Oxford Revise AQA GCSE Combined Science Foundation | Chapter B6 answers

B6: Organising plants

Question

Answers

Extra information

Mark

AO / Specification reference

01.1

to compare with no petroleum jelly

1

AO2

4.2.3.2

01.2

balance

do not accept scales

1

AO2

4.2.3.2

01.3

2.8 – 0.7 = 2.1 g

1

AO2

MS3a

4.2.3.2

01.4

more water is lost from the lower surface than the upper surface

water is lost from both surfaces

1

1

AO3

4.2.3.2

01.5

(more) stomata are found on the lower surface

1

AO3

4.2.3.2

02.1

plant

leaf / flower

spongy mesophyll

1

1

1

AO2

4.2.3.1

02.2

meristem tissue – contains rapidly dividing cells for growth

xylem – transports water around the plant

phloem – carries dissolved food around the plant

one mark for one or two correct

two marks for all correct

2

AO1

4.2.3.1

02.3

chloroplasts

1

AO1

4.2.3.1

02.4

it contains different types of tissues (working together) / named tissues

1

AO2

4.2.3.1

03.1

palisade mesophyll

1

AO2

4.2.3.2

03.2

contains chloroplasts

1

AO1

4.1.1.3

4.2.3.2

03.3

osmosis

from a region of high water potential to a region of lower water potential

1

1

AO1

4.1.3.2

4.2.3.2

03.4

Level 3: all three layers described

5–6

AO1

4.1.1.3

4.2.3

Level 2: two layers described

3–4

Level 1: one layer described

1–2

No Relevant content

0

Indicative content

Any six from:

Top of leaf:

  • (tightly packed) palisade cells
  • contain many chloroplasts for photosynthesis
  • upper cells protected by epidermis
  • waxy surface reduces water loss from upper surface

Middle of leaf:

  • spongy mesophyll cells
  • have large air spaces / surface area to maximise gas exchange
  • xylem supplies water for photosynthesis
  • phloem transports dissolved sugars from photosynthesis to plant

Lower part of leaf:

  • stomata open and close through action of guard cells
  • let carbon dioxide diffuse in
  • allow oxygen / water vapour to diffuse out

04.1

Place several strips of (nail) varnish on the leaf/several leaves and allow to dry

Peel the varnish off the leaf and place on a microscope slide

Observe the strip of varnish (under a set magnification) and count stomata in the field of view

1

1

1

AO2

2.3.2

04.2

\( (36 + 42 + 35 + 41 + 37) \div 5 = 38.2 \)

= 38 (2 s.f.)

Calculation of mean

Two significant figures

1

1

AO2

2.3.2

MS 2a, b

04.3

Upper surface is exposed to the sun / greater heat

Which would cause greater rate of evaporation if stomata on top side

Accept converse

1

1

AO1

2.3.2

05.1

sugars

1

AO1

4.2.3.2

05.2

Feature

Found in xylem

Found in phloem

living cells

sieve plates

walls containing lignin

supported by companion cells

one mark for each correct row

4

AO1

4.2.3.2

05.3

translocation

1

AO1

4.2.3.2

06.1

from top:

upper epidermis

palisade mesophyll

spongy mesophyll

lower epidermis

1

1

1

1

AO2

4.2.3.1

06.2

carries out most photosynthesis in the leaf: palisade mesophyll

contains the stomata: lower epidermis

contains air spaces: spongy mesophyll

1

1

1

AO1

4.2.3.1

06.3

stomata

1

AO1

4.2.3.1

07.1

the rate of water loss from the leaves of a plant

1

AO1

4.2.3.2

07.2

potometer

1

AO1

4.2.3.2

07.3

Factor change

Increase

Decrease

increase in temperature

increase in humidity

increase in air speed

greater light intensity

one mark for each correct row

4

AO1

4.2.3.2

08.1

large surface area available – to speed up movement of water into cell by osmosis

many mitochondria – to transfer energy needed for active transport into the cell

1

1

AO1

4.2.3.2

08.2

(Process) Y

active transport / concentration of mineral ions is usually lower in soil than in plant cells

one mark for name of process

one mark for explanation

1

1

AO2

4.2.3.2

08.3

xylem

1

AO1

4.1.1.3

4.2.3.2

08.4

any one from:

  • magnesium needed for chlorophyll manufacture
  • nitrates to produce amino acids/proteins

both mineral and use required for mark

accept other correctly named mineral and its use

1

AO1

4.2.3.2

09.1

stoma labelled (gap between cells on the lower surface of the leaf)

1

AO2

4.2.3.2

09.2

when less water is available the guard cells close

this reduces rate of diffusion of water vapour out of leaf / plant loses less water through transpiration

accept converse argument

1

1

AO1

4.2.3.2

09.3

39 µm

accept range 33 – 45 µm

(250 / (value between 5.5 and 7.5 mm))

1

AO2

4.2.3.2

MS1d

Loading...