practice 4 mark questions Flashcards
Explain the concept of negative feedback within the carbon cycle.
Feedback is an important aspect of systems and their tendency towards dynamic equilibrium (1).
Negative feedback nullifies / returns a system towards equilibrium (1) and counteracts the impact of earlier changes in the system (1) (d)
For example, increased atmospheric CO2 leads to both warmer temperatures and availability of CO2 for uptake by plants (1).
This promotes increased photosynthesis rates and carbon capture/storage by plants (1) (d),
reducing the carbon levels back to state of balance (1) (d).
Outline an example of positive feedback in the water cycle.
Higher temperatures increase the melting of snow and ice (1) leading to a reduction of surface albedo (1)
As such, more sunlight is absorbed by the land and sea.
Temperatures further increase which leads to further melting
Release of carbon leads to global warming
Global warming and increase in temperatures leads to melting of permafrost (Siberia)
This leads to the release of methane (x20) and further heats up the atmosphere.
This leads to more rapid heating and melting
Explain the role of cryosheric change in the water cycle.
In the cryosphere, accumulation and ablation change the amount of water stored as ice in the cryosphere therefore changing the water cycle, these processes and the balance between them are affected by temperature.
During periods of global cold temperatures, inputs into the cryosphere in the form of ice are greater than outputs, water is imputed into the system as snow and less water is transferred away due to melting therefore reducing the level of water in the water cycle and storing it in the cryosphere.
Outline the role of living organisms in the carbon cycle. (4 Marks)
Living organisms contribute massively to the functionality of the carbon cycle, photosynthesis is a key flow within the carbon cycle and within it, plants transfer carbon stored in the atmosphere into biomass.
Decomposition affects all living things within the biosphere also transferring carbon from dead biomass into the atmosphere and the soil which is then broken down by fungi outlining how living organisms can accelerate elements of the biomass.
Living organisms also contribute to the carbon cycle as phytoplankton fall through the oceanic shelves onto the seabed after death eventually forming part of the lithosphere through tectonic action.
Outline how changes to the carbon cycle can affect the oceans. (4 Marks)
Within the carbon cycle, carbon dioxide is dissolved directly into the oceans from the atmosphere, carbon dioxide within the oceans is used by organisms such as phytoplankton and seaweed during photosynthesis and by other marine organisms to form calcium carbonate shells and skeletons.
Increases in the CO2 levels of the atmosphere affect the oceans by increasing its acidity which can impact marine life also.
Global warming also affects oceans, organisms which cannot survive temperature increases will die in higher temperatures meaning less CO2 is used by them and less carbon is removed from the atmosphere.
Outline the impact of long-term global temperature changes on the water cycle. (4 Marks)
Global temperature changes alter the volume of water stored in the various stores of water within the water cycle.
Temperature increases will lead to a reduction of the level of water stored in the cryosphere and an increase in the amount stored in the hydrosphere and atmosphere whilst also reducing the level of water stored in the lithosphere as evaporation rates increase therefore reducing the amount of water which infiltrates the topsoil.
This process works in vice versa also as periods of global cooling increase the cryosphere water stores and decrease the amount of water within the hydrosphere store.
Outline seasonal changes in the water balance. (4 Marks)
The water balance is worked out from input (Precipitation and outputs (Channel discharge and evapotranspiration) and it impacts the amount of water which is stored in the basin.
The UK follows seasonal patterns. In wet seasons, precipitation exceeds evapotranspiration leading to a water surplus, ground stored fill with water leading to surface runoff and higher river discharge.
In drier seasons, evapotranspiration is greater than precipitation, ground stores are depleted and there is a deficit of water supply in the ground.
Outline the differences between open and closed systems. (4 Marks)
In open systems, both matter and energy can enter and leave meaning they are inputs and outputs of both; an example of this is a river drainage basin.
Conversely, in closed systems matter cannot enter or leave meaning it is fixed however energy still can leave or enter the system, it is dynamic - An example of a closed system this is the carbon cycle.
Explain how a positive feedback can alter a natural system. (4 Marks)
Positive feedback are cycles which enhance the affect which gave rise to them, an example is global warming as temperatures rise, more carbon dioxide is released, enhancing the greenhouse affect and leading to further global warming.
They can significantly alter a natural system,
The primary impact of positive feedback loops is that they can enhance the system from its previous state.
Explain the role of cryospheric change in the water cycle. (4 Marks)
In the cryosphere, accumulation and ablation change the amount of water stored as ice in the cryosphere therefore changing the water cycle, these processes and the balance between them are affected by temperature.
During periods of global cold temperatures, inputs into the cryosphere in the form of ice are greater than outputs, water is imputed into the system as snow and less water is transferred away due to melting therefore reducing the level of water in the water cycle and storing it in the cryosphere.
Outline flows within the water cycle operating on a hill slope. (4 Marks)
On a hill slope infiltration occurs which is the action of the water soaking into the soil, infiltration rates are influenced by soil type, a soil with a high clay content will absorb less water whilst a soil with a high sand content will allow more soil to infiltrate, the amount of soil already soaked into their soil impacts this process also in relation to the water table.
Surface run-off will also occur and is simply the movement of water over land and it can flow over the whole surface or in channels and this process occurs because water is falling as precipitation faster than it can be absorbed.
Outline the process of decomposition in the carbon cycle. (4 Marks)
Decomposition transfers carbon from dead biomass in the biosphere to the atmosphere in the form of methane and carbon dioxide gas releases and into the soil as nutrients.
After the initial decomposition of the living organism into the soil, fungi break down the organisms which is where the gases are released.
Some carbon is also tranferred into the soil in the form of humus.
