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Biology🧪🌱💦 > Lecture 22 > Flashcards

Lecture 22 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What are the two fundamental processes in ecosystems?

A

1) Energy flow
2) Nutrient Cycling

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2
Q

How does energy enter ecosystems?

A

Energy enters ecosystems as radiant energy, primarily from the SUN.

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3
Q

What happens to radiant energy once it enters an ecosystem? (2)

A

converted into chemical energy and
stored in the bonds of organic molecules

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4
Q

Name an organic molecule and what processes it?

A

Glucose (processed by photosynthesis)

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5
Q

Is energy transfer in ecosystems 100% efficient?

A

No, energy transfer in ecosystems is never 100% efficient.

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6
Q

What is nutrient cycling?

A

process where nutrients cycle from the abiotic (non-living) to the biotic (living) components of ecosystems

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7
Q

How do energy flow and nutrient cycling relate in ecosystems?

A

While energy flows through ecosystems, matter cycles within them through nutrient cycling.

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8
Q

How does energy flow through an ecosystem?

A

by entering as light, usually from the sun, and exiting as heat.

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9
Q

Describe the flow of energy from primary producers to consumers.

A

primary producers (autotrophs) -> primary consumers (herbivores) -> secondary consumers (carnivores)

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10
Q

What role does decomposition play in ecosystems?

A
  • connects all trophic levels in ecosystems by recycling essential chemical elements.
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11
Q

What are considered to be decomposers? (2)

A

Fungi and bacteria

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12
Q

What do decomposers do?

A

they recycle essential chemical elements

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13
Q

How do they recycle essential chemical elements?

A

By decomposing organic material and returning elements to inorganic reservoirs

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14
Q

What would happen if decomposition stopped?

A

all life on Earth would CEASE!!

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15
Q

What defines heterotrophic organisms?

A

Heterotrophic organisms obtain energy from food intake.

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16
Q

Name 2 examples of heterotrophs

A

animals & fungi

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17
Q

What are autotrophs known as?

A

organisms capable of making their own nutrients from simple inorganic compounds, such as CO2.

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18
Q

How do autotrophs produce nutrients?

A

plants produce the glucose needed for energy from CO2, H2O and sunlight (photoautotrophs)

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19
Q

What is the difference between autotrophs and heterotrophs in terms of nutrient acquisition?

A

Autotrophs -> produce their nutrients from simple inorganic compounds,
Heterotrophs -> rely on consuming other organisms or organic matter for their nutrient intake.

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20
Q

What is the source of energy for ecosystems?

A

SUN = primary source of energy

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21
Q

What organisms occupy the first trophic level?

A

Producers

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22
Q

Give examples of producers (those who occupy the first trophic level)

A

green plants

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23
Q

Who are the primary consumers in ecosystems?

A

herbivores (second trophic level)

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24
Q

What do herbivores eat?

A

They eat producers

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25
Q

Who are the secondary consumers in ecosystems?

A

Carnivores (occupy third trophic level)

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26
Q

What is the role of tertiary consumers in ecosystems?

A

They eat secondary consumers and occupy the fourth trophic level.

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27
Q

What function do decomposers serve in ecosystems?

A

Decomposers, or saprotrophs, break down dead organic material, returning nutrients to the environment

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28
Q

What happens to the energy content of food as it moves through the food chain?

A

As energy moves through the food chain, some of it is used for growth and metabolic processes

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29
Q

How is most of the energy lost as?

A

most of it is lost as heat, requiring a continual input of energy from the sun.

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30
Q

What does a community consist of at each trophic level?

A

A community consists of many species at each trophic level, including primary producers, herbivores, and carnivores.

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31
Q

How does energy pass through the trophic structure of a community?

A

Energy passes through the trophic structure of a community from producers to consumers.

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32
Q

Describe a simple food chain scenario.

A

a plant (producer) is consumed by a single grazer (primary consumer), which is then eaten by a single carnivore (secondary consumer)

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33
Q

Are simple food chains relatively common or rare in nature

A

relatively RARE

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34
Q

If food chains don’t accurately represent our food distribution, what is better?

A

a FOOD WEB

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35
Q

How do animals in most communities feed?

A

animals do not feed in a specialized manner but may eat many types of plants

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36
Q

How do carnivores typically feed at the next trophic level?

