5.3 Energy and Ecosystems

Question 1

explain how farming practises increase the produtivity of agricultural crops (6)

Answer 1

fertilisers added to soil
fertilisers contain phosphate for ATP

ploughing soil allows nitrification

selective breeding of crops for more favourable charachteristics

greenhouses enchaces temp/co2/light

pesticides/weed killers remove competition

Question 2

suggests how you can determine the dry mass of a sample of a plant (2)

Answer 2

heat to 100 to evaporate water
weigh and heat until no further change in mass

Question 3

what is the advantage of using dry mass and not fresh mass to compare the yield of plants (2)

Answer 3

ammount of water present may vary
will affect fresh mass not dry mass as no water in dry mass

Question 4

Gross primary production (GPP)

Answer 4

total chemical energy store in a given volume of plant at a given time

KJ m yr

Question 5

net primary production

Answer 5

NPP = GPP - R

R = respiration

Question 6

Net production

Answer 6

N= I (F+R)
I - chemical energy
F - energy loss in faecaes
R - resp loss