Section 7 - 19 Populations in ecosystems

Question 1

What is ecology?

Answer 1

The study of the inter-relationships between organisms and their environment.

The environment included both non-living and living factors.

Question 2

What is an ecosystem?

Answer 2

Dynamic systems made up of a community and all the non-living factors of its environment.

Question 3

What are the two major processes that occur in ecosystems?

Answer 3

• the flow of energy through the system
• the cycling of elements within the system

Question 4

What is a population?

Answer 4

A group of individuals of one species that occupy the same habitat at the same time and are potentially able to interbreed.

Question 5

What is the carrying capacity?

Answer 5

An ecosystem supports a certain size of population of a species.

Question 6

What factors affect the size of a population?

Answer 6

• the effect of abiotic factors
• interactions between organisms. - intraspecific and interspecific competition and predation.

Question 7

What is a community?

Answer 7

All the populations of different species living and interacting in a particular place at the same time.

Question 8

What is a habitat?

Answer 8

The place where an organism normally lives and is characterised by physical conditions and the other types of organisms present.

Question 9

What is a microhabitat?

Answer 9

Smaller units inside a habitat that each have their own habitat.

Question 10

What is a niche?

Answer 10

Descirbes how an organism fits into the environment.

Where an organism lives and what it does there.

Includes biotic and abiotic factors.

Question 11

What is the competitive exclusion principle?

Answer 11

No two species occupy exactly the same niche.

Question 12

What is a population?

Answer 12

A group of individuals of the same species that occupy a habitat at the same time.

Question 13

what is the population size?

Answer 13

The number of individuals in a population.

Question 14

When might it not be possible to plot a growth curve?

Answer 14

Where the population grow rapidly over a short period of time.

Question 15

List abiotic factors that influence the size of a population

Answer 15

• temperature
• light
• pH
• water and humidity

Question 16

What makes up an ecosystem?

Answer 16

The interacting biotic and abiotic factors in a particular area within which there are a number of communities of organisms.

Question 17

In what two ways do species alter the environment during succession?

Answer 17

• Make it less suitable for the existing species - New species may out-compete the existing one and so take over a given area.
• Make more suitable for other species with different adaptions - this species may be out-competed by the better adapted new species.

Question 18

What is the first stage of succession?

Answer 18

Colonisation of an inhospitable environment.

By organisms called pioneer species.

Question 19

What is a pioneer species?

Answer 19

Organisms that can colonise an inhospitable environment.

In first stage of succession.

They make up a pioneer community and often have features that suit them to colonisation.

Question 20

What features suits pioneer species to colonise?

Answer 20

• Asexual reproduction
• Production of vast quantities of wind-dispersed seeds or spores.
• rapid germination of seeds
• ability to photosynthesis.
• Ability to fix nitrogen from the atmosphere
• Tolerance to extreme conditions

Question 21

Give an example of a pioneer species

Answer 21

Lichens

Question 22

In the UK what is the most ultimate community?

Answer 22

Deciduous oak woodland.

Question 23

What is a climax community?

Answer 23

State where many species flourish and there is much biodiversity.

Stable equilibrium with the prevailing climate. Abiotic factors such as climate that determine the dominant species of the community.

Question 24

What are the common features that emerge during succession?

Answer 24

Each one leads to the next:

• non-living abiotic environment becomes less hostile
• greater number and variety of habitats and niches produce
• increased biodiversity.
• more complex food webs
• increased biomass.

Question 25

What is secondary succession?

Answer 25

The process by which ecosystems return after the clearance of land for agriculture or a forest fire.

The climax community occurs more rapidly as soil already exists.

Question 26

Describe the process of succession

Answer 26

Question 27

What is conservation?

Answer 27

The management of the Earths natural resources by humans in such a way that maximum use of them can be made in the future.

Involves active intervention by humans to maintain ecosystems and biodiversity. - dynamic process

Question 28

What are the main reasons for conservation?

Answer 28

Personal - maintain plant and our life support machine.

ethical - other species occupied Earth before humans

Economic - gigantic pool of genes with capacity of making millions of substances

cultural and aesthetic - habitats and organisms enrich our lives.

Question 29

Why don’t original species still exist in the climax community?

Answer 29

Their habitats have diappeared as a result of succession or species have been out-cpmpeted by other species or been taken over for human activities.

Question 30

How is a natural climatic climax achieved?

Answer 30

If the factor that is preventing further succession is removed then the ecosystem can develop naturally into its climatic climax.

secondary succession