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BIOLOGY A LEVEL > Ecosystem > Flashcards

Ecosystem Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is a habitat

A

The place where an organism lives

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2
Q

Definition of population

A

All organisms of one species in a habitat

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3
Q

What is a producer

A

An organism that produces organic molecules using sunlight energy

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4
Q

What is a consumer

A

An organism that eats other organisms

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5
Q

What is a decomposer

A

An organism that breaks down dead or undigested organic material

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6
Q

What is a trophic level

A

A stage in a food chain occupied by a particular group of organisms

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7
Q

What is an ecosystem

A

All organisms living in a certain area and all the non-living conditions found there

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8
Q

What are biotic factors

A

The living features of an ecosystem

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9
Q

Examples of biotic factors

A

Presence of predators or food

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10
Q

What are abiotic factors

A

The non living features of an ecosystem

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11
Q

Examples of abiotic factors

A

Temperature, rainfall, soil nutrients availability

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12
Q

What is the main route by which energy enters an ecosystem

A

Photosynthesis

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13
Q

What is the main route by which energy enters an ecosystem

A

Photosynthesis

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14
Q

How do plants store energy

A

As biomass

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15
Q

What is biomass

A

Biomass is the mass of living material

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16
Q

How much energy is lost

A

90%

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17
Q

What is ecology

A

This is the study of the relationship between organisms and their environment

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18
Q

Why is soil important for plants

A

It provides the minerals needed for growth
Water (for photosynthesis)
Anchorage for the roots

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19
Q

What does sandy soil contain

A

0-10% clay, 0-10% silt, 80-100% sand

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20
Q

What does clay contain

A

50-100% clay, 0-45% silt, 0-45% sand

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21
Q

What does loam contain

A

10-30% clay, 30-50% silt, 25-50% sand

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22
Q

How does particle size affects the air content and permeability of soils

A

Few air spaces retain water and flood easily
Lots of large air spaces does not retain water

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23
Q

Describe clay

A

Clay has fine particle, is easily waterlogged, and forms clumps when wet. The particles are small. They have a permeability to water as water is retained in soil.

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24
Q

Describe loam

A

Particles are small and large. They have a medium permeability to water as their retention is good. It retains water but doesn’t become waterlogged

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25
Q

Describe sandy soil

A

They have many and large air spaces. They have poor permeability, little water is retained in soil. Has coarse and well separated particles. Sandy soil does not retain water and easily eroded.

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26
Q

What is a producer

A

An organism that converts light energy into chemical energy by the process of photosynthesis

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27
Q

What is a carnivore

A

Eats only other animals

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28
Q

What is a herbivore

A

Eats only plants

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29
Q

What is an omnivore

A

Eats both animals and plants

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30
Q

What is a primary consumers

A

Eats a producers. Usually, a herbivore

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31
Q

What is a secondary consumer

A

Eats a primary consumer, usually a carnivore but also be a herbivore

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32
Q

How is biomass lost

A

Biomass is lost in urine, faeces,and used to provide energy for movement, growth etc

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33
Q

How to calculate biomass at each trophic level

A

Multiply the biomass present in each organism by the total number of organisms in that trophic level

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34
Q

How is biomass measured for areas of land and areas of water

A

Areas of land- gm^-2
Areas of water- gm^-3

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35
Q

What is ecological efficiency

A

The efficiency with which biomass or energy is transferred from one trophic level to the next

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36
Q

What is net production

A

Gross production - respiratory losses

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37
Q

What is gross production

A

Total solar energy that plants convert to organic matter

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38
Q

Why is the concentration of CO2 greater at night than during the day

A

No light so no photosynthesis occurs
Lower temperature means that respiration happens at a slower rate

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39
Q

Why have the levels of CO2 increased over the past few hundred years

A

Combustion of fossil fuels CO2 which was locked up million of years ago below the Earth’s surface
Deforestation- removes photosynthesising biomass. Reduces volume of CO2 that can be removed from the atmosphere from the atmosphere

40
Q

How is methane produced

A

Methane is produced when decomposers break down dead remains of organisms

41
Q

Why has methane levels have more than doubled in the last 150 years

A

More extraction of fossil fuels
More decaying waste
More cattle
Natural stores such as frozen ground thawed

42
Q

What is succession

A

The process of ecosystem change over time

43
Q

State features of a pioneer species

A

Produces large quantities of easily dispersible seeds/spores
Withstand extreme conditions
Ability to fix nitrogen. Even if there is soil, it has few/no nutrients
Ability to photosynthesise
Rapid germination of seeds

44
Q

Adaptations that enable marram grass to be a pioneer species

A

Deep roots
Tolerates salty environment

45
Q

Describe primary successions

A

Begins by the colonisation of an inhospitable environment. This is the first serial stage. There is no soil. Pioneer species colonises the rock/bare ground and release minerals which enable other species to survive. As plants die and decompose the soil deepens and larger plants can now survive- stability increases. Diversity increases

46
Q

What is climax community

A

Soil now rich and deep enough to support large trees

47
Q

What is deflection succession

A

A community that remains stable only because human activity prevents succession from running its course

48
Q

How does random sampling take place

A

Mark out a grid at right angles
Use a random number generator to pick the x coordinate the. The y coordinate
Take a sample from that place

49
Q

Stage an advantage of random sampling

A

Data is not biased by selective sampling

50
Q

State disadvantages of random sampling

A

May not cover all areas equally
Species with low presence may be missed

51
Q

What is systematic sampling

A

It is a type of non-random sampling. Samples taken from fixed intervals across the habitat

52
Q

State an advantage of systematic sampling

A

Useful when habitat shows a clear gradient in environmental factors

53
Q

State an advantage for systematic sampling

A

Only species on the line/belt are recorded leading to an underestimate

54
Q

What is stratified sampling

A

A type of non-random sampling that divides habitat into areas which appear to be different and sample each section separately

55
Q

State an advantage of stratified sampling

A

Ensures all areas of habitat are sampled. Species are under represented

56
Q

State disadvantages of stratified sampling

A

May lead to over representation
Could have a disproportionate number of samples taken in smaller areas that look different

57
Q

What is opportunistic sampling

A

A type of non random sampling in which researchers takes samples based out on prior knowledge or during the process of collecting data. May sample on area that they know contains a particular species.

