populations in ecosystems

Question 1

community

Answer 1

all pop of Dif species
live in same place at same time

Question 2

ecosystem

Answer 2

community and non living components of envi

Question 3

niche

Answer 3

specifc role of species within its habitat
what it eats and where it feeds
governed by adaptations to both abiotic and biotic factors

Question 4

adv of species occupying Dif niches

Answer 4

less comp for food and resources
if two species occupy same niche one would outcompete the other

Question 5

carrying capacity

Answer 5

max stable population size of species an ecosystem can support

Question 6

what influences carrying capacity

Answer 6

abiotic factors like light intensity temp soil ph
and the interaction between organisms
interspecific competition and intraspecifc competition and predation

Question 7

how can abiotic factors affect carrying capacity and population size

Answer 7

favourable codlins organism more Riley to survive and reproduce
increasing carrying capacity
eg if light intensity increases - increases rate of photosynthesis in plants
increasing carrying capacity of variety of plant species
so increases the number and variety of habitats niches and food sources for animals
increasing carrying capacity for a variety of animal species

Question 8

interspecific comp affect. on population size

Answer 8

reduces something available to both species
limiting their chance of survival and reproduction
so reduces pop size of both species
if one species better adapted itll outcompete other
so population size of less well adapted species declines - could lead to extinction

Question 9

intraspecifc comp affect on pop size

Answer 9

population increase
resource available per organism decreases
comp increases
chance of survival and reproducing decreases
so pop size decreases
resources available per organism increase comp decreases
chances of survival and reproduction increase
pop size will increase

Question 10

changes in populations of predator and prey

Answer 10

prey pop increase
predators have more food and survive and reproduce
predator pop increases so more prey killed and eaten
less prey survive and reproduce
prey pop decreases so predators have less food less survive and reproduce
predator pop declines less prey killed and eaten so more prey survive and reproduce

Question 11

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

Answer 11

divide area into grid
place two tape measures at right angles
place quadrat and count number of named species
repeat a large number pf time and calculate a mean per quadrat
population size total area of habitat / quadrat area times mean per quadrat

Question 12

Describe how the mark-release-recapture method can be used to estimate
the size of a population of motile organisms

Answer 12

capture sample of species mark and release
ensure marking not harmful and doesnt affect survival
allow time for organisms to randomly distribute before collecting second sample
● Population = (number in sample 1 x number in sample 2) / number marked in sample 2

Question 13

assumptions made in mark release recapture

Answer 13

sufficient time for marked individuals to mix evenly
marking not removed and doesnt affect survival and predation
no immigration
no briths and deaths or changes in pop size

Question 14

why is mark release capture unreliable

Answer 14

unlikely organisms distribute evenly
less chance of recapturing organism that was marked initially

Question 15

primary succession

Answer 15

colonisation by pioneer species - change abiotic conditions eg die decompose humus
so envi less hostile for other species with different adaptions
and less suitable for previous species so better adapted species outcompete the previous sepcies
as succession goes on biodiversity increases
climax community means final stable community and no more succession

Question 16

features of climax community

Answer 16

same species present - stable community over a long time
abiotic facts constant over time
population fairly stable

Question 17

explain how conservation of habitat involves mangnagment of succession

Answer 17

further succession prevented to stop climax community forming
by removing or preventing growth of species associated with later stages of growing eg by allowing grazing
this preserves ecosystem in its current stage of succession
so earlier species aren’t outcompeted by later species and habitats and niches aren’t lost

Question 18

conflict between human needs and conservation as well as importance of management

Answer 18

Human demand for natural resources like timber seed to habitat destruction and loss of biodiversirty
conservation needed tp protect habitats niches