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Surname Centre Number Candidate Signature Other Names Candidate Number Leave blank General Certificate of Education June 2004 Advanced Level Examination BIOLOGY/HUMAN BIOLOGY (SPECIFICATION A) Unit 5 Inheritance, Evolution and Ecosystems Tuesday 22 June 2004 Morning Session No additional materials are required. You may use a calculator. BYA5 For Examiner’s Use Number 1 2 Mark Number Mark Time allowed: 1 hour 30 minutes Instructions • Use blue or black ink or ball-point pen. • Fill in the boxes at the top of this page. • Answer all questions in the spaces provided. All working must be shown. Do all rough work in this book. Cross through any work you do not want marked. Information • The maximum mark for this paper is 75. • Mark allocations are shown in brackets. • You will be assessed on your ability to use an appropriate form and style of writing, to organise relevant information clearly and coherently, and to use specialist vocabulary, where appropriate. • The degree of legibility of your handwriting and the level of accuracy of your spelling, punctuation and grammar will also be taken into account. 3 4 5 6 7 8 Total (Column 1) Total (Column 2) TOTAL > Examiner’s Initials APW/0204/BYA5 BYA5 2 Answer all questions in the spaces provided. LEAVE MARGIN BLANK 1 The drawings show three cells. Two of the cells are from multicellular organisms and one is a single-celled organism. The three organisms belong to different kingdoms. 30 µm 60 µm 1 µm Cell A Cell B Cell C Name the kingdom to which each organism belongs. In each case, give one feature of the cell, visible in the drawing, which is characteristic of the kingdom and which helps to distinguish it from cells of organisms belonging to the other two kingdoms. Cell A Kingdom ................................................................................................................................ Feature ................................................................................................................................... ................................................................................................................................................. Cell B Kingdom ................................................................................................................................ Feature ................................................................................................................................... ................................................................................................................................................. Cell C Kingdom ................................................................................................................................ Feature ................................................................................................................................... ................................................................................................................................................ (6 marks) 6 APW/0204/BYA5 3 LEAVE MARGIN BLANK 2 Division of the nucleus by meiosis produces haploid cells from a diploid cell. Nuclei produced by mitosis have the same number of chromosomes as the parent nucleus. (a) What is the biological importance of reducing the chromosome number when the cell divides by meiosis? ....................................................................................................................................................... ...................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... (2 marks) (b) The table gives one difference between meiosis and mitosis. Complete the table by giving three further differences. Meiosis Mitosis 1 Reduces the chromosome number Maintains the same chromosome number as in the parent nucleus 2 3 4 (3 marks) 5 Turn over APW/0204/BYA5 4 LEAVE MARGIN BLANK 3 Phytoplankton are microscopic photosynthesising organisms which live in water. In favourable environmental conditions they have a very high rate of reproduction. They are eaten by microscopic animals called zooplankton. In an investigation, samples of water were removed from a lake at intervals over a twelve-month period and the biomasses of these organisms were determined. The results are shown in the graph. Phytoplankton Biomass Zooplankton Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month The diagram shows the relationship between the biomass of the phytoplankton and the biomass of the zooplankton for one of the months during this investigation. Zooplankton Phytoplankton (a) Use the graph to give one month in which this relationship would have been found. ....................................................................................................................................................... (1 mark) APW/0204/BYA5 5 LEAVE MARGIN BLANK (b) Explain why the biomass of the primary consumers is less than the biomass of the producers in most communities. ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... ............................................................................ .......................................................................... ....................................................................................................................................................... ....................................................................................................................................................... (3 marks) (c) Explain why the biomass of the phytoplankton in the lake could be less than that of the zooplankton, as shown in the diagram. ...................................................................................................................................................... ....................................................................................................................................................... (1 mark) 5 TURN OVER FOR THE NEXT QUESTION Turn over APW/0204/BYA5 6 LEAVE MARGIN BLANK 4 The two sets of apparatus shown in the diagram were used to find the volume of oxygen used and the volume of carbon dioxide produced by germinating castor oil seeds. Both A and B contained the same mass of seeds. Apparatus A also contained a small test tube of potassium hydroxide pellets which absorbed carbon dioxide from the air in the apparatus. Over a 24-hour period, the water rose up the glass tube in each apparatus. The water rose further in apparatus A than in apparatus B. A Test tube containing potassium hydroxide pellets (absorb carbon dioxide) 70 60 50 40 30 20 10 0 B Germinating castor oil seeds Water APW/0204/BYA5 7 LEAVE MARGIN BLANK (a) The changes in volume of gas in apparatus A and in apparatus B were calculated. Explain how the changes in volume in apparatus A and apparatus B could be used to find (i) the volume of oxygen used by the seeds; ...................................................................... ............................................................................................................................................. ............................................................................................................................................. (1 mark) (ii) the volume of carbon dioxide produced by the seeds. ................................................ ............................................................................................................................................ ............................................................................................................................................. ............................................................................................................................................. (2 marks) (b) (i) The main food reserve of castor oil seeds is a substance called triricinolein. The equation shows oxidation of this substance. 2 C57H104O9 + 157 O2 14 CO2 + 104 H2O Use the equation to calculate the respiratory quotient (RQ) when triricinolein is used as the respiratory substrate. Show your working. RQ = ............................................... (2 marks) (ii) The RQ for the germinating castor oil seeds, determined using the apparatus in the diagram, was 0. 85. Apart from experimental error, suggest one reason for the difference between this value and the answer to part (b)(i). ............................................................................................................................................. ............................................................................................................................................ (1 mark) 6 Turn over APW/0204/BYA5 8 LEAVE MARGIN BLANK 5 Mayflies are insects which lay their eggs in streams and rivers. The nymphs which hatch from the eggs live in the water for several years. Mayfly nymphs were collected by disturbing the gravel of a stream bed. A net placed immediately downstream caught any animals which were washed out of the gravel. Eight samples were collected from shallow, fast-flowing parts of the stream and eight from deeper, slow-flowing parts. Nymphs from two different families of mayfly were found. The results are given in the table. Family Caenidae Shallow water Mean number of nymphs Standard deviation 2. 38 1. 51 Deep water 12. 88 7. 92 Family Baetidae Shallow water 24. 50 6. 72 Deep water 6. 00 1. 51 (a) Describe how you would have collected the samples in order to ensure they were representative of the habitats being investigated and could be compared with each other. ...................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... ...................................................................................................................................................... ....................................................................................................................................................... (3 marks) (b) Which one of the four samples showed the greatest variation within the sample? Give evidence from the table for your answer. ....................................................................................................................................................... ...................................................................................................................................................... (1 mark) (c) The two families of mayfly nymph occupy different ecological niches. (i) What is meant by the term ecological niche? ............................................................................................................................................. ............................................................................................................................................. 1 mark) APW/0204/BYA5 9 LEAVE MARGIN BLANK (ii) Describe the evidence in the table which suggests that the two families of mayflies occupy different ecological niches. ............................................................................................................................................. ............................................................................................................................................. (1 mark) (iii) Explain the advantage to these two families of mayflies of occupying different ecological niches. ............................................................................................................................................ ............................................................................................................................................. ............................................................................. ................................................................ ............................................................................................................................................. 2 marks) 8 TURN OVER FOR THE NEXT QUESTION Turn over APW/0204/BYA5 10 LEAVE MARGIN BLANK 6 The diagram shows the light-dependent reactions of photosynthesis. Electron acceptor B Electron acceptor NADP C electrons electrons ATP electrons Chlorophyll Chlorophyll electrons 4H2O 4OH– + 4H+ LIGHT LIGHT 2H2O + A (a) In which part of a chloroplast do the light-dependent reactions occur? ....................................................................................................................................................... 1 mark) (b) Name the substances in boxes A, B and C. A ................................................................ B ............................ + ............................. C ................................................................. (3 marks) APW/0204/BYA5 11 LEAVE MARGIN BLANK (c) Use information in the diagram to explain (i) the role of chlorophyll in photolysis; ............................................................................................................................................. ............................................................................................................................................ ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................ (3 marks) (ii) how the energy of light is converted into chemical energy in the light-dependent reactions. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................ ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. 3 marks) QUESTION 6 CONTINUES ON THE NEXT PAGE Turn over APW/0204/BYA5 12 LEAVE MARGIN BLANK (d) In an investigation, single-celled algae were kept in bright light and were supplied with carbon dioxide containing radioactive carbon atoms. After 300 seconds, the carbon dioxide supply was turned off. The graph shows how the concentrations of carbon dioxide, glycerate 3-phosphate (GP) and ribulose bisphosphate (RuBP) changed. 3 Carbon dioxide 2 Concentration / arbitrary units GP RuBP 1 0 100 200 Time / s (i) Explain why, between 0 seconds and 300 seconds, the concentration of radioactive GP remained constant. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................ ............................................................................................................................................. ............................................................................................................................................. (3 marks) 300 400 (ii) Explain why, between 300 seconds and 380 seconds, the concentration of radioactive RuBP increased. ............................................................................................................................................ ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (2 marks) 15 APW/0204/BYA5

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