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Mark Scheme Q1.

Indicative Content Mark

QWC * A explanation including some of the following points Light dependent resistors (LDR)

Resistance changes with light intensity

Bright light , low resistance

No light (dark), high resistance

Low resistance gives high current.(RA) Thermistor

Resistance changes with temperature

Negative temperature coefficient

High temperature, low resistance

Low temperature, high resistance

Low resistance gives high current (RA) (6)

Level 0 No rewardable content

1 1 - 2

a limited explanation linking light affecting LDR AND heat affecting thermistor OR a correct relationship for one device, e.g. thermistors change resistance when the temperature changes and LDRs change resistance when it gets dark OR the resistance decreases/ current increases of a LDR when the light gets brighter

the answer communicates ideas using simple language and uses limited scientific terminology

spelling, punctuation and grammar are used with limited accuracy

2 3 - 4

a simple explanation correctly linking the temperature and light with resistance or current for both devices OR a correct relationship for one device with a link to the way this affects the current and resistance. e.g. the resistance of a LDR increases when the light gets dimmer and when the temperature lowers the resistance of a thermistor increases OR the resistance of a LDR decreases when the light gets brighter and this increases the current

the answer communicates ideas showing some evidence of clarity and organisation and uses scientific terminology appropriately

spelling, punctuation and grammar are used with some accuracy

3 5 - 6

a detailed explanation including the qualitative relationships for both devices and a link to the way resistance change affects the current in BOTH of them, e.g. the resistance of a LDR is less when the light gets brighter which increases the current. When the temperature lowers the resistance of a thermistor increases. This means that the current will decrease as the thermistor cools down.

the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately

spelling, punctuation and grammar are used with few errors

Q2.


QWC

* An explanation including some of the following ideas Need for measurement (N)Background radiation

is always present/all around us

has (natural) source(s) exemplified by space, living things, rocks, food, nuclear/medical sources etc.

would give false reading in experiment How and why to measure(H) Background radiation measurement

is taken at site of experiment because it is different in different places

is taken with all apparatus except source in place

is taken before and after because it can change with time / they need an average

must be worked out for same time as (or longer than) experiment / rate found so analysis is simpler

It is taken several times/ averaged because it is random Analysis (A) Background radiation measurement

must be subtracted from measurements with source /main count rate

(6)

Level

0 No rewardable content

2 3 - 4

A simple explanation linking aspects of two ideas i.e. N + H OR N + A OR H + A e.g Take readings without source (H) and subtract them from the main readings with source present.(A) OR It should be taken several times because it is random (H)so that the average can be subtracted from the main readings (A)



3 5 - 6

A detailed explanation linking A with EITHER N + an idea from H OR two or more ideas from H e.g.Background radiation is there all the time. (N) You need to take readings at the place where you will do the experiment and with all the apparatus set up except the source because BR changes from place to place.(H) Then you should subtract background readings from the main experimental readings.(A) OR Take several readings of count rate for averaging since the effect is random (H) and make sure that they are taken in the same place.(H) Then subtract from readings in main experiment.(A)



Q5.

Question Number


QWC * An explanation linking some of the following points Either momentum • item must lose momentum in order to come to rest • force of impact depends on rate of change of momentum • if item is dropped from greater height then velocity at impact is greater • so momentum to be lost is greater • bubble wrap works by increasing the time taken for the item to come to rest • reduces the rate of change of momentum • this reduces the force of impact to a safe value Or kinetic energy • item must lose kinetic energy in order to come to rest • force of impact depends on work done • if item is dropped from greater height then velocity at impact is greater • so kinetic energy to be lost is greater • loss of kinetic energy equals work done bringing item to rest • bubble wrap works by increasing the distance travelled for the item to come to rest • this reduces the force of impact to a safe value (6)


1 1 - 2 • a limited explanation of the cushioning effect e.g. bubble wrap reduces the force of impact • the answer communicates ideas using simple language and uses limited scientific terminology • spelling, punctuation and grammar are used with limited accuracy

2 3 - 4 • some explanation linking cushioning effect with either increased time of impact or increased distance of impact e.g. bubble wrap reduces the force of impact by increasing the time of impact • the answer communicates ideas showing some evidence of clarity and organisation and uses scientific terminology appropriately • spelling, punctuation and grammar are used with some accuracy

3 5 - 6 • a detailed explanation linking either force with rate of change in momentum or energy with work done and distance e.g. the bubble wrap increases the time of impact which reduces the rate of change of momentum which reduces the force of impact • the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately • spelling, punctuation and grammar are used with few errors

Q6.

