Question 1

Given that most nutrients can dissolve into water which of the following statements is false?

Accepted Answer

Atmospheric nitrogen does not dissolve into water because it is a non-polar molecule.Even if it did it would not be useful to plants since they cannot use N₂;they require that the nitrogen be fixed by bacteria into an ionic form.

Question 2

Which of these is NOT a requirement or influence on chemical cycling of inorganic nutrients in a natural ecosystem?

Accepted Answer

Chemical cycling includes reservoirs,exchange pools,and the biotic community.Human activities influence the cycling by removing the chemicals.

Question 3

Which is not true about a complex food web?

Accepted Answer

Energy moves from trophic level to level,but some is lost between the various levels because energy has been used to do biological work.

Question 4

What happens to the amount of energy while going up a ecological pyramid?

Accepted Answer

In general,only about 10% of the energy of one trophic level is available to the next higher trophic level because of energy losses between trophic levels.

Question 5

What human activities have affected the phosphorus cycle and led to eutrophication of the waterways?

Accepted Answer

Humans boost the supply of phosphate by mining phosphate ores for producing fertilizer and detergents.Runoff of phosphate and nitrogen due to fertilizer use,animal wastes from livestock feedlots,and discharge from sewage treatment plants results in eutrophication (overenrichment)of waterways.

Question 6

During mutualism one species benefits while the other is harmed.

Accepted Answer

During mutualism both species receive a positive benefit from the relationship.During parasitism or predation one species benefits while the other is harmed.

Question 7

The three locations where a nutrient may be found in an ecosystem are

Accepted Answer

The exchange pool keeps the necessary elements available to producers while storing them either long term or short term depending on the needs of the producers.Reservoirs serve as long term storage but typically not in a form that is usable by producers.Living organisms also serve to store nutrients,typically short term - while the organism is living;upon the death of the organism the nutrient is released back into the environment through the action of decomposers.

Question 8

The greenhouse effect is:

Accepted Answer

The greenhouse gases allow solar radiation to pass through but hinder the escape of infrared rays (heat)back into space.The greenhouse gases are contributing to an overall rise in the Earth's ambient temperature,a trend called global climate change.

Question 9

Which of the following is NOT required in robust chemical cycling of inorganic nutrients in a natural ecosystem?

Accepted Answer

In order for nutrients to be cycled the two groups of organisms that are required are autotrophs and decomposers.The method of capturing energy and the energy source can be either chemical,chemosynthesis,or solar,photosynthesis,so the producers can be plants,algae or bacteria.Decomposers are also necessary to return organic molecules to a form that is usable for the producers.Any other organism is not absolutely required for nutrient cycling.

Question 10

Which of the following is not a method in which phosphorus gets added to the soil?

Accepted Answer

Geological uplift is a method in which phosphate is brought up to the surface instead of down into the soil.

Question 11

Which sequence correctly illustrates the most plausible food chain?

Accepted Answer

A producer must be the first link in a food chain so algae,as the only producer listed must come first.They can be fed on by either insect larvae or fish but it is unlikely that fish would be fed on by insect larvae so insect larvae must come next with fish feeding on the insect larvae and humans feeding on fish.

Question 12

The theory that plants cannot grow on a particular area until the soil has been developed enough by an earlier community is the

Accepted Answer

A facilitated model of succession occurs when each successive community improves conditions in the area for the community that follows.The improvement usually takes the form of increased nutrients in the soil.

Question 13

A carbon atom cycles between an organism and the atmosphere where it is then taken up by a producer and is then eventually eaten by an herbivore and passed back into the atmosphere through respiration.The carbon atom has passed through which portions of a nutrient cycle?

Accepted Answer

The carbon atom released through cellular respiration moves from a living organism to the exchange pool of the atmosphere.It is then taken in by another living organism,the producer where it is then respired back into the exchange pool of the atmosphere.

Question 14

Nitrification refers to the production of:

Accepted Answer

The production of nitrates during the nitrogen cycle is called nitrification.

Question 15

A detritus food chain begins:

Accepted Answer

In the detrital food web,the food chain includes: detritus F1F1F1S1F1F1F10 earthworms F1F1F1S1F1F1F10 carnivore.

Question 16

Which of the following is not a carbon reservoir?

Accepted Answer

Living and dead organisms contain organic carbon and serve as one of the reservoirs for the carbon cycle These include trees,coal,oil,natural gas,limestone and in calcium carbonate shells.

Question 17

Which of the following is not true about the phosphorus cycle?

Accepted Answer

The phosphorus cycle is sedimentary.Geologic upheavals move phosphorus from the ocean to land.Slow weathering of rocks returns phosphorus to the soil.Most phosphorus is recycled within a community,and phosphorus is a limiting nutrient.

Question 18

In an experiment carried out to study the energy flow through an ecosystem scientists measure the total solar energy captured by plants to be 10,000 kilocalories.The portion of this available to the next trophic level will be

Accepted Answer

Since the plants will use all of the energy except approximately 10% the amount of energy available to the next level will be 1,000 kilocalories.

Question 19

If you were studying the nitrogen cycle you would know that all of the following are true except:

Accepted Answer

The nitrogen cycle is gaseous.Plants cannot use nitrogen gas,the most abundant gas in the atmosphere.During nitrogen fixation,N₂ converts to ammonium,making nitrogen available to plants.Nitrification is the production of nitrates,while denitrification is the conversion of nitrate back to N₂,which enters the atmosphere.Human activities increase transfer rates in the nitrogen cycle.Acid deposition occurs when nitrogen oxides and sulfur dioxide combine with water vapor to form acid rain.

Quiz 39: Community and Ecosystem Ecology