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Transcript
Including Examiner Comments R3101 PLANT TAXONOMY, STRUCTURE & FUNCTION Level 3 Wednesday 25 June 2014 09:30 – 11:00 Written Examination Candidate Number: Candidate Name: Centre Number/Name: IMPORTANT – Please read carefully before commencing: i) The duration of this paper is 90 minutes; ii) ALL questions should be attempted; iii) EACH question carries 10 marks; iv) 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) Use black or blue ink only. Pencil may be used for drawings only; vii) Where plant names are required, they should include genus, species and where appropriate, cultivar; viii) 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; ix) 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/….. ANSWER ALL QUESTIONS MARKS Q1 Describe FIVE characteristics of angiosperms that allow them to grow and reproduce on land. 10 …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. Please see over/….. 2 MARKS …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. Total Mark ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. Please turn over/….. 3 MARKS Q2 a) State what is meant by the term ‘species’ giving ONE NAMED plant example. 2 …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... b) Differentiate between subspecies and varietas (variety) giving a NAMED example for EACH. 4 …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. Please see over/….. 4 MARKS …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. c) State the reasons for changes in plant nomenclature. 4 …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. Total Mark …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. Please turn over/….. 5 MARKS Q3 Describe, with the aid of diagram(s), the structure AND function of: i) ii) phloem sieve tube elements; phloem companion cells. 5 5 Please see over/….. 6 MARKS …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. Total Mark …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. Please turn over/….. 7 MARKS Q4 a) Describe the following types of inflorescence giving a NAMED example for EACH: i) ii) iii) spike; panicle; verticillaster. 2 2 2 …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. Please see over/….. 8 MARKS b) Compare the structure of a raceme and a cyme. 4 …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. Total Mark …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. Please turn over/….. 9 MARKS Q5 Explain, using ONE NAMED plant example in EACH case, how specific names can indicate: i) ii) iii) iv) v) plant origin; habitat; colour; growth habit; leaf form. 2 2 2 2 2 …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. Please see over/….. 10 MARKS ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... ………………………………………………………………………………………..... ………………………………………………………………………………………..... ………………………………………………………………………………………..... Total Mark …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. Please turn over/….. 11 MARKS Q6 a) State the environmental factors that could affect the rate of photosynthesis for EACH of the following: i) ii) light dependent reaction; light independent reaction. 3 2 …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. Please see over/….. 12 MARKS b) Explain how levels of carbon dioxide can be manipulated in protected cultivation to produce an optimum rate of photosynthesis. 5 …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. Total Mark …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. Please turn over/….. 13 MARKS Q7 State the role of the following tissues in secondary thickening in a woody stem: i) ii) vascular cambium; cork cambium. 6 4 …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. Please see over/….. 14 MARKS …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. Total Mark …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. Please turn over/….. 15 MARKS Q8 a) Describe the process of water transport in a plant. 8 …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. Please see over/….. 16 MARKS …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. b) Explain how this process can still occur in conditions of very high humidity. 2 …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. ………………………………………………………………………………………..... Total Mark …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. Please turn over/….. 17 MARKS Q9 Compare aerobic and anaerobic respiration by completing the table below. Aerobic respiration Anaerobic respiration Environmental requirements 2 Products 2 Energy yield ATP 2 Location in cell 2 Example of growing situation where process occurs 2 Please see over/….. 18 MARKS (Use this page for any notes/workings) …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. Total Mark …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. Please turn over/….. 19 MARKS Q10 a) State what is meant by a synthetic plant growth regulator. 2 ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. ………………………………………………………………………………………..... b) Describe the use of TWO NAMED synthetic plant growth regulators. 