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Biology A level > Ecosystems > Flashcards

Ecosystems Flashcards

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1
Q

What is an ecosystem

A

All the abiotic and biotic components in a specific area and their interactions

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2
Q

What are the components of an ecosystem and their definitions

A

Habitat - place where an organism or population live
Population - group of organisms of the same species, living in the same place that can interbreed
Community - all the populations of different species in a specific area that interact with each other

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3
Q

What is a niche

A

An organisms role in the ecosystem

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4
Q

What is a producer

A

An autotrophic organism that obtains food from inorganic sources via photosynthesis or chemosynthesis

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5
Q

What is a consumer

A

Heterotrophic organism that obtains food in organic form

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6
Q

What is a decomposer

A

Saprotrophs that feed on dead organic matter to release molecules, mineral and energy that then becomes available in that ecosystem

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7
Q

Why is energy lost between trophic levles

A

Organisms die, egestion, some parts of organism not eaten, lost in respiration

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8
Q

How to measure energy content of an organism

A

Dry the sample
Burn sample in a bomb calorimeter and heat water
Use specific heat capacity to find the amount of energy transferred to the water
this is the amount of energy that was stored

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9
Q

What is productivity

A

The rate at which energy passes through each trophic level - it takes time into account

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10
Q

What is NPP

A

Net primary productivity - rate at which plants convert light energy to chemical energy
Gross PP - Respiratory heat loss = NPP

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11
Q

What environmental factors can be manipulated to improve NPP

A

Light, water, temperature, pests, nutrients

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12
Q

What are saprotrophs

A

Organisms that feed by secreting enzymes onto food and absorbing digested enzymes across their outer walls

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13
Q

What is the formula for efficiency

A

Biomass transferred / biomass intake * 100

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14
Q

What is nitrogen fixing

A

Nitrogen is converted to ammonium ions
Fixed by Rhizobium bacteria in root nodules and azotobacter in the soil
Catalysed by nitrogenase

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15
Q

How do plants and animals use fixed nitrogen

A

Use NH4+ to make amino acids and protein
In animals, excess amino acids are deaminated in liver and nitrogen is excreted

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16
Q

What is nitrification

A

The process in which ammonium compounds in the soil is converted into nitrogen containing compounds
Done by nitrifying bacteria

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17
Q

How is the relationship between rhizobium and plants symbiotic

A

Plant gains amino acid from nitrogen fixing, bacteria gain carbohydrates made during photosynthesis

18
Q

What are the stages of nitrification

A

NH4 oxidised by nitrosomonas to NO2 -
NO2 - oxidised by nitrobacter to NO3 -

19
Q

What is denitrification

A

Denitrifying bacteria convert nitrate to N2 in anaerobic conditions (waterlogged soils)

20
Q

What is the carrying capacity

A

The max population size that can be supported sustainably in a particular habitat

21
Q

What is a limiting factor

A

The one factor affecting a process as it is nearest to its lowest value

22
Q

What are K-strategists

A

A species whose population size is determined by carrying capacity

23
Q

What are r-strategists

A

A species whose population size increases so quickly that it can exceed carrying capacity of the habitat before limiting factors have an effect

24
Q

What are the two types of competition

A

Intraspecific - within the same species
Interspecific - between different species

25
Q

What is competitive exclusion

A

The idea that two species with exactly the same niches cannot co-exist

26
Q

What is sustainability

A

The responsible management of resources - including environmental, economic and social dimensions

27
Q

What is rotational coppicing

A

When trees or shrubs are cut very close to the ground, leaving a short stool that wood grows out of
Each year a different area is coppice till all of it is done

28
Q

What are the positive and negative aspects of coppicing

A

+ lets in light for other plants - inc biodiversity
+ Different parts of the woodland are at different stages - maxes biodiversity
+ Prevents succesion
- Some species rely on larger trees for grazing and habitats

29
Q

What is Pollarding

A

Branches are cut off the tree higher to the trunk

30
Q

What is Clear Felling

A

Removal of all trees in an area at once

31
Q

What are the negatives of clear felling

A

Dec soil fertility
Pollution from soil goes into water ways
Destroys habitats

32
Q

What are techniques to increase timber production sustainability

A

Selective cutting
Long rotation
Coppicing

33
Q

How do you calculate population size of a species

A

Mean number of individuals in each quadrat/fraction of total area covered by each quadrat

34
Q

What is Primary succession

A

The succession that occurs on an area where no living beings are present by a pioneer species

35
Q

What do pioneer species do

A

First species to colonise bare ground, they are able to survive in difficult conditions
Cause an inc in soil, soil fertility + nutrients, provide shelter, inc water holding capacity of soil

36
Q

What happens when a new area is uncovered

A

Primary succession - pioneer species
They get displaced in the next seral stage
Climax community develops

37
Q

What is a climax community

A

The final community in a succession

38
Q

What is deflected succession

A

When human activities prevent the climax community from being developed

39
Q

What are the key principles of ecotourism

A

Ensure tourism doesnt exploit the natural environment and local communities
Consult and engage with local communities on planned developments
Ensure that infrastructure improvements benefit locals and tourists

40
Q

What techniques are used to promote sustainable fishing

A

Use nets with different mesh sizes - allow immature fish to escape
Only allow fishing at certain times of the year
Fish farming

41
Q

What conditions are needed for nitrogen fixing

A

Supply of Hydrogen and ATP
Anaerobic conditions

Biology A level (15 decks)

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