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Plant Structures and their functions – Mark Scheme

Q1.

Q2.

Answer Acceptable answers

Mark

(i) D positive phototropism

(1)

(ii) An explanation to include the following linked points (auxins) move to the shaded side of a shoot (1) causing cells on the shaded side to elongate (1)

accept move to the side opposite the light accept get longer for elongate Ignore references to cell division (2)

Q3.

Q4.

Q5.

Q6.


Mark

(i) there is an increase in the % of bananas that ripen as the ethylene concentration increases

Ignore positive effect

(1)(ii) An explanation to

include two of the following points · concentration of ethylene to use is 3% (1) · would be more expensive to increase the ethylene concentration above 3% · when there is no added ripening benefits past 3%(1) · below 3% not all bananas are ripe (1)

Do not credit ideas related to longer shelf life as the question asks about ripening (2)

Q7.

Indicative Content Mark

QWC * A description to (6)

include some of the following points · selective weedkillers· allows broad-leaved plants to grow uncontrollably and die· narrower-leaved plants and crops left unaffected· auxins and or gibberellins are used· rooting powders· plant cuttings are dipped into rooting powder· roots develop rapidly· large number of plants can be produced from the same plant· no need to wait for plants to grow from seeds· auxins are used· seedless fruit production· the fruit will develop but the seeds inside will not· fruits are able to grow larger (larger biomass)· gibberellins are used

Level 0 No rewardable content 1 1 - 2

· a limited description of at least one use of plant hormones· 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 of two or more uses of plant hormones

· 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 of two or more uses of plant hormones with at least auxin,

gibberellins or other relevant hormone in the correct context· the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately· spelling, punctuation and grammar are used with few errors

Q8.

Q9.


Mark

(a) A suggestion including any three linked points · ref to use of enzymes (1) · isolate / remove /cut out gene / DNA (for resistance)(1) · (coding for) enzyme (1)

Any named enzyme must be in correct context. Ignore plasmids Reject replace

(3)

· from bacteria (1) · insertion of gene / DNA into crops / plants (1)

(b)· in the phloem (1)

Accept phonetic spelling e.g. phloem /flowem

(1)

(c)(i) A description including two of the following points · 0 to 10/11 no effect / change / difference (1) · 10/11 to 28 / 29/30 decrease in mass / yield (1) · Over 28 / 29/30 no change (1)

Accept decreases for 1 mark (if no other marks awarded) ecf throughout

(2)(c)(ii) B - 30 arbitrary units (1)(d)(i)

· number of species increase / go up (1)

Ignore number of weeds

(1)(d)(ii) Suggestions

including two of the following linked points · increased use of herbicideresistant crops (1) · increased use (concentration / time) of herbicide (1) · ref to transfer of genes into weeds from other plants / cross pollination (1) · mutation(1)

Ignore ref to evolution / natural selection Ignore immune (to herbicide) Accept a description eg continued use of herbicide Accept cross breeding / reproduction / contamination

(2)

Q10.

Q12.

Q13.

Q14.


Mark

(i) A description including three of the following points: · into root hairs (1)

· through a partially permeable membrane (1) · by osmosis (1) · down a concentration gradient (1)

accept: through leaves (as correct for water plants) reject: active transport ignore: refs to diffusion accept: from a high concentration (of water) to a low concentration (of water) (3)

(ii) An explanation including two of the following points: · less /slower movement of water

accept: lowers concentration of water outside the plant (than inside) ORA

(2)

into the plant (1)OR · more / faster movement of water out of the plant (1) · (because) less (free) water outside the plant than inside (1)

(iii) A diffusion (1)

Q15.


Mark

(i) D 9.0% (1)(ii)

· lowered the level of carbon dioxide / carbon dioxide removed / taken in (1) · increased the level of oxygen / oxygen produced / made(1)

accept: percentage for level If CO2 written must be correct, do not accept CO2

(2)(iii) Any two from:

· large organisms more complex/carry out greater number of functions / more cells · for (more aerobic) respiration · for (more) energy

(2)

Q16.


Mark

(i) B (1)(ii) Any two from the

following: · diffusion (1) · from an area of high concentration to an area of low concentration/down a concentration gradient (1) · through stoma / stomata (1)

Accept pores / between guard cells Ignore through guard cells (2)

(iii) Any three from the following: · (by) photosynthesis (1)

Ignore incorrect balancing of equations throughout Reject (and)

(3)

· ref to chloroplast / chlorophyll (1) · requires carbon dioxide and water (1)

· light (energy) needed (for photosynthesis)(1) · (to produce) glucose (1)

respiration Accept if written on arrow in word / formula equation Accept correct formulae word / formula equation Accept if written on arrow in word / formula equation Reject energy is created / produced Accept sugar from word / formula equation

Q17.


