Populations in ecosystems

Question 1

define ecosystem

Answer 1

community of species and the abiotic factors in that habitat and can range in size

Question 2

define carrying capacity

Answer 2

the maximum pop. size a climax community/ecosytem can support and sustain

Question 3

what are the 3 key things of ecosystems?

Answer 3

1. dynamic
2. have energy flow
3. recycles elements

Question 4

what 2 things can affect carrying capacity?

Answer 4

1. effect of abiotic factors

2. biotic factors (interactions between organisms)

Question 5

name the 5 abiotic factors which can effect carrying capacity?

Answer 5

temp, light, pH, H2O availability, humidity

Question 6

how can temp affect carrying capacity?

Answer 6

increase: enzymes denature
decrease: reduce metabolic rate
= reduce carrying capacity

Question 7

how can light affect carrying capacity?

Answer 7

increase = increase photo.

= carrying capacity of plants + those who consume them increases

Question 8

how does pH affect carrying capacity?

Answer 8

pop. of species increase where there’s the optimum pH

Question 9

how does a limited H2O availability affect carrying capacity?

Answer 9

pop. scarce

Question 10

how does humidity affect carrying capacity?

Answer 10

affects transpiration rates (increase, decrease transpiration)
= depends on the adaptations to humidity

Question 11

define interspecific competition?

Answer 11

competition between different species

Question 12

define intraspecific competition?

Answer 12

competition between same species

Question 13

how does predation affect carrying capacity?

Answer 13

decrease prey = increase comp between predators = decrease food availability

Question 14

define community

Answer 14

populations of different species occupying the same area/habitat

Question 15

define population

Answer 15

all organisms of the same species which occupy the same area/habitat

Question 16

define habitat

Answer 16

where an organism lives

Question 17

define microhabitat

Answer 17

smaller unit of an ordinary habitat

Question 18

define ecological niche

Answer 18

where an organism lives and its role in the niche

Question 19

increase repeats increases the _______ of the ____ which means its representative of the population so can make _____ conclusions.

Answer 19

reliability, mean, valid

Question 20

when are quadrats used?

Answer 20

for slow moving or non-motile organisms

Question 21

what does a point quadrat work out?

Answer 21

frequency

Question 22

what does a frame quadrat work out?

Answer 22

% cover (each square represents a %)

Question 23

name the 3 things you have to consider when using quadrats

Answer 23

1. size of quadrat
2. no. of samples
3. position of quadrat

Question 24

describe random sampling in 6 steps

Answer 24

1. 2 tape measures at right angles
2. random no. generator
3. place at the coordinate
4. cound/collect
5. record data
6. calculate mean after repeating at least 20 times

Question 25

how many repeats should i do? (4)

Answer 25

1. large no. = reliable 2. carry out a stats test 3. calculate a running mean 4. need to be done in time available

Question 26

when should systematic sampling be used?

Answer 26

environmental gradient or change to the abundance/distribution of organisms

Question 27

name the 2 types of systematic sampling

Answer 27

1. line | 2. belt

Question 28

describe belt transect method in 3 steps

Answer 28

1. lay out tape + place frame quadrat at right angle 2. predetermined, equal intervals move quadrat 3. record % cover

Question 29

what is the advantage of using a transect

Answer 29

measures abundance (% cover of frequency)

Question 30

name the 2 disadvantages of using a transect

Answer 30

1. can take a long time for large sample | 2. species overlooked if interval too large

Question 31

define abundance

Answer 31

no. of individual species in an area

Question 32

name the 2 ways abundance is measured

Answer 32

% cover and frequency

Question 33

what is % cover?

Answer 33

estimate of an area that a species covers

Question 34

what are the advantages and disadvantage of % cover?

Answer 34

+: useful if species abundant, difficult to count + data collected quickly -: overlapping of plants

Question 35

what is frequency? + formula

Answer 35

likelihood of species in quadrat | no. of quadrats containing species / total no. of quadrats x 100

Question 36

name the advantages and disadvantages of calculating frequency

Answer 36

+: quick idea of the species present/distribution | -: not as much data + not as reliable

Question 37

when is MRR used?

Answer 37

for estimating the pop. size of motile organisms

Question 38

describe the method of MRR in 5 steps

Answer 38

1. capture organism 2. mark (avoid harming them + increase predation) 3. release + allow enough time to reintegrate 4. collect 2nd sample, count/record how many marked/unmarked 5. use formula (lincoln Index)

Question 39

what is the formula for MRR (lincoln)?

Answer 39

no. of organism in sample 1 x no. of organisms in sample 2 / no. of recaught organisms

Question 40

name the 5 assumptions of MRR?

Answer 40

1. sufficient time to reintegrate 2. no immigration/migration 3. few/no deaths/births 4. mark/label doesn't rub off 5. marking doesn't increase predation

Question 41

define succession

Answer 41

change in community over time due to change in abiotic factors and/or species present

Question 42

define pioneer species + 2 examples

Answer 42

1st species to colonise an area i.e. lichen, algae

Question 43

name the 5 features of pioneer species

Answer 43

1. wind dispersed seeds 2. rapid germination (no dormancy period) 3. ability to photo. 4. can fix nitrogen 5. tolerant to extreme conditions

Question 44

define climax community

Answer 44

table community of species, no further succession

Question 45

4 features of climax community

Answer 45

1. increased biomass 2. complex food webs 3. increase variety of food/habitats 4. abiotic conditions less hostile

Question 46

define primary succession

Answer 46

no soil, bare rock

Question 47

define secondary succession

Answer 47

succession faster as soil already present + seeds still present

Question 48

define plagioclimax

Answer 48

- human interference to prevent succession - done to conserve a habitat that would be outcompeted i. e. grazing, coppicing, pollarding

Question 49

describe primary succession in 7 steps

Answer 49

1. pioneer species 2. weathering of rock = soil 3. pioneer species decompose (OM added) 4. mosses/ferns colonise = less hostile 5. organisms die/decompose + continued weathering 6. small flowering plants, grasses, shrubs, trees 7. climax community = equilibrium

Question 50

define conservation

Answer 50

- management of the earth's natural resources so that max. use can be made in future - intervention by humans to maintain biodiversity

Question 51

name the 3 reasons why we conserve habitats?

Answer 51

- ethical (respect for organisms) - economic (potential to make different substances/medicines/biomimetics) - cultural (entertain us, adds interests, fulfill us)