cycles

Question 1

what is meant by a system?

Answer 1

• a set of interrelated events or components working together
• a system has to contain many components to become a system

Question 2

what are the 2 types of systems?

Answer 2

open system- both energy and matter can enter and leave an open system e.g. in a drainage basin energy from the sun enters and leaves the system, water is the input and output as rive discharge into the sea
closed system- matter cannot enter or leave a closed system- it can only cycle between stores
- energy can enter and leave- it can be input or output e.g. in a carbon cycle energy is input from the sun, from photosynthesis, and output from respiration, but the amount of carbon on earth stays the same because there are no inputs or outputs of matter
isolated systems- these have no interactions with anything outside of the system boundary, there is no input or output of energy or matter

Question 3

what are the main processes a system is made up of?

Answer 3

inputs- when matter or energy is added to the system
outputs- when matter or energy leaves the system
stores- where matter or energy builds up
flows- when matter or energy moves from one store to another
boundaries- the limits of the system

Question 4

what is a dynamic equilibrium?

Answer 4

• when there is a balance between the inputs and outputs in a system
• however, if one of the elements change e.g. one of the inputs increase without any corresponding change in the outputs then the stores change and the equilibrium is upset, this is called feedback

Question 5

what is meant by positive feedback?

Answer 5

• this is when mechanisms amplify the change in inputs and outputs meaning the system responds by increasing the effects of the change, moving the system even further from it’s previous state
  e.g. (1) temperature rises, (2) ice covering cold parts of earth melts due to higher temperature (3) less ice cover means less of the suns energy is reflected (4) less of suns energy being reflected means more is absorbed by the earth

Question 6

what is meant by negative feedback?

Answer 6

• this is when mechanisms counteract the change in the inputs or outputs meaning the system responds by decreasing the effects of the change, keeping the system closer to it’s previous state
  e.g. (1) large amounts of CO2 emitted (2) CO2 in atmosphere increases (3) extra CO2 causes plants to increase growth (4) plants remove and store more CO2 from atmosphere (5) amount of CO2 in atmosphere reduces

Question 7

what are the 4 main cascading systems?

Answer 7

1. atmosphere- clouds are the most visible stores of water
2. lithosphere-
3. hydrosphere
4. biosphere