C1 Topic 1 - Revision

L.O. To revise some key aspects of topic 1

01/03/2015

The Early Atmosphere

Gas How much?

Carbon dioxide Lots

Water vapour Quite a lot

Oxygen Very, very little if any

Formation of oceans

• Early atmosphere hot

• Volcanoes release water vapour

• Earth cools

• Water vapour condenses

• Oceans form

Role of the oceans

• Oceans dissolved carbon dioxide

• Marine organisms used this to make shells of calcium carbonate

• When they died the shells sunk to the bottom to form sedimentary rock

Question

Number

Answer Acceptable answers Mark

(i) water vapour /

steam condensed/

changed to liquid

Allow steam cooled

(1)

Question

Number

Answer Acceptable answers Mark

(ii) (carbon dioxide)

dissolved/ absorbed

/ trapped

Ignore refs to plants/

rocks

(1)

Question

Number

Answer Acceptable answers Mark

(iii) A description

including the

following points

• (primitive) plants

(produce oxygen) (1)

• (by)

photosynthesis (1)

Allow named plants

Reject answers

involving respiration

(2)

Photosynthesis

• When plants started to photosynthesise, they took in CO2 and released O2

• Over time more plants grew and so there was more photosynthesis and more O2

Question

Number

Answer Acceptable answers Mark

(i) C (1)

Question

Number

Answer Acceptable answers Mark

(ii) An explanation

linking two of the

following points:

• decrease the

percentage of

/removes / takes in

carbon dioxide (1)

• increase the

percentage of

/produces / gives out

oxygen (1)

• photosynthesis (1)

Ignore ‘breathes in

or out’ Ignore

decreases amount of

oxygen Ignore

increases amount of

carbon dioxide

Current Atmosphere

Current atmosphere changing

Change Effect

Volcanoes Release sulfur dioxide

Burning fossil fuels More carbon dioxide

Farming More methane

Deforestation Less photosysnthesis, so more carbon dioxide

Question

Number

Indicative Content Mar

k

QWC *(c) An explanation linking some of the following points

carbon dioxide is added to the atmosphere by

• volcanic activity - gases burnt out in eruption

• burning fossil fuels - because they contain

carbon • deforestation - because less tress to

absorb carbon dioxide • respiration - process of

breathing forms carbon dioxide carbon dioxide is

removed from the atmosphere by • dissolving in

oceans - because carbon dioxide is soluble

• carbon dioxide taken from ocean - to make

corals and shells • photosynthesis - because

carbon dioxide converted to sugars in plants

• relative amounts added and removed determine

whether amount of carbon dioxide in atmosphere

rises, falls or remains the same (6)

Level 0 No rewardable content

1 1 - 2 • two points identified as addition or removal with one justified

/ three points identified addition or removal • the answer

communicates ideas using simple language and uses limited

scientific terminology • spelling, punctuation and grammar are

used with limited accuracy

2 3 - 4 • one point identified as addition and one point identified as

removal, with both justified / four points identified, at least one

of which must be an addition and at least on eof which must be a

removal, with any one justified • 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 • four points identified as addition or removal, with all justified

and at least one addition and at least one removal / six points

identified as addition or removal with two justified • the

answer communicates ideas clearly and coherently uses a range

of scientific terminology accurately • spelling, punctuation and

grammar are used with few errors

Oxygen in the atmosphere

Question

Number

Answer Acceptable answers Mark

An explanation linking

four of the following

points • (during

experiment) oxygen

removed (1) • water

level stops rising when

all oxygen removed (1)

• phosphorus oxide

(formed) (1) • volume

of air = 50 cm3 (1)

• volume of oxygen =

50 - 40 cm3 (1) = 10

(cm3) • percentage of

oxygen (in air) = 10 ÷

50 × 100 (1) = 20%

(4)

Question

Number

Indicative Content Mark

QWC * A description including some of the following

points: • push / pull syringes to move air

• volume of air in syringes decreases • oxygen

removed from air • copper reacts / joins with

oxygen • copper oxide formed • continue until no

further change • allow (apparatus) to cool • final

reading on gas syringe = 100 – 21 / 79 (80) cm3

• because 21 (20) cm3 of oxygen has reacted (6)

Level 0 No rewardable content

1 1 - 2 • a limited description e.g. push in syringe A to pass air over the copper /

copper reacts with oxygen • 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 description e.g. (hot) copper reacts with oxygen to produce

copper oxide / copper oxide is formed and the volume of air decreases

• 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 description e.g. when the air is passed over the (hot) copper,

oxygen reacts with copper so the volume of air decrease until there is no

further change /by 21 cm3 • the answer communicates ideas clearly and

coherently uses a range of scientific terminology accurately • spelling,

punctuation and grammar are used with few

Question

Number

Answer Acceptable answers Mark

(i) C (1)

(ii) all oxygen reacted /

used up / excess

copper (present)

no oxygen left /

insufficient oxygen

Reject not enough

time / not hot

enough (1)

(iii) volume gas used =

32-24 (1) = 8 (cm3)

percentage = 32-

24/32 × 100 (1) =

25 (%)

(2)

(iv) oxygen in air in test

tube also reacted

/more than 32 cm3 of

air because of air in

test tube / air in test

tube will react but is

not measure

some gases leaked

out of apparatus

allow another gas has

reacted with copper

(1)