8 …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. Please see over/….. 20 MARKS …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ……………………………………………………………………………………….… ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………..... …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ******* 21 Total Mark DO NOT USE THIS PAGE 22 DO NOT USE THIS PAGE 23 ©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: 222879/SC038262 24 R3101 PLANT TAXONOMY, STRUCTURE & FUNCTION Level 3 Wednesday 25 June 2014 Candidates Registered Candidates Entered Candidates Absent Candidates Deferred Candidates Withdrawn 70 50 13 1 6 71.43% 18.57% 1.43% 8.57% Total Candidates Passed Passed with Commendation Passed Failed 36 19 17 14 72.0% 38.0% 34.0% 28.0% General comments Candidates should ensure that they are prepared to answer questions on all aspects of the syllabus and to attempt all questions. Diagrams should be large, clear, labelled and preferably drawn in pencil. Examples of plant names should include genus, species and where appropriate cultivar. There should be sufficient room in the answer booklet for candidates to complete drawings/answers on the page without using the marks column. Q1 Describe FIVE characteristics of angiosperms that allow them to grow and reproduce on land. This question required candidates to identify and describe five structural and reproductive characteristics of angiosperms in relation to their adaptation to terrestrial life. Two marks were awarded for each correctly identified characteristic with a description which indicated successful adaptation for growth and reproduction on land. Many acceptable answers were given and credited where specific characteristics of angiosperms, such as production of flowers for sexual reproduction to protect sex cells/gametes, or to attract specific pollinators, were linked to their success as terrestrial plants. Other credited characteristics included efficient water transport by xylem vessels and tracheids, production of seeds protected by a fruit, variety of seed /fruit dispersal methods, a range of life cycles and growth habits which enables 25 plants to exploit a variety of habitats, structural adaptations to reduce water loss such as bark. Marks were not awarded to answers which related to the general characteristics of plants, such as autotrophic or able to photosynthesise/respire. Q2 a) State what is meant by the term ‘species’ giving ONE NAMED plant example. b) Differentiate between subspecies and varietas (variety) giving a NAMED example for EACH. c) State the reasons for changes in plant nomenclature. In part a), marks were awarded to candidates who understood the term ‘species’, which is the basic unit of classification consisting of a group of similar individuals which can interbreed to produce fertile offspring, and were able to give a correctly named example of a plant species, such as Hedera helix. Some candidates confused ‘species’ with ‘specific epithet’ the second part of the binomial, in this example ‘helix’. The second part of the question asked candidates to differentiate between subspecies and varietas. Subspecies is above varietas in the plant classification hierarchy and differs from the species in a number of characteristics, which have often arisen in a widely geographically isolated population. An example is Malva sylvestris subsp. mauritanica. A varietas (variety), differs from species in one or more characteristics, is ranked lower in hierarchy than subspecies and may evolve due to a more local geographical isolation, an example being Malva alcea var. fastigiata. Marks could not be awarded to candidates who confused the terms variety and cultivar. In part c), candidates were asked to state reasons for changes in plant nomenclature. The reasons for changes in plant nomenclature and reclassification include: reclassification due to advances in plant taxonomic research, particularly advances in DNA profiling, changes following rulings by the International Code of Nomenclature (ICN) or International Code of Nomenclature for Cultivated Plants (ICNCP) such as plant family name changes or implementation of the rule of priority, and changes due to misidentification or misnaming of plant specimens. Marks were awarded to candidates who stated four of the above points. Candidates will have been alerted to the fact that four points were required because of the marks attributed to the question. Q3 Describe, with the aid of diagram(s), the structure AND function of: i) ii) phloem sieve tube elements; phloem companion cells. 