Component 1.5 - Energy And Ecosystems Flashcards
What is an ecosystem?
A characteristic community of interdependent species interacting with the abiotic components of their habitat
Where does the energy come from to support ecosystems?
- Mainly from the sun incorporated by photosynthesis
- Chemical reactions incorporated in chemosynthesis e.g in hydrothermal vents
What is a meant by a community?
Interacting populations of two or more species in the same habitat at the time
What is a trophic level?
Feeding level - the number of times that energy has been transferred between the sun and successive organisms along a food chain
What are saprobiants?
A micro-organism that obtains its food from the dead or decaying remains of other organisms
What are decomposers and detrivores?
Detrivores- organisms which feed on small fragments of organic debris (detritus) e.g fallen leaves and remains of dead organisms
Decomposers - microbes such as bacteria that obtain nutrients from dead organisms and animal waste (complete process of decomposition started by detrivores)
Why is a food chain limited to 4 or 5 trophic levels?
After 4 or 5 trophic levels, there is not enough energy energy to support another one
Why are tropical food chains usually longer than arctic ones?
In tropical environments more energy is fixed in photosynthesis, so more energy can be passed on to the next trophic level.
What is the formula for photosynthetic efficiency?
PE = Quantity of light energy incorporated into product/Quantity of energy falling on the plant x100
Why may the light that falls on the plant not be absorbed?
1) Wrong wavelength
2) Reflected
3) Transmitted straight through the leaf
What is Gross Primary Productivity and Production?
The rate of production of chemical energy in organic chemicals by photosynthesis measured in kJ m^-2 y^-1
Gross primary production which is the total energy incorporated in photosynthesis is 0.2% of global sunlight energy
What is net primary productivity and production?
The rate at which energy is incorporated into a plants biomass and made available to heterotrophs measured in kJ m^-2 y^-1
Net primary production which is the total chemical energy made available to heterotrophs is 0.1% of global sunlight energy
How do you work out Net primary production from Gross primary production?
GPP - respiration = NPP
Why do crop plants have a higher GPP and NPP?
Because they have been selectively bred for high productivity (PE)
What is Primary productivity?
The rate at which energy is converted by producers to biomass
What is secondary productivity?
The rate at which consumers convert the chemical energy of their food into biomass
How is energy lost from the food chain?
1) Excretion or egestion
2) Respiration and muscle contraction (heat)
3) Energy remains in molecules in parts of animal that have not been eaten e.g fur and bones
What are limitations of the pyramid of number?
- It does not take into account size of organisms
- Does not recognise the difference between juvenile and adult forms
- May be difficult to draw to scale
- Pyramid may be inverted
What are the limitations of the pyramids of biomass?
- Difficult to accurately measure (e.g plants roots)
- May be inverted
- May seem to contribute more to the next trophic level e.g bones and beaks
What is a pyramid of energy?
- As energy is passed from one level to the next, some is lost and the bars decrease in size - never inverted
Why is a pyramid of energy the most accurate way of representing feeding relationships?
- Make it easy to compare efficiency of energy transfer between trophic levels in different communities
- Shows energy transferred from one level to the next, per unit area of volume, per unit time.
Define habitat
The place in which an organism lives
Why are farm animals often kept in smaller spaces?
1) Factory farms more efficient as less energy is lost
2) Reduces energy losses via respiration by controlling the temperature as less energy needed to maintain body temperature
3) Animals are stocked at high densities which restricts movement so reduces energy loss via respiration for muscle contraction
4) Herbivores are lower down the food chain than carnivores so less energy is lost via respiration or being expelled
