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A-levels > Biology UNIT 5- Ecology > Flashcards

Biology UNIT 5- Ecology Flashcards

1
Q

Define Ecology?

A

The study of living organisms and their interdependence within an ecosystem.

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2
Q

What is inter/intra specific competition?

A

Intraspecific- competition within a species

Interspecific- competition within a species

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3
Q

What are abiotic factors of an ecosystem?

A

Non-living features:

  • Water/air temperature
  • pH
  • Turbidity (suspended solids)
  • Oxygen levels in air and water
  • Mineral levels in air and water
  • Soil depth and texture
  • windspeed and direction
  • Humidity
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4
Q

What are the biotic factors of an ecosystem?

A

Living components that affects the population of another organism or environment:

  • Competition
  • PRedation
  • Grazing
  • Parasitism
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5
Q

What are the different methods of measuring samples?

A

Abundance- SACFOR
percentage cover- percentage of a quadrat covered by a species
Density- Number of individual species in a quadrat
Frequency- Whether a species is present

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6
Q

What is SACFOR?

A 
Super abundant
Abundant
Common
Frequent
Occasional
Rare
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7
Q

What is spearmans rank?

A

rs= 1 - 6SUMD^2/n(n^2 - 1)

SUM= Sum of
D= Differences between ranks
n= Number of repeats
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8
Q

What is a null hypothesis?

A

THe hypothesis stating that there is nosignificant difference/relationship between specified populations/factors.

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9
Q

Define Population

A

A group of individuals of one species that occupy the same habitat at the same time and are potentially able to interbreed.

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10
Q

Define Carrying capacity

A

The size of a population that an ecosystem can support sustainably.

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11
Q

Define community

A

All populations of different species living and interacting in a particular place at the same time.

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12
Q

Define habitat

A

The place where an organism normally lives and is characterised by physical conditions and other types of organisms present.

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13
Q

Define Niche

A

The interrelationship of a species with all the biotic and abiotic factors affecting it.

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14
Q

How is random sampling carried out?

A

1) Lay out two tape measures at right angles along the boundary of the study area.
2) Randomly generate a series of co-ordinates by using a computer/table
3) Place left hand corner of quadrat at the intersection of co-ordinates and record species present.

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15
Q

How is systematic (belt transect) sampling carried out?

A

Stretch a tape measure from one area along the sampling area. A quadrat is then placed at intervals (interupted or contiuous transect) and at each location the species are recorded.

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16
Q

What is the mark release recapture sampling method?

A

A known number of animals are caught and marked in some way.
They are then released back to where they were found and some time later, a given number of animals are recaptured or collected.
The number of recaptured marked animals is recorded..
The population can then be calculated by:

Pop size= (No. of animals in 1st sample x No. of animals in second sample) / No. of recaptured animals.

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17
Q

What assumptions must be made when using mark-release recapture method?

A
  • Individuals released evenly into the population
  • No births/deaths occur (birth to death rate is unchanged)
  • No immigration or emmigration
  • Marking method is non-toxic/damaging/endangering
  • Mark/lable is not washed/rubbed off.
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18
Q

When is the spearmans rank test used?

A

To summarise the relationship between 2 variables.

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19
Q

When is the student T-test used?

A

When testing a hypothesis using 2 samples/sampling areas.

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20
Q

Define Zonation

A

The distribution of plants/animals into specific zones according to such parameters as altitude, depth. Each czone is characterised by its dominant species.

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21
Q

What is an indicator species and waht must you consider when using them?

A

A species whos presence, absence or abundance reflects a specific environmental condition, habitat or community.

  • They cannot be a base result to conclude an answer
  • Need lots of data
  • Species need to be linked to the environmental condition being measured.
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22
Q

What is the student t test?

A

t= |mean of area 1 - mean of area 2|/ squre root ( (s1^2)/n1 + (s2^2)/n2

23
Q

When can the null hypothesis be rejected?

A

If t is greater than or equal to the critical value there is a less than 5% probability that the dfference in speices richness occured by chance so the difference is statistically significant and the null hypothesis can be rejected.

If t is smaller than the critical value then there is a greater than 5% probability that the difference in species richness occured by chance and the null hypothesis must be accepted.

24
Q

What is the Lincoln Index?

A

Used to generate an estimated population size:

Number marked in 1st sample / total number in population = Number of recaptured organisms / Total caught in second sample.

25
Q

How do you calculate total population?

A

Total population = Total marked in 1st sample x total caught in 2nd sample / No. marked organisms recaptured.

26
Q

What is biomass?

A

Mass of living matter/tissue/orgaism.

Biomass units = Kgm^-2 yr^-1 or KJm^-2 yr^-1

27
Q

What is the difference between wet and dry biomass and which is more reliable?

A
  • Wet/fresh biomass - water is in cells when weighed
  • Dry biomass - water has been removed from cells

Dry biomass is more accuraet as there is different amounts of water in different tissues of species / different species contain different volumes of water.

28
Q

How is biomass measured?

