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BIOL 3012 > 55 Chapter > Flashcards

55 Chapter Flashcards

1
Q

Ecosystem

A

The sum of all the organisms living in a given area and the abiotic factors with which they interact.

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2
Q

Regardless of an ecosystem’s size, two key ecosystem processes cannot be fully described by population or community phenomena:

A

Energy flow and chemical cycling

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3
Q

Because energy flowing through ecosystems is ultimately dissipated into space as heat, most ecosystems would vanish if the sun were not continuously providing energy to Earth.

A

True

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4
Q

Law of conservation of mass

A

A physical law stating that matter can change form but cannot be created or destroyed. In a closed system, the mass of the system is constant.

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5
Q

Example of chemical cycling of carbon atom in CO2.

A

A carbon atom in CO2 is released from the soil by a decomposer, taken up by a grass through photosynthesis, consumed by a grazing animal, and returned to the soil in the animal’s waste.

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6
Q

Primary producers

A

An autotroph, usually a photosynthetic organism. Collectively, autotrophs make up the trophic level of an ecosystem that ultimately supports all other levels.

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7
Q

Primary consumers

A

An herbivore; an organism that eats plants or other autotrophs.

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8
Q

Secondary consumers

A

A carnivore that eats herbivores.

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9
Q

Tertiary consumer

A

A carnivore that eats other carnivores.

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10
Q

Detritivores

A

Refers to consumers that get their energy from detritus.

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11
Q

Detritus

A

Nonliving organic material, such as the remains of dead organism, feces, fallen leaves, and wood.

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12
Q

Many detritivores are eaten by ______________

A

Secondary and tertiary consumers

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13
Q

Two important groups of detritivores:

A

Prokaryotes and fungi

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14
Q

What is the critical role detritivores play in recycling chemical elements to primary producers?

A

They convert organic matter from all tropic levels to inorganic compounds usable by primary producers, closing the loop of an ecosystem’s chemical cycling.

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15
Q

Primary production

A

The amount of light energy converted to chemical energy (organic compounds) by the autotrophs in an ecosystem during a given time period.

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16
Q

The intensity of the solar energy striking Earth varies with ___________, with the tropics receiving the greatest input.

A

Latitude

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17
Q

Gross primary production (GPP)

A

The total primary production of an ecosystem per unit time.

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18
Q

Net primary production (NPP)

A

The gross primary production of an ecosystem minus the energy used by the producers for respiration.

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19
Q

NPP=

A

NPP= GPP - R(sub)a
R(sub)a = autotrophic respiration

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20
Q

Standing crop

A

A measurement of the total biomass of photosynthetic autotrophs present.

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21
Q

The net primary production is the amount of new biomass added in a given period of time.

A

True

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22
Q

Biomass

A

The total mass of organic matter comprising a group of organisms in a particular habitat.

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23
Q

Net ecosystem production

A

The gross primary production of an ecosystem minus the energy used by all autotrophs and heterotrophs for respiration.

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24
Q

R(sub)T

A

Total respiration of all organisms in a system

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25
Q

NEP=

A

NEP= GPP - R(sub)T

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26
Q

NEP is useful to ecologists because…

A

Its value determines whether an ecosystem is gaining or losing carbon over time.

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27
Q

The most common way to estimate NEP is to …

A

Measure the net flux (flow) of CO2 or O2 entering or leaving the ecosystem. If more CO2 enters than leaves, the system is storing carbon. Because O2 release is directly coupled to photosynthesis and respiration, a system that is giving off O2 is also storing carbon.

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28
Q

More than light, nutrients limit primary production in most oceans and lakes.

A

True

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29
Q

Limiting nutrient

A

An element that must be added for production to increase in a particular area. For example, in aquatic ecosystems.

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30
Q

The nutrient most often limiting marine production is either _________ or ________.

A

Nitrogen, phosphorus

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31
Q

Area of upwelling, where deep, nutrient-rich waters circulate to the ocean surface, have exceptionally high primary production. This fact supports the hypothesis that nutrient availability determines marine primary production.

A

True

32
Q

Eutrophication

A

A process by which nutrients, particularly phosphorus and nitrogen, become highly concentrated in a body of water, leading to increased growth of organisms such as algae or cyanobacteria.

33
Q

At regional and global scales, __________ and ___________ are the main factors controlling primary production in terrestrial ecosystems.

