5.3 Energy and Ecosystems Flashcards
How does energy enter an ecosystem?
via light energy from the sun
What are the 2 uses of glucose in an ecosystem?
storage as starch
convert into any carbon containing compound
How is energy tranferred to the next trophic level?
by chemical energy transferred in biomass
How is energy lost from a system?
heat energy via resp
chemical energy lost to dead organic matter
What are the insoluble parts of an organism?
bones, fur, teeth, hair, feathers
What is the effect of cellulose being indigestable?
primary consumers that eat plants can’t digest the cellulose, so it contributes as faeces in dead organic matter
Why do birds/invertebrates pass on more energy than mammels?
invertebrates and birds are not endotherms so they have a lower rate of resp
Why are herbivores more efficient at energy conversion?
it takes up more energy from the sun to produce meat for a carnivore than to produce plants for a herbivore
What is the max no. of trophic levels in a food chain?
4
What is photosynthetic efficiency?
a measure of how well a plant is able to harvest the light energy and convert it into chemical energy
What are all the ways light is not absorbed into a plant?
absorbed by water
transmitted
reflected
light is the wrong wavelength (green light)
low CO2 conc for photosyn
Why is light absorbed by water on a leaf?
water has a high latent heat of vapourisation for evapouration
Why is some light reflected off a leaf?
thw waxy cuticle
What is GPP?
the total quantity of the chemical energy store in plant biomass in a given area/volume in a given time
What is NPP?
the chemical energy store that is left once resp losses have been accounted for
What is the NPP and GPP equation?
NPP = GPP - R
What is the net production of consumers (N) equation?
N = I - (F + R)
I = chemical energy store of indigested food
F = energy lost in faeces and urine
R = energy lost in resp
What are 2 ways biomass can be measured?
mass of carbon
or dry mass of tissue in an area
How is primary and secondary productivity measured?
the biomass in a given area at a given time
What happens to most of the sugars synthesised by plants?
used as resp substrate
What is biomass?
the total mass of organic material, measured in a specific area over a set time period
What units are used to measure biomass?
g/ m2
What is a method for finding the dry mass of a plant?
heat and weight until a constant mass
Why might it be useful to measure the dry mass of a sample rather than the fresh mass?
fresh mass can fluctuate due to water content fluctuating
What is the equation for calculating the % efficiency of enegy transfer?
amount of biomass transferred / amound of biomass available
x 100
= % efficiency of energy transfer
What is primary producivity?
the rate at which plants or primary producers create new organic matter through photosynthesis
What is secondary productivity?
the rate which consumers (animals) convert chemical energy in their food into their own biomass
Explain why an increase in shoot biomass can be taken as a measurement of net primary productivity
Represents dry mass / mass of carbon
Represents gross production minus respiratory losses
