B14e Trophic levels (triple only)

Question 1

What are trophic levels?

Answer 1

Stages in a food chain

Question 2

Describe the organisms present in trophic level 1?

Answer 2

Plants and algae

Make their own food through photosynthesis -

Called producers

Question 3

Describe the organisms in trophic level 2?

Answer 3

Herbivores

Eat producers

Called primary consumers

Question 4

Describe the organisms in trophic level 3?

Answer 4

Carnivores

Eat herbivores

Called secondary consumers

Question 5

Describe the organisms in trophic level 4?

Answer 5

Carnivores

Eat other carnivores

Called tertiary consumers

Question 6

What is an apex predator?

Answer 6

A carnivore with no predators

Question 7

How do decomposers breakdown dead material?

Answer 7

Decomposers release enzyme which catalyse the breakdown of dead material into smaller molecules.

Soluble small food molecules than diffuse into the microorganism

Question 8

What is biomass?

Answer 8

Dry mass of all of the living organisms in an area

Question 9

Why is dry mass used the measure biomass?

Answer 9

Wet mass varies as the volume of water in organisms varies

Question 10

How is the efficiency of biomass transfer calculated?

Answer 10

Efficiency =
(energy transferred/total energy available) x 100

Question 11

What percentage of the energy from light do producers transfer?

Answer 11

1%

Question 12

What percentage of the biomass from one trophic level is transferred

to the next trophic level?

Answer 12

Approximately 10%

Question 13

Why is biomass transfer not 100% efficient?

Answer 13

Energy is lost through:
Faeces - not all material is absorbed
Respiration - large amounts of glucose used and carbon dioxide and water lost in respiration
Excretion eg urine
Production of inedible bones and shells

Question 14

How does the efficiency of biomass transfer
affects the number of trophic levels in a biomass pyramid?

Answer 14

Less efficient transfers results in fewer trophic levels
and fewer organisms in higher trophic levels.

Question 15

What is a pyramid of biomass?

Answer 15

A pyramid that show the total dry mass of organisms at each trophic level
Trophic level 1 is always at the bottom

Question 16

What is a pyramid of numbers?

Answer 16

A pyramid that shows the number of organisms at each trophic level

Question 17

The pyramid of numbers is not pyramid shaped.

Explain why

Answer 17

There is only one tree

There are are large numbers of caterpillars

The tree is huge compared to the caterpillars

Tree can provide sufficient resources for large numbers of caterpillars.

Question 18

The diagram shows the biomass of each trophic level.

What shape is the pyramid of biomass for this food chain?

Answer 18

Pyramid shaped

Question 19

Which diagram correctly shows the pyramid of biomass?

Answer 19

B

Pyramids of biomass always narrow.

Question 20

Name the organism at trophic level 2 for this pyramid of biomass

Answer 20

Grasshoppers

Question 21

Name the organism at trophic level 4 for this pyramid of biomass

Answer 21

Snake