A

Temperature, moisture

34
Q

Evaprotranspiration

A

The total amount of water transpired by plants and evaporated from a landscape.

35
Q

In terrestrial ecosystems, NPP can be predicted using:

A

Annual precipitation and evapotranspiration.

36
Q

Evapotranspiration increases with…

A

The temperature and amount of solar energy available to drive evaporation and transpiration.

37
Q

Secondary production

A

The amount of chemical energy in consumers’ food that is converted to their own new biomass during a given time period.

38
Q

Energy flows through, not cycles within, ecosystems.

A

True

39
Q

Only the chemical energy stored by herbivores as biomass, through growth or the production of offspring, is available as food to secondary consumers.

A

True

40
Q

Net secondary production

A

Is the energy stored in biomass represented by growth and reproduction of herbivores.

41
Q

Assimilation of primary production

A

Consists of the total energy taken in by herbivores, not including losses in feces, used for growth, reproduction, and respiration.

42
Q

Production efficiency

A

The percentage of energy stored in assimilated food that is not used for respiration or eliminated as waste.
(Contradiction in definitions; ask)

43
Q

Trophic efficiency

A

The percentage of production transferred from one trophic level to the next higher trophic level.

44
Q

Why must trophic efficiency always be less than production efficiencies?

A

Because they take into account not only the energy lost through respiration and feces, but also the energy in organic material in a lower trophic level not consumed by the next trophic level.

45
Q

Pyramid of net production

A

A pyramid in which the trophic levels are arranged in tiers. The width of each tier is proportional to the net production, expressed in joules, of each trophic level.

46
Q

Biomass pyramid

A

Each tier represents the standing crop (the total dry mass of all organisms) in one trophic level.

47
Q

Most biomass pyramids narrow sharply from primary producers at the base to top-level carnivores at the apex because energy transfers are so inefficient.

A

True

48
Q

Turnover time

A

The time required to replace standing crop of a population or group of populations, calculated as the ratio of standing crop to production.

49
Q

Inverted biomass pyramids occur because…

A

The producers grow, reproduce, and are consumed so quickly by the consumers that they never develop a large population size, or standing crop. In other words, they have a short turnover time, which means they have a small standing crop compared to their production.

50
Q

Turnover time formula

A

Turnover time = Standing crop (g/m^2) / Production [g/ (m^2 • day)]

51
Q

Although most ecosystems receive abundant solar energy, chemical elements are available only in limited amounts. Life therefore depends on the recycling of essential chemical elements.

A

True

52
Q

Biogeochemical cycles

A

Any of the various chemical cycles, which involve both biotic and abiotic components of ecosystems.

53
Q

Two general categories of biogeochemical cycles:

A

Global and local

54
Q

Gaseous forms of carbon, oxygen, sulfur, and nitrogen occur in the atmosphere, and cycles of these elements are essentially global. For example, some of the carbon and oxygen atoms a plant acquires from the air as CO2 may have been released into the atmosphere by the respiration of an organism in a distant locale.

A

True

55
Q

The Water Cycle - Biological Importance

A

Water is essential to all organisms, and its availability influences the rates of ecosystem processes, particularly primary production and decomposition in terrestrial ecosystems.

56
Q

The Water Cycle - Forms available to life

A

All organisms can exchange water directly with their environment. Liquid water is the primary physical phase in which water is used, though some organisms can harvest water vapor. Freezing of soil water can limit water availability to terrestrial plants.

57
Q

The Water Cycle - Reservoirs

A

The ocean contain 97% of the water in the biosphere. Approximately 2% is bound in glaciers and polar ice caps, and the remaining 1% is in lakes, rivers, and groundwater. A negligible amount is in the atmosphere.

58
Q

The Water Cycle - Key Processes

A

The main processes driving the water cycle are evaporation of liquid water by solar energy, condensation of water vapor into clouds, and precipitation. Transpiration by terrestrial plants also moves large volumes of water into the atmosphere. Surface and groundwater flow returns water to the oceans, completing the water cycle.

59
Q

The Carbon Cycle - Biological Importance

A

Carbon forms the framework of the organic molecules essential to all organisms.

60
Q

The Carbon Cycle - Forms available to life

A

Photosynthetic organisms utilize CO2 during photosynthesis and convert the carbon to organic forms that are used by consumers. All organisms can return carbon directly to their environment as CO2 through respiration.

