[13.2] energy transfer and productivity Flashcards
1
Q
what percentage of energy is lost between different stages of a food chain?
A
- 97% is lost when plant absorbs sun’s energy
- 90% is lost between producer and primary consmer
- ~80% of biomass is lost between consumers
2
Q
why is only 3% of sunlight converted in chemical energy? [6]
A
- light falls onto non-photosynthetic part of the plant
- light misses the plant and hits the ground
- green light is reflected by the leaves
- only some wavelengths absorbed
- some light passes through the leaf (transmission)
- inefficient conversion of light energy to organic molecules by chlorophyll
3
Q
why are there energy losses between producer and consumer? [4]
A
- not all parts of plant can be eaten
- not all parts can be digested, so lost as faeces
- some energy lost via excretory processes eg. urine
- heat energy losses during consumer’s digestive process
4
Q
what is gross primary production (GPP)?
A
- amount of light energy converted to chemical energy in the biomass in a given area
- unit = kJ m⁻²
- 50% of GPP is lost by plant as heat through respiration
5
Q
what is net primary production (NPP)?
A
- amount of chemical energy left after respiration
- unit = kJ m⁻²
6
Q
what is the equation for NPP?
A
NPP = GPP - R
7
Q
what is net production in consumers (N)?
sometimes called secondary production
A
energy left in animals after it ingests plants and loses energy to faeces / urine and heat through respiration
8
Q
what is the equation for net production in consumers (N)?
A
N = I - (F + R)
- I = ingested chemical energy
- F = chemical energy in faeces and urine
- R = energy lost through heat in respiration
