3.1.3 MS
3.1.3 – Transport in plants – Question Booklet – Mark Scheme
1. (i) stem; 1
(ii) B; 1
[2]
2. (a) sucrose; 1
(b) (i) P = companion (cell);
Q = sieve (tube) element / sieve tube cell; R sieve tube / sieve cell 2
(ii) ecf - do not penalise sieve tube here
1 sieve elements / Q, end to end or sieve plates perforated /
sieve pores , for ease of flow / AW;
2 companion cells / P, metabolically active / have many mitochondria /
produce ATP / release energy / AW; R make energy
3 (active) loading into, companion cell / P; A into, sieve elements / Q
4 ref to proton pump;
5 ref to co-transporter;
6 role of plasmodesmata (between P and Q); R pores
7 sieve element / Q, has few organelles / AW, for, ease of flow /
more sucrose / AW;
8 ref to, unloading mechanism / (hydrostatic) pressure gradient;
9 ref to one role for sieve plate e.g. electro-osmosis or stops
‘bulging’; 3 max
[6]
3. source when root converts, starch / insoluble carbohydrate, into sugars / AW;
sink when root either stores starch / (named) carbohydrate / assimilate
or uses carbohydrate for, respiration / growth / AW;
high hydrostatic pressure makes it a source and low hydrostatic pressure a sink;
when loading it is a source and when unloading a sink;
treat refs to (potato) tubers as neutral 2 max
[2]
4. (a) stem; 1
(b) phloem; R sieve tube, phloem vessel, single cell type 1
(c) C; 1
(d) feature and role must match for 2 marks
mark for feature may be awarded even if role is incorrect
both marks may be given in right hand column.
Feature how it helps
either D or E
living; allows active process / AW;
stops escape of metabolites;
hydrogen pump / co-transporter; (role in) loading / AW;
plasmodesmata / connections between allow exchange /AW;
sieve tube and companion cell;
D / companion cell
(many) mitochondria provide, energy / ATP;
much respiration / metabolically active;
nucleus; controls functioning of both cells;
, 3.1.3 MS
E / sieve tube
clear of most organelles / less resistance / ease of transport
organelles at edge / little cytoplasm / AW; / AW / more space for transport;
R empty
(if specific organelles given, need
at least 2)
long / elongated / AW; less resistance / ease of
transport / AW;
sieve plate / (sieve) pores; connects elements / lets
materials through / AW;
A reduces resistance
joined end to end; continuous / long distance,
transport;
bi-directional flow; allows sugar to go to sink
both up and downward / AW; 6 max
[9]
5. (a) open tap to allow water column to fill capillary tube; check for leaks with tap closed/eq ; equilibration ;
note level of water column/meniscus on scale;
record distance moved along scale in fixed time/time taken for column to travel fixed distance; reset
water column by opening tap;
repeat at least 3 times;
calculate (mean) volume of water taken up qualified;
suitable method of measuring leaf area described / eg draw round leaves on graph paper and count
squares of known volume
(6 marks)
(b) maintain constant conditions surrounding the plant;
at least two of temperature/light/humidity / air movement named;
check apparatus is free from bubbles / air locks / completely filled with water / eq;
read bottom of the meniscus / eq;
fix plant firmly to prevent movement which could affect reading;
cut stem under water;
(3 marks)
[Total 9 marks]
6. (a)
A vascular bundle / vascular tissue / vein / xylem and phloem / eq.
B epidermis / epidermal cell; (2 marks)
(b)
presence of hairs / eq. of epidermis / surface;
reduce air movement / trap air / trap water vapour / humidity ref;
thick cuticle; reduces evaporation / diffusion of water / water loss;
leaf rolled / eq;
reduces external / exposed surface area / reduction in air movement / humidity ref;
hinge cells;
3.1.3 – Transport in plants – Question Booklet – Mark Scheme
1. (i) stem; 1
(ii) B; 1
[2]
2. (a) sucrose; 1
(b) (i) P = companion (cell);
Q = sieve (tube) element / sieve tube cell; R sieve tube / sieve cell 2
(ii) ecf - do not penalise sieve tube here
1 sieve elements / Q, end to end or sieve plates perforated /
sieve pores , for ease of flow / AW;
2 companion cells / P, metabolically active / have many mitochondria /
produce ATP / release energy / AW; R make energy
3 (active) loading into, companion cell / P; A into, sieve elements / Q
4 ref to proton pump;
5 ref to co-transporter;
6 role of plasmodesmata (between P and Q); R pores
7 sieve element / Q, has few organelles / AW, for, ease of flow /
more sucrose / AW;
8 ref to, unloading mechanism / (hydrostatic) pressure gradient;
9 ref to one role for sieve plate e.g. electro-osmosis or stops
‘bulging’; 3 max
[6]
3. source when root converts, starch / insoluble carbohydrate, into sugars / AW;
sink when root either stores starch / (named) carbohydrate / assimilate
or uses carbohydrate for, respiration / growth / AW;
high hydrostatic pressure makes it a source and low hydrostatic pressure a sink;
when loading it is a source and when unloading a sink;
treat refs to (potato) tubers as neutral 2 max
[2]
4. (a) stem; 1
(b) phloem; R sieve tube, phloem vessel, single cell type 1
(c) C; 1
(d) feature and role must match for 2 marks
mark for feature may be awarded even if role is incorrect
both marks may be given in right hand column.
Feature how it helps
either D or E
living; allows active process / AW;
stops escape of metabolites;
hydrogen pump / co-transporter; (role in) loading / AW;
plasmodesmata / connections between allow exchange /AW;
sieve tube and companion cell;
D / companion cell
(many) mitochondria provide, energy / ATP;
much respiration / metabolically active;
nucleus; controls functioning of both cells;
, 3.1.3 MS
E / sieve tube
clear of most organelles / less resistance / ease of transport
organelles at edge / little cytoplasm / AW; / AW / more space for transport;
R empty
(if specific organelles given, need
at least 2)
long / elongated / AW; less resistance / ease of
transport / AW;
sieve plate / (sieve) pores; connects elements / lets
materials through / AW;
A reduces resistance
joined end to end; continuous / long distance,
transport;
bi-directional flow; allows sugar to go to sink
both up and downward / AW; 6 max
[9]
5. (a) open tap to allow water column to fill capillary tube; check for leaks with tap closed/eq ; equilibration ;
note level of water column/meniscus on scale;
record distance moved along scale in fixed time/time taken for column to travel fixed distance; reset
water column by opening tap;
repeat at least 3 times;
calculate (mean) volume of water taken up qualified;
suitable method of measuring leaf area described / eg draw round leaves on graph paper and count
squares of known volume
(6 marks)
(b) maintain constant conditions surrounding the plant;
at least two of temperature/light/humidity / air movement named;
check apparatus is free from bubbles / air locks / completely filled with water / eq;
read bottom of the meniscus / eq;
fix plant firmly to prevent movement which could affect reading;
cut stem under water;
(3 marks)
[Total 9 marks]
6. (a)
A vascular bundle / vascular tissue / vein / xylem and phloem / eq.
B epidermis / epidermal cell; (2 marks)
(b)
presence of hairs / eq. of epidermis / surface;
reduce air movement / trap air / trap water vapour / humidity ref;
thick cuticle; reduces evaporation / diffusion of water / water loss;
leaf rolled / eq;
reduces external / exposed surface area / reduction in air movement / humidity ref;
hinge cells;