A

The dry biomass is measured using calorimetry:

Q=MCΔT

29
Q

How can you calcuate biomass/energy flow through an ecosystem for plants?

A

NPP= GPP - R

Net Primary productivity
Gross primary productivity
Respiratory losses

NPP = Biomass left after respiratory losses have been removved
GPP = Biomass produced in an ecosystem.
30
Q

How can you calcuate biomass/energy flow through an ecosystem for animals?

A

N = I - (F+R)

N= Net productivity of consumer
I= Energy injested (food)
F= Faeces
R= Respiratory losses.
31
Q

How do farmer’s increase yields for crops and animal products

A

Crops:

  • climate control
  • herbicide/ pesticides
  • polytunnels
  • green houses
  • nutritional soil
  • genetic engineering

Animals:

  • restrict movement
  • Temperature control
  • nutritional diet
32
Q

What is mycorrhizae?

A

A structure in which a symbiotic union between a fungus and the roots of the plant confers increases in fitness to one or both participants

33
Q

What are the advantages sand disadvantages of natural fertilises?

A

Advantages:

  • less pollution
  • lower cost/ production
  • sustainable

Disadvantages:

  • limited quantity
  • high Application cost
34
Q

What are the advantages sand disadvantages of artificial fertilises?

A

Advantages:

  • fast acting
  • quick and easy to apply
  • specific nutrients

Disadvantages:

  • high production cost
  • polluting
  • easily wasted off
35
Q

What do mycorrhizae do?

A

Mycorrhizal fungi act like extensions to the roots to increase the surface area for greater absorption of mineral ions and water.

36
Q

What is a mutualistic relationship

A
  • plant benefits from improved water and mineral ions uptake.
  • mycorrhiza benefits from organic compounds ( sugars and amino acids) produced by the plant
37
Q

How is biomass dried?

A

In special drying ovens at not too high temperatures.
Organism must be weighed at constant intervals until the weight becomes concordant / plateaus at this point the water has been removed

38
Q

What are the stages in the nitrogen cycle

A
  • nitrogen fixing bacteria ( nitrogen fixation)
  • nitrifying bacteria ( nitrification)
  • saprobiotic bacteria ( decomposers)
  • dentrifying bacteria (dentrification)
39
Q

What happens in nitrogen fixation?

A

N2 + 3H2 —–> NH3 (NH4+)

Free living bacteria in the soil
Symbiotic relationship in roots of leguminous plants

40
Q

What happens during nitrification?

A

NH4+ —-> NO2 —-> NO3

41
Q

What do saprobiotic do?

A

Protein and other nitrogenous bio-molecues —-> NH4+

ammonification

42
Q

What happens during dentrificstion

A

Dentrifying bacteria ( dentrification)

Anaerobic conditions) NO3 —–> nitrogen gas (back into the atmosphere

43
Q

What is Eutrophication?

A

The process where nitrates get into lakes/rivers and streams and cause the ecosystem to die

44
Q

What are the steps in the Eutrophication cycle?

A

1) Nutrients overload
2) Increased photosynthesis rate so algae grow rapidly 3) Algal bloom blocks light so other plants cannot photosynthesise
4) Therefore plants die and decompose by saprobiotic bacteria which increase O2 consumption
5) Death of ecosystem due to a lack of water.

45
Q

What is succession?

A

Transition in the species competition over a period of time. The gradual change that happens in a community

46
Q

What is a pioneer species?

A

The first species to colonise an area (often damaged by ecological tragedies)

47
Q

What are the features of the pioneer species?

A
  • Asexual reproduction
  • Tolerance to extreme conditions
  • Ability to photosynthesise
  • Ability to fix nitrogen
  • Rapid germination of seeds
  • Easily dispersed seeds/spores
48
Q

What are the stages of succession?

A

1) Algae and lichen begin to live bare rock (pioneer species)
2) Erosion of rock and build up of dead material leads to soil formation which can support larger organisms.
3) Process repeats
4) Eventually a final stable community is achieved called the climax community

49
Q

Define climatic climax

A

Defines the major types of vegetation covering a large geographical area (biome)
A Biome is determined by rainfall and temperature

50
Q

Define deflected climax (Plagioclimax)

A

A plant community that is stable but prevented from reaching its true climax community due to HUMAN INTERVENTION

51
Q

What are common features that emerge form succession?

A
  • Non living environment becomes less hostile
  • A greater number of habitats and niches
  • Leads to increased biodiversity
  • Leads to more complex food webs
  • Leads to an increased biomass especially during mid-succession.
52
Q

How is succession managed?

A

By…

  • Low impact human activities (eg livestock grazing and shrub clearance)
  • Reinstating grazing regimes
  • Reseeding heathers
  • Campaign for protection from development and encouraging local people not to disturb ground nesting birds.
53
Q

Define Xerophyte

A

Species of plant that has adapted to survive in an environment with little/no water (liquid) such as a desert or ice/snow covered region.

54
Q

Define Halophyte

A

A plant that grows in waters of high salinity (salt content) coming into contact with saline water through it’s roots or by salt spray.

A-levels (23 decks)

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