Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A-level Biology > Ecosystems > Flashcards

Ecosystems Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is an ecosystem?

A

Any group of living and non living things and the interrelationships between them

They are:
Cyclic
Directional
Unpredictable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a habitat?

A

The area which an organism lives

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is a population?

A

All the organisms of one species living in the same habitat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is a community?

A

All the populations of all species living in a habitat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the biotic factors of an ecosystem?

A 
Predation
Disease
Producers
Consumers
Decomposers
Every species occupies a niche
Competition
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the abiotic factors of an ecosystem?

A 
pH 
Temperature 
Humidity
Water availability 
CO2 
Light

Abiotic features influence the survival, growth and reproduction of a species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is carrying capacity?

A

The maximum population size that can be maintained over a period of time in a habitat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

On a population time graph explain the lag phase, log phase and stationary phase

A

Lag phase- individuals are still acclimatising to their environment

Log phase- plenty of resources and good conditions so reproduction can happen quickly

Stationary phase- population reaches carrying capacity and the rate of reproduction is equal to the rate of mortality

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are predator prey relationships like?

A

Cyclic fluctuations

Periodical population crashes which are important for evolution as these select individuals who are better adapted to their habitat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is intraspecific competition?

A

Competition between individuals of the same species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What affect does Intraspecific competition have on population sizes?

A

Smaller population size:
Decreases competition
Population growth

Larger population size:
Increased competition
Population shrink

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is interspecific competition?

A

Competition between individuals of different species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the competition exclusion principle?

A

More overlap between niches
And so there is more intense competition for resources

No two species can occupy the same niche indefinitely when resources are limited

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How do you carry out random sampling?

A
  1. Lay down 2 tape measures at right angles to each other along the boundary of the area to be sampled
  2. Generate pairs of numbers randomly (via a calculator or computer) and use these pairs as coordinates
  3. Place the left hand corner of the quadrat at each coordinate
  4. Record the species present in the quadrat
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How do you calculate total population size?

A

Total population size = mean number of individuals of species in each quadrat / fraction of total ha it’s covered by a single quadrat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How do you carry out systematic sampling?

A

Using a belt or line transect

Belt transect:

  1. Place tape measure from object affect in. Habitat
  2. Place quadrat at regular intervals and record the number of species present

Line transect:

  1. Place tape measures leading away from the object
  2. Record the number of species touching the tape measure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How do you do the mark release recapture method of sampling?

A
  1. Capture organisms from an area or habitat
  2. Mark the and release them back into their habitat at the same place
  3. A few days later recapture organisms and record the number of marked organisms recaptured
  4. Estimate the population size
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What equation is used to estimate the population size when doing mark release recapture methods?

A

Estimate pop = total number of individuals in first sample X total number of individuals of second sample / number of recaptured individuals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What assumptions are made when doing mark release recapture methods?

A

Marks are not rubbed off or toxic
No emigration or immigration
No births or deaths
Spread evenly into the habitat after release

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the transfer of biomass?

A

Materials in ecosystems are constantly recycled as energy flows through the organism. All living things need energy and materials

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the tropic levels in an ecosystem?

A

Light energy

Producers

Primary Consumers

Secondary consumers

Tertiary consumers

(Decomposers digest the dead material)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How may energy be lost at each tropic stage?

A

Faeces

Respiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the equation for the net production of consumers?

A

Net production of consumers = injection - ( faeces + respiratory losses)

N=I-(F+R)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is a pyramid of numbers?

A

Area of the bar represents the number of individuals at each tropic level

(Not always a generic shape)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is a pyramid of biomass?

A

Area of each bar is proportional to the dry mass of all organisms at that trophies level (gm^-2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How do you obtain the dry mass of an organism?

A

Put organisms in an oven to evaporate any moisture to obtain the dry mass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How can you work out ecological efficiency?

A

Ecological efficiency = biomass of higher trophic level / biomass of lower trophic level X 100

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is productivity?

A

The rate at which energy passes through each trophic level

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is gross primary productivity? (GPP)

A

Rate at which plants concert light energy to chemical energy

insufficient as only about 1/8th of the suns energy enters the food chain.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

How do you calculate the net primary productivity? (NPP)

A

NPP = GPP - Respiratory losses

31
Q

How can humans increase NPP and limit energy loss?