26 Candidates’ answers varied in their detail of knowledge about phloem tissue. Marks were awarded to candidates who drew large, clear and accurate diagrams as were candidates who were able to describe aspects of both structure and function of the cells. Marks were awarded in either the diagram or the description. A sieve tube element’s most noticeable structural feature is the sieve plate at each end of the cell. It has a cellulose cell wall, some cell contents but no nucleus and is linked by plasmodesmata to the adjacent companion cell. This has a thin cell wall, nucleus, and cytoplasm containing many mitochondria. The function of the sieve tube elements is to transport sucrose, organic solutes and plant hormones from source to sink. The stacked sieve tubes allow ingress/entry and egress/exit of water from xylem and mass flow. Perforated sieve plates allow movement of water and solutes from tube to tube. The functions of the companion cells include aerobic respiration to provide an energy supply for loading and unloading of sucrose into and out of sieve tube elements and transport within the sieve tube elements. Q4 a) Describe the following types of inflorescence giving a NAMED example for EACH: i) ii) iii) spike; panicle; verticillaster. b) Compare the structure of a raceme and a cyme. Many candidates were able to answer part a) of the question well. Some used diagrams to help describe the structure of each inflorescence. Where named plant examples are asked for candidates should give the full binomial name. A Spike is an inflorescence with a group of flowers sessile on the peduncle, without individual flower stalks. A NAMED example is Acanthus spinosus. A Panicle is a branched raceme. (A flower spike where flowers have stalks of equal length). Each branch has a smaller raceme of flowers. The terminal bud of each branch continues to grow, producing more side shoots and more flowers. A NAMED example is Lagerstroemia indica. A Verticillaster is a whorled inflorescence, where the flowers are borne in rings at intervals up the stem. The tip continues to grow, producing more whorls. A NAMED example is Phlomis russeliana. Fewer candidates were able to achieve full marks describing this inflorescence. Marks were not awarded to candidates who stated that Digitalis purpurea has a spike inflorescence which is wrong as each flower has a short pedicel rather than being sessile on the axis of the inflorescence. In part b), candidates found it difficult to distinguish between a raceme and a cyme. A raceme has the oldest (stalked) flower at the base, and growth of the main inflorescence stalk (peduncle) is not stopped by flower production. Growth is monopodial or indeterminate. 27 A cyme has the oldest flower at the top of inflorescence stalk and all succeeding flowers are formed on succeeding side branches. Growth is sympodial or determinate. Marks were awarded for accurate comparisons and diagrams were helpful, although not asked for, if they showed the structure of the inflorescence and positioning of flowers. Q5 Explain, using ONE NAMED plant example in EACH case, how specific names can indicate: i) ii) iii) iv) v) plant origin; habitat; colour; growth habit; leaf form. This question was answered well by most candidates. Full marks were awarded for examples like v) Leaf form:, if the named plant was Acer palmatum, ‘palmatum’ meaning palmate or shaped like palm leaves with five or more veins arising from a point. Marks were not awarded if candidates confused habitat with growth habit, stating the wrong genus with appropriate specific epithet, giving the wrong interpretation of a stated specific epithet, giving an example of a cultivar name rather than specific epithet and not interpreting their choice of specific epithet. Q6 a) State the environmental factors that could affect the rate of photosynthesis for EACH of the following: i) ii) light dependent reaction; light independent reaction. b) Explain how levels of carbon dioxide can be manipulated in protected cultivation to produce an optimum rate of photosynthesis. Marks were awarded to candidates who mentioned that the light dependent reaction could be affected by light intensity, duration and quality. Candidates were credited who mentioned the appropriate wavelengths of light for PAR. Marks were awarded for mentioning that water is also required for the light dependent reaction and for the uptake of nutrients such as N, Mg, and Fe which are essential for chlorophyll production. Marks were awarded for the factors affecting the light independent reaction that are temperature and atmospheric levels of carbon dioxide (CO2), which can also be affected by levels of water availability. If leaves are water stressed, stomata will close reducing the diffusion of carbon dioxide gas into the leaf. Marks were not awarded when candidates did not distinguish between the light dependent and light independent reactions. Valid answers in part b) covered technical details for method of supply and monitoring of levels of carbon dioxide (CO2) in protected production. 