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Biology > Energy Flow and Nutrient Cycle > Flashcards

Energy Flow and Nutrient Cycle Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

define ecology

A

the study of living organisms, their interactions with each other, and the environment

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2
Q

ecosystem definition

A

a single working unit consisting of a group og interating organisms (biotic factors) and their physical environment (abiotic factors)

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3
Q

define habitat

A

the actual place where an organism is found, where it feeds, reproduces and spends most of its time

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4
Q

what is a population?

A

all the organisms of the same species found in a particular area

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5
Q

define community

A

consists of all the populations of different species living and interacting with each other in the same area

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6
Q

what is an ecological niche?

A

the role of an organism in an ecosystem

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7
Q

definition of detroitivore

A

an organism that feeds on the dead body of another, breaking down the body into smaller pieces or fragments

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8
Q

what is a decomposer?

A

an organism that breaks down the dead organic material chemically into simpler inorganic molecules

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9
Q

sequence of a food chain

A

Producer > Primary Consumer > Secondary Consumer > Tertiary Consumer

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10
Q

what is a food chain?

A

a sequence diagram which shows the feeding relationship between an organism at one trophic level and another at a higher trophic level

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11
Q

what is not shown in a food chain?

A

The food chain does not show number of organisms, their mass, energy content

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12
Q

what is a grazing food chain?

A

based on a living plant, which is eaten by a herbivore.

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13
Q

what is a detrital food chain?

A

it is based on dead bodies of organisms

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14
Q

what is a food web?

A

A food web is a complex diagram that shows how many different food chains in an ecosystem interact with each other.

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15
Q

what factors can a food web show?

A

• How an organism may feed at more than one trophic level

• Can be used to predict the effects of introducing or removing one or more organisms into and out of an ecosystem

• Can be used to show the importance of decomposers within an ecosystem

• Can be used to show that organisms receive energy along various pathways in an ecosystem (for example, the herring gull receives energy from the edible crab, sea urchin and the common prawn)

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16
Q

how is energy from the sun converted to chemical energy in photosynthesis to supply a food chain?

A

Energy from the Sun passes through space and reaches the earth.

Along the way, some energy is absorbed by the atmosphere (about 20%), and some of that energy is reflected back into the atmosphere.

Only about 50% of the energy reaches the earth’s surface. About 50% of that is visible light and only about 2-10% of the incoming energy is converted into chemical energy during photosynthesis

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17
Q

how do autotophs produce food?

A

The autotroph produces food by transforming light energy into chemical energy during photosynthesis.

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18
Q

what is GPP (gross primary product)?

A

the rate at which plants convert light energy into chemical energy during photosynthesis in a given time period

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19
Q

what is NPP (net primary productivity)?

A

the amount of energy that is now available to herbivores, detroitivores and decomposers in a given period

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20
Q

how does energy flow through an ecosystem?

A

Energy enters the ecosystem, where light energy is converted to chemical energy during photosynthesis.
Chemical energy is then transferred from one biotic component to another.
Heat energy is lost permanently at each trophic level.

Nutrients are constantly cycled through the biotic and abiotic components of the environment by various processes (ex. decomposition, feeding processes)

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21
Q

what are phytoplankton?

A

Phytoplankton are autotrophic microorganisms (ex.algae). These organisms synthesize their own food during photosynthesis.

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22
Q

what are zooplankton?

A

Zooplankton are tiny animals which are heterotrophic and are found near the surface of the ocean. They include tiny crustaceans and protozoan which are non-photosynthetic.

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23
Q

what is an ecological pyramid?

A

a diagram consisting of rectangular bars of the same height stacked one on top of the other to represent changes in numbers, biomass or energy at each trophic level of an ecosystem.

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24
Q

what is a pyramid of numbers?

A

Diagrammatic representation of the number of different organisms at each trophic levelin an ecosystem at one time

25
Q

how are pyramids of numbers constructed?

