Populations in ecosystems

Question 1

Define community

Answer 1

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

Question 2

Define ecosystem

Answer 2

All the living organisms found in one
area, combined with non-living aspects
of their environment. Can vary from very
large to very small

Question 3

Describe biotic and abiotic factors, giving
examples

Answer 3

Biotic= living features of an ecosystem
e.g. predators, disease.
Abiotic= non-living features of an
ecosystem e.g. light, temperature

Question 4

Define habitat

Answer 4

The place where an organism lives
within an ecosystem

Question 5

Define a niche

Answer 5

The role of a species within its habitat,
consisting of both its biotic interactions
e.g. what it eats, and abiotic interactions
e.g. time of day it is active

Question 6

What is meant by carrying capacity?

Answer 6

The maximum size of population an
ecosystem can support

Question 7

Name four abiotic factors that affect
population growth

Answer 7

1. Temperature
2. Light
3. pH
4. Water/humidity

Question 8

What is meant by intraspecific and
interspecific competition?

Answer 8

Intraspecific = competition between
organisms of the same species.
Interspecific = competition between
organisms of different species

Question 9

What resources might organisms
compete for?

Answer 9

Food, water, shelter, minerals, light,
mates (intraspecific only)

Question 10

Describe the pattern of a typical
predator-prey relationship in terms of
population change

Answer 10

● Prey is eaten by predator, resulting in predator
population increasing and prey population decreasing.
● Fewer prey means increased competition for food, so
predator population decreases.
● Fewer predators means more prey survives, and the
cycle begins again

Question 11

What is meant by primary succession?

Answer 11

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

Question 12

Summarise the process of primary
succession

Answer 12

● Pioneer species can survive harsh conditions &
colonise the area.
● They change abiotic factors of their environment
e.g. decomposition adds nutrients to ground.
● Over time, this allows more complex organisms to
survive

Question 13

What is the climax community and how
is it reached?

Answer 13

The final stage of succession, where the
ecosystem is balanced and stable. It is
reached when the soil is rich enough to
support large trees or shrubs, and the
environment is no longer changing

Question 14

How might a species alter the
environment that develops during
succession?

Answer 14

A species may improve the environment to
make it more suitable for other species.
Alternatively, a species may worsen the
environment by making it less suitable for
other species

Question 15

Define conservation

Answer 15

The protection and management of
species and habitats, in order to maintain
biodiversity. Methods need to be adapted
to the ecosystem in question

Question 16

How might succession be managed in
order to aid conservation?

Answer 16

Sometimes succession needs to be
prevented in order to preserve an
ecosystem at a certain point, e.g. stopping
moorland from progressing into spruce
forest. This is called a plagioclimax