R3101 PLANT TAXONOMY, STRUCTURE & FUNCTION

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1 INCLUDING EXAMINERS COMMENTS R3101 PLANT TAXONOMY, STRUCTURE & FUNCTION Level 3 Wednesday 22 June :30 11:10 Written Examination Candidate Number:. Candidate Name:. Centre Number/Name: IMPORTANT Please read carefully before commencing: i) The duration of this paper is 100 minutes; ii) iii) iv) ALL questions should be attempted; EACH question carries 10 marks; Write your answers legibly in the spaces provided. It is NOT necessary that all lined space is used in answering the questions; v) Use METRIC measurements only; vi) vii) viii) ix) Use black or blue ink only. Pencil may be used for drawing purposes only; Where plant names are required, they should include genus, species and where appropriate, cultivar; Where a question requires a specific number of answers; only the first answers given that meet the question requirement will be accepted, regardless of the number of answers offered; Please note, when the word distinct is used within a question, it means that the items have different characteristics or features. Ofqual Unit Code H/505/2966 Please turn over/..

2 ANSWER ALL QUESTIONS MARKS Q1 a) Place EACH of the following plants in the group to which they belong, by completing the table below: i) cycads; ii) ginkgo biloba; iii) liverworts; iv) horsetails. 4 BRYOPHYTES PTERIDOPHYTES GYMNOSPERMS i) ii) iii) iv) Please see over/.. 2

3 b) c) Describe how mosses spread. State the conditions that favour the growth of mosses in a garden.... MARKS 4 2 Total Mark Please turn over/.. 3

4 Q2 a) Describe what is meant by the taxonomic hierarchy. MARKS 6 Please see over/.. 4

5 b) c) One type of Michaelmas daisy used to be called Aster novae-angliae L. State what L. signifies. Aster novae-angliae is now called Symphyotrichum novae-angliae. Explain ONE possible reason for changes in nomenclature. MARKS 2 2 Total Mark Please turn over/.. 5

6 MARKS Q3 a) Label the position of EACH of the following tissues on the diagram below: i) phellogen (cork cambium); ii) phelloderm (secondary cortex); iii) secondary phloem; iv) phellem (cork). 4 Please see over/.. 6

7 MARKS b) Describe the structure of the cells in EACH of the following tissues: i) phellem; ii) phellogen. 2 2 c) Describe the structure and function of radial parenchyma (ray) Total Mark Please turn over/.. 7

8 Q4 a) Describe EACH of the following plant growth regulators by completing the table below. MARKS 8 Properties Effects Abscisic acid Ethene (ethylene) Please see over/.. 8

9 MARKS b) State ONE use of synthetic ethene in a NAMED horticultural crop.. 2 Total Mark Please turn over/.. 9

10 Q5 Identify EACH of the following types of inflorescence and give a NAMED plant example of each. MARKS 10 a) Type of inflorescence Named plant example.... b) Type of inflorescence Named plant example Please see over/..

11 MARKS c) Type of inflorescence... Named plant example..... d) Type of inflorescence Named plant example.... Total Mark e) Type of inflorescence Named plant example.... Please turn over/.. 11

12 Q6 a) b) Describe the light independent reaction of photosynthesis. State how photosynthesis in CAM plants differs from C3 plants in terms of carbon dioxide fixation. MARKS 4 2 Please see over/.. 12

13 MARKS c) Explain how CAM photosynthesis enables a NAMED plant to thrive in its natural habitat. 4 Total Mark Please turn over/.. 13

14 Q7 a) b) Describe TWO distinct examples of horticultural situations where anaerobic conditions may develop. Describe the effect on a plant of anaerobic conditions developing. MARKS 4 3 Please see over/.. 14

15 MARKS c) Describe how plants can survive in temporary or permanent anaerobic conditions. 3 Total Mark Please turn over/.. 15

16 MARKS Q8 a) Describe the apoplast route of water movement across the root from the soil to the vascular tissue. 6 Please see over/.. 16

17 b) State what is meant by the symplast pathway. MARKS 1 c) Describe how mineral nutrients enter the symplast pathway in the root.. Please turn over/ Total Mark

18 MARKS Q9 Explain how successful pollination is achieved when growing EACH of the following: i) apples in orchards; ii) maize on an allotment. 7 3 Please see over/.. 18

19 MARKS Total Mark... Please turn over/.. 19

20 Q10 Describe how natural plant growth regulators bring about EACH of the following plant responses: i) growth in length of plant stems; ii) boxed cut flower stems of Gladiolus cultivars bend upwards if the boxes are laid flat. MARKS 6 4 Please see over/.. 20

