2A. Autumn 2019-2020 question paper.

University of Cambridge **We aren't endorsed by this school
MATH 1410
Material Science
May 11, 2023
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MAT1411 CANDIDATES ARE ADVISED TO READ THROUGH THE INSTRUCTIONS GIVEN ON THIS PAGE CAREFULLY BEFORE ATTEMPTING ANY QUESTIONS BIOMATERIALS 1 Autumn Semester Exam 2019-2020 Duration of Exam: 2 Hours SECTION A - Compulsory - Answer ALL of Section A Section A is worth a possible total of 20 Marks SECTION B - Answer any TWO Questions Each Question is worth a possible total of 20 Marks PLEASE WRITE YOUR ANSWERS IN THE ANSWER BOOK PROVIDED NOT ON THE EXAM PAPER. ANYTHING WRITTEN ON THIS PAPER WILL NOT BE CONSIDERED. Department Of Materials Science & Engineering.
MAT1411 3 MAT1411 SECTION A - Compulsory - Answer ALL of Section A 1. (a) What are hypertonic, isotonic and hypotonic solutions and how is a cell expected to behave in the presence of each of them? What physical effect causes this behaviour? [4 marks] (b) Explain how the surface-to-volume ratio defines a minimum possible size for mammals and a maximum possible size for insects. [4 marks] (c) Give four requirements that a tissue implant should meet. [4 marks] (d) Classify the amino acids shown below into the following groups: polar, non-polar, positively charged, negatively charged. Do you find non-polar amino acids preferentially on the surface or in the bulk of a globular protein? Explain why. [4 marks] (e) Metallic corrosion is a redox reaction. During the reaction, which component reduces and which one oxidises? Why does corrosion occur? [4 marks] SECTION B over page - TURN OVER
MAT1411 4 MAT1411 SECTION B - Answer any TWO Questions 2. (a) Explain what is meant by compact, trabecular, woven and lamellar bone. [8 marks] (b) Name four distinct roles that bones play in the body and briefly discuss how each of these roles is fulfilled. [8 marks] (c) Estimate the longitudinal modulus of dry bone given that the elastic moduli of apatite and collagen are 40 GPa and 0.1 GPa respectively and that 45% of the volume of the dry bone is mineral. Briefly discuss the reasons for any inaccuