Unit 5 Energy & Ecosytems

Question 1

Explain how plants utilise sugars from photosynthesis

Answer 1

• Used as respiratory substrates

* Biological molecules( proteins, starch, lipids, cellulose, DNA)

Question 2

What does the biological molecules form

Answer 2

They form the biomass of the plants

Question 3

How is biomass measured & give units

Answer 3

Biomass can be measured in terms of mass of carbon and dry mass of tissue per given area

•remove all water so there’s only Co2 present

to make sure is dry
•dry in oven
•weight until mass is constant

g/kg m(-3) year(-1)

Question 4

Define GPP(gross primary production)

Answer 4

GPP is the chemical energy store in plants biomass giver per area+volume

Basically the total energy from photosynthesis

kJ m(-3) yr(-1)

Question 5

Define NPP(net primary production) and explain How to calculate NPP

Answer 5

NPP is the chemical energy store in plant biomass after respiratory losses to the environment

Basically total energy from photosynthesis-energy lost from respiration

NPP= GPP - R

Question 6

What is the energy left over from the NPP used for

Answer 6

The energy is used to create a new biomass to be used in next tropical level which is each stage of food chain

Question 7

What’s the Net production of consumers(N) and do you calculate it

Answer 7

Is the chemical energy stored in new animal cells

Question 8

How energy is loss and what is used to calculate energy loss in plants and animals

Answer 8

Energy losses occurs due to respiration as heat, excretion in faeces and urine

•In plants GPP / NPP is used
NPP=GPP-R

•In animals Net production for consumers(N) is used
N=I-(F+R)

Question 9

How to calculate Net Production of consumers

Answer 9

N= I - (R + F)

• I is energy store in ingested food
• R is energy lost to environment in faeces and urine
• F is respiratory losses to environment

Question 10

How to calculate %efficiency of net production of consumers

Answer 10

N/I x 100

• N is the net production of consumers
• I is the energy store in ingested food

Question 11

What are the units used for rate of productivity, justify them

Answer 11

kJ ha(-1)/m(-3) year(-1)

• kJ unit used for energy
• ha/m to standardise results so there’s fair comparisons of different environments
• yr because of different seasons so yr to provide annual average to allow fair comparison