21 MARKS ******* 21 Total Mark

22 DO NOT USE THIS PAGE 22

23 DO NOT USE THIS PAGE 23

24 These questions are the property of the Royal Horticultural Society. They must not be reproduced or sold. The Royal Horticultural Society, Wisley, Woking, Surrey GU23 6QB. Charity Registration Number: /SC

25 R3101 PLANT TAXONOMY, STRUCTURE & FUNCTION Level 3 Wednesday 22 June 2016 Candidates Registered 57 Total Candidates Passed % Candidates Entered 47 Passed with Commendation % Candidates Absent/Withdrawn 10 Passed % Candidates Deferred 0 Failed % Senior Examiner s Comments On the whole this paper was well answered with the majority of candidates attempting and completing all the questions. The following guidelines should be of help to future candidates. 1. Where named plant examples are asked for, full botanical names (genus and species) are required to achieve full marks. Common names will not be given a mark. 2. Use the command statements e.g. list or name (single words only), state (a few sentences), describe or explain (a fuller answer) together with the mark allocation, to judge the depth of the answer. Half marks are often allocated where the basic information given is correct but needs further qualification to gain the full mark. 3. Where a number of answers are specified in the question, the examiner will not select correct answers from a list e.g. if the question states State TWO plant names, only the first two names given will be marked. 4. Labels on diagrams should be correctly positioned to avoid ambiguity and diagrams should be clearly drawn and annotated. No marks will be awarded for artistic merit. 5. Candidates should use unambiguous plant examples as reference sources from, for example, the RHS Find a Plant Service available on the RHS Website. 25

26 Q1 a) Place EACH of the following plants in the group to which they belong, by completing the table below: v) cycads; vi) ginkgo biloba; vii) liverworts; viii) horsetails. MARKS 4 i) BRYOPHYTES PTERIDOPHYTES GYMNOSPERMS ii) iii) iv) Q1 b) Describe how mosses spread. 4 c) State the conditions that favour the growth of mosses in a garden. 2 Q1a) Generally well answered. Most candidates recognised that cycads and Ginkgo biloba are Gymnosperms, liverworts are Bryophytes and horsetails are Pteridophytes. Q1b) Better candidates focussed on the spread of mosses by describing the production and release of wind-borne spores from the sporophyte rather than by giving details of moss reproduction and lifecycle. Many incorrectly stated that mosses spread by sperm rather than spores. Q1c) The most common condition mentioned was moisture, followed by shade and high humidity. Better candidates qualified their answers e.g. shade due to overhanging trees or moisture due to poor drainage in a lawn. 26

27 MARKS Q2 a) Describe what is meant by the taxonomic hierarchy. 6 b) One type of Michaelmas daisy used to be called Aster novae-angliae L. State what L. signifies. 2 c) Aster novae-angliae is now called Symphyotrichum novae-angliae. Explain ONE possible reason for changes in nomenclature. 2 Q2a) Some of the candidates had difficulty in describing clearly what was meant by the taxonomic hierarchy and tended to give a lot of irrelevant information. Better candidates stated that it is a classification system which progressively subdivides the Plant Kingdom into a series of groups or ranks based on the similarity of plants within each rank with the species being the basic unit. Credit was given for naming ranks. Some candidates confused classification with nomenclature, the former is the process of putting plants into groups in the hierarchy whilst the latter is about giving them a name. Q2b) Most of the candidates knew that L. signifies the person who named or published the name of the plant species, in this case L. standing for Carl Linnaeus. Q2c) The most popular reason for name changes given was reclassification often due to new discoveries, which places a species in a different genus or family. Better candidates described what the new information could be based on, or gave an example. Some candidates correctly stated that a name change can be due to an earlier name being found, the Rule of Priority, and good candidates recognised that this is change due to the rules of nomenclature rather than a reclassification. A very few candidates also mentioned plants being introduced with the wrong name altogether, i.e. misidentification. Credit was also given where the change in name of Aster novae-angliae specifically was given as reclassification due to DNA evidence. 27

MARKS Q3 a) Label the position of EACH of the following tissues on the diagram below: 4 v) phellogen (cork cambium); vi) phelloderm (secondary cortex); vii) secondary phloem; viii) phellem (cork).