A

Light levels - plant earlier (longer for growing season)
Water availability- irrigation
Temperature- greenhouses
Nutrients- crop rotations / fertilisers
Biotic factors- protection from pests diseases and competition

32
Q

How can humans increase secondary productivity?

A

N= I-(F+R)

Harvest animals before adulthood
Selective breeding
Protection against disease and pests
Reduced movement
Control temperature

(Balance between ethics and efficiency)

33
Q

Why are fertilisers important?

A

Plants need mineral ions (nitrates)
Mass food production removes naturally occurring mineral ions form the soil and so it is important to replenish the soil to prevent it inhibiting plant growth.

34
Q

What are natural fertilisers?

A

Dead and decaying remains of plants an animals

Animal wastes
Slurry manure bone meals

35
Q

What are artificial fertilisers?

A

Minerals mined from rocks and converted into different forms and mixed (nitrogen phosphorus and potassium)

36
Q

What are the environmental issues with nitrogen containing. Fertilisers?

A

Reduced species diversity:
Fertilisers provide nutrients and therefore those species which grow faster will use up the nutrients and out compete other species

Leaching:
Nitrogen containing compounds could be washed into bodies of water (water pollution)

Eutrophication

37
Q

How is eutrophication caused?

A

By the leaching of artificial and some organic fertilisers

Most lakes have relatively low nitrate concentrations and thereforeI limits the amount of algal growth

38
Q

How does eutrophication occur?

A
  1. When the nitrate content in water rises (due to leaching) algae can begin to grow rapidly
  2. Algae grow mostly at the waters surface creating an algal bloom
  3. This prevents sunlight from reaching lower surfaces of the water and therefore plants cannot photosynthesise and die
  4. This allows saprobiontic populations to grow and feed of the dead material. The saprobionts will respire and reduce the O2 availability in the water
  5. Lack of O2 causes aerobic organisms to die and increase the nitrate concentrations in the water
  6. Less competition for anaerobic organisms and their numbers rise releasing more nitrates and toxic waste into the waters
39
Q

What is succession?

A

Gradual directional changes which happen in a habitat or community over time

40
Q

What is primary succession?

A

The change to an environment which was previously uninhabited

41
Q

What is secondary succession?

A

From damaged but previously colonised environments

42
Q

Explain the process of primary succession.

A
  1. Algae and lichen ( pioneer species) begin to live on the bare rock
  2. The erosion of the rock and build up of dead material caused by the pioneer species leads to some nutrients build up
  3. This build up of nutrients can start a soil and causes the environment to become less hostile enabling larger organisms to be supported and can now grow
  4. These larger organisms increase the habitats and niches available to organisms allowing more to grow and reproduce
  5. These organisms can replace the pioneer species (their numbers are reduced) and this process keeps repeating
  6. Over time the biodiversity will increase producing more complex food webs and increasing biomass
  7. Eventually a final stable community will be established called the climax community
43
Q

What does succession do to an area?

A

Causes the environment to become less hostile so more habitats and niches can form
This leads to increased biodiversity and therefore the production of more complex food webs increasing the overall biomass

44
Q

What is a pioneer species?

A

Usually algae or lichen

The first organisms to inhabit an area

45
Q

What are some features of a pioneer organism?

A

Have tolerance to extreme conditions
Can reproduce asexually
Widespread germination
Photosynthesisers (photoautotrophs)

46
Q

What is deflected succession?

A

Agriculture can pause succession mid way causing a sub climate community to become established

A plagioclimax (caused by human intervention)

47
Q

Define preservation

A

Keeping species and habitats as they are now by limiting the human affects on the ecosystem

48
Q

Define conservation

A

Active process which aims to maintain or improve biodiversity of an ecosystem

49
Q

How have humans caused threats to biodiversity?

A

Our exploitation- food/ sport / commerce

Habitat destruction- agriculture / resource

Pollution

Urbanisation

Introduction of invasive species

50
Q

What are some conservational strategies?

A

Raise carrying capacity by providing extra food

Restrict individuals by fencing

Control predators poachers and disease

National parks

Green belts

Zoos

SSSI

51
Q

Why is it important to maintain biodiversity?

A

Ethics:
Every species is important and has its place

Social and economical:
Biodiversity harbours future potential
Tourism / recreation
Natural predation acts as pest control

52
Q

What are some sustainable management techniques?

