Productivity

Question 1

gross primary productivity

Answer 1

• the rate at which energy is converted into organic matter in plants
• it is all the organic matter produced in photosynthesis ad is measured in kJ/m2/y

Question 2

biomass

Answer 2

the dry mass of organic matter contained in an organism

Question 3

net primary productivity

Answer 3

• the rate at which organic matter accumulates as plant biomass
• it is the organic matter left over from GPP after some has been used in respiration

Question 4

units for gross primary productivity

Answer 4

kilojoules (kJ) per meter square (m2) per year (y-1)

Question 5

productivity equation for plants

Answer 5

GPP - R = NPP

Question 6

how to work out percentage efficiency of photosynthesis.

Answer 6

GPP / total amount of energy falling on a leaf x 100

Question 7

percentage efficiency of energy transfers between trophic levels

Answer 7

biomass of trophic level / total amount of energy eaten x 100

Question 8

why does some energy fail to get passed on between producers and primary consumers

Answer 8

• not all sunlight energy reaching the leaf is absorbed ;
• some light may be the wrong wavelength
• some may be reflected
• some may miss the chlorophyll
• the chlorophyll may already be saturated with light rays
• a herbivore will only eat some parts of the plant
• the energy may be used by the producer through respiration
• energy may also be lost as heat

Question 9

why does some energy fail to get passed on from primary consumers to secondary consumers

Answer 9

• energy may be lost as heat from respiration
• some biomass of the previous trophic level is indigestible
• excretion of waste from the primary consumer
• some biomass of the primary consumer might be inedible (toxic)