Advanced Subsidiary Unit 1: Lifestyle, Transport, Genes and Health

Transcription

1 Write your name here Surname Other names Edexcel GCE Biology Centre Number Candidate Number Advanced Subsidiary Unit 1: Lifestyle, Transport, Genes and Health Wednesday 9 January 2013 Morning Time: 1 hour 30 minutes You do not need any other materials. Paper Reference 6BI01/01 Total Marks Instructions t t t t Use black ink or ball-point pen. Fill in the boxes at the top of this page with your name, centre number and candidate number. Answer all questions. Answer the questions in the spaces provided there may be more space than you need. Information t The total mark for this paper is 80. The marks for each question are shown in brackets use this as a guide as to how much time to spend on each question. Questions labelled with an asterisk (*) are ones where the quality of your written communication will be assessed you should take particular care with your spelling, punctuation and grammar, as well as the clarity of expression, on these questions. Candidates may use a calculator. Advice t P39878A 2013 Pearson Education Ltd. 1/1/1/1/ Read each question carefully before you start to answer it. Keep an eye on the time. Try to answer every question. Check your answers if you have time at the end. *P39878A0124* Turn over

2 Answer ALL questions. Some questions must be answered with a cross in a box. If you change your mind about an answer, put a line through the box and then mark your new answer with a cross. 1 Read through the following passage on the cardiac cycle, then write on the dotted lines the most appropriate word or words to complete the passage. The cardiac cycle consists of three stages: atrial systole, ventricular systole and...diastole During atrial systole, the atria contract and the ventricles are relaxed. The atrioventricular valves are open. During ventricular systole, the...semi lunar valves open as oxygenated blood is forced out of the heart through the aorta to the body and through the pulmonary arteries to the lungs. (Total for Question 1 = 6 marks) 2 *P39878A0224*

3 2 Messenger RNA (mrna) and transfer RNA (trna) are important nucleic acids involved in the process of protein synthesis. (a) Describe how a molecule of mrna is made during transcription. (4) DNA Helicase; Breaks hydrogen bonds between two DNA strands / eq; (Strands separate and) the DNA molecule uncoils; Antisense strand is used as a template; RNA nucleotides pair up with the specific bases on the temple strand; idea that mrna molecule is a genetic copy of the DNA; of the protein being synthesised Idea that mrna molecules leaves nucleus for translations *P39878A0324* 3 Turn over

4 { (b) The diagram below represents a trna molecule. X { Y For each of the statements below, put a cross ( ) in the box that corresponds to the correct statement. Z (i) Part X binds to A an amino acid for transcription B an amino acid for translation C mrna for transcription D mrna for translation (ii) Part Y is a A glycosidic bond B hydrogen bond C peptide bond D phosphodiester bond 4 *P39878A0424*

5 (iii) Part Z binds to A an amino acid during transcription B an amino acid during translation C mrna during transcription D mrna during translation (c) Using the information shown in the diagram, describe two ways in which the structure of a trna molecule differs from the structure of a mrna molecule. (2) trna short chain versus mrna long chain trna clover leaf shape versus mrna straight chain trna folded versus mrna straight trna fixed length versus mrna variable length (Total for Question 2 = 9 marks) *P39878A0524* 5 Turn over

6 3 Molecules are transported across the cell membrane in a number of different ways. (a) Describe the structure of a cell membrane. (3) Phospholipid bilayer hydrophobic tails / Hydrophilic head...move in an aqueous environment so tails aren t in contact referrence to Membrane proteins/glycoproteins/glycolipids reference to fluidity refrerence to cholesterol reducing fluidity *P39878A0624*

7 BLANK PAGE Question 3 continues on page 8 *P39878A0724* 7 Turn over

8 (b) Cells were placed in a solution containing two different solutes, solute P and solute R. The diagram below represents the concentration of the two solutes outside one of the cells, when this cell was placed in the solution. Cell Molecule of solute P Molecule of solute R The cells were left in the solution for 50 minutes. The diagrams below represent the concentrations of the two solutes, inside and outside the cell after 10, 20, 30 and 40 minutes in the solution. After 10 minutes After 20 minutes After 30 minutes After 40 minutes (i) Using the information in the diagrams, describe the changes that have taken place in the concentrations of solute P and solute R, in the 40 minute period. Suggest an explanation for these changes. (5) Reference to (facilitated) diffusion; Idea that Solute R molecules were too large to pass through; Solute P molecules entered the cell between mins; Solute P molecules didn't diffuse anymore from 30 minutes onwards because the concentration was the same inside and outside / eq ; *P39878A0824*

9 (ii) Complete the diagram below, to show the concentration of solute P and solute R inside and outside the cell, after 50 minutes. Same as last picture above, with particles in different positions (Total for Question 3 = 9 marks) *P39878A0924* 9 Turn over

10 Heart rate as a percentage of base heart rate (%) 4 An investigation was carried out to study the effect of caffeine on the heart rate of a chicken embryo. The heart from a chicken embryo was removed and placed in a glucose solution. The heart rate was determined and recorded as the base heart rate. The experiment was repeated using glucose solutions containing five different concentrations of caffeine. The heart rate was determined and recorded as a percentage of the base heart rate for each solution. The graph below shows the results of this investigation Concentration of caffeine / mg cm 3 10 *P39878A01024*

11 (a) (i) Suggest why glucose was included in the solutions. (2)...Used as a control used for respiration respiration produces energy energy used by heart muscles to beat /pump blood (ii) Suggest how the caffeine solutions were prepared to obtain valid results....reference to same type of caffeine used use of distilled/deionised water made up to the same volume (iii) State how these results could be made more reliable....reference to repeats at every concentration (iv) Using the information in the graph, describe the effect of caffeine on the heart rate of the chicken embryo. (3)...Overall decrease in heart rate...heart rate increases for the first 0.1mg cm *P39878A01124* 11 Turn over

12 ...Decreases are fairly constant no heart rate at 1mg cm Correct manipulation of figures *P39878A01024*

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14 (b) (i) Describe how this investigation could be carried out using Daphnia instead of chicken embryos. (4)...Reference to independent variable remaining the same use of microscope to record how many beats occur in (10/15 seconds) multiply this value by (6/4) to measure heart rate reference to repeats plot data on a graph and compare results reference to a controlled variable any named controlled variable (ii) Suggest one ethical issue in the use of chicken embryos in this investigation....idea that the harm may be inflicted upon the embryo/ embryo could die (Total for Question 4 = 12 marks) 12 *P39878A01224*

15 5 Atherosclerosis is responsible for many deaths that result from cardiovascular disease (CVD). The diagram below shows an external view of a human heart. The position of an atheroma (plaque) is shown and a region of dead heart muscle is shaded. Aorta Position of atheroma Region of dead heart muscle (a) (i) Explain how the structure of the aorta relates to its function. (3)...Aorta is an atery...narrow lumen allows blood to travel under high pressure smooth endothelium reduces friction of blood elastic fibres stretch and recoil any other suitable structure and function *P39878A01324* 13 Turn over

16 (ii) Describe two differences between the structure of a capillary and the structure of a vein. (2) Veins have thick lumens, capillaries lumen are one cell wide Valves present in veins, not in a capillary any other suitable difference (b) (i) Suggest how the location of the atheroma results in the position and size of this region of dead heart muscle. (3) Reference to atheroma blocking a coronary artery...blood flow is stopped from reaching heart muscles respiration reduced in a large area that is affected...large region of heart muscles die *P39878A01424*

17 (ii) On the diagram below, shade an area to show the position and size of dead heart muscle, if the atheroma occurred at position B. (2) Position B The areas outside the coronary artery in this box (Total for Question 5 = 10 marks) *P39878A01524* 15 Turn over

18 6 Enzymes act as biological catalysts. Amylase is an enzyme present in saliva that catalyses the hydrolysis of starch into maltose. *(a) Describe the structure of starch. (5) Contains amylose and amylopectin; Amylose (not a mark) : Long and unbranched chains; 1-4 glycosidic bonds between (alpha) glucose monomers; coiled structure; (so) compact; Amylopectin (not a mark) : (long), branched chains; (has) 1-4 and 1-6 glycosidic bonds between (alpha) glucose monomers; side branches which can be broken down quickly; (b) Explain the meaning of the following terms. (i) Catalyst (2)...Molecule that (speeds up a rate of reaction / reduces activation energy of a reaction) but is not itself (chemically changed/used up) in the reaction *P39878A01624*

19 (ii) Hydrolysis (2)...Breaking of bonds formed in a condensation reaction...by adding water (c) Bread contains a high proportion of starch. If bread is chewed for a long period of time it begins to taste sweet. Suggest why bread tastes sweet after chewing for a long period of time....water in saliva hydrolyses the starch in bread starch breaks down to glucose/maltose glucose/maltose are sugars (Total for Question 6 = 10 marks) *P39878A01724* 17 Turn over

20 7 There is evidence for a causal relationship between blood cholesterol levels and cardiovascular disease (CVD). (a) Explain the meaning of the term causal relationship....in essence, a correlation;...a change in one variable is reflected by a change in another (b) Lipoproteins are composed of phospholipids, cholesterol and proteins. (i) Proteins are made up of amino acids. Describe how amino acids join together to form the three-dimensional structure of a protein. (4) different types fibrous and globular proteins amino acids join by peptide bonds and form the primary structure the specific order of amino acids determines the bonds in secondary and tertiary structures any named bond......difference in structure between fibrous and globular proteins...named example of a fibrous and globular protein...in globular proteins, hydrophobic R groups are faced outside - or reverse *P39878A01824*

21 (ii) The diagrams below show part of the structure of the surface of high-density lipoprotein (HDL) and low-density lipoprotein (LDL). Phospholipid Protein Cholesterol HDL LDL Using the information in the diagram, describe the differences between the structure of HDL and the structure of LDL. (2)...Numerical differences accepted...hdl has (more/3) proteins molecules, LDL has (less/ 1) protein molecules......same number of phospholipids hdl has (less/3) cholesterol molecule, LDL has (more/ 11) cholesterol molecules...difference between cholesterol is 3x larger than difference between protein molecules ldl have a larger surface area than HDL *P39878A01924* 19 Turn over

22 Percentage of people with CVD (%) (c) Obesity and high blood pressure are also factors that increase the risk of CVD. The graph below shows the percentage of people with CVD who have high blood pressure or have high blood cholesterol or are obese for the period 1960 to Key High blood pressure.. High blood cholesterol Obesity Year (i) Using the information in the graph, describe the overall changes that have occurred in these risk factors during this period. (3)...Overall decrese in both high blood pressure AND high blood cholesterol levels overal increase in obesity levels...increases are fairly constant decreases are not constant correct manipulation of figures *P39878A02024*

23 (ii) Suggest two reasons for the overall change in high blood cholesterol as a risk factor. (2) (I ve got to say this question still confuses me) I still read it as why is the reduce in cholesterol levels a risk factor? (iii) State two factors, other than obesity, high blood pressure and high blood cholesterol, that increase the risk of CVD Increased age male Diet high in saturated fats...any appropriate risk factors (Total for Question 7 = 13 marks) *P39878A02124* 21 Turn over

24 8 Cystic fibrosis and albinism are examples of recessive genetic disorders. Tay-Sachs disease is another example of a recessive genetic disorder. (a) Explain the meaning of the term recessive genetic disorder. (2)...Disorder in which BOTH ALLELES need to be present in the genotype...for the phenotype to be expressed (b) The genetic pedigree diagram below shows the inheritance of Tay-Sachs disease in one family. Jen Adrian Unaffected female Jane Sara Pete Unaffected male Female with Tay-Sachs disease Male with Tay-Sachs disease Dan Max Lilly 22 *P39878A02224*

25 For each of the statements below, put a cross ( ) in the box that correctly completes the statement. (i) The female who definitely has a homozygous genotype is A Jane B C Jen Lilly D Sara (ii) The female whose genotype cannot be identified from the diagram is A Jane B C Jen Lilly D Sara (iii) A male who definitely has a heterozygous genotype is A Adrian B C Dan Max D none of them (iv) A male who definitely is homozygous dominant is A Adrian B C Dan Max D none of them *P39878A02324* 23 Turn over

26 *(c) Tay-Sachs disease is caused by a gene mutation that results in the build up of lipid in the brain. It is hoped that gene therapy will be able to treat this disease in the future. Sheep can also suffer from Tay-Sachs disease. Investigations have found that gene therapy increases the life span of these animals. Suggest how these gene therapy investigations could have been carried out. (5)......Reference to isolation desired (not normal) gene.eq gene that codes for functional protein insert in in a vector...named vector insert into body to reach cells in brain...injection to spine, use of a nebuliser not injection to the head/brain idea that gene will enter CELLS/NUCLEUS and undergo protein synthesis...reference to repetition of treatment (Total for Question 8 = 11 marks) 24 *P39878A02424*

27 TOTAL FOR PAPER = 80 MARKS 25 *P39878A02424*