A

Timber production

Fisheries (fish stocks)

Agriculture

53
Q

What is natural selection?

A

The mechanism by which evolution occurs

54
Q

What evidence is there for natural selection?

A

Fossils:
New species are often similar to previous species which died out

Biological molecules:
Certain molecules are found throughout the living world (DNA)
Two closely related species will have separated recently and so their biological molecules are likely to be similar

55
Q

What was Charles Darwin’s evidence for evolution?

A
  1. Offspring generally appear similar to parents
  2. No two individuals are identical
  3. Organisms have the ability to produce large numbers of offspring
  4. Populations in nature remain fairly stable

Conclusions:
Better adapted individuals out compete others and overtime changes give rise to a new species

56
Q

How does natural selection work?

A
  1. Mutations create alternative versions of a gene (allele frequencies change)
  2. This creates genetic variation between the individuals of a species (intraspecific variation)
  3. A selection pressure in the environment favours the survival of the individual with the more advantageous characteristics
  4. These selected individuals survive and reproduce
  5. The pass on their characteristics to their offspring via inheritance
  6. The next generation I’ll have a higher proportion of individuals with the successful characteristics
  7. Overtime the group of organisms becomes better adapted to the environment
  8. Leads to evolution
57
Q

What are the 3 types of selection and what affect do they have?

A

Stabilising- environment is unchanged and favours the intermediate phenotype

Directional- changing environments cause s gradual shift in the optimum phenotypes

Disruptive- changing environments favours the extreme phenotypes

58
Q

What is genetic drift?

A

When allele frequencies change overtime due not to selection pressures but simple due to mutation genetic bottlenecking or the founder effect

59
Q

What is genetic bottlenecking?

A

A sharp reduction in the size of population due to environmental events (eg earthquakes floods disease)

60
Q

What is the founder effect?

A

The loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population.

61
Q

What is speciation?

A

When 2 populations of the same species become so genetically different they can no longer interbreed to produce fertile offspring and 2 new species are formed

62
Q

What are the different types of isolation barriers and what types of speciation do they cause?

A

Geographical barriers cause allopatric speciation

Reproductive barriers cause sympatric speciation

63
Q

What kind of barriers cause allopatric speciation?

A 
Floods
Volcanoes 
Human intervention 
Rivers
Mountains
64
Q

What kind of barriers cause sympatric speciation?

A

Behavioural differences
Physiological differences
Genetically difference
Biochemically different

65
Q

How does speciation occur?

A
  1. Mutation in a gene pool
  2. An isolation barrier occurs (allopatric or sympatric)
  3. Natural selection and selection pressures occur
  4. Allele frequency changes
  5. Overtime the two isolated populations can no longer interbreed
  6. 2 new species arise
66
Q

What are the stages in the Nitrogen cycle?

A

Ammonification

nitrification

nitrogen fixation

denitrification

(each stage involves saprobiontic organisms)

67
Q

What is Ammonification?

A

The production of ammonia from organic nitrogen containing compounds. saprobiontic bacteria feed on decaying material releasing ammonia which then forms ammonium ions in the soil enabling nitrogen to return to the non living component of the ecosystem.

68
Q

What is Nitrification?

A

Nirtifying bacteria convert ammonium ions to nitrite ions and then to nitrate ions. This is an oxidation reaction which releases energy. These nitrate ions can then be assimilated by plants and up-taken for the production of amino acids, proteins, growth etc.

69
Q

What is Nitrogen fixation?

A

The process by which Nitrogen gas is converted into nitrogen containing compounds. this is carried out by saprobiontic organisms.

70
Q

What is De-nitrification?

A

when denitrifying bacteria convert soil nitrates into nitrogen gas which is then returned to the atmosphere and the process repeats.

71
Q

What is the phosphorous cycle?

A

The movement of phosphorus (phosphate ions) between rocks, bodies of water, animals and plants. This is an important cycle as phosphorus is an important biological element for ATP and phospholipids therefore essential for life.

72
Q

What is Mycorrhizae?

A

A fungi that can act as extensions onto roots of plants to increase their surface area form more efficient and greater up take of nutrients and water.

73
Q

What is a mutualistic relationship?

A

One where both the plant and fungi benefit from each other.

eg. Mycorrhizae will provide the plant with better water and inorganic ion up-take and in return be provided with sugars and amino acids from the plant.

A-level Biology (23 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions