2024 VJC H2 Bio P4 MS

VICTORIA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION 2024 HIGHER 2 NAME : ……………………………………………………….………………. CT CLASS: ………………..……… BIOLOGY Paper 4 Practical 9744 / 04 29/08/2024 2 hours 30 minutes Candidates answer on the Question Paper. Additional Materials: As listed in the Confidential Instructions. READ THESE INSTRUCTIONS FIRST Write your name and CT in all the work in hand in. Give details of the practical shift and laboratory, where appropriate, in the boxes provided. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Answer all questions in the spaces provided on the Question Paper. The use of an approved scientific calculator is expected, where appropriate. You may lose marks if you do not show your working or if you do not use appropriate units. At the end of the examination, fasten all your work securely together. The number of marks is given in bracket [ ] at the end of each question or part question. Shift Laboratory Question Marks 1 2 Total This document consists of 18 printed pages. [Turn over]

Answer all questions. Question 1 Researchers are exploring the development of plant-based, biode gradable plastics as an alternative to petroleum-based plastics. Switchgrass is an example of a c rop that synthesises polymers n aturally and is used for biodegradable plastic production. Switchgrass which are genetical ly modified with genes from anot her organism can result in the plants synthesising more polymers. These plants are termed as transgenic plants. The ability to synthesise polymers is highly dependent on the growth rate of the plants, which in turn depends on the rate of photosynthesis. (a) (i) For the same concentration of chloroplasts, predict how the ra te of photosynthesis in the commercially-available switc hgrass chloroplast extract woul d compare to that in the transgenic plant. [1]  The chloroplast extract from the transgenic plant will have a higher rate of photosynthesis; To test for the rate of photosynthesis, the blue dye, DCPIP, wh ich acts as a substitute for NADP+ can be used. oxidised DCPIP (dark blue) photosynthesising tissues reduced DCPIP (colourless) You are required to:  investigate the rate of photosynthesis in different concentrat ions of commercially available switchgrass chloroplast extract  obtain a chloroplast extract from the transgenic plant  estimate the concentration of chloroplasts in the transgenic plant. You are provided with:  15 cm3 commercially available 10% swi tchgrass chloroplast extract, in a small vial labelled SE1  A leaf from transgenic plant labelled T  cold buffer solution, in a large vial labelled B  distilled water, in a large vial labelled W  a block of agar stained with DCPIP. The DCPIP agar may stain your ski