Energy And Ecosystems

Question 1

What is net primary production

Answer 1

Amount of energy / biomass that the animal has for growth

Question 2

What is GPP

Answer 2

Total amount of energy an animal consumes

Question 3

Equation linking GPP, NPP and R

Answer 3

NPP = GPP-R

Question 4

What is R

Answer 4

Respiratory losses

Question 5

How to work out dry biomass

Answer 5

• heat biological material In an oven at 103°C
• this will evaporate any water
• weigh to find the mass
• repeat process until mass remains constant

Question 6

How to calculate % efficiency energy transfer between organisms

Answer 6

Energy in trophic level after transfer / energy in previous trophic level (before transfer) x 100

Question 7

How to calculate net production of consumers

Answer 7

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

Question 8

Why is only a small percentage of light energy transferred to the next organism

Answer 8

• reflected back into space / the atmosphere
• not all wavelengths of light absorbed
• light might not fall on the chlorophyll molecule
• other factors (such as limited CO2)

Question 9

How to work out NPP

Answer 9

GPP-(R + U + F)
U= organic matter lost in urine (excretion)
F= organic matter lost in faeces (egestionj

Question 10

Why is only a small percentage of energy passed onto the next organism

Answer 10

• energy lost to environment as heat in respiration
• not all of the organisms are consumed
• some parts that can be consumed are not digested- lost as faeces
• some energy lost in urine
• energy used by mammals + birds to maintain body temp

Question 11

Why is it favourable to keep cattle in barns

Answer 11

• maintain body temp
• less energy used
• more energy transferred

Question 12

Use of calorimetry

Answer 12

Estimate chemical energy stored in biomass

Question 13

Explain how calorimetery works

Answer 13

• burning a sample of dry biomass (of known mass) in the calorimeter
• this combustion causes the stored energy to be released as heat, raising the temperature of the water
• the change in temperature of the water provides an estimate of the chemical energy in the sample

Question 14

How does calorimetrey enable valid measurements of the total heat energy released

Answer 14

• water has a high SHC
• stirrer distributes heat energy
• air insulates, preventing heat loss