A

Carnivores tend to eat several different prey.

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37
Q

How are food chains related to food webs?

A

How are food chains related to food webs?

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38
Q

What is a food web?

A

A food web is a complex network of interconnected food chains within a community.

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39
Q

Why are food webs more representative of natural communities than food chains?

A

because they illustrate the multiple feeding relationships and interactions among different species in a community.

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40
Q

What is primary production?

A

the amount of light energy converted to chemical energy

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41
Q

Who performs primary production in an ecosystem?

A

Autotrophs, such as plants

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42
Q

What sets the spending limit for the energy budget of the entire ecosystem?

A

the extent of photosynthetic production

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43
Q

What is total primary production in an ecosystem called?

A

the ecosystem’s gross primary production (GPP).

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44
Q

Is all of the GPP stored as organic material in plants?

A

No, not all of the GPP is stored as organic material in the growing plants.

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45
Q

What does NPP stand for?

A

Net primary production

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46
Q

What is NPP?

A

NPP = GPP minus the energy used by the primary producers for cellular respiration.

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47
Q

What is the main equation then?

A

NPP = GPP -R

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48
Q

What is R in the equation?

A

R is the energy used by PRIMARY producers for respiration

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49
Q

What portion of primary production is available to consumers?

A

Only NPP is available to consumers.

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50
Q

Productivity of terrestrial environments is limited by what?

A

is limited by a combination of temperature, availability of water & sunlight

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51
Q

Primary production is positively correlated with WHAT?

A

evapotranspiration

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52
Q

What is evapotranspiration?

A

= amount of water transpired by plants & evaporated from landscape

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53
Q

Primary production increases with 2 things, name them:

A
  • amount of precipitation
  • solar energy
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54
Q

How come these factors help increase primary production? (what do they drive?)

A

these factors drive evaporation & transpiration

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55
Q

Which terrestrial ecosystem is the most productive?

A

Tropical rain forests

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56
Q

What conditions contribute to the high productivity of tropical rainforests? (2)

A

warm + wet conditions

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57
Q

Which ecosystems are generally low in productivity?

A

Deserts and arctic tundra

58
Q

What are the typical conditions in low-productivity ecosystems?

A

Low-productivity ecosystems are typically dry (deserts) or dry and cold (arctic tundra).

59
Q

What is actual evapotranspiration?

A

amount of water annually transpired by plants and evaporated from a landscape

60
Q

To ecologists, what is hte key measurement?

A

net primary production

61
Q

Why is net primary production (NPP) important to ecologists?

A

NPP is important because it represents the storage of chemical energy that is available to consumers in the ecosystem.

62
Q

What does NPP represent in an ecosystem?

A

NPP represents the storage of chemical energy available to consumers.

63
Q

What is secondary production in an ecosystem?

A

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

64
Q

How is secondary production different from NPP?

A

Secondary production refers to the energy converted into new biomass by consumers, while NPP refers to the energy stored by primary producers that is available to consumers.

65
Q

How much of the energy in a plant leaf is used for secondary production when a caterpillar feeds on it?

A

one-sixth of the energy in the leaf is used

66
Q

What happens to the energy contained in the caterpillar’s feces?

A

The energy in the feces remains in the ecosystem temporarily

67
Q

Most of the energy is lost as what?

A

mostly lost as heat after the feces are consumed by detritivores.

68
Q

What portion of the caterpillar’s energy is available to secondary consumers?

A

Only the chemical energy stored herbivore (caterpillar) biomass

69
Q

What is an example of a secondary consumer in this context?

A

Other organisms that will eat the caterpillar act as secondary consumers.

70
Q

Complete the sentence, _______ of energy with each transfer in a _____ _______

A

LOSS of energy with each transfer in a FOOD CHAIN

71
Q

What is the average trophic efficiency b/w trophic levels?

A

10%

72
Q

Why is much of the NPP unavailable to herbivores?

A

because it resides as indigestible substances

73
Q

Give an example of an indigestible substance:

A

like lignin

74
Q

How is most of the chemical energy stored in carbon compounds lost?

A

it’s lost as heat (when metabolized or used to keep the consumer alive)

75
Q

Is all the energy ingested by secondary consumers converted to biomass?
(yes/no + why?)