28 Marks were awarded for identifying optimum levels of CO2, methods of supplementing with piped CO2, or by burning propane, kerosene or paraffin, or by utilising exhaust gases from adjacent industry, monitoring CO2 levels with sensors, and ventilating on very bright, warm days to allow more gas exchange with the atmosphere. Q7 State the role of the following tissues in secondary thickening in a woody stem: i) ii) vascular cambium; cork cambium. Some candidates were able to show the role of vascular cambium and cork cambium in secondary thickening. Other candidates showed limited knowledge of the different roles of both tissues. Marks were awarded for answers including statements like vascular cambium is a secondary, lateral meristem, which develops from intra and interfasicular cambium to form a ring of meristematic tissue. As the cambium cells divide they produce secondary xylem tissue to inside of the cambium, and secondary phloem tissue to the outside. Other products are parenchyma for the medullary rays and sclerenchyma. The variation in lumen diameter of the secondary xylem from spring to autumn creates annual rings. The activity of the vascular cambium increases the girth of the stem and also enables greater transport capacity in a woody plant. Six valid points gained full marks for this section. The cork cambium is also a secondary meristem and arises in the outer cortex parenchyma outside the secondary phloem. The meristematic cells (phellogen) divide to produce suberised cork cells (phellem), a protective outer layer to stem, and parenchyma secondary cortex (phelloderm). The activity of the cork cambium also increases the girth of the stem. Candidates who stated terms such as ‘phelloderm’ or labelled layers in their diagrams similarly with no explanation were not given full marks. Four valid points gained full marks for this section. Q8 a) Describe the process of water transport in a plant. b) Explain how this process can still occur in conditions of very high humidity. Many candidates achieved high marks on this question. Some candidates used diagrams, although these were not asked for, to illustrate their answers. In part a), marks were awarded to candidates able to describe the movement of water from the growing medium into the root or root hairs by diffusion into the apoplast pathway or osmosis into the symplast pathway. This root pressure ensured that the flow of water continued across the cortex to the endodermis and then took the symplast pathway because the apoplast route was blocked by the suberised Casparian strip. Water then moved into the xylem vessels in the stele. The main force moving water up the plant in the xylem is transpiration pull, aided by capillary rise and the forces of cohesion between water molecules and adhesion to the walls of the xylem vessels. Water is distributed through the vascular system to the leaves where it evaporates into the air spaces and diffuses into the atmosphere mainly through stomata. 29 Water follows a water potential gradient from the soil, through the plant to the atmosphere. In part b), many candidates understood that transpiration would be slower in conditions of high humidity surrounding the leaves and aerial parts of the plant. Root pressure would continue to force water into the xylem and excess water could be lost by guttation of water droplets from hydathodes on the leaves. Marks were awarded for answers reflecting any two of the above points. Q9 Compare aerobic and anaerobic respiration by completing the table below. The majority of candidates showed detailed knowledge of the processes of aerobic and anaerobic respiration and were able to complete the table. An outline of correct answers is given below. Aerobic respiration Anaerobic respiration Oxygen Low/no oxygen Water Carbon dioxide Ethanol Carbon dioxide Energy yield ATP 38 ATP 2 ATP Location in cell Cytoplasm Mitochondria Cytoplasm Example of growing situation where process occurs Well aerated growing medium Water logged or compacted growing media Environmental requirements Products Q10 a) State what is meant by a synthetic plant growth regulator. b) Describe the use of TWO NAMED synthetic plant growth regulators. This question asked candidates to define what a synthetic plant growth regulator was and to describe the use of two named synthetic plant growth regulators. In part a), many candidates were awarded marks by being able to state that a synthetic plant growth regulator is a manufactured chemical applied to the plant in order to produce specific growth responses or to mimic or inhibit endogenous plant growth regulators. In part b), it was expected that candidates would choose two synthetic PGRs from the syllabus list and describe their mode of action, their purpose in terms of horticultural process, and application method with possible details of formulation and timing for maximum marks. 30 An example of a full answer for one synthetic plant growth regulator would be: Paclobutrazol, which inhibits gibberellin production, is used in bedding plant production to produce uniform, compact, sturdy plants, and increase flowering. Details of its application could include that it is applied as a spray from when plants have made new growth, two weeks after pricking out, and repeated as necessary. Some candidates were able to give the technical details required for their chosen named synthetic plant growth regulators but many were not. ©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: 222879/SC038262 31