28 MARKS Q3 a) Label the position of EACH of the following tissues on the diagram below: 4 v) phellogen (cork cambium); vi) phelloderm (secondary cortex); vii) secondary phloem; viii) phellem (cork). b) Describe the structure of the cells in EACH of the following tissues: iii) iv) phellem; phellogen. c) Describe the structure and function of radial parenchyma (ray) Q3a) Some candidates confused phelloderm with cortex and primary phloem with secondary phloem on the diagram. The correct location of the named tissues is as shown below. Q3b) Better candidates described the structure of phellem and phellogen tissues and cells. Details of the function of these tissues were not asked for. For example, phellem is made up of cube-shaped cells whose contents have been replaced by a central lumen. Their cell wall is thickened with the wax suberin. Since it is a meristem, phellogen contains cells which are tightly packed with dense cytoplasm, a small vacuole and thin cell walls. Q3c) Full marks were obtained where candidates described at least one function and one structural characteristic of radial parenchyma cells/tissue. MARKS 28

29 Q4 a) Describe EACH of the following plant growth regulators by completing the table below. 8 Properties Effects Abscisic acid Ethene (ethylene) b) State ONE use of synthetic ethene in a NAMED horticultural crop. 2 Q4a) Candidates often found it difficult to distinguish between properties and effects of plant growth regulators, (PGRs) and were more familiar with the latter. Properties could include site of synthesis and direction of movement for each, the fact that abscisic acid (ABA) is continuously broken down and remade, or that ethene is a gas and is produced as a precursor which is transported through the plant. Most candidates knew that ABA is involved in stomatal closure due to water stress, and promotion of dormancy in seeds and buds. Similarly almost all gave fruit ripening as an effect of ethene but were less familiar with its promotion of senescence, abscission and epinasty. Better candidates stated whether the PGR promoted or inhibited a particular plant function or process rather than just saying it was involved in it. Q4b) Since there were only 2 marks allocated for this part of the question, successful candidates did not spend time describing the use of ethene in a horticultural crop in detail but just gave an application and a botanical name for the appropriate crop e.g. suppression of sprouting in stored potatoes (Solanum tuberosum). The full botanical name of the crop should be given. 29

30 Q5 Identify EACH of the following types of inflorescence and give a NAMED plant example of each. MARKS 10 a) Type of inflorescence Named plant example.... b) Type of inflorescence Named plant example.... c) Type of inflorescence Named plant example

31 d) Type of inflorescence Named plant example.... e) Type of inflorescence Named plant example.... Q5) This question was answered well. Most candidates were able to identify some of the Inflorescences and give a named example. These were in order, a raceme, a corymb, a cyme, a spike and a panicle. Full marks were given where the full binomial name of a plant example was given rather than just a genus since a mark could only be awarded if all the species in a genus have the particular type of inflorescence. Marks could not be given for obscure plant examples which could not be easily verified. 31

32 MARKS Q6 a) Describe the light independent reaction of photosynthesis. 4 b) State how photosynthesis in CAM plants differs from C3 plants in terms of carbon dioxide fixation. 2 c) Explain how CAM photosynthesis enables a NAMED plant to thrive in its natural habitat. 4 Q6 a) Although the process of photosynthesis was generally well understood, many candidates described both light dependent (light reactions) and light independent (dark reactions) reactions rather than the latter as asked. Mention of the uptake of carbon dioxide and production of glucose by a multiple stage enzyme driven process, using ATP and NADPH generated from the light dependent reactions, and the location of the light independent reaction in the stroma of the chloroplast all gained marks. Q6 b) Many candidates spent time giving detailed descriptions of CAM plants although there were only 2 marks for this section. The difference between C3 and CAM plants only in terms of CO2 fixation was asked for and could be simply given as CO2 is initially fixed into a 4-carbon molecule (e.g. malic acid) in CAM plants rather than a 3-carbon molecule in C3 plants. Q6 c) Most candidates were able to describe how CAM plants live in high temperature arid environments and open their stomata at night to trap CO2. Fewer mentioned that they closed them during the day to reduce transpiration loss. Better candidates understood that CO2 is trapped in malic acid and stored in cell vacuoles at night. Some wrongly stated that photosynthesis takes place at night rather than during the day. CO2 is released from the malic acid during the day and fed into the light independent reaction to allow the production of glucose. Most candidates were able to name a CAM plant e.g. Kalanchoe daigremontianum, or Crassula ovata. Details of other adaptations to low water environments were not credited. 32

33 MARKS Q7 a) Describe TWO distinct examples of horticultural situations where anaerobic conditions may develop. 4 b) Describe the effect on a plant of anaerobic conditions developing. 3 c) Describe how plants can survive in temporary or permanent anaerobic conditions. 3 Q7 a) Marks were awarded for describing a horticultural situation e.g. a flooded border or overuse of heavy machinery, together with a description of why anaerobic conditions develop such as water filling the pore spaces or compaction reducing pore space for air in the soil. Q7 b) Better candidates stated that anaerobic conditions lead to anaerobic respiration in the roots which gives a lower energy yield and produces toxic ethanol. They went on to fully describe how this leads to reduced growth and leaf symptoms such as wilting or chlorosis due to death of root tissue and reduced uptake of water and minerals. Q7 c) Candidates who scored highly gave detailed descriptions of mechanisms plants use to overcome anaerobic conditions. For example, oxygen can be channelled to roots from the aerial parts of the plant through aerenchyma in the stem, (parenchyma with large air - filled spaces) which connects with root parenchyma. Other methods included detoxification of ethanol, and stomata on the upper surface rather than the lower surface of floating leaves. 33

