Energy and ecosystems 5.3

Question 1

What is the definition of an ecosystem?

Answer 1

The community and the non-living components of its environments

Question 2

How does energy enter an ecosystem? What is it converted into?

Answer 2

-Uses light energy and carbon dioxide
-Photosynthessis synthesises organic compounds eg glucose
-Energy is stored in the organic compounds

Question 3

What is biomass?

Answer 3

The mass of organic molecules

Question 4

What are the two ways biomas can be presented as?

Answer 4

Dry biomass - mass of organic material with water removed because water content can vary
Mass of carbon

Question 5

How do you measure dry biomass?

Answer 5

Heat grass in oven to evaporate water at 95’C
Measure mass of grass
Repeat heating and weighing untill mass becomes constant

Question 6

What are example units of biomass?

Answer 6

Area per unit per time eg KJM-2year-1

Question 7

What is the process of calorimetry?

Answer 7

Estimates energy in biomass in joules
-The sample of living tissue is burnt in a combustion chamber
-Heat energy is transferred to a known volume of water surrounding the tissue
-The increase of temperature of water is measured and used to calculate chemical energy in the biomass

Question 8

What is the equation to calculate energy released from a sample during calorimetry?

Answer 8

Energy released (J) = volume of water x temperature increase x specific heat capacity of water (4.2J)

Question 9

What is GPP

Answer 9

The chemical energy stored in plant biomass in a given area or time eg KJ M-2 Year -1

Question 10

What is NPP

Answer 10

The chemical energy stored as plant biomass after respiration losses in a given area or time eg KJ M-2 year -1

Question 11

What is NPP

Answer 11

Chemical energy store in plant biomass after respiratory losses
Energy available for plant growth and reproduction
Energy available to next tropic level
10% npp transferred to consumer

Question 12

How is energy lost between trophic levels

Answer 12

-heat
-egestion and excretion faeces and urine
-not all organism eaten - cellulose difficult to digest so less is absorbed

Question 13

How to calculate npp

Answer 13

Npp = gap -respiratory losses

Question 14

Calculation for net production of consumers (N)

Answer 14

N = I - (f+r)
I - ingested (chemical enrgy in ingested food)
F energy lost in faeces and urine
R energy lost in respiration

Question 15

What is N

Answer 15

Chemical energy stored as biomass in the a consumer available to next trophic level