Populations in ecosystems (19)

Question 1

What is a community?

Answer 1

all the different species that live in one area and interact with each other

Question 2

What is an ecosystem?

Answer 2

all living organisms found in one area, combined with non-living aspects of their environment

Question 3

What is intraspecific competition?

Answer 3

competition between organisms of the same species

Question 4

What is interspecific competition?

Answer 4

competition between organisms of different species

Question 5

What are biotic features?

Answer 5

living features of an ecosystem

Question 6

What are the 3 examples of biotic features?

Answer 6

predators
disease
food

Question 7

What are abiotic features?

Answer 7

non-living features of an ecosystem

Question 8

What are 5 examples of abiotic features?

Answer 8

temperature
pollution
light intensity
pH
water/humidity

Question 9

What are 6 resources organisms might compete for?

Answer 9

food
water
shelter
mates
minerals
light

Question 10

What is a habitat?

Answer 10

place where an organism lives within an ecosystem

Question 11

What is a niche?

Answer 11

role of a species within its habitat, consisting of both its biotic and abiotic interactions

Question 12

What is meant by carrying capacity?

Answer 12

max size of a population an ecosystem can support

Question 13

What are the 3 stages of the pattern of typical predator-prey relationships?

Answer 13

1) prey is eaten by predator so prey population decreases and predator population increases
2) fewer prey means more competition for food so predator population decreases
3) fewer predators means more prey survives and cycle begins again

Question 14

How are quadrats used for estimating population size?

Answer 14

can be placed on grid coordinates, or at intervals along a belt transect, and results are reported as either a % cover or frequency

Question 15

What type of organisms can quadrats be used on?

Answer 15

slow-moving organisms
non-motile organisms

Question 16

What type of organisms can the mark-release-recapture method be used on?

Answer 16

fast-moving organisms
motile organisms

Question 17

How is the mark-release-recapture method used for estimating population size?

Answer 17

1) sample of species is captured, marked and released back into same area they were caught
2) after a certain period of time another sample of the same species is captured and the number of marked organisms are counted

Question 18

What 2 ways can population size be estimated?

Answer 18

quadrats
mark-release-recapture method

Question 19

What is the equation for estimated population size?

Answer 19

(total number of individuals in first sample x total number of individuals in second sample)
____________________________
number of individuals recaptured

Question 20

What 5 assumptions does the mark-release-recapture method make?

Answer 20

1) marked individuals distribute evenly
2) no migration in/out population
3) few births or deaths
4) mark does not come off
5) method of marking does not affect survival

Question 21

What are 3 reasons why ecosystems described as being dynamic?

Answer 21

• populations constantly rise and fall
• any small change can have a large effect
• biotic + abiotic factors may alter the ecosystem conditions

Question 22

What is meant by conservation?

Answer 22

protection and management of species and habitats in order to maintain biodiversity

Question 23

What is primary succession?

Answer 23

where an area previously devoid of life is colonised by a community of organisms

Question 24

What are the 3 steps in the process of primary succession?

Answer 24

1) pioneer species can survive harsh conditions and colonise the area
2) they change abiotic factors of their environment such as decomposition which adds nutrients to the ground
3) overtime this allows more complex organisms to survive

Question 25

What is meant by climax community?

Answer 25

final stage of primary succession where ecosystem is balanced and stable

Question 26

How is climax community reached?

Answer 26

when soil is rich enough to support large trees or shrubs, and environment no longer changes

Question 27

How might succession be managed in order to aid conservation?

Answer 27

sometimes succession needs to be prevented in order to preserve an ecosystem at a certain point (this is known as plagioclimax)

Question 28

What is an example of managing succession in order to aid conservation?

Answer 28

stopping moorland from progressing into spruce forest

Question 29

What are 2 features of a climax community?

Answer 29

• abiotic factors are constant
• populations are stable