A
  1. Recognize and count all organisms in a given area at each trophic level at a part time.
  2. Record the information in a table.
  3. Represent the results as rectangular block, each of the same height but varying in width. A scale must be decided on. Width of the bars is proportional to the numbers at each trophic level.
26
Q

advantages of using pyramid by numbers?

A
  1. Data is fairly easy to collect.
  2. No harm to living organisms.
  3. Organisms are not removed from their habitat and ecosystem remains relatively undisturbed.
27
Q

disadvantages of pyramid of numbers

A
  1. There may be very large numbers at one trophic level and very small numbers at other levels. It becomes difficult to decide on a scale.
  2. Inverted pyramids can be obtained.
  3. Sizes of organisms vary but a single treeis given the same status as millions of phytoplankton
  4. Difficult to decide on the trophic level to which an organism belongs. Some feed on more than one level.
  5. Sometimes it is difficult to decide if one plant alone is present or not (ex. runners)
28
Q

what is a pyramid of biomass?

A

Representation of total living omass or organic matter presentiat different trophic levels in an ecosystem

29
Q

how are pyramids of biomass constructed?

A
  1. Observations will be made on the number of organisms of each type at each trophic level in a particular ecosystem.
  2. The organisms will be collected or a representative sample will be obtained and this will be taken to the lab where the sample will be weighed, then heated to 100 degrees Celsius in an oven, reweighed. The process is then repeated until a constant weight is obtained as the dry mass.
  3. The total dry mass is then multiplied by the total number of the particular organism at each trophic level in order to find the total dry mass at each trophic level.
  4. An appropriate scale is decided on to represent the biomasses at each trophic level when constructing the pyramid of biomass
30
Q

advantages of pyramids of biomass

A
  1. Less likely to obtain inverted pyramids compared with pyramid of numbers
  2. Less likely to encounter problems with deciding what scale to use
31
Q

disadvantages of pyramids of biomass

A
  1. An inverted pyramid can still be obtained
  2. It does not give an idea of productivity and can therefore not be used to indicate whether or not a particular trophic level has high or low productivity
  3. Difficult to decide on the trophic level to which an organism belongs
32
Q

what is turnover?

A

Turnover refers to the rate of growth and reproduction balanced by the rate of consumption and death of a particular organism.

33
Q

what is standing crop biomass?

A

The standing crop biomass is the biomass at the time of sampling a particular ecosystem.

34
Q

what is a pyramid of energy?

A

A pyramid of energy represents the rate of flow of energy through each trophic level in an ecosystem in a fixed time period (ex. 1 year)

The rate can be represented as kilojoules per square meter per year

35
Q

construction of pyramids of energy

A
  1. Count the number of organisms of each particular species at each trophic level.
  2. Find the total biomass (dry mass).
  3. Burn a representative sample of the material in a calorimeter to determine the energy value. Then estimate for the organisms observed.
  4. Decide on an appropriate scale to use and construct the pyramid of energy.
36
Q

advantages of pyramids of energy

A
  1. Never obtained an inverted pyramid
  2. Takes into account the rate of production of organic matter over a long period of time
  3. Solar energy input can be added at the base as a separate bar
  4. Ecosystems can be compared with productivity since the rate at which energy flow is taken into consideration when constructing
37
Q

disadvantages of pyramids of energy

A
  1. Many more measurements are required in order to construct
  2. Organisms have to be tracked over a long period of time
  3. It is a destructive method
  4. It is still difficult to assign organisms to trophic levels
38
Q

what is a nutrient cycle?

A

The cycling of nutrients refers to the constant circulation of specific nutrients (ex. nitrogen) between the biotic and abiotic components of the environment.