Mark

(a)(i) D positive phototropism

(1)

(a)(ii) An explanation to include the following linked points (auxins) move to the shaded side of a shoot (1) causing cells on the shaded side to elongate (1)

accept move to the side opposite the light accept get longer for elongate Ignore references to cell division (2)

(b)(i) there is an increase in the % of bananas that ripen as the ethylene concentration increases

Ignore positive effect

(1)(b)(ii) An explanation to

include two of the following points · concentration of ethylene to use is 3% (1) · would be more expensive to increase the ethylene concentration above 3% · when there is no added ripening benefits past 3%(1) · below 3% not all bananas are ripe (1)

Do not credit ideas related to longer shelf life as the question asks about ripening (2)


QWC *(c) A description to include some of the following points · selective weedkillers· allows broad-leaved plants to grow uncontrollably and die· narrower-leaved plants and crops left unaffected· auxins and or gibberellins are used· rooting powders· plant cuttings are dipped into rooting powder· roots develop rapidly

(6)

· large number of plants can be produced from the same plant· no need to wait for plants to grow from seeds· auxins are used· seedless fruit production· the fruit will develop but the seeds inside will not· fruits are able to grow larger (larger biomass)· gibberellins are used


· a limited description of at least one use of plant hormones· 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 of two or more uses of plant hormones

· 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 of two or more uses of plant hormones with at least auxin, gibberellins or other relevant hormone in the correct context· the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately· spelling, punctuation and grammar are used with few errors

Total for question = 12 marks

Q19.


Mark

(a)(i) B (1)(a)(ii) Any two from the

following: Accept pores / between guard cells

(2)

· diffusion (1) · from an area of high concentration to an area of low concentration/down a concentration gradient (1) · through stoma / stomata (1)

Ignore through guard cells

(a)(iii) Any three from the following: · (by) photosynthesis (1) · ref to chloroplast / chlorophyll (1) · requires carbon dioxide and water (1)

· light (energy) needed (for photosynthesis)(1) · (to produce) glucose (1)

Ignore incorrect balancing of equations throughout Reject (and) respiration Accept if written on arrow in word / formula equation Accept correct formulae word / formula equation Accept if written on arrow in word / formula equation Reject energy is created / produced Accept sugar from word / formula equation (3)

(b) water o

smosis (1)

(1)

3 lines, 1 correct = 0 mark 3 lines, 2 correct = 1 mark 4 lines, 1 correct = 0 mark 4 lines, 2 correct = 0 mark (2)

Q20.


Mark

water o

smosis (1)

(1)

3 lines, 1 correct = 0 mark 3 lines, 2 correct = 1 mark 4 lines, 1 correct = 0 mark 4 lines, 2 correct = 0 mark (2)

Q21.

Q24.


Mark

· in the phloem (1)

Accept phonetic spelling e.g.

(1)

phloem /flowem

Q25.

Q26.


Mark

(a)(i) A description including three of the following points: · into root hairs (1)

· through a partially permeable membrane (1) · by osmosis (1) · down a concentration gradient (1)

accept: through leaves (as correct for water plants) reject: active transport ignore: refs to diffusion accept: from a high concentration (of water) to a low concentration (of water) (3)

(a)(ii) An explanation including two of the following points: · less /slower movement of water into the plant (1)OR · more / faster

accept: lowers concentration of water outside the plant (than inside) ORA

(2)

movement of water out of the plant (1) · (because) less (free) water outside the plant than inside (1)

(a)(iii) A diffusion (1)


QWC *(b)(ii) An explanation including some of the following points: water · through the xylem· capillary action· osmosis into cells in the leaf· evaporation from leaves· transpiration stream· diffusion into the atmosphere· through stomataglucose · converted to sucrose· dissolved in water· through the phloem·

bidirectionalmineral salts · dissolved in water· through the xylem· from root to tip (6)


· a limited explanation of the transport of one molecule e.g. water moves from roots to leaves· 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 of the transport of two molecules including correct reference to at least one of the vessels phloem or xylem.· 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 of the transport of all three molecules with correct reference to movement through phloem and xylem· the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately· spelling, punctuation and grammar are used with few errors

Q27.


QWC *(ii) An explanation including some of the following points: water · through the xylem· capillary action· osmosis into cells in the leaf· evaporation from leaves· transpiration stream· diffusion into the atmosphere· through stomataglucose · converted to sucrose· dissolved in water· through the phloem·

bidirectionalmineral salts · dissolved in water· through the xylem· from root to tip (6)


· a limited explanation of the transport of one molecule e.g. water moves from roots to leaves· 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 of the transport of two molecules including correct reference to at least one of the vessels phloem or xylem.· 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 of the transport of all three molecules with correct reference to movement through phloem and xylem· the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately· spelling, punctuation and grammar are used with few errors

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