58
Q

State an advantage of opportunistic sampling

A

Easier and faster than random sampling

59
Q

State disadvantages of opportunistic sampling

A

Data may be biased
Overestimate of biodiversity

60
Q

What is species richness

A

The number of different species living in a habitat

61
Q

What is species evenness

A

A comparison of the number of individuals of each species living in a community

62
Q

What is secondary succession

A

This occurs on areas of land where soil is present, but it contains no plants or animal species

63
Q

What is the organic component of soil know as

A

Humus

64
Q

When the soil becomes able to support the growth of new species of plants what is it known as

A

Secondary colonisers

65
Q

What are dominant species

A

The most abundant species (by mass) present in the ecosystem at a given time

66
Q

How do plants develop strategies to cope with different light intensities

A

In areas of low light they may have larger leaves. They may also develop photosynthesis pigments that require less light, or reproductive systems that operate only when light availability is at an optimum

67
Q

What happens to a plant if they don’t have water

A

They will wilt as water is needed to keep cells turgid and so keep the plant upright. It is also required for photosynthesis

68
Q

Why is fast flowing cold water a necessity in aquatic ecosystems

A

It contains high concentrations of oxygen

69
Q

What happens if water in aquatic systems is too warm

A

The flow rate becomes too slow resulting in a drop in oxygen concentration that can lead to the suffocation of aquatic organisms

70
Q

How is oxygen availability for plants reduced in waterlogged soil

A

The air spaces between the soil particles are filled with water

71
Q

Shat do decomposers do

A

They break down dead organisms releasing nutrients back into the ecosystem

72
Q

What percentage of the total energy originally present in the incident sunlight is ginally embodies as biomass in s tertiary consumer

A

Around 0.001%

73
Q

How do you calculate biomass consumed

A

Mass (per metre squared per year) x area of land

74
Q

What is decomposition

A

A chemical process in which a compound is broken down into smaller molecules or its constituent elements

75
Q

What is a decomposer

A

This is an organism that feeds on and breaks down dead plant or animal matter, thus turning organic compounds into inorganic compounds. Decomposers are saprotrophs because they obtain their energy from dead organisms or organic material. This is saprobiotic nutrition.

76
Q

What are detritivores

A

They help speed up the decay process by feeding on detritus. They break it down into smaller pieces of organic material, which increases the surface area for the decomposers to work on

77
Q

What are detritus

A

Dead and decaying material

78
Q

How is nitrogen used by living organisms

A

Nitrogen needs to be combined with other elements such as oxygen and hydrogen. Without bacteria, nitrogen would quickly become a limiting factor in ecosystems

79
Q

Describe nitrogen-fixing bacteria

A

E.g. azotobacter and rhizobium, contain the enzyme nitrogenase, which combines atmospheric nitrogen with hydrogen to produce ammonia

80
Q

What is ammonia

A

A form if nitrogen that can be absorbed and used by plants.

81
Q

What is nitrogen fixation

A

When nitrogen is absorbed and used by plants.

82
Q

State an example of free-living soil bacterium

A

Azotobacter

83
Q

Describe rhizobium

A

Rhizobium live inside root nodules.

84
Q

What are root nodules

A

These are growths on the roots of leguminous

85
Q

What is nitrification

A

The process by which ammonium compounds in the soil are converted into nitrogen-containing molecules that can be used by plant

86
Q

State the two steps in which nitrification takes placed

A

Nitrifying bacteria- oxidise ammonium compounds into nitrites (NO2-)
Nitrobacter- this is another genus of nitrifying bacteria. Oxidise nitrites into nitrates (No3)

87
Q

What is denitrification

A

In the absence of oxygen e.g. in waterlogged soils,denitrifying bacteria convert nitrates in the soil back to nitrogen gas. It happens under anaerobic conditions

88
Q

What is ammonification

A

The process by which decomposers convert nitrogen- containing molecules in dead organisms, faeces, and urine into ammonium compounds

89
Q

Why are atmospheric carbon dioxide levels higher at night than during the day

A

Respiration is carried out by all living organisms throughout the day and night, releasing carbon dioxide at a relatively constant rate into the atmosphere.

90
Q

Why is CO2 called a greenhouse gas

A

Increased levels of CO2 traps more thermal energy in the atmosphere

91
Q

What is the final stage called when succession is artificially stopped

A

Plagioclimax

92
Q

Which provides more information a line transect or belt transect and why

A

A belt transect as two parallel lines are marked and samples are taken of the area between these specific points

93
Q

What is a population

A

A population is a group of similar organisms living in a given area at a given time

94
Q

How do you calculate the estimated number in population

A

Number of individuals in sample / area of sample

95
Q

How do you measure animal abundance

A

Use the capture-mark-release-recapture technique

96
Q

State the formula for estimated population size

A

Number of individuals in 1st sample x number of individuals in 2nd sample / number of recaptured marked individuals

97
Q

Index of diversity formula

A

D=N(N-1) / sum of(n-1)

D= diversity index
N= total number of organisms in an ecosystem
n= number of individuals in each species

BIOLOGY A LEVEL (12 decks)

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