A

NO, some lost as heat or used to stay alive & capture prey

76
Q

Are all herbivores eaten by secondary consumers?

A

no, not all

77
Q

Why is not all energy at each trophic level used for growth or reproduction?

A

because it is also metabolized for maintenance and lost as heat

78
Q

How do toxic substances enter the food chain?

A

Through accumulation in the environment.

79
Q

What happens if an organism does not metabolize a toxin?

A

It gets stored in the body.

80
Q

Define bioaccumulation.

A

The build-up of toxins in an organism’s body.

81
Q

What is biomagnification?

A

Increase in toxin concentration across trophic levels.

82
Q

Why do toxins become more concentrated at higher trophic levels?

A

Each predator consumes multiple prey, accumulating toxins.

83
Q

How do nutrients cycle through an ecosystem?

A

They cycle through biotic and abiotic forms.

84
Q

Why must nutrients cycle between the biotic and abiotic parts of an ecosystem?

A

To ensure continuous availability for living organisms.

85
Q

Where do nutrient pools exist in an ecosystem?

A

In the air, soil, rocks, sediments, and water.

86
Q

What are biogeochemical cycles?

A

They are cycles where nutrients move between living organisms and the abiotic environment.

87
Q

Give an example of nutrient cycling in an ecosystem.

A

Nutrients move from one organism to another and back to the abiotic environment, completing the cycle.

88
Q

Why is nitrogen (N) essential?

A

for proteins, nucleic acids (DNA, RNA), and other biomolecules.

89
Q

Where are large reservoirs of nitrogen found?

A

in the atmosphere

90
Q

The air comprises of how much Nitrogen? (%)

A

comprising 78% of the air

91
Q

What is the role of bacteria in the nitrogen cycle?

A

microbial transformations within the nitrogen cycle

92
Q

What is nitrogen fixation?

A

for converting atmospheric nitrogen into biologically useful forms

93
Q

Is it carried out by prokaryotes or eukaryotes?

A

PROkaryotes

94
Q

What does Nitrogen fixation involve?

A

the use of nitrogenase

95
Q

What is nitrogenase?

A

an enzyme that works in the absence of oxygen

96
Q

Why is nitrogenase important in nitrogen fixation?

A

it converts atmospheric nitrogen into ammonia or related compounds.

97
Q

SO, What is nitrogen fixation?

A

conversion of atmospheric nitrogen (N2) into ammonia (NH3) and ammonium (NH4+)

98
Q

What are the 2 types of nitrogen fixers?

A

Free-living nitrogen fixers & Mutualistic prokaryotic nitrogen fixers

99
Q

What are some examples of mutualistic prokaryotic nitrogen fixers?

A
  • Rhizobium/legume symbiosis
  • Frankia symbiosis with woody plants
  • lichen symbioses involving Cyanobacteria such as Nostoc
100
Q

Where do Rhizobium bacteria typically fix nitrogen?

A

found in legume plants

101
Q

How do nitrogen-fixing cyanobacteria adapt to aquatic environments?

A

In aquatic environments, nitrogen-fixing cyanobacteria have specialized cells called heterocysts

102
Q

What are the 5 steps in the nitrogen cycle?

A

1) Nitrogen fixation
2) Nitrifcation
3) Assimilation
4) Ammonification
5) Dentifrication

103
Q

Which one involves Bacteria?

A

ALL of them but Assimilation
(therefore, BACTERIA is very important)

104
Q

1) What is nitrogen fixation?

A

Bacteria convert atmospheric nitrogen (N2) into forms that plants can use, such as ammonium (NH4+) or ammonia (NH3).

N2 -> NH4+ or NH3

105
Q

2) What is Nitrification?

A

Bacteria convert some of the products of nitrogen fixation into nitrates (NO3-) and nitrites.

ex.: NH4+ or NH3 -> NO3-

106
Q

3) What is assimilation?

A

Plant roots absorb organic forms of nitrogen from the soil.

107
Q

4) What is Ammonification?

A

Bacteria decompose organic nitrogen into ammonium (NH4+).

108
Q

5) What is Denitrification?

A

Bacteria convert organic nitrogen back into atmospheric nitrogen (N2) gas.

