Ecosystems

Question 1

What is an ecosystem?

Answer 1

A functional unit that tends to be fairly sustaining

Question 2

What is a habitat?

Answer 2

The place with a distinct set of conditions where an organism lives

Question 3

What is a community?

Answer 3

Various populations sharing a habitat or ecosystem

Question 4

What is a population?

Answer 4

A group of interbreeding individuals of the same species in the same area

Question 5

What can ecological factors be broken down into?

Answer 5

Biotic and abiotic factors

Question 6

What is an abiotic factor?

Give three examples

Answer 6

Non-living or physical and chemical factors

• Solar energy input; affects plants, length of days
• Climate; such as rainfall, winds and temperature
• Topography; types of landscape such as high altitude which would affect climate
• Oxygen exposure
• Edaphic factors; soil pH and mineral ion concentration
• Pollution
• Catastrophes; earthquakes, floods, volcanic eruption and fires

Question 7

What is a biotic factor?

Give three examples

Answer 7

Living factors that effect a habitat

• Interspecific and intraspecific competition
• Predation
• Disease
• Mutualism; a relationship where both species benefit

Question 8

‘Biotic factors are usually density dependant’

Explain this

Answer 8

The effects are related to the size of the population relative to the area available

Question 9

What are density independent factors?

Answer 9

• Factors whose effects does not change proportionally when the population increases or decreases
• This are more typically abiotic factors

Question 10

What are anthropogenic factors?

Answer 10

Abiotic and biotic factors that are caused by human activity

Question 11

Why do species survive in a habitat?

Answer 11

They have adaptations that enable them to cope with both the biotic and abiotic conditions in their niche

Question 12

What is primary succession?

Answer 12

Colonisation of a newly formed habitat where there has never been a community before

Question 13

Give an example of a pioneer species

Answer 13

• Lichens

- Algae

Question 14

Another name for population size

Answer 14

Abundance

Question 15

‘The population sizes of Predator and prey are linked’

Explain this

Answer 15

• As prey population increases, there’s more food for predators so their population increases
• As the predator population increases, the prey population decreases
• Theres now less prey so the predator population decreases

Question 16

What affects distribution as well as abundance of a species?

Answer 16

Biotic and abiotic factors

ie where a plant can grow and how well it can grow

Question 17

What is a niche?

Answer 17

The role of a species within its habitat

Includes biotic interactions and abiotic interactions

Question 18

What happens in primary succession?

Answer 18

• Pioneer species grow because they’re specialised to cope with the harsh conditions of the environment at this stage
• They die and microorganisms decompose the organic material, forming a basic soil
• They soil helps to retain water which allows new species to grow there
• These then die and microorganisms decompose them, making the soil deeper and richer in nutrients
• This allows even more species to grow and the overall conditions less hostile

Question 19

How does secondary succession differ from primary succession?

Answer 19

• Secondary succession is land that has been cleared of all plants but soil is remains
• Therefore it starts at a later seral stage; starts with the bigger plants instead of the pioneer species

Question 20

What is climax community?

Answer 20

• The ecosystem is supporting the largest and most complex community of plants and animals it can
• Its in a steady state

Question 21

What is deflected succession?

Answer 21

A community that remains stable only because human activity prevents succession

Question 22

What is another name for producers?

Answer 22

Autotrophs

Question 23

What are tertiary consumers?

Answer 23

Consumers that eat other consumers

Sometimes called top carnivores

Question 24

What is trophic level?

Answer 24

The position a species occupies in a food chain

Question 25

What are detritivores?

Answer 25

Primary consumers that feed on dead organic material called detritus

Question 26

Why isn’t all sunlight absorbed into a plant?

Answer 26

Chlorophyll can only adsorb certain wavelengths

Question 27

Why are there different pigments in a chlorophyll?

Answer 27

Each pigment absorbs a different wavelength of light so more pigments means a greater amount of light is absorbed

Question 28

Give the equation and units for calculating gross primary productivity

Answer 28

GPP = NPP + R

KJ m-2 year-1

Question 29

What is gross primary productivity?

Answer 29

The rate at which energy is incorporated into organic molecules

Question 30

What is net primary productivity?

Answer 30

The rate of which energy is transferred into the organic molecules that make up new plant biomass

NPP = GPP - R

Question 31

What are primary consumers?

Answer 31

Consumers that eat plant material

Question 32

What are heterotrophs?

Answer 32

Organisms that obtain energy as ready made organic matter by ingesting material from other organisms

Question 33

Why does only 2-10% of energy get passed on from produces to primary consumers?

Answer 33

• Not all available food gets eaten
• Some undigested food is lost in faeces
• Energy used in respiration