Biology A2

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS widely distributed Certificate of Education Advanced Level * 2 3 0 8 9 6 9 9 7 3 * BIOLOGY Paper 5 Planning, Analysis and Evaluation Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS eldest Write your Centre bod, candidate number and name on exclusively the work you hand in. Write in dark blue or black ink. You may use a pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. final result all distrusts.At the end of the examination, fasten all your work securely together. The number of marks is given in brackets at the end of each question or part question. 9700/51 October/November 2011 1 hour 15 proceedings For testers custom 1 2 Total This memorandum consists of 8 printed pages. DC (CB (SE/DJ)) 34786/4 UCLES 2011 Turn over 2 1 Photosynthesis was investigated in a species o f unicellular alga using the apparatus shown in Fig. 1. 1. reprieve of unicellular algae in water For Examiners Use 10. 0 light of known wavelength oxygen probe magnetic scaremonger Fig. 1. Two different material bodys of the species of alga were tested using a shop of different wavelengths of light. Light of known wavelength was passed through the tube containing algae for 2 hours. The light transmission through the suspension and the oxygen concentration were accordingly measured. light meter oxygen meter The results were apply to plot the tightness spectrum and the action spectrum for each strain of alga. Fig. 1. 2 shows these spectra. strain A strain B absorbance absorption spectra 400 500 600 700 wavelength of light / nm lay of photosynthesis action spectra 400 500 600 700 wavelength of light / nm Fig. . 2 UCLES 2011 9700/51/O/N/11 3 (a) (i) farming the 2 unfree variables in this investigation. 1. 2. .. 2 (ii) Apart from temperature and pH, which have little eff ect, evidence two variables that should be standardised during this investigation. 1. . .. 2 (b) (i) Water with no suspended algae transmits 100% of the light. State how the data to plot the absorption spectrum was obtained. . .. 1 (ii) State the data which would be used to plot the action spectrum. . 1 The photosynthetic pigments of the algae were extracted and were illogical by bipartizan chromatography. The pigments were first separated by virtuoso settlement and then separated again by a second dis resultant at honorable angles to the first solvent. Fig. 1. 3. shows the results for the two different strains. strain A solvent cause 1 4 3 2 direction of first solvent 1 origin 6 1 origin 5 3 2 6 strain B 5 solvent face 1 For Examiners Use solvent front 2 direction of second solvent Fig. . 3 solvent front 2 (c) Using the information in Fig. 1. 3, suggest why using two different solvents gives a better separation of these pigments than just using one solvent. .. . 2 UCLE S 2011 9700/51/O/N/11 Turn over 4 (d) chalk out a action that a student could use to extract the photosynthetic pigments and obtain these chromatograms. .. .. .. .. .. .. . .. . 8 For Examiners Use UCLES 2011 9700/51/O/N/11 5 (e) Different photosynthetic pigments absorb different wavelengths of light. elude 1. 1 shows some information about the pigments, P, Q, R, S and T, found in these unicellular algae, including the wavelength of light at which maximum light absorption occurs. circuit card 1. 1 pigment wavelength of light / nm 620 545 and 547 420 and 660 490 430 and 645 Rf value solvent 1 0. 20 0. 60 0. 65 0. 91 0. 82 solvent 2 0. 89 0. 29 0. 11 0. 19 0. 92 For Examiners Use P Q R S T Rf = distance moved by pigment distance moved by solvent frontOne of the strains of algae lacks one of the pigments. Using the information in flurry 1. 1, Fig. 1. 2 and Fig. 1. 3 (i) identify the strain of alga that lacks one of these pigments and state the letter of the missin g pigment .. 1 (ii) state the evidence that supports your answer to (i). . . .. 2 (iii) In water, the shorter the wavelength of light, the deeper it travels. Suggest why it is an advantage to have the pigment that you identified in (i). . . .. 1 Total 20 UCLES 2011 9700/51/O/N/11 Turn over 2 A student carried out some investigations into the inheritance of body colour and lengthiness length in the fruit fly, Drosophila melanogaster, to test the hypothesis The inheritance of body colour and wing length in fruit travel is controlled by two genes on separate chromosomes. The student carried out troika genetic crosses. To carry out each cross the following procedure was used male and virgin female adult fruit travel were placed into a breeding unit containing a culture intermediate for their larvae after mating and egg laying, the adult fruit flies were aloof newly emerged adult fruit flies were sexed by observant the shape of the last