39
Q

stages in the nitrogen cycle

A

Nitrogen fixation
Incorporation of Ammonium
Feeding
Excretion
Putrefaction/ Ammonification
Nitrification of Ammonium ions to nitrates using nitrosomonas bacteria (oxidation)
Nitrification using Nitrobacteria to convert nitrites to nitrates
Lightning discharges
Absorption and Nitrate reduction
Denitrification

40
Q

nitrogen fixing bacteria

A

rhizobium (found in root nodules of leguminous plants; mutualistic bacteria which receives sugars from leguminous plant and provide the plant with ammonium to make amino acids)

azotobacter (found in soil; carry out autotrophic nutrition and fix nitrogen from the air into ammonium)

41
Q

requirements for nitrogen fixation

A

anaerobic conditions

42
Q

nitrogen fixation process

A

• The 2 nitrogen atoms in each molecule of N2 (g) are separated from each other using ATP from respiration that is carried out by the nitrogen fixing bacteria.
• Reduced NAD is then used to supply hydrogen tha brings about the reduction of each nitrogen atom to ammonia.
• Ammonia is rapidly converted to ammonium ions.
• Nitrogenase enzyme is present in nitrogen fixing bacteria and catalyzes the conversion of oxygen to ammonia.

43
Q

incorporation of ammonium

A

• Ammonium is used to synthesize amino acids in the plant and these are then used to synthesize proteins in the plant

44
Q

feeding

A

• Animals feed on plants and on other animals.
• Nitrogen from plants is passed on to animals in the form of proteins.
• Digestion then follows, amino acids are released and then excess are deaminated in the bodies of the animals.

45
Q

excretion

A

• When amino acids are deaminated one of the products is urea which is excreted in the urine of the animal.

46
Q

which organisms undergo ammonification?

A

plants and animals

47
Q

what brings about the process of putrefaction?

A

the actions of decomposers, decayed bacteria or fungi

48
Q

is decomposition aeorbic or anaerobic?

A

aerobic

49
Q

process of ammonification

A

enzymes in the bacteria and fungi are used to break down:
proteins –> amino acid
amino acids –> ammonia
urea –> ammonia –> ammonium salts
nucleic acids –> ammonia –> ammonium salts

50
Q

lightning discharges

A

• When lightning strikes, nitrogen gas in the air combines with oxygen gas to form gases such as NO2 which dissolve in rain war to produce nitric acid.
• Nitrogen monoxide dissolves in water to produce nitrous acid. Both acids are present in the soil and react with other chemicals to form nitrates.
• Nitrates can then be taken up by plants in solution.

51
Q

process of absorption and nitrate reduction

A

• Nitrates are taken up in solution by plants. Thet undergo nitrate reduction in which the nitrates are reduced to nitrites and the nitrites are further reduced to ammonium ions.
• Ammonium ions are then used by the plants to synthesize amino acids.

52
Q

what conditions are preferred for absorption and nitrate reduction?

A

a low concentration of oxygen

53
Q

examples of denitrifying bacteria

A

pseudomonas denitrificans
thiobacillus denitrificans

54
Q

denitrification

A

involves denitrifying bacteria which reduces nitrates and ammonium salts to nitrogen gas
it returns nitrogen to the atmosphere

55
Q

characteristics of energy flow

A

constant input of energy from new sources needed
energy is lost permanently from each trophic level
energy flows in one direction
decomposers are not involved

56
Q

characteristics of nutrient cycling

A

no need for constant input of nutrients
no net gain or loss of nutrients
nutrients flow in a cyclic manner
decomposers are involved in the cycling of nutrients to keep the cycle going

57
Q

why is energy flow important for an ecosystem?

A

• Energy flow sustains ecosystems since all of the organisms at each trophic level will receive the correct amount of energy needed to sustain them.

• Energy flow maintains interdependence among organisms in the exosystem.

• Energy flow plays a role in maintaining the balance in number at each trophic level in an ecosystem.

• Energy flow ensures the stability of the ecosystem is maintained and it does not collapse.

58
Q

why is the nutrient cycle important for an ecosystem?

A

• Nutrient cycling ensures that there is no need to constantly find a new source of a particular nutrient to sustain the ecosystem.

• Nutrient cycling ensures that the nutrient is in a form that can be used by specific organisms at each trophic level in the ecosystem.

• Nutrient cycling facilitates interdependence between organisms and their environment.

• Nutrient cycling maintains a healthy balance of nitrogen ensuring that there is no deficiency nor excess in the ecosystem.

Biology (5 decks)

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