Question Number


QWC * A description including some of the following stages Fission• absorption of slow moving / thermal neutron by U-235 • to produce daughter nuclei, two or more neutrons and two or more neutrons and Controlled chain reaction• use of moderators to produce thermal neutrons • use of control rods to capture neutrons • idea of keeping number of further fissions to just over one per fission reaction Energy transfer• (kinetic) energy (of fission products) is converted to thermal energy • use of coolant to transfer the thermal energy (from the reactor vessel to a heat exchanger) to produce steam • use of steam to drive a turbine • use of turbine to drive a generator / produce electricity (6)


1 1 - 2 • a limited description e.g. heat from the reactor makes steam for the turbine • the answer communicates ideas using simple language and uses limited scientific terminology • spelling, punctuation and grammar are used with limited accuracy

2 3 - 4 • some description including some points from all three stages or most points from any two stages • the answer communicates ideas showing some evidence of clarity and organisation and uses scientific terminology appropriately • spelling, punctuation and grammar are used with some accuracy

3 5 - 6 • a a detailed description including most points from all three stages: fission, controlled chain reaction and energy transfer • the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately • spelling, punctuation and grammar are used with few errors

Q8.


* An explanation linking some of the following points

kinetic energy varies during swing

kinetic energy maximum at bottom of swing

kinetic energy minimum at top of swing

gravitational potential energy(gpe) varies during swing

gpe maximum at top of swing

gpe minimum at bottom of swing

(continuous) interchange of KE and gpe

total amount of energy is constant during one swing

over a number of swings max KE and max PE decreases

energy is dissipated/'lost' to surroundings

because of air resistance / friction

amplitude/size of swings decrease ( as energy 'lost' to surroundings) ignore references to momentum

(6)

Level Mark Descriptor


1 1 - 2

a limited explanation which states some facts e.g. (max) Kinetic energy decreases over time. KE will transfer to GPE. or KE increases and decreases over one swing. The height which the swing reaches gets less over time.



2 3 - 4

a simple explanation with links between facts; either over one period of oscillation or over several periods of oscillations. Kinetic energy decreases as he gets higher and the GPE increases. There is a continuous interchange of KE and gpe as he swings. or KE is gradually transferred to heat so swing rises to a slightly lower height each time.



3 5 - 6

a detailed explanation with links between facts over one period of oscillation and over several periods of oscillations e.g. kinetic energy is at a maximum at bottom of swing There is a continuous interchange of KE and gpe. KE (and gpe) reduce over a number of swings as energy is dissipated to the surroundings due to friction.



Q9.


A explanation including some of the following points Light dependent resistors (LDR)

Resistance changes with light intensity

Bright light , low resistance

No light (dark), high resistance

Low resistance gives high current.(RA) Thermistor

Resistance changes with temperature

Negative temperature coefficient

High temperature, low resistance

Low temperature, high resistance

Low resistance gives high current (RA) (6)


1 1 - 2

a limited explanation linking light affecting LDR AND heat affecting thermistor OR a correct relationship for one device, e.g. thermistors change resistance when the temperature changes and LDRs change resistance when it gets dark OR the resistance decreases/ current increases of a LDR when the light gets brighter



2 3 - 4

a simple explanation correctly linking the temperature and light with resistance or current for both devices OR a correct relationship for one device with a link to the way this affects the current and resistance. e.g. the resistance of a LDR increases when the light gets dimmer and when the temperature lowers the resistance of a thermistor increases OR the resistance of a LDR decreases when the light gets brighter and this increases the current



3 5 - 6

a detailed explanation including the qualitative relationships for both devices and a link to the way resistance change affects the current in BOTH of them, e.g. the resistance of a LDR is less when the light gets brighter which increases the current. When the temperature lowers the resistance of a thermistor increases. This means that the current will decrease as the thermistor cools down.



Q10.

