13.1: Food chains and energy transfer

Question 1

Biomass

Answer 1

The total mass of living material in a specific area at a given time

Question 2

Producer

Answer 2

Photosynthetic organisms that manufacture organic substances using: light energy, water, CO2 and mineral ions

Question 3

Primary Consumer

Answer 3

Animals that directly eat producers

Question 4

Secondary Consumer

Answer 4

Animals that eat primary consumers

Question 5

Tertiary Consumer

Answer 5

Animals that eat secondary consumers

Question 6

Consumers

Answer 6

Organisms that obtain their energy by feeding on other organisms (rather than directly using sunlight energy)

Question 7

Predators

Answer 7

Usually secondary and tertiary consumers but also scavengers and parasites

Question 8

Scavengers

Answer 8

An organism that consumes decaying biomass eg: meat or plant material

Question 9

Parasites

Answer 9

An organism that obtains nourishment and shelter on another organism
(usually parasites benefit and the host does not)

Question 10

Saprobiont

Answer 10

(decomposers)

Organisms that break down the complex materials in dead organisms into simple ones

Question 11

Food chain

Answer 11

Feeding relationship and each stage in the chain is a trophic level

Question 12

Food web

Answer 12

Very complex link of lots of food chains

Question 13

Fresh mass

biomass

Answer 13

Easy access but presence of water makes it unreliable

Question 14

Dry mass/ carbon

biomass

Answer 14

Overcomes (fresh mass) problem but means killing the organisms so only a small sample can be taken which may not be representative

Question 15

Measuring biomass units

Answer 15

dry mass per given area in a given time

area: gm-2
volume: gm-3

Question 16

Chemical energy store estimated?

Answer 16

using calorimetry

Question 17

Bomb calorimetry

Answer 17

weigh sample of dry material
burn in a sealed chamber (bomb) in pure o2
surrounded by a water bath
heat of combustion = calculate energy released from the mass of burnt biomass
kJkg-1