently utilized as a source of energy.

Question 11

Water contracts when it freezes, making ice more dense than liquid water.

Accepted Answer

Water actually expands when it freezes, which makes ice less dense than liquid water. This is why ice floats on top of water.

Question 12

Sometimes ecologists carry out controlled experiments by isolating and changing a variable in part of an area and comparing the results with nearby unchanged areas.

Accepted Answer

This statement is true. Ecologists do sometimes conduct controlled experiments to compare the effects of changing a variable in one area with the effects in a nearby area where the variable remains unchanged. This type of experiment allows researchers to draw conclusions about cause-and-effect relationships in ecological systems.

Question 13

Omnivores are animals that feed only on the flesh of other animals.

Accepted Answer

The statement is false. Omnivores are animals that eat both plants and animals. They have a mixed diet.

Question 14

The amount of carbon dioxide in the atmosphere is affected by the carbon cycle.

Accepted Answer

The carbon cycle involves processes such as photosynthesis, respiration, decomposition, combustion, and fossil fuel use, all of which can either remove or release carbon dioxide into the atmosphere, thus affecting its concentration.

Question 15

Because the earth does not get significant inputs of matter from space, its essentially fixed supply of nutrients must continually be recycled to support life.

Accepted Answer

The earth's nutrient supply must be recycled to support life because there are no significant inputs of matter from space.

Question 16

A sphere of energy flow shows the amount of energy lost from one trophic level to the next.

Accepted Answer

A pyramid of energy flow, not a sphere, shows the amount of energy lost from one trophic level to the next in an ecosystem.

Question 17

As a primary consumer, a deer is part of the second trophic level.

Accepted Answer

A deer is considered a primary consumer as it feeds on plants, which are at the first trophic level, and is therefore part of the second trophic level.

Question 18

Detritivores, such as earthworms, consume wastes and dead organisms to obtain nutrients.

Accepted Answer

Detritivores are organisms that feed on detritus, which includes dead plant and animal matter, feces, and other waste materials. Earthworms are one example of detritivores that play an important role in breaking down and recycling organic matter in the soil.

Question 19

Lightning is one of the natural mechanisms by which atmospheric nitrogen is converted to ammonia or ammonium ions.

Accepted Answer

Lightning provides energy for atmospheric nitrogen to react with oxygen and form nitrogen oxides. These nitrogen oxides can then dissolve in rainwater and form nitric acid, which can react with ammonia in the atmosphere to form ammonium ions.

Question 20

The hydrologic cycle collects, purifies, and distributes the earth's fixed supply of water.

Accepted Answer

The hydrologic cycle is a continuous process that collects, purifies, and distributes the earth's fixed supply of water, which includes precipitation, surface water runoff, infiltration into soil, groundwater flow, and evapotranspiration. This process helps maintain the availability of freshwater for humans and other living organisms on the planet.

Quiz 3: Ecosystems: What Are They and How Do They Work