61
Q

The Carbon Cycle - Reservoirs

A

The major reservoirs of carbon include fossil fuels, soils, the sediments of aquatic ecosystems, the oceans (dissolved carbon compounds), plant and animal biomass, and the atmosphere (CO2). The largest reservoir is sedimentary rocks such as limestone; however, this pool turns over very slowly.

62
Q

The Carbon Cycle - Key processes

A

Photosynthesis by plants and phytoplankton removes the substantial amounts of atmospheric CO2 each year. This quantity is approximately equaled by CO2 added to the atmosphere through cellular respiration by producers and consumers. The burning of fossil fuels and wood is adding significant amounts of additional CO2 to the atmosphere. Over geologic time, volcanoes are also a substantial source of CO2.

63
Q

The Phosphorus Cycle - Biological Importance

A

Organisms require phosphorus as a major constituent of nucleic acids, phospholipids, and ATP and other energy-storing molecules and as a mineral constituent of bones and teeth.

64
Q

The Phosphorus Cycle - Forms available to life

A

The most biologically important inorganic form of phosphorus is phosphate (PO4^3-), which plants absorb and use in the synthesis of organic compounds.

65
Q

The Phosphorus Cycle - Reservoirs

A

The largest accumulations of phosphorus are in sedimentary rocks of marine origin. There are also large quantities of phosphorus in soil, in the oceans (in dissolved form), and in organisms. Because soil particles bind PO4^3-, the recycling of phosphorus tends to be quite localized in ecosystems.

66
Q

The Phosphorus Cycle - Key processses

A

Weathering of rocks gradually adds PO4^3- to soil; some leaches into groundwater and surface water and may eventually reach the sea. Phosphate taken up by producers and incorporated into biological molecules may be eaten by consumers. Phosphate is returned to soil or water by either decomposition of biomass or excretion by consumers. Because there are no significant phosphorus-containing gases, only relatively small amounts of phosphorus move through the atmosphere, usually in the forms of dust and sea spray.

67
Q

The Nitrogen Cycle - Biological importance

A

Nitrogen is part of amino acids, proteins, and nucleic acids and is often a limiting plant nutrient.

68
Q

The Nitrogen Cycle - Forms available to life

A

Plants can assimilate (use) two inorganic forms of nitrogen—ammonium (NH4+) and nitrate (NO3-)—and some organic forms, such as amino acids. Various bacteria can use all of these forms as well as nitrite (NO2-). Animals can use only organic forms of nitrogen.

69
Q

The Nitrogen Cycle - Reservoirs

A

The main reservoir of nitrogen is the atmosphere, which is 78% free nitrogen gas (N2). The other reservoirs of inorganic and organic nitrogen compounds are soils and the sediments of lakes, rivers, and oceans; surface water and groundwater; and the biomass of living organisms.

70
Q

The Nitrogen Cycle - Key processss

A

The major pathway for nitrogen to enter an ecosystem is via nitrogen fixation, the conversion of N2 to forms that can be used to synthesize organic nitrogen compounds. Certain bacteria, as well as lightning and volcanic activity, fix nitrogen naturally. Nitrogen inputs from human activities now outpace natural inputs on land. Two major contributors are industrially produced fertilizers and legume crops that fix nitrogen via bacteria in their root nodules. Other bacteria in soil convert nitrogen to different forms. Some bacteria carry out denitrification, the reduction of nitrate to nitrogen gases. Human activities also release large quantities of reactive nitrogen gases, such as nitrogen oxides, to the atmosphere.

71
Q

Decomposers usually grow faster and decompose material more quickly in ______________.

A

Warmer ecosystems

72
Q

Decomposition on land is also slower when conditions are either too dry for decomposers to thrive or too wet to supply them with enough oxygen.

A

True

73
Q

The Hubbard Brook deforestation study showed that the amount of nutrients leaving an intact forest ecosystem is controlled mainly by the plants.

A

True

74
Q

Two key strategies in biological restoration:

A

Bioremediation and biological augmentation

75
Q

Bioremediation

A

The use of organisms to detoxify and restore polluted and degraded ecosystems.

76
Q

Biological augmentation

A

An approach to restoration ecology that uses organisms to add essential materials to a degraded ecosystem.

BIOL 3012 (14 decks)

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