HCI 2023 JC2 Prelim H2 Biology Paper 4 MS (Sharing)

HWA CHONG INSTITUTION / 2022-2023 H2 BIOLOGY / Preliminary Examination Paper 4 / MS 1 HWA CHONG INSTITUTION (COLLEGE SECTION) 2023 JC2 9744 H2 BIOLOGY PRELIMINARY EXAMINATIONS PAPER 4 MARK SCHEME QUESTION 1 Part A Observe and make brief notes of any differences between a leaf from plant A and a leaf from plant B. leaf from plant A is green whereas leaf from plant B has patches of yellow (a) State two differences between the chloroplasts from specimen A and specimen B. [2] any two: 1 extract A has more chloroplasts 2 extract A has green chloroplasts but extract B has colourless / yellow chloroplasts 3 extract A has more developed chlorophyll than extract B (b) Prepare the space below to record your results in an appropriate format so that you can compare extract A with extract B. Include the R f value for each pigment calculated as instructed in step 21. [4] 1 correct table headings without units 2 table layout that compares colour and Rf in the 2 extracts 3 correct observation of colour of pigments 4 location of pigments (c) Label your chromatograms A and B and paste them in the space below using the sticky tapes provided. [1] distance shown to solvent front and front of at least one pigment (d)(i) Other than lack of replicates, suggest one source of error in this procedure and explain how it affects your results. [2] one mark for each statement of the following pairs: L1 location of the pigment position E1 calculation of Rf value may be inaccurate L2 extract may not have been concentrated enough E2 not certain if all the pigments have been extracted (d)(ii) Suggest an improvement that can be made to eliminate the error. [1] any one: 1 use a longer piece of chromatography paper 2 use more leaves to make the extract

HWA CHONG INSTITUTION / 2022-2023 H2 BIOLOGY / Preliminary Examination Paper 4 / MS 2 (e) Plot a graph of the absorbance for the young plants against wavelength of light. [3] 1 scale + correct axis orientation with appropriate labels & units 2 use of different symbols to represent each graph 3 all correct plots (f) From the graph plotted, suggest what conclusions can be made about the number of pigments and about the concentration of pigments in the two sets of young plants. [2] 1 same number of pigments 2 leaf extract from plant A has a higher concentration of pigments (g) Seedlings A and B were grown in different conditions. (i) Based on all your observations and the experimental data available, suggest how the growing conditions were varied. [1] seedling A is grown in light but seedling B is grown in the absence of light (ii) Explain how the results from all your observations and the e