Populations in ecosystems

Question 1

Define Community

Answer 1

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

Question 2

Define ecosystem

Answer 2

All 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 & abiotic factors, giving examples

Answer 3

Biotic = living features of ecosystem e.g. predators, disease

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

Question 4

Define habitat

Answer 4

Place where an organism lives within an ecosystem

Question 5

Define Niche

Answer 5

Role of species within its habitat, consisting of both its biotic interactions (e.g. what it eats), and abiotic interactions (e.g. tine of day it is active).

Question 6

What is meant by carrying capacity?

Answer 6

Maximum size of population an ecosystem can support

Question 7

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 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 pattern of typical predator-prey relationship in terms of population change

Answer 10

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

Question 11

Why are ecosystems described as being dynamic?

Answer 11

• Populations constantly rise & fall
• Any small change can have large effect
• Biotic & abiotic factors may alter the conditions of ecosystem

Question 12

What is meant by primary succession?

Answer 12

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

Question 13

Summarise process of Primary Succession

Answer 13

• Pioneer species can survive harsh conditions & colonise 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 14

What is climax community & how is it reached?

Answer 14

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

Question 15

How might species alter environment that develops during succession?

Answer 15

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

Question 16

Define conservation

Answer 16

Protection & management of species & habitats, to maintain biodiversity. methods need to be adapted to ecosystem in question

Question 17

How might succession be managed to aid conservation?

Answer 17

Sometimes succession needs to be prevented to preserve an ecosystem at certain point (e.g. stopping moorland from progressing into spruce forest) - this is called Plagioclimax