B17 - Organising an ecosystem Flashcards
How can feeding relationships be represented, and what do they always start with?
-food chain/web
-always starts with a producer
What do the arrows on a food chain/web represent?
the transfer of biomass/energy
What are producers?
photosynthetic organisms (plants/algae) that synthesise glucose molecules from PS to produce the biomass for all the life on earth
How do algae get energy?
from light that is absorbed by its chloroplasts
What are the types of consumers?
-primary (eats producer)
-secondary (eats primary)
-tertiary (eats secondary)
(top is apex predator)
What is a predator/prey?
-predators hunt + eat other animals
-prey are eaten by predators
Describe the cyclic relationship between the populations of predators and prey:
-food availability increases, prey increases (grows and reproduces successfully)
-more food for predators, predators increase
-prey decreases because they get eaten, less food for predators so they decrease too
-less predation, so the prey population increases again
-repeat
What is a problem that a primary consumer might have with their food?
-must use a variety of methods to digest cellulose which is hard to do
-needs to find/eat enough food to get nutrients
What is a problem that a higher consumer (secondary/tertiary) might have with getting food?
must hunt the prey because they move around, but it is good because they are high in protein/fat
What gets recycled in an ecosystem, and why is it important?
-chemical abiotic factors (water, carbon) gets cycled through other abiotic and biotic factors in an ecosystem
-important as it provides the building blocks for future organisms
Why is the water cycle important?
continuously provides fresh water for animals/plants on land before draining into the sea again
What are the main processes that occur during the water cycle?
-evaporation/transpiration/respiration
-condensation
-precipitation
-runoff (surface/river)
(E, CPR)
What is a carbon sink? Give some examples:
-a “locked up” store of carbon that absorbs more CO₂ than it can release
-carbonate-based rocks (limestone)
-oceans (CO₂ dissolved in it)
-fossil fuels
-atmosphere
-peat bogs
Why is the carbon cycle important?
it returns carbon from organisms to the atmosphere as CO₂ which can then be used by plants for PS, which produce the biomass for all life on Earth
Describe the full process of the carbon cycle:
-plants take in CO₂ from the atmosphere for PS
-plants eaten by primary consumers that both respire
-plants + consumers die/produce waste
(2 paths after)
-either decomposed, returns CO₂ to atm. (by resp.) and releases mineral ions to soil
-or it is fossilised and forms fossil fuels which are combusted, releasing the carbon back into the atm.
What role do microorganisms have in an ecosystem?
they cycle materials through an ecosystem by returning carbon to the atmosphere as CO₂, and mineral ions to the soil
What factors affect the rate of decomposition?
-temperature (enzymes)
-moisture (microorganisms grow faster)
-oxygen (for resp.)
-presence of decomposers (more = ^rate)
What happens if decay occurs without oxygen, and what can it be used for?
-slower anaerobic decay, which produces methane gas
-process can be done in a biogas generator for fuel
How is compost made and what is it used for?
-food/garden waste is decomposed (gardener’s try to ensure optimum conditions for the process)
-natural fertiliser for growing garden plants/crops
How can the distribution of species in an ecosystem be affected?
-environmental changes in temperature, water availability, and atmospheric gas composition
-these changes may be seasonal, geographical, or caused by human interaction
An example of how composition of gases affects the ecosystem is with lichen - it doesn’t grow as much in areas which have lots of air pollution
RP10 - How would you prepare the apparatus for investigating the effect of temperature on the rate of milk decay?
-add lipase to labeled boiling tube
-add Cresol red to another boiling tube then add milk and label it
-add sodium carbonate to the milk tube (should make it purple)
-put both milk and lipase tubes into water bath and allow temperatures to equilibrate
RP10 - Using the previously made test tubes in the water bath, how would you use them to find the effect of temperature on the rate of decay?
-use pipette to transfer 1cm^3 lipase to the milk and start timing
-record time for colour change of purple to yellow
-repeat experiment for at least 5 temperatures
-plot graph of time taken vs temperature
The lipase accelerates the decay of the milk
Remember the practical where you asked for a reference colour to compare to the yellow solution
RP10 - Explain the reason for the colour change in the milk decay experiment:
-lipids in milk are broken down into fatty acids by lipase
-the fatty acids decrease the pH
-the Cresol red indicator turns from purple to yellow (more acidic)
The original colour of purple is from the sodium carbonate solution added, which makes the solution more alkaline