5.3 Energy and Ecosystems Flashcards
What is biomass?
The total amount of dry mass in an organism
What is another name for a producer? Definition?
Autotroph
Manufactures organic substances using light energy, water and CO2
What is another name for a consumer? Definition?
Heterotroph
Obtain their energy by consuming other organisms rather than using the energy of the sunlight directly
What is another name for a decomposer? Definition?
Saprobiotic organism
When producers and consumers die, the energy they contain can be used by decomposers that break down these complex materials into simple components again
What are detritivores?
Distinguishable from decomposers as they cannot digest as many complex chemical molecules as bacteria and fungi
Eg - millipedes, woodlice and worms
What is a food chain?
It describes the feeding relationship in which the producers are eaten by primary consumers then secondary and tertiary consumers
What is trophic level?
Each stage in the food chain
How can dry biomass be found?
Use a balance to find the mass
Heat it up to evaporate the water
Once all the water has evaporated the mass stops decreasing
Why do food chains rarely have more than 5 trophic levels?
Insufficient energy is available to support a large enough breeding population at trophic levels higher than these
Due to energy lost and less biomass available
Why does only 1-3% of energy from the sun form plant biomass?
The sunlight doesn’t hit the leaf
It’s not the right wavelength to absorb
90% reflected back into space
Low CO2 could limit the rate of photosynthesis
Why is only 5-10% of energy in plant tissues passed on to primary consumers?
Some of the organism isn’t consumed
Not all parts of the plant material can be digested (cellulose) and it is lost in faeces
Energy is lost in excretory materials
Energy lost as heat from respiration
Why is only 10-20% of energy in primary consumers passed on to secondary consumers?
Some of the organism isn’t consumed
Little biomass is available
Energy is lost in excretory materials
Energy lost as heat from respiration
What is significant about energy lost as heat in respiration?
The loss is higher in mammals and birds due to a high body temperature- as more energy is needed to maintain their high body temperature
Why are primary consumers less efficient than secondary consumers at converting energy stored in the previous trophic levels?
Primary consumers excrete more and lose more energy
Whereas secondary consumers need to hunt and lose their energy through respiration
What is the equation for primary production?
NPP = GPP - R
NPP - Net primary production
GPP - Gross Primary production
R - Respiratory losses
