Organisation of an ecosystem (7.2) (M) Flashcards
What is the role of photosynthetic organisms on Earth?
the producers of biomass for life on Earth
Feeding relationships within a community can be represented by what?
food chains
What do food chains always begin with?
a producer which synthesises molecules
2 needed
What organisms are commonly producers? How do they contribute to the food chain?
green plant or alga
they make glucose by photosynthesis
Techniques such as quadrats and transects are used by ecologists to do what?
to determine the distribution and abundance of species in an ecosystem (by sampling)
Describe the levels of the food chain starting from a producer?
Producers are eaten by primary consumers, which in turn may be eaten by secondary consumers and then tertiary consumers
What are predators?
Consumers that kill and eat other animals
What are prey?
consumers that are eaten
In a stable community, what is the relation between the numbers of predators and prey?
the numbers of predators and prey rise and fall in cycles
Why is sampling carried out?
counting all of the individuals of a species can be difficult and time consuming
What is most important when using sampling?
sampling should be representative of the whole area
3 needed
What are the biotic factors that could affect distribution?
- trampling by humans
- grazing by sheep
- competition
4 needed
What are the abiotic factors that could affect distribution?
- pH
- light intensity
- distance to stream
- application of fertiliser/weedkiller
What do many different materials cycle through in an ecosystem?
many different materials cycle through the abiotic and biotic components of an ecosystem
Why are all materials in the living world recycled?
to provide the building blocks for future organisms
What does the carbon cycle do?
returns carbon from organisms to the atmosphere as carbon dioxide to be used by plants in photosynthesis
How do microorganisms contribute to the carbon cycle?
Respiration by microorganisms decays dead plants and animals. releasing carbon dioxide.
This carbon dioxide can be used by plants in photosynthesis to make new biological molecules (carbohydrates, proteins and fats)
When is carbon returned to the atmosphere?
when living organisms respire giving off carbon dioxide
Water is continuously..
evaporated and precipitated
What does the water cycle do?
provides fresh water for plants and animals on land before draining into the seas as water is continuously evaporated and precipitated
How are mineral ions returned to the soil from animals and plants?
mineral ions are returned to the soil from dead animals and plant material when microorganisms break the dead material down
What is decomposition?
The process of breaking down material
3 needed
Which factors affect the rate of decay of biological material?
- temperature
- availability of oxygen
- water level
How does temperature affect the rate of decay of biological material? (and how/why?)
Increases it
An increased temperature causes faster reactions (e.g. respiration)
or increased rate of enzyme action
How does the availability of oxygen affect the rate of decay?
Increases it
Oxygen needed for aerobic respiration (and used to release energy)
Gardeners and farmers try to provide what for decomposition?
optimum conditions for rapid decay of waste biological material
What is the compost produced from decomposition used as?
a natural fertiliser for growing garden plants or crops
What does anaerobic decay produce?
methane gas
What are biogas generators used to do?
to produce methane gas as a fuel
What would the fastest rate of decay indicate for that temperature?
It is at or near the optimum temperature
Why might a farmer spread dead plant material onto his field?
Dead plant material contains nitrate ions
which leads to faster growth
2 needed
Which microorganisms decay dead plant/animal material?
bacteria
fungi
4 points
What role do producers play in the ecosystem?
Synthesise molecules/produce glucose by photosynthesis
Using light energy from the sun
and make carbon dioxide and water
and produce biomass for primary consumers
6 marks
Describe the carbon cycle
- Photosynthesis by green plants / algae
- Removes CO2 from atmosphere
- To make glucose
- Animals eat plants
- which transfers carbon compounds to them
- Both plants and animals respire, releasing CO2 back into the atmosphere
- When plants and animals die
- The carbon compounds in their bodies are released as CO2
- When microorganisms break down their bodies
- and respire
What is a consequence to the living world of substances such as carbon not being recycled?
There would eventually be no building blocks for future organisms to build their bodies with
as there is a finite amount of molecules on Earth
Why would a biogas generator produce more carbon dioxide over time when air is present?
Oxygen in air, which allows microorganism to respire aerobically, releasing carbon dioxide
What role do microorganisms play in cycling nutrients through an ecosystem?
Return carbon to atmosphere as CO2 when they respire
and release mineral ions into the soil
by process of decomposition
How does water affect the rate of decay?
Many decomposers secrete enzymes onto decaying matter and then absorb any dissolved molecules. Without water these reactions cannot occur
likely removed content
6 marks - VERY important to learn
Describe the carbon cycle
- (green) plants photosynthesise
- photosynthesis takes in carbon dioxide
- (green) plants use carbon to make carbohydrate / protein / fat / organic compounds / named (e.g. enzymes / cellulose)
- animals eat (green) plants (and other animals)
- (green) plants respire
- animals respire
- respiration releases carbon dioxide
- (green) plants and animals die
- microorganisms decay / decompose / rot / break down / feed on dead organisms
- microorganisms respire
5 marks
A large amount of untreated sewage containing organic matter and bacteria entered the river. Many fish died, explain why.
bacteria decay organic matter
by digestion
bacteria respire aerobically
which lowers oxygen concentration (in water)
reduced energy supply causes death of fish
A disease kills many of the (primary consumers). Why does the number of (producers) increase?
Fewer are eaten
Why would a lower volume of biogas produced be lower at a lower temperature?
enzymes are denatured
so won’t work (as efficiently)
How would limiting animals movement make food producing more efficient?
reduces energy transfer
How would limiting animals movement make food producing more efficient?
reduces energy transfer
Why might decomposition stop?
all dead plant/animal material decayed/decomposed
