Oxford Revise AQA GCSE Combined Science Foundation | Chapter B10 answers

B10: Photosynthesis and respiration

Question

Answers

Extra information

Mark

AO / Specification reference

01.1

stoma

1

AO2

4.2.3.1

4.4.1.1

01.2

to prevent water loss

1

AO2

4.2.3.1

4.4.1.1

01.3

either

leaves are broad

large surface area for light to fall on

or

palisade cells contain many chloroplasts / chloroplasts contain chlorophyll

to maximise light absorption

to gain full marks students must state one features with linked explanation

2

AO1

4.4.1.2

01.4

either:

guard cells open and close stomata

to allow carbon dioxide to diffuse into the leaf

or

air spaces in leaf

allow carbon dioxide to diffuse into leaf cells

or

leaves are thin

diffusion distance for carbon dioxide is short

to gain full marks students must state one feature with linked explanations

2

AO1

4.4.1.2

02.1

D

1

AO2

4.4.2.1

02.2

carbon dioxide and water

1

AO1

4.4.2.1

02.3

any one from:

  • movement
  • keeping warm

to build larger molecules

1

AO1

4.4.2.1

02.4

anaerobic respiration

1

AO1

4.4.2.1

02.5

any one from:

  • more energy is transferred per glucose molecule
  • no lactic acid is made

build-up of lactic acid can cause muscle fatigue

1

AO1

4.4.2.1

03.1

light intensity / distance from light source

1

AO2

4.4.1.2

03.2

provide carbon dioxide / to ensure carbon dioxide is not a limiting factor

1

AO2

4.4.1.2

03.3

collect gas in a syringe / upturned test tube

add a glowing splint – it will relight / Add a burning splint – it will burn more brightly

1

1

AO2

4.4.1.2

03.4

data points plotted accurately

correct line of best fit drawn

all points gains 2 marks, 2 or 3 points gains 1 mark

allow a tolerance of ± 1 small square

2

1

AO3

4.4.1.2

MS 4c

03.5

as light intensity decreases / distance from source increases the rate of photosynthesis decreases

1

AO3

4.4.1.2

03.6

accept value between 5 and 6 bubbles per minute

1

AO2

4.4.1.2

MS 4a

03.7

bubbles were different sizes / easy to miss

accept any reasonable suggestion

1

AO2

4.4.1.2

03.8

collect gas given off and measure volume collected per unit time

1

AO3

4.4.1.2

04.1

more rapidly

faster

increases

deeply

oxygen

5

AO1

4.4.2.2

04.2

exercise / jogging caused the heart rates of all students tested to increase

the time taken for the students’ heat rates to return to normal was variable

1

1

AO3

4.4.2.2

04.3

Student B

1

AO2

4.4.2.2

04.4

either

student A

smallest increase in heart rate

or

student E

heart rate returned quickest to normal

one mark for the identified student, and one mark for the linked explanation

no marks if the explanation does not match the student identified

2

AO3

4.4.2.2

05.1

to release energy to the cells / provide cells with energy

to use in chemical reactions (needed to maintain life)

1

1

AO1

4.4.2.1

05.2

no

yes

no

ethanol

1

1

1

1

AO1

4.4.2.1

05.3

  • anaerobic respiration in yeast produced ethanol
    • used in alcohol production / named alcoholic product
  • anaerobic respiration in yeast produces carbon dioxide

used to make bread rise

1

1

1

1

AO1

4.4.2.1

06.1

water

oxygen

answers must be in the correct order

1

1

AO1

4.4.1.1

06.2

chloroplast

1

AO1

4.4.1.1

06.3

endothermic

1

AO1

4.4.1.1

06.4

stomata

1

AO1

4.4.1.1

07.1

light intensity: Increase rate of photosynthesis

nutrient availability: No change to rate of photosynthesis

carbon dioxide availability: Decrease rate of photosynthesis

chlorophyll level: Increase rate of photosynthesis

award one mark for each correct row in the table

4

AO1

4.4.1.2

07.2

C

1

AO2

4.4.1.2

07.3

any two from:

  • used for respiration
  • converted into starch (for storage)
  • used to produce fat or oil (for storage)
  • used to produce cellulose (for cell walls)
  • used to produce amino acids (for proteins)

2

AO1

4.4.1.3

08.1

oxygen

water

answers must be in the correct order

1

1

AO1

4.4.2.1

08.2

aerobic respiration is an exothermic reaction

aerobic respiration transfers more energy per glucose molecule than anaerobic respiration

1

1

AO1

4.4.2.1

08.3

mitochondria

1

AO1

4.4.2.1

09.1

sum of all the reactions which take place inside a cell / organism

1

AO1

4.4.2.3

09.2

respiration releases the energy needed for reactions to occur

respiration required to maintain body temperature

so enzyme-controlled reactions occur efficiently

1

1

1

AO1

4.4.2.3

09.3

fatty acids

glycerol

1

1

AO1

4.4.2.3

09.4

both storage molecules

converted back into glucose when energy is needed

1

1

AO1

4.4.2.3

10.1

for example:

circulatory system – transports materials around the body in the body

nervous system – transmits impulse around the body

reproductive system – produces offspring

award one mark for a named organ system and one mark for linked description

accept any other correct system not listed

2

AO1

4.2.1

10.2

H

1

AO2

4.2.2.1

10.3

absorb nutrients

1

AO2

4.2.2.1

10.4

any one from:

  • provides optimum conditions for (protease) enzymes to work
  • speeds up protein digestion
  • kills microorganisms

1

AO2

4.2.2.1

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