Dunman 2024 6093 P2 prelims QP

This document consists of 22 printed pages. DUNMAN SECONDARY SCHOOL CANDIDATE NAME CLASS INDEX NUMBER PRELIMINARY EXAMINATION 2024 SECONDARY 4 EXPRESS BIOLOGY 6093/02 Paper 2 27 August 2024 1 hour 45 minutes Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name, class and index number on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, glue or correction fluid. Section A Answer all questions. Write your answers in the spaces provided on the Question Paper. Section B Answer all the questions, the last question is in the form either/or. Write your answers in the spaces provided on the Question Paper. The use of an approved scientific calculator is expected, where appropriate. The number of marks is given in brackets [ ] at the end of each question or part question. Section A

2 6093/02/Prelims/4Exp/2024 Answer all questions. 1 Fig. 1.1 shows a drawing of an epithelial cell from the lining of the small intestine. Fig. 1.1 (a) Identify structure A in Fig. 1.1 and describe its function in the intestinal epithelial cell. A ………………………………………………………………………….……….………….………… function in the cell …………………………………………………………………………….………..…………………… …………………………………………………………………………….………..…………………… [2]

3 6093/02/Prelims/4Exp/2024 (b) The cholera bacterium can survive in the small and large intestine. The bacterium releases a toxin that interacts with the cell membrane. The toxin stimulates the secretion of ion X out of the intestinal cell. Fig. 1.2 shows the effect of the toxin on the epithelial cells. Fig. 1.2 (i) Secretion of ion X into the lumen of the small intestine can cause diarrhoea. Using your understanding of the movement of substances, explain how secretion of ion X causes diarrhoea. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. …………….…………………………………………………………………….…..…….... [4]

4 6093/02/Prelims/4Exp/2024 (c) Cholera is an infectious disease spread through contaminated water and food. Cholera vaccines can be taken orally to reduce the risk of contracting cholera. (i) Describe how the vaccine reduces the risk of contracting cholera. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. …………….…………………………………………………………………….…..…….... [2] (ii) Suggest two other ways to prevent the spread of cholera. 1 ………………………………………………………………………………………………... ………………………………………………………………………………………………….. 2 ………………………………………………………………………………………………... …………….…………………………………………………………………….…..…….... [2] [Total: 10]

5 6093/02/Prelims/4Exp/2024 2 A man visits an eye doctor for a check-up. Fig. 2.1a shows a section of the eye on a poster in the clinic. Fig. 2.1a Fig. 2.1b (a) During the eye check-up, the doctor shines a bright light into the eye and takes a picture. Fig. 2.1b shows layer D and the choroid layer behind it. (i) Identify structures D and E. D …………………………………………………………….………….……….…….….......... E …………………………………………………………….………….……….…….….... [2] (ii) Layer D does not contain blood vessels. Explain how the blood vessels in the choroid layer are important for layer D. ……………….………………………………………………..………………………………… ……………….………………………………………………..………………………………… ……………….………………………………………………..………………………………… ……………….………………………………………………..………………………………… ……………….………………………………………………..………………………………… ………………………………………………………………..………….……….……….... [3]

6 6093/02/Prelims/4Exp/2024 (b) In another eye test, the change in the shape of the lens w hile the patient look s at a chart 10 m away and reads from a book was recorded. The results are shown in Fig. 2.2. Fig. 2.2 (i) Write the letter F on Fig. 2.2 to show a time when the patient was looking at the chart that was 10 m away. [1] (ii) Describe how the change in shape of the lens during the time G was brought about. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. …………….…………………………………………………………………….…..…….... [2] (c) Receptors receive stimuli and convert them into electrical impulses. Fig. 2. 3 shows the pathway taken by electrical impulses in a reflex action. Fig. 2.3 Complete Fig. 2.3 by writing the names of the appropriate component in the empty boxes. [2] [Total: 10]

7 6093/02/Prelims/4Exp/2024 3 Huntington’s disease (HD) is an inherited disorder. It is caused by a mutation in the gene for a protein called huntingtin. This protein damages nerve cells in the brain. HD is caused by a dominant allele. (a) Define the term dominant allele. …………………………………………………………………………………………….…………….. …………….………………………………………………………………………….……….….... [1] (b) (i) A man heterozygous for HD and a healthy woman have a child. Complete the genetic diagram for this cross using the symbol H for the dominant allele and h for the recessive allele. father x mother genotypes of parents ……………………… ……………………… gametes ………. ………. ………. ………. genotypes of offspring ………. ………. ………. ………. …………….………………………………………………………………………….………... [3] (ii) Calculate the percentage chance of the child inheriting Huntington’s disease. Percentage chance of the child inheriting Huntington’s disease ............................ [1]

8 6093/02/Prelims/4Exp/2024 (c) Fig. 3.1 is a pedigree diagram showing the inheritance of Huntington’s disease in one family. Fig. 3.1 (i) State the possible genotypes for person 3 in Fig. 3.1. …………….………………..………………………………………………………….….... [1] (ii) State the evidence from Fig. 3.1 that suggests that the allele for Huntington’s disease is dominant. …………….…………………………………………………………………………………….. …………….………………..………………………………………………………….….... [1] (d) A drug can reduce the damage to nerve cells in the brains of people with HD. The drug binds to messenger RNA produced by the mutated gene for huntingtin protein. Suggest and explain the ways that the drug reduces damage to nerve cells in people with HD. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………….………………………………………………………………………….……….….... [3] [Total: 10]

9 6093/02/Prelims/4Exp/2024 4 Marimo moss balls are made up of green algae. They are found in lakes and are known to rise and fall during different times of the day. Fig. 4 .1 shows some moss balls in a beaker of water. Fig. 4.1 (a) Scientists predict that the moss balls rise because they are covered in tiny bubbles of oxygen. The scientists test their prediction by using a chemical that stops a biological process in the algae. When the chemical is added to some moss balls, they found that these moss balls did not rise. (i) State the biological process affected by the chemical. ………………………………………………………………..………….……….……….... [1] (ii) Explain why the moss balls did not rise. ……………….………………………………………………..………………………………… ……………….………………………………………………..………………………………… ……………….………………………………………………..………………………………… ………………………………………………………………..………….……….……….... [2]

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