109
Q

Show the path from nitrogen fixation to denitrification of chemicals:

A

Nitrogen Fixation (N2) –> Ammonium (NH4+) or Ammonia (NH3) –> Nitrification (NH4+ or NH3 to NO3-) –> Assimilation (Absorption by roots) –> Ammonification (Organic nitrogen to NH4+)

110
Q

What other chemical is important?

A

C = Carbon

111
Q

What biomolecules rely on carbon as an essential component? (4 main)

A

Proteins, nucleic acids, carbohydrates, lipids, etc.

112
Q

What role does carbon dioxide play in the carbon cycle?

A

It serves as an important gas in the carbon cycle

113
Q

Where is carbon dioxide found in the environment?

A

It is found in the ocean, freshwater, and rocks. + AIR

114
Q

What % does Carbon hold in air?

A

approximately 0.04%

115
Q

How do plants acquire carbon?

A

during photosynthesis

116
Q

What processes return carbon dioxide to the environment?

A

cellular respiration, combustion, and erosion

117
Q

What does the water cycle renew?

A

renews the supply of water on Earth

118
Q

What are the key components involved in the water cycle exchange? (4)

A

land, ocean, atmosphere, and organisms

119
Q

How does water enter the atmosphere? (2)

A
  • through evaporation from bodies of water
  • transpiration from plants
120
Q

Describe the steps involved in the water cycle from the atmosphere to the land. (3 first steps)

A

Step 1: Precipitation (from atmosphere to land)
Step 2: Evaporation (from land to atmosphere)
Step 3: Transpiration (loss of water from plants to the atmosphere)

121
Q

How does water return to the ocean in the water cycle? (2)

A

through runoff and percolation through soil into groundwater.

122
Q

What strongly regulates nutrient cycling?

A

vegetation

123
Q

How does internal cycling within a terrestrial ecosystem impact mineral nutrients?

A

It conserves most of the mineral nutrients.

124
Q

Describe the experiment conducted at Hubbard Brook Experimental Forest.

A

Some areas were completely logged and then sprayed with herbicides for three years to prevent re-growth of plants. All the original plant material was left in place to decompose.

125
Q

What were the effects of the experiment on nutrient cycling?

A

loss of nutrient cycling

126
Q

How did the treatment of logged areas affect nutrient cycling?

A

It disrupted nutrient cycling.

127
Q

How did deforestation impact water runoff? (due to what? (2))

A

due to the absence of plants to absorb and transpire water from the soil

128
Q

Water runoff increased by __-__%

A

30-40%

129
Q

What were the consequences of increased water runoff?

A

increased loss of minerals

130
Q

Name 3 types of minerals

A

Calcium (Ca) & Potassium (K) & Nitrate

131
Q

What does the study demonstrate about nutrient control in intact forest ecosystems?

A

the amount of nutrients leaving an intact forest ecosystem is controlled by the plants.

132
Q

What insights did the study provide regarding human activities and ecosystem processes?

A

human activities (deforestation) affect ecosystem processes

133
Q

How are humans skilled at disrupting nutrient cycles?

A

By adding new materials, often toxic, to ecosystems and moving nutrients around the biosphere.

134
Q

How do humans intentionally and unintentionally change nutrient distribution?

A

intentional actions = agriculture
unintentional events = soil runoff (causing eutrophication)

135
Q

What environmental impacts result from burning fossil fuels?

A

releases compounds like carbon, sulfur oxides, and nitrogen oxides,

136
Q

How do these releases of chemicals affect our planet?

A

atmospheric warming, climate change, ozone depletion, and acid precipitation.

137
Q

How can humans aid in the recovery of damaged ecosystems?

A

By initiating/accelerating ecological succession.

138
Q

What is bioremediation?

A

It involves using living organisms, like prokaryotes, fungi, or plants, to detoxify or remove toxins from polluted ecosystems.

139
Q

Provide an example of bioremediation.

A

Using lichen to absorb uranium, a toxic substance, from polluted environments.

140
Q

What is biological augmentation?

A

It involves reintroducing living organisms to restore essential materials to ecosystems.

140
Q

Name a few living organisms that help restore essential materials to ecosystems:

A

like bacteria, archaea, or plants

141
Q

Offer an example of biological augmentation.

A

Colonizing former pastureland with the original tropical forest in Costa Rica.

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