L39 The trophic structure of ecosystems

Question 1

All organisms need energy, where might they get it

Answer 1

The sun or chemicals

Question 2

What is Gross primary production (GPP)

Answer 2

Total amount of energy generated by autotrophs in an ecosystem

Question 3

What is Net primary productivity (NPP)

Answer 3

GPP-respiration by autotrophs

Question 4

Does NPP vary dramatically across Earth

Answer 4

yes

Question 5

Where is NPP greatest

Answer 5

In equatorial regions, with high rainfall

Question 6

What is NPP constrained by

Answer 6

Energy (e.g. temperature or light ( for aquatic ecosystems))
Water (for terrestrial ecosystems)
Limiting Nutrients (nitrogen and phosphorus

Question 7

What are the trophic levels and food chain

Answer 7

Plants (primary producers) ->
Herbivores (primary consumers)->
Carvivores (secondary consumers)->
Top carnivores (tertiary consumers)

Question 8

What is lost at each step of the food chain

Answer 8

Energy

Question 9

What does the loss of energy at each stage of food chain limit

Answer 9

Number of links in the chain

Question 10

What ways can an ecosystem be driven by

Answer 10

Bottom-up: input at bottom of the food chain
Top-down or trophic cascade: pressure from predators

Question 11

What are dominant species

Answer 11

are simply the most common/ have biggest biomass

Question 12

What are keystone species

Answer 12

Play a pivotal role due to their niche

Question 13

Examples of keystone species

Answer 13

Beavers, elephants, pisaster (starfish)

Question 14

What is bioaccumulation

Answer 14

Increasing concentrations of pollutants and other non-metabolised molecules up the food chain

Question 15

Examples of pollutants that cause bioaccumulation

Answer 15

DDT, PCBs, methyl mercury

Question 16

What other parts of the food web can bioaccumulate

Answer 16

Detritivores and scavengers