7.4

Question 1

community

Answer 1

all populations of different species living in same place at the same time

Question 2

ecosystem

Answer 2

community and the non living component of its environment

Question 3

niche

Answer 3

specific role of a species within its habitat eg what it eats
governed by its adaptations to both abiotic and biotic factors

Question 4

advantages of species occupying different niches

Answer 4

less competition for food and resources
if two species tried to occupy the same niche it would outcompete the other

Question 5

carrying capacity

Answer 5

max stable population size of a species that an ecosystem can support

Question 6

factors influencing carrying capacity

Answer 6

abiotic factors eg light intensity temperature soil ph and humidity
interactions between organisms interspecific intraspecifc comp and predation

Question 7

abiotic factors effect on population size and carrying capacity

Answer 7

if conditions favourable organisms more likely to survive and reproduce increasing the carrying capacity
eg increase in light intensity increase rate of photo synthesis in plants
this incr carrying capacity of a variety of plant species
so increases the numbering variety of habitats niches and food sources for animals
increasing carrying capacity of a variety of animal species

Question 8

interspecific comp affect on population size

Answer 8

resources available reduced to both species
limit chance of survival and reproduction
reduce population size of both species
if species better adapted outcompete other
so pop size of less well adapted species declines = extinct

Question 9

intraspecifc comp affect on pop size

Answer 9

as pop incr resources available per organism decreases so comp increases
chance of survival and reproduction decreases so population size decreases
pop size decrease more resources available PP so comp decrease
change of survival reproduction and population increases

Question 10

changes in populations of predator and prey

Answer 10

prey pop increase
predators have more food
predator population increase so prey killed
less prey service and reproduce
prey pop decrease predators have less food
less predator survive and reproduce
so prey pop increase again as less killed and eaten

Question 11

how can size of population of slow moving or non motile organisms be estimated

Answer 11

divide area into grid
place w tape measures at right angles
generate pair of coordinates using random number generator
place quadrat here and count freq of species
repeat like thirty times and calc a mean

Question 12

pop size eq

Answer 12

(total area of habitat/quadrat area) times mean per quadrat

Question 13

describe mark release capture

Answer 13

capture sample of species mark and release
ensure marking isn’t harmful and doesn’t affect survival
allow time for organisms to randomly disturbute before collecting 2nd sample

Question 14

population MRC eq

Answer 14

no in sample 1 times no in sample 2 / number marked in sample 2

Question 15

assume of MRC

Answer 15

Sufficient time for marked individuals to mix and distribute evenly within the population
marking not removed and doesn’t affect chance of survival and reproduction
no immigration
no births death or breeding like change in population sizes

Question 16

MRC unreliable?

Answer 16

unlikely that organisms distribute randomly and evenly
less chance of recapturing organims that were marked originally

Question 17

succession

Answer 17

change in community overtime due to change in abiotic factors and species

Question 18

primary succession how does it occur

Answer 18

colonisation by pioneer species
pioneer species change abiotic conditions
eg they die and decompose forming soil which retains water
so envi less hostile and more suitable to species with different adaptions
less suitable to previous species so they are outcompeted
biodiversity increases
climax community is reached which is final stable community

Question 19

features of climax community

Answer 19

same species present like a stable community over a long time
abiotic factors fairly constant over long tine
population fairly stable around carrying capacity

Question 20

how does conservation of habitat involve managing succession

Answer 20

further succession can be prevented to stop a climax community forming
prevent growth of species associated with later stages
preserve ecosystem at certain point
so early species aren’t outcompeted by later species
niches not lost

Question 21

how could you investigate effect of envi factor on disturb of species in habitat

Answer 21

divide two areas into grids
place two tape measures at right angles
generate pare of coordinates using random no generator
place quadrat here and count frequency of named species
standardise this
repeat 30 times calc mean and measure envi factor In each area

Question 22

why might percentage cover be used instead of frequency

Answer 22

too difficult to count individuals organism or they may be too small to count

Question 23

importance of large sample size

Answer 23

minimise effect of anomalies
ensure sample representative if population

Question 24

how to decide the number of quadrants that should be used

Answer 24

calc running mean
when enough quadrates this shows little change
enough to carry out stat test

Question 25

how to investigate effect of a factor on the distribution of species in a habitat

Answer 25

place transect line across area with envi gradient
place quadrates at regular intervals
repeat in other parallel areas and calculate a mean number of plants at each point along the transect

Question 26

How to determine percentage cover

Answer 26

Random number generator
Large sample of quadrants
Divide total percentage by number of quadrants