(19) Populations in ecosystems

Question 1

define ecology

Answer 1

the study of the inter-relationships between organisms and their environment. Includes abiotic and biotic factors

Question 2

define habitat

Answer 2

the place where an organism lives normally

Question 3

define population

Answer 3

all the organisms of one species in a habitat

Question 4

define community

Answer 4

populations of different species in a habitat

Question 5

define ecosystem

Answer 5

a community plus all the non living (abiotic) conditions in the area in which it lives - can be small or large eg a pond or an ocean

Question 6

define abiotic conditions

Answer 6

the non living features of an ecosystem eg temp and availability of water

Question 7

define biotic conditions

Answer 7

the living features of the ecosystem eg predators / food

Question 8

define niche

Answer 8

the role of a species within its habitat eg what it eats, where and when it feeds
some species may appear similar but their nesting habits or other aspects of their behaviour will be different- only one species can occupy a particular niche

Question 9

define adaptation

Answer 9

a feature that members of a species have that increases their chance of survival and reproduction

Question 10

what does the niche a species occupies within its habitat include

Answer 10

1) its biotic interactions eg the organisms it eats and those its eaten by
2) its abiotic interactions eg oxygen it breathes in and carbon dioxide it breathes out

Question 11

what is the competitive exclusion principle

Answer 11

the fact that no two species can occupy the same niche and where 2 species are competing for limited resources the one that uses them most effectively will eliminate the other

Question 12

what are microhabitats

Answer 12

smaller units within habitats that have their own microclimate

Question 13

what are the 3 different types of adaptations

Answer 13

physiological- processes inside their body
behavioural- the way an organism acts
anatomical- structural features of their body

Question 14

what is carrying capacity

Answer 14

the maximum stable population size of a species that an ecosystem can support

Question 15

what is interspecific competition

Answer 15

when organisms of different species compete for the same resources- resources and therefore populations will be limited

Question 16

what is intraspecific competition

Answer 16

when organisms of the same species compete for the same resources

Question 17

describe how to take samples to investigate populations

Answer 17

1) choose an area to sample and then a smaller area within to investigate
2) should be random to avoid bias (divide field into grid and use random number generator to select coordinates
3) take as many samples as possible to reduce likelihood of results being down to chance
4) multiply by size to estimate population for whole area

Question 18

what is mark release recapture used for

Answer 18

to measure the abundance of more motile species

Question 19

how to carry out mark release recapture

Answer 19

1) capture a sample of species using an appropriate technique
2) mark them in a harmless way
3) release them back into their habitat
4) wait a week and take a second sample from same population
5) count how many are marked and use the equation : total population = ( number caught 1st x number caught 2nd) / number marked in 2nd

Question 20

what are 3 assumptions made in mark, release, recapture

Answer 20

1) marked sample has enough time and opportunity to mix back in with the population
2) the marking hasn’t affected the individuals chance of survival and the marking is still visible
3) no changes in population size due to birth, death, migration during period of study

Question 21

define succession

Answer 21

the process by which an ecosystem changes over tim. the biotic conditions change as the abiotic conditions change

Question 22

what is primary succession

Answer 22

happens on land that has been newly formed or exposed eg where a volcano has erupted to form a new rock suface

Question 23

what is secondary succession

Answer 23

happens on land that has been cleared of all the plants but just the soil remains eg after a forest fire or when a forest has been cut down by humans

Question 24

what are pioneer species

Answer 24

species that colonise an inhospitable environment in the first stage of succession

Question 25

what is a climax community

Answer 25

in stable equilibrium with the prevailing climate. few if any species replace those that have become established- many species flourish and there is biodiversity