T3W5 ZHSS 4E BIO Prelim P2 2023 A4 Final

[Turn over ZHONGHUA SECONDARY SCHOOL PRELIMINARY EXAMINATION 2023 SECONDARY 4 EXPRESS Candidate Name Class Register Number 4E5 BIOLOGY 6093 /02 14 September 2023 1 hour 45 minutes Additional Materials: Nil READ THESE INSTRUCTIONS FIRST Write your name, index number and class in the spaces at the top of this page. Write in dark blue or black pen. You may use a pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Section A Answer all questions. Write your answers in the spaces provided on the question paper. Section B For Examiner’s Use Answer all three questions, the last question is in the form Either/Or. Write your answers in the spaces provided. Section A 50 B7 10 You are advised to spend no longer than one hour on Section A and no longer than 45 minutes on Section B. B8 10 B9 E / O 10 The number of marks is given in brackets [ ] at the end of each question or part question. All essential working must be shown clearly. Total 80 This document consists of 20 printed pages.

2 Section A Answer all questions. Write your answers in the spaces provided. 1 A contractile vacuole is found in some unicellular organisms. It is a structure that periodically expands, filling with water, and then contracts, expelling its contents out of the cell. In an experiment, a marine unicellular organism was placed in several dilutions of seawater. The output rate of its contractile vacuole and changes in its body volume were measured and recorded. Fig. 1.1 shows the data collected during the experiment. Fig. 1.1 (a) Besides water, name another substance that can also enter the contractile vacuole. [1]

3 [Turn over (b) Describe and explain the effect on the rate of contractile vacuole output as the percentage of seawater increases from 20% to 100%. [3] (c) Describe one other relationship observed in Fig. 1.1 as the percentage of seawater increases from 20% to 100%. [1] (d) Suggest and explain what has happened to the marine unicellular organism at 10% seawater. [2] [Total: 7]

4 2 Fig. 2.1 shows the oxygen uptake before, during and after strenuous exercise. Fig. 2.1 Fig. 2.2 shows the lactic acid concentration in blood samples taken at different time intervals during and after exercise. Fig. 2.2 (a) (i) On Fig. 2.1, mark with the letter D, the area that shows oxygen deficit. [1] lactic acid / mMl-1 time / min

5 [Turn over (ii) State a reason for this oxygen deficit. [1] (b) With refe