SNGS Prelim 2025 Biology P2 QP

1 Name: _________________________ ( ) Class: _____________ PRELIMINARY EXAMINATION GENERAL CERTIFICATE OF EDUCATION ORDINARY LEVEL BIOLOGY 6093/02 Wednesday 27 August 2025 1 hour 45 minutes _____________________________________________________________________________________ READ THESE INSTRUCTIONS FIRST Write your name, register number, and class on all the work you hand in. Write in dark blue or black pen. You may use a soft pencil for any diagrams or graphs. Do not use paper clips, glue or correction fluid. Answer all questions. Write all answers in the answer space provided. The use of a scientific calculator is expected, where appropriate. You are reminded of the need for clear presentation in your answers. The number of marks is given in brackets [ ] at the end of each question or part question. ___________________________________________________________________________________ This document consists of 23 printed pages. [Turn over] For Examiner’s Use Section A (70) Section B (10) 10 Either 10 Or Total (80)

2 Section A Answer all questions in this section. Write your answers in the spaces provided. 1 a) Fig. 1.1 is a diagram representing the concentration of oxygen inside and outside an animal cell. Fig. 1.1 (i) Identify the part of the cell that X represents. ……………………………………………………………………………………... [1] (ii) Draw an arrow on Fig. 1. 1 to show the net direction of movement of the oxygen molecules in the absence of energy. [1] outside cell inside cell oxygen molecule X

3 b) Fig. 1.2 shows a dialysis machine for treating people who have kidney failure. The dialysate is a solution of glucose and salts. Fig. 1.2 When the patient is undergoing dialysis, explain (i) why red blood cells and blood proteins are not lost from blood, ………………………………………………………………………………………. ………………………………………………………………………………………. [1] (ii) how the normal glucose concentration of blood is maintained. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. [2] blood vessels dialysis membrane blood out blood in dialysate out dialysate in

4 A person with kidney failure received regular dialysis treatment for 17 days. Fig. 1.3 shows how the concentration of urea in the blood changed over the 17 days. Fig. 1.3 (iii) State how many times the person received dialysis treatment. ………………………………………………………………………………………. [1] (iv) The patient was given a restricted diet during his treatment. Suggest a possible restriction and explain how it leads to the overall decrease in urea concentration in the blood as shown in Fig. 1.3. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. [2] [Total: 8 marks] concentration of urea in the blood / mg per dm3 time / days

5 2 Fig. 2.1 shows two structures found in the human digestive system. [not drawn to scale] Fig. 2.1 a) Describe and explain how the tooth and the salivary gland contribute to digestion. Tooth: …………………………………………………………………………. …………………………………………………………………………. …………………………………………………………………………. …………………………………………………………………………. Salivary gland: …………………………………………………………………………. …………………………………………………………………………. …………………………………………………………………………. …………………………………………………………………………. [2] b) A hormone called gastrin stimulates cells in the stomach wall to release the substances involved in digestion. Some of the gastrin is produced in the duodenum. Describe how this gastrin reaches the stomach. …………………………………………………………………………………………….. …………………………………………………………………………………………….. [1] c) Explain why bile is not considered a digestive enzyme. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. [2] tooth salivary gland

6 d) Fig. 2.2 shows the stages involved in protein synthesis. The segment A codes for a polypeptide. Fig. 2.2 (i) State the name of the parts represented by the letters A, C, and Q in Fig. 2.2. A: ……………………………………………………………………………….. C: ……………………………………………………………………………….. Q: ……………………………………………………………………………….. [3] (ii) State what determines the order in which the parts labelled B are assembled. ………………………………………………………………………………………. [1] A DNA stage 1 nuclear membrane stage 2 DNA nuclear membrane strand Q stage 3 B C

7 (iii) State a difference between DNA and strand Q. ………………………………………………………………………………………. ………………………………………………………………………………………. [1] [Total: 10 marks] 3 A researcher investigated the effect of temperature on two different biological washing powders, A and B. Two identical pieces of clothing of the same size were stained with the same type and amount of food. The researcher timed how long each washing powder took to remove the stains, at different temperatures. Fig. 3.1 is a graph of the results. Fig. 3.1 a) With reference to Fig. 3.1 , d etermine the time taken for washing powder A to remove the stain at 20 °C. Show on the graph how you arrived at your answer. ……………………………. minutes [2] b) With reference to Fig. 3.1, compare the effect of A and B on stain removal. 1. ……………………………………………………………………………...……… ……………………………………………………………………………...……… 2. ……………………………………………………………………………...……… ……………………………………………………………………………...……… [2] time taken to remove the stain / minutes Temperature / oC

8 c) State one factor, other than temperature, that affects enzyme activity. ……………………………………………………………………………………………... [1] [Total: 5 marks] 4 Fig. 4.1 is a diagram of a section through a human heart. Fig. 4.1 a) Name vessel E and state its function. ……………………………………………………………………………………...……… ……………………………………………………………………………………...……… [2] b) Label the left ventricular wall “ F” on Fig. 4.1 and explain why it is the thickest compared to other chamber walls. ……………………………………………………………………………………...……… ……………………………………………………………………………………...……… ……………………………………………………………………………………...……… [2] c) State and e xplain the consequence if the part labelled D in Fig. 4.1 cannot fully close. ……………………………………………………………………………………...……… ……………………………………………………………………………………...……… ……………………………………………………………………………………...……… [2] [Total: 6 marks] D E

9 5 Ecologists study plants and animals in their natural environment. Some ecologists inserted probes into two positions of the same water-conducting tissue in trees, as shown in Fig. 5.1. The ecologists measured the time taken for water to move. Fig. 5.1 a) Name an adaptation these water-conducting tissues have. ……………………………………………………………………………………………... ……………………………………………………………………………………………... [1] b) Name the primary force that draws water up the water-conducting tissue. ……………………………………………………………………………………………...