Question Number


QWC * An explanation linking some of the following points Either momentum • item must lose momentum in order to come to rest • force of impact depends on rate of change of momentum • if item is dropped from greater height then velocity at impact is greater • so momentum to be lost is greater • bubble wrap works by increasing the time taken for the item to come to rest • reduces the rate of change of momentum • this reduces the force of impact to a safe value Or kinetic energy • item must lose kinetic energy in order to come to rest • force of impact depends on work done • if item is dropped from greater height then velocity at impact is greater • so kinetic energy to be lost is greater • loss of kinetic energy equals work done bringing item to rest • bubble wrap works by increasing the distance travelled for the item to come to rest • this reduces the force of impact to a safe value (6)


1 1 - 2 • a limited explanation of the cushioning effect e.g. bubble wrap reduces the force of impact • the answer communicates ideas using simple language and uses limited scientific terminology • spelling, punctuation and grammar are used with limited accuracy

2 3 - 4 • some explanation linking cushioning effect with either increased time of impact or increased distance of impact e.g. bubble wrap reduces the force of impact by increasing the time of impact • the answer communicates ideas showing some evidence of clarity and organisation and uses scientific terminology appropriately • spelling, punctuation and grammar are used with some accuracy

3 5 - 6 • a detailed explanation linking either force with rate of change in momentum or energy with work done and distance e.g. the bubble wrap increases the time of impact which reduces the rate of change of momentum which reduces the force of impact • the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately • spelling, punctuation and grammar are used with few errors

Q11.


* A explanation including some of the following points

drops near the top are accelerating

due to force of gravity

travel a greater distance in given time

there is air resistance on the drops as they fall

this increases with velocity

resultant force is downward

this reduces resultant force

eventually resultant force is zero

drops have reached terminal/ maximum velocity

drops near bottom are all travelling at terminal velocity

so travel same distance in given time

(6)


1 1 - 2

a limited explanation such as one which correctly addresses either why the drops at the bottom are evenly spaced or why the drops at the top are not e.g. drops at bottom are all going at the same speed OR drops at top are speeding up



2 3 - 4

a simple explanation such as a correct comparison of the motion of the drops at top and bottom e.g. drops at bottom are travelling at terminal velocity whereas drops at top are still accelerating. Or a complete explanation of motion at either top or bottom e.g.at the bottom, air resistance and gravity forces are balanced so they travel at constant speed



3 5 - 6

a detailed explanation such as one which explains why the motion of the drops at top and bottom are different e.g. The drops were initially accelerating due to a resultant force downwards. The acceleration decreased as they fell and eventually reached zero. With no acceleration their velocity was constant and so equal distance travelled in given time at the bottom.



Q12.


* A explanation including some of the following points

drops near the top are accelerating

due to force of gravity

travel a greater distance in given time

there is air resistance on the drops as they fall

this increases with velocity

resultant force is downward

this reduces resultant force

eventually resultant force is zero

drops have reached terminal/ maximum velocity

drops near bottom are all travelling at terminal velocity

so travel same distance in given time

(6)


1 1 - 2

a limited explanation such as one which correctly addresses either why the drops at the bottom are evenly spaced or why the drops at the top are not e.g. drops at bottom are all going at the same speed OR drops at top are speeding up



2 3 - 4

a simple explanation such as a correct comparison of the motion of the drops at top and bottom e.g. drops at bottom are travelling at terminal velocity whereas drops at top are still accelerating. Or a complete explanation of motion at either top or bottom e.g.at the bottom, air resistance and gravity forces are balanced so they travel at constant speed



3 5 - 6

a detailed explanation such as one which explains why the motion of the drops at top and bottom are different e.g. The drops were initially accelerating due to a resultant force downwards. The acceleration decreased as they fell and eventually reached zero. With no acceleration their velocity was constant and so equal distance travelled in given time at the bottom.



Q13.

Question Number

Indicative content Mark

* QWC

an explanation including some one of the following: • distinguishes clearly between fission (splitting large nuclei) and fusion (joining - small nuclei) • relative safety issues if things go wrong • difficulties of producing conditions for fusion/ease of producing conditions for fission • radioactive waste from fission but not fusion • availability of fuels better for fusion • energy potential per reaction from fusion is greater • at present, difficulties of producing and controlling fusion are the major problem • despite difficulties, fission is feasible at present, fusion is not explanation of principle of each process discussion of advantages/disadvantages of each conclusion of why fission is currently feasible although fusion would be more desirable

(6)

1 1-2 • makes a limited attempt at an explanation of similarities/differences between the two in terms of process, energy potential, the conditions needed to initiate the process, safety or control issues • makes little or no effort to suggest why fission is in use or why fusion isnt, but might be good in future • the answer communicates ideas using simple language and uses some scientific terminology as given in the question. Spelling, punctuation and grammar are used with limited accuracy.

2 3-4 • explains similarities/differences between key features of the two processes in terms of process, energy potential, the conditions needed to initiate the process, safety or control issues • explains either why fission is currently used or why fusion is preferred • the answer communicates ideas showing some evidence of clarity and organisation and uses scientific terminology appropriately. Spelling, punctuation and grammar are used with some accuracy.

3 5-6 • gives a clear explanation of similarities/differences between the two in terms of process, energy potential, the conditions needed to initiate the process, safety and control issues • clearly explains why existing systems use fission but with reasons for preference of fusion if attainable • the answer communicates ideas clearly and uses a range of scientific terminology appropriately. Spelling, punctuation and grammar are used with few errors.

16.

Question Number


* QWC

an explanation including some one of the following: • distinguishes clearly between fission (splitting large nuclei) and fusion (joining - small nuclei) • relative safety issues if things go wrong • difficulties of producing conditions for fusion/ease of producing conditions for fission • radioactive waste from fission but not fusion • availability of fuels better for fusion • energy potential per reaction from fusion is greater • at present, difficulties of producing and controlling fusion are the major problem • despite difficulties, fission is feasible at present, fusion is not explanation of principle of each process discussion of advantages/disadvantages of each conclusion of why fission is currently feasible although fusion would be more desirable

(6)

1 1-2 • makes a limited attempt at an explanation of similarities/differences between the two in terms of process, energy potential, the conditions needed to initiate the process, safety or control issues • makes little or no effort to suggest why fission is in use or why fusion isnt, but might be good in future • the answer communicates ideas using simple language and uses some scientific terminology as given in the question. Spelling, punctuation and grammar are used with limited accuracy.

2 3-4 • explains similarities/differences between key features of the two processes in terms of process, energy potential, the conditions needed to initiate the process, safety or control issues • explains either why fission is currently used or why fusion is preferred • the answer communicates ideas showing some evidence of clarity and organisation and uses scientific terminology appropriately. Spelling, punctuation and grammar are used with some accuracy.

3 5-6 • gives a clear explanation of similarities/differences between the two in terms of process, energy potential, the conditions needed to initiate the process, safety and control issues • clearly explains why existing systems use fission but with reasons for preference of fusion if attainable • the answer communicates ideas clearly and uses a range of scientific terminology appropriately. Spelling, punctuation and grammar are used with few errors.

Q18.

Question Number


* QWC

an evaluation including some of the following: • makes some sensible effort at quantification with speed • eg uses the extension of thinking distance trend to 21 m for part (ai) at 70 mph and estimates the value for braking distance for that speed • mentions need for keeping a safe distance apart • discusses this safe distance in terms of different reaction time of people (the effects of drugs, age etc) and road/car conditions • reaches some judgement of the appropriateness of 40 m under various conditions Factors that affect thinking distances include: • drugs/alcohol • tiredness • music/radio/phones/talking • light conditions Factors that affect braking distances include: • condition of brakes • condition of road • weather conditions • substances on road idea that stopping distance is affected by all of these. Conclusion e.g 40 m is a compromise between being ultra-safe and being unrealistically too far apart (for the conditions).

(6)

1 1-2 • there is limited discussion of factors that influence thinking distances, only mentioning one factor • there is limited discussion of factors that influence braking distances, only mentioning one factor • there is little or no evidence of any calculation of what the probable stopping distance would be at 70mph • limited or no mention of appropriateness of separation of markings • the answer communicates ideas using simple language and uses some scientific terminology as given in the question. Spelling, punctuation and grammar are used with limited accuracy

2 3-4 • there is some discussion of factors that influence thinking distances, with more than one factor given • there is some discussion of factors that influence braking distances, with more than one factor given • there is some evidence of working out the stopping distance at 70mph • maybe a mention of the appropriateness or not of separation of markings • the answer communicates ideas showing some evidence of clarity and organisation and uses scientific terminology appropriately. Spelling, punctuation and grammar are used with some accuracy

3 5-6 • there is a clear discussion of the key factors that influence thinking distances • there is a clear discussion of the key factors that influence braking distances • there is clear evidence of working out the stopping distance at 70mph • suitable conclusion based on arguments given e.g a comment about the appropriateness of motorway markings for certain conditions but innappropriateness in other conditions compromise • the answer communicates ideas clearly and uses a range of scientific terminology appropriately. Spelling, punctuation and grammar are used with few errors

Q19.


* An explanation linking some of the following points

kinetic energy varies during swing

kinetic energy maximum at bottom of swing

kinetic energy minimum at top of swing

gravitational potential energy(gpe) varies during swing

gpe maximum at top of swing

gpe minimum at bottom of swing

(continuous) interchange of KE and gpe

total amount of energy is constant during one swing

over a number of swings max KE and max PE decreases

energy is dissipated/'lost' to surroundings

because of air resistance / friction

amplitude/size of swings decrease ( as energy 'lost' to surroundings) ignore references to momentum

(6)

Level Mark Descriptor


1 1 - 2

a limited explanation which states some facts e.g. (max) Kinetic energy decreases over time. KE will transfer to GPE. or KE increases and decreases over one swing. The height which the swing reaches gets less over time.



2 3 - 4

a simple explanation with links between facts; either over one period of oscillation or over several periods of oscillations. Kinetic energy decreases as he gets higher and the GPE increases. There is a continuous interchange of KE and gpe as he swings. or KE is gradually transferred to heat so swing rises to a slightly lower height each time.



3 5 - 6

a detailed explanation with links between facts over one period of oscillation and over several periods of oscillations e.g. kinetic energy is at a maximum at bottom of swing There is a continuous interchange of KE and gpe. KE (and gpe) reduce over a number of swings as energy is dissipated to the surroundings due to friction.



Q20.

Question Number


* QWC

an evaluation including some of the following: • makes some sensible effort at quantification with speed • eg uses the extension of thinking distance trend to 21 m for part (ai) at 70 mph and estimates the value for braking distance for that speed • mentions need for keeping a safe distance apart • discusses this safe distance in terms of different reaction time of people (the effects of drugs, age etc) and road/car conditions • reaches some judgement of the appropriateness of 40 m under various conditions Factors that affect thinking distances include: • drugs/alcohol • tiredness • music/radio/phones/talking • light conditions Factors that affect braking distances include: • condition of brakes • condition of road • weather conditions • substances on road idea that stopping distance is affected by all of these. Conclusion e.g 40 m is a compromise between being ultra-safe and being unrealistically too far apart (for the conditions).

(6)

1 1-2 • there is limited discussion of factors that influence thinking distances, only mentioning one factor • there is limited discussion of factors that influence braking distances, only mentioning one factor • there is little or no evidence of any calculation of what the probable stopping distance would be at 70mph • limited or no mention of appropriateness of separation of markings • the answer communicates ideas using simple language and uses some scientific terminology as given in the question. Spelling, punctuation and grammar are used with limited accuracy

2 3-4 • there is some discussion of factors that influence thinking distances, with more than one factor given • there is some discussion of factors that influence braking distances, with more than one factor given • there is some evidence of working out the stopping distance at 70mph • maybe a mention of the appropriateness or not of separation of markings • the answer communicates ideas showing some evidence of clarity and organisation and uses scientific terminology appropriately. Spelling, punctuation and grammar are used with some accuracy

3 5-6 • there is a clear discussion of the key factors that influence thinking distances • there is a clear discussion of the key factors that influence braking distances • there is clear evidence of working out the stopping distance at 70mph • suitable conclusion based on arguments given e.g a comment about the appropriateness of motorway markings for certain conditions but innappropriateness in other conditions compromise • the answer communicates ideas clearly and uses a range of scientific terminology appropriately. Spelling, punctuation and grammar are used with few errors

Q21.


QWC * An explanation including some of the following ideas Need for measurement (N)Background radiation

is always present/all around us

has (natural) source(s) exemplified by space, living things, rocks, food, nuclear/medical sources etc.

would give false reading in experiment How and why to measure(H) Background radiation measurement

is taken at site of experiment because it is different in different places

is taken with all apparatus except source in place

is taken before and after because it can change with time / they need an average

must be worked out for same time as (or longer than) experiment / rate found so analysis is simpler

It is taken several times/ averaged because it is random Analysis (A) Background radiation measurement

must be subtracted from measurements with source /main count rate (6)


2 3 - 4

A simple explanation linking aspects of two ideas i.e. N + H OR N + A OR H + A e.g Take readings without source (H) and subtract them from the main readings with source present.(A) OR It should be taken several times because it is random (H)so that the average can be subtracted from the main readings (A)



3 5 - 6

A detailed explanation linking A with EITHER N + an idea from H OR two or more ideas from H e.g.Background radiation is there all the time. (N) You need to take readings at the place where you will do the experiment and with all the apparatus set up except the source because BR changes from place to place.(H) Then you should subtract background readings from the main experimental readings.(A) OR Take several readings of count rate for averaging since the effect is random (H) and make sure that they are taken in the same place.(H) Then subtract from readings in main experiment.(A)



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