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biology > topic 10.1 - nature of ecosystems > Flashcards

topic 10.1 - nature of ecosystems Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is an ecosystem

A
  • an environment including all the living and non living factors which they interact with
  • can be many sizes
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2
Q

population

A

a group of organisms of the same species that breed together in the same habitat

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3
Q

community

A
  • group of population of different species interacting in the same habitat
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4
Q

niche

A
  • role of an organism in a community
  • includes everything with which the organism interacts
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5
Q

habitat

A
  • place where an organism lives
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6
Q

biotic factors

A
  • living elements of a habitat that affect ability of organisms to live there
  • e.g. availability of prey, bacteria
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7
Q

abiotic factors

A
  • non-living elements of a habitat
  • e.g. sunlight, temp, soil, pH, rainfull, O2 in water
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8
Q

biosphere

A
  • all the areas of the surface of the earth where living organisms survive
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9
Q

biome

A
  • the major ecosystems of the world
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10
Q

what is meant by trophic levels

A
  • describe the feeding relationships and position of an organism in a food chain or web
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11
Q

how can trophic levels be represented

A
  • pyramids of numbers
  • biomass (dry)
  • energy
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12
Q

different trophic levels within a food web

producers

A
  • producers are the first stgae in any food chain
  • plant & algae use sunlight to photosynthesise - nutrients from soil and CO2 from air
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13
Q

different trophic levels within a food web

primary consumers

A
  • organisms which consume producers
  • harbivores digest plant materials to obtain energy and nutrients
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14
Q

different trophic levels within a food web

secondary consumers

A
  • organisms which feed on herbivores
  • carnivores prey on herbivores to obtain nutrients & energy
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15
Q

different trophic levels within a food web

tertiary consumers

A
  • organisms which eat other carnivores
  • top carnivores prey on other carnivores to obtain nutrients and energy
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16
Q

different trophic levels within a food web

decomposers

A
  • digest dead organic material
  • final trophic level in any feeding relationship
  • microorganisms (i.e. bacteria & fungi) that break down remains of animals & plants
  • return nutrients to soil
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17
Q

advnatages and disadvantages of pyramids of numbers

as representation of ecosystem structure & how biomass & energy transferred

A

ADV
- easiest to meausure
DISADV
- least accurate

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18
Q

advantages & disadvantages of biomass

as representation of ecosystem structure & how biomass & energy transferred

A

ADV
- more accurate
DISADV
- don’t take into account rate of production of biomass
- using dry mass is bad bc dehydration kills organisms
- using wet mass is less accurate

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19
Q

advantages and disadvantages of energy levels

as representation of ecosystem structure & how biomass & energy transferred

A

ADV
- most accurate
DISADV
- hardest to measure
- rarely used in practice

20
Q

abundance

A
  • the relative representation of a species in a particular ecosystem
  • total number of individuals of a species present in an ecosystem relative to other organims in the same habitat
21
Q

distribution

A
  • where species of organisms are found in the environment & how it is arranged
  • how spread out the organisms are from eachother
22
Q

ecological techniques

A
  • quadrat
  • transect
  • ACFOR scales
  • percentage cover
  • individual counts
23
Q

quadrats

A
  • square gridded frames placed randomly
  • count the number of individual organisms inside (individual counts)
  • find area covered by organisms using divided grid (percentage cover)
  • take multiple reading & find mean
24
Q

issue with quadrats

A
  • issues about decisions on whether to include organisms partly covered by quadrat
  • need to make these decisions before starting
25
Q

uniform distribution

A
  • when resources are thinly but evenly spread
26
Q

clumped distribution

A
  • distribution in groups (e.g. herd of animals)
  • groups of animals/plants which have specific resource requirements
  • clump in areas where they are found
27
Q

random distribution

A
  • result of plentiful resources and no antagonism
  • e.g. dandelions in a field
28
Q

ACFOR scale

A
  • use ACFOR scale to measure abundance of organisms in a quadrat or area
    A = abundant
    C = common
    F = frequent
    O = occasional
    R = rare
29
Q

what is the issue with the ACFOR scale

A
  • it is subjective
  • 2 people will not come up with the same rating
  • no set definition of term
  • i.e. what is ‘common’?
30
Q

line transect

A
  • runs across the area to be investigated
  • records organisms touching a line between two points
31
Q

belt transect

A
  • 2 tapes laid out
  • area between them surveyed using quadrats along a line
32
Q

interrupted belt transect

A
  • sample at regular intervals rather than recording a whole belt
33
Q

other measures of abundance

A
  • light traps to attract flies/insects
  • capture/recpature techniques for animals that move around
  • beating of branches to collect what falls out
34
Q

what are transects mostly used for

A
  • to discover correlations between species distribution and environmental factors
  • i.e. light intensity or soil pH
  • these factors are also measured along the transect
35
Q

aspects of making comparisons between sampling techniques

A
  • transects & random sampling
  • belt & interrupted transects
  • different quadrat sizes
  • types of quadrats
  • counting individuals & percentage cover
36
Q

statistical testing to analyse data

what is observer value

A
  • on table of critical values
  • need to look up the osberver value for each test to see which probability value this corresponds with
  • then you can see if the null hypothesis should be accepted or not
37
Q

statistical testing to analyse data

null hypothesis

A
  • hypothesis that any differences between data sets are simply due to chance
38
Q

Statistical tests can indicate if differences in results (from sampling methods) are significant

A
  • significant = less than 0.05
  • corresponds to the p < 0.05
39
Q

statistical tests

Spearman’s rank correlation coefficient - why is it used?

A
  • to measure the correlation between two variables

the extent to which changing one variable affects the other variable

40
Q

statistical tests

Spearman’s rank correlation coefficient - how to use it

A
  1. state the null hypothesis
  2. give rank to each item in each set of measurements
  3. find the differences between ranks for each pair of measurements
  4. add all the differences together and use formula to calculate the correlation coefficient; r(s)
41
Q

statistical tests

Spearman’s rank correlation coefficient - interpreting results

A
  • closer to 1 - more positive correlation
  • closer to -1 - more negative correlation
  • around 0 - no correlation
42
Q

statistical tests

Spearman’s rank correlation coefficient - what is the null hypothesis

A
  • that there is no correlation between the two variables
43
Q

statistical tests

Spearman’s rank correlation coefficient - deciding whether to accept the null hypothesis or not

A
  • state null hypothesis
  • compare to critical value (0.05)
  • <0.05 = significant
  • > 0.05 = not significant
44
Q

statistical tests

Student’s t-test - why is it used

A
  • to see if there is a difference between means values from two sets of measurements
45
Q

statistical tests

student’s t-test - how to do it

A
  1. state the null hypothesis
  2. calculate observer value (t) using formula
  3. use table to see if t is above or below p = 0.05 for (n1 + n2) - 2 degrees of freedom
46
Q

statistical tests

student’s t-test - intepreting the results

A
  • t value compared to a critical value for a particular p value chosen by researcher
  • find degrees of freedom (total nuber of data - 2)
  • find probability, p, that relates to oberver value & degree of freedom
  • if p < 0.005, difference is significant

biology (29 decks)

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