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Paper 3 Flashcards

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1
Q

Define community

A

group of populations, living together and interacting with each other in an area

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2
Q

What is the law of tolerance?

A

The distribution of the species in an ecosystem is determined by the limits of physical and chemical factors that can be tolerated

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3
Q

Define keystone species

A

Species that has a disproportionate effect on the structure of an ecological community
Eat exerts a top down influence on lower trophic levels
Prevent lower traffic levels from monopolising critical resources

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4
Q

Define niche

A

The unique role a species plays in a community

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5
Q

What is a fundamental niche?

A

The potential mode of existence of a species, given its adaptations

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6
Q

What is a realised niche?

A

The actual mode of existence, which results from its adaptations and competition with other species

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7
Q

Describe the symbiotic relationship between zooxanthellae and Coral

A

Coral provides algae with a protected environment, and compounds they need for photosynthesis

The algae provide coral with oxygen , help with a waste removal, and supplies, coral with glucose glycerol, and amino acids

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8
Q

What does the competitive exclusion principle state?

A

No two species can occupy the same niche for extended periods of time

One species will have an advantage over the other
The less well adapted species will struggle to survive and reproduce
The less well adapted species will be eliminated

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9
Q

Define food chain

A

A linear sequence, showing feeding relationships and energy flow between species each of which feeds on the previous one

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10
Q

What are pyramids of energy?

A

Show the flow of energy between trophic levels
Measured in units of energy per unit area per unit time

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11
Q

Define biomass

A

The total dry mass of organic matter in organisms or ecosystems

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12
Q

What is the food conversion ratio?

A

A measure of an animals efficiency in converting feed mass into the desired output

Mass of food eaten divided by desired output

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13
Q

Define ecological succession

A

The predictable and orderly changes in composition of an ecosystem over time

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14
Q

Define primary succession

A

The emergence of an entirely new ecosystem

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15
Q

Define secondary succession

A

The replacement of one ecosystem by another following environmental change

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16
Q

Define biome

A

A geographical area that has particular climate and sustains a specific community of plants and animals

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17
Q

Define biosphere

A

The total of all areas were living things are found

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18
Q

Define climograph

A

A diagram which shows the relative combination of temperature and precipitation in an area

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19
Q

What are Gershmel diagrams?

A

They show the differences in nutrient flow and storage between different ecosystems

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20
Q

What are the sinks for nutrient storage in Gershmel diagrams?

A

Biomass
Litter
Soil

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21
Q

What are the nutrient inputs of Gershmel diagram?

A

Nutrients dissolved in raindrops
Nutrients from weathered rocks

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22
Q

What are the nutrient outputs from Gershmel diagrams?

A

Nutrients lost through surface run-off
Nutrients lost through leeching

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23
Q

What are the flows between sinks in Gershmel diagrams?

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A

Biomass to litter is littering
Litter to soil is decomposition
Soil to biomass is plant uptake

24
Q

Features of a taiga Gershmel diagram

Study These Flashcards
A

Litter is the main store
Slow rate of nutrient transfer between stores

25
What is the construction of a desert Gershmel diagram?
Soil is the main store Slow rate of nutrient transfer between stores (except for the transfer from biomass to litter)
26
What is the construction of the Gershmel diagram for a tropical rainforest?
Biomass is the main storage Fast rate of nutrient transfer between stores
27
Define alien species
One which arrives in a non-native habitat and can become invasive
28
What’s the relationship between competitive exclusion an alien species
Competitive exclusion in the absence of predators can lead to reduction in the number of endemic species when alien species become invasive
29
Define biomagnification
A process in which chemical substances become more concentrated at each trophic level
30
Explain the effect of DDT
It’s a synthetic pesticide It can be used against malaria mosquitoes It is washed into waterways at low concentrations It is biomagnified up the food chain It is highly toxic at high concentrations It reduces reproductive function It is responsible for shell thinning in birds Can cause cancers
31
What are the pros of DDT?
It is affordable and effective at killing mosquitoes that carry malaria Alternative strategies are not successful Health costs of treating malaria greatly reduced
32
What are the cons of DDT?
People exposed may suffer serious health effects Persist in the environment for long periods of time
33
Define indicator species
An organism used to assess a specific environmental condition
34
What is the biotic index?
It compares the relative frequency of indicator species Provides an overall environmental assessment of an ecosystem A change in the biotic index overtime may indicate change in environmental conditions A high biotic index indicates an abundance of pollution, sensitive organisms A low biotic index indicates the absence of pollution, sensitive organisms
35
Define biodiversity
The variety of organisms present in an ecosystem
36
Define richness
The number of different species present
37
Define evenness
A habitat that has similar abundance for each species
38
What is the Simpsons reciprocal index?
Calculate biodiversity Takes into account, richness and evenness The greater the biodiversity, the higher, the value of D The lowest possible defined value of D is one
39
Define in situ
The preservation of a species inside the natural habitat
40
Define ex situ
The preservation of species outside the natural habitats
41
Define species diversity
The number of species and their relative abundance
42
What is the area affect?
The effect of area on species richness The larger, the geographic area, the more species, it can support
43
What is the edge affect?
Describes what occurs at boundaries between two habitats or ecosystems Add edge effect increases there is greater biodiversity
44
What is a limiting factor?
And environmental selection, pressure that limits population growth
45
What are top down factors?
Pressure is applied by other organisms at higher trophic levels Predators
46
What are bottom up factors?
Those that involve resources are lower trophic levels The availability of nutrients
47
What is the effect of Natality on population size?
Increases to population size through reproduction
48
What is the effect of immigration on population?
Increases population size from external populations
49
What is the effect of mortality on population?
Decrease is a population size as a result of death
50
What is the effect of emigration on population?
Decreases to population size as a result of loss of external populations
51
Define a population
A group of organisms of the same species who live in the same area the same time
52
What is the Lincoln index?
Estimates the population of an animal species in a given area at a given time
53
Explain the role of bacteria in the nitrogen cycle
- bacteria decompose, the dead remains of plants - Convert nitrogenous compounds into ammonia - Nitrifying, bacteria, converts ammonia to nitrates - Nitrogen fixation is the conversion of atmospheric nitrogen to ammonia - Rhizobium have a mutualistic relationship with the plants - Rhizobium bacteria in root, nodules of legumes, fix nitrogen - Nitrates are absorbed by plants - Denitrifying bacteria, convert nitrates into nitrogen gas
54
Impact of waterlogging on nitrogen cycle
- reduces the oxygen availability in soils - encourages the process of denitrification - Food crops are affected - Leaching of nutrients
55
Define nutrient leaching
Leaching of minerals and nutrients from agricultural land into rivers, causes, eutrophication, and leads to increase by chemical oxygen demand
56
Describe the impact of run-off
- rainfall, leeches, water, soluble nutrients from the soil and carries them into rivers and lakes - an increase in nutrients in aquatic ecosystems lead to eutrophication - rapid growth’s in algal populations leading to algal blooms, this also increase is the number of dead algae - number of bacteria that feeds on dead algae also increases - an increase in via chemical, oxygen demand by the bacteria result in deoxygenation of water supply

Biology (9 decks)

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