34 MARKS Q8 a) Describe the apoplast route of water movement across the root from the soil to the vascular tissue. 6 b) State what is meant by the symplast pathway. 1 c) Describe how mineral nutrients enter the symplast pathway in the root. 3 Q8 a) Many candidates described the pathway of water movement through the whole plant rather than just through the root, or described the symplast pathway as well as or instead of the apoplast pathway. In the apoplast pathway water moves between the cells in the cell walls and intercellular spaces, from the root hairs/epidermis across the cortex to the endodermis. Here it leaves the apoplast and enters the symplast pathway by crossing the cell membrane. Better candidates described the Casparian strip as a band of waterproof wax (suberin) in the endodermal cell walls (not in the cell membrane) which prevents further movement between cells in the apoplast pathway. Few candidates mentioned water returning to the apoplast to cross the pericycle to the xylem. Q8 b) A simple statement that the symplast pathway is through living cells was sufficient to gain the mark. Q8 c) Full marks were awarded for candidates who stated that minerals cross the cell membrane selectively and enter the symplast by active transport using energy on protein carriers, then diffuse through the symplast in the cytoplasm via plasmodesmata. Many candidates stated that mineral uptake is by osmosis which is incorrect as this is the uptake of water across the cell membrane, not minerals, and some described cation exchange between roots and soil particles rather than mineral transport into the root cells. 34

35 MARKS Q9 Explain how successful pollination is achieved when growing EACH of the following: iii) iv) apples in orchards; maize on an allotment. 7 3 Q9 i) Some candidates described the process of pollination which was not asked for. When stating correctly that apples must be cross pollinated, some candidates incorrectly said this was due to dioecy and/or diploidy. Better candidates stated that two different cultivars (not trees or species) are needed for fruit set in diploid apples. These cultivars need to be genetically compatible and flower at the same time i.e. be in similar flowering groups. For triploid apples, three cultivars are required if all trees are to fruit as the triploid apple does not produce viable pollen. Any method used to encourage or facilitate cross pollination in orchards including introducing bee hives, grafting scions of compatible cultivars onto trees, interplanting the different cultivars, providing shelter from wind, avoiding frost pockets and using pesticides appropriately were rewarded. Bees and other insect pollinators can be attracted by planting flowering plants around the edges of orchards. Q9 ii) Some candidates wrongly described maize as dioecious rather than monoecious but all were able to state that it is wind pollinated and most commented that it must be cross pollinated. The most popular method for enhancing pollination was by growing in blocks or in rows aligned with the prevailing wind, also some candidates mentioned hand pollination by shaking the tassels to release pollen. 35

36 MARKS Q10 Describe how natural plant growth regulators bring about EACH of the following plant responses: iii) iv) growth in length of plant stems; boxed cut flower stems of Gladiolus cultivars bend upwards if the boxes are laid flat. 6 4 Q10 i) Full marks were awarded where the three plant growth regulators involved in stem elongation were mentioned together with their contributions. Cytokinin brings about cell division at the apex, auxin causes cell expansion behind the apex and gibberellin stimulates cell expansion leading to internode elongation especially in rosette biennials. Q10 ii) Descriptions of negative geotropism, where candidates assumed that the boxes did not allow entry of light, or positive phototropism, where candidates described the effect of light on the cut flower stems, were both credited. Auxin produced at the apex is translocated down the stem and accumulates on the lower/bottom side or shaded side of the stem causing cell expansion. This leads to growth upwards. For geotropism description of the gravity sensing mechanism also gained marks. These questions are the property of the Royal Horticultural Society. They must not be reproduced or sold. The Royal Horticultural Society, Wisley, Woking, Surrey GU23 6QB. Charity Registration Number: /SC

R2101 PLANT CLASSIFICATION, STRUCTURE & FUNCTION

R2101 PLANT CLASSIFICATION, STRUCTURE & FUNCTION WITHOUT EXAMINERS COMMENTS R0 PLANT CLASSIFICATION, STRUCTURE & FUNCTION Level Monday 5 February 08 09:30 0:50 Written Examination Candidate Number: Candidate Name: Centre Number/Name:.. IMPORTANT Please