AMERIAN NATINAL SL General ertificate of Education Advanced Subsidiary Level and Advanced Level BILGY 9700/01 Paper 2 Structured Questions AS December 2009 lass A1 1 hour 15 minutes andidates answer on the Question Paper. Additional Materials: Electronic calculator Ruler READ TESE INSTRUTINS FIRST Write your entre number, candidate number and name in the spaces provided at the top of this page. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs, or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer all questions. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner s Use 1 2 3 If you have been given a label, look at the details. If any details are incorrect or missing, please fill in your correct details in the space given at the top of this page. Stick your personal label here, if provided. 4 5 7 Total This document consists of 13 printed pages. [Turn over
2 1 atalase is an enzyme with a molecular structure composed of four identical sub-units. Fig. 1.1 is a diagram that shows how catalase is produced in cells. DNA A mrna amino acid molecules B D polypeptide produced by organelle haem sub-unit of catalase assembly of four identical sub-units molecule of catalase Fig. 1.1
(a) With reference to Fig. 1.1, 3 (i) name process A... molecule B... structure.... sequence of bases D...[4] (ii) state two ways in which the structure of catalase is similar to the structure of haemoglobin and one way in which it differs structural similarities 1.... 2....[2] structural difference...[1] (iii) State why it is possible for a catalase molecule to bind to four substrate molecules at the same time....[1] (b) The enzyme amylase catalyses the following reaction: starch + water maltose The progress of this reaction may be followed by measuring either the starch concentration or the maltose concentration at intervals of time. State which chemicals you would use to detect the disappearance of the substrate and the appearance of the product, in order to follow the progress of the reaction. disappearance of substrate... appearance of product......[2] [Total: 10] [Turn over
2 Starch, glycogen and cellulose are all polysaccharides. They are made from monomers that are joined by covalent bonds. 4 (a) omplete the table below to show which of the statements apply to each of the polysaccharides. Fill in each box using a tick ( ) to show that the statement applies and a cross ( ) if it does not. statement starch glycogen cellulose glycosidic bonds between monomers monomer is β glucose stored within chloroplasts stored in muscle cells exists in two forms branched and unbranched chains A solution of the enzyme amylase was added to a solution of starch and kept at 25. The starch was broken down by hydrolysis. [5] (b) Explain how you would determine the rate of hydrolysis....[5] [Total: 10] [Turn over
3 Fig. 3.1 shows a β glucose molecule. 5 4 6 2 5 3 2 1 Fig. 3.1 (a) State how α glucose differs from β glucose as shown in Fig. 2.1....[1] (b) Fig. 2.2 shows a molecule of β glucose that is about to be added to the end of a growing chain of a polysaccharide. E Fig. 2.2 (i) Name the bond E....[1] (ii) Use the diagram below to show how the β glucose molecule will attach to the end of the growing chain of the polysaccharide. You may annotate the diagram if you wish. [3]
6 (iii) Name a polysaccharide that is formed entirely from β glucose molecules in the way shown in Fig. 3.2....[1] (c) A solution of starch was poured into six separate test-tubes, labelled F to K. The testtubes were kept at 35 for 5 minutes and then treated as shown in Table 3.1. After a further 30 minutes the contents of the test-tubes were tested for the presence of reducing sugar. Table 3.1 presence or absence of test-tubes substances added after 5 minutes reducing sugar after 30 minutes F distilled water absent G amylase + boiled maltase present amylase + distilled water present I boiled amylase + maltase absent J amylase + maltase present K maltase + distilled water absent Explain the results shown in Table 3.1....[4] [Total : 10] [Turn over
4 Phospholipids are components of cell surface membranes. 7 (a) Describe how phospholipid molecules are arranged in a cell surface membrane. You may use the space below for a simple annotated diagram if you wish. Fig.4.1 shows the structure of the lipids: [2] tristearin, which is a triglyceride; phosphatidylcholine, which is a phospholipid. 3 N + 3 3 = P = = = = = tristearin Fig.4.1 phosphatidylcholine
8 (b) State two ways, visible in Fig.4.1, in which phosphatidylcholine differs from tristearin. 1.... 2.......[2] (c) Explain how the structure of triglycerides, such as tristearin, makes them more suitable for energy storage than carbohydrates, such as glycogen....[2] [Turn over
9 The enzyme lipase catalyses the hydrolysis of ester bonds in triglycerides. As the reaction proceeds there is a decrease in p. The progress of the reaction may be followed by using a p meter. A solution containing tristearin was placed in a water bath at 25. When the solution had reached this temperature, lipase was added and the mixture stirred. The p of the reaction mixture was recorded every minute for 20 minutes. The results are shown in Fig.4.2. 11 10 9 p 8 7 6 5 4 0 5 10 time / min 15 20 Fig.4.2 (d) Using the data in Fig.4.2, state the time when (i) lipase was added;...[1] (ii) the reaction ended....[1] (e) Explain why the p decreases during this reaction....[1] (f) A similar solution was placed in a water bath at 35 and left for the same length of time to reach this temperature. Lipase was added as before. Sketch on Fig.4.2 the results that you would expect. [2] [Total: 11]
5 aemoglobin is a globular protein that shows quaternary structure. It is composed of two types of polypeptide, known as α and β globin. 10 (a) Explain how a globular protein differs from a fibrous protein, such as collagen....[2] Fig.5.1 shows part of the base sequence of the mrna that codes for the first ten amino acids of β globin. Table 6.1 shows some of the codons and the amino acids for which they code. GUG A UG AU U GAG GAG AAG UU G Fig.5.1 Table 5.1 amino acid abbreviation codons alanine ala GA G GG GU glutamic acid glu GAA GAG histidine his A AU leucine leu UUA UUG UA U UG UU lysine lys AAA AAG proline pro A G U serine ser UA U UG UU AG AGU threonine thr AA A AG AU valine val GUA GU GUG GUU (b) Use the information in Table 5.1 to complete the sequence of amino acids at the beginning of β globin using the first three letters of each amino acid. Some of them have been done for you. val his glu ala [3]
11 (c) β globin has a tertiary structure that consists of eight helices arranged to give a precise three-dimensional shape. Describe how the precise three-dimensional shape of a polypeptide is maintained....[4] [Total: 9]
6 Scientists have developed a variety of ways to represent the three dimensional structure of proteins. Fig. 6.1 shows one way of representing the structure of the protein, haemoglobin. 12 A Fig. 6.1 (a) (i) Name A and state its role. name... role.........[3] (ii) With reference to Fig. 6.1, explain why a molecule of haemoglobin is said to show both tertiary structure and quaternary structure................[2] [Total: 5]
13 7 Fig. 7.1 shows a bacterial cell dividing by binary fission. magnification = x 37 500 Fig. 7.1 (a) With reference to Fig. 7.1, state three structural features of prokaryotic cells that are not shown by eukaryotic cells. 1... 2... 3...[3] (b) Plant cells divide by mitosis, not by binary fission. (i) State tw0 roles of mitosis in plants. 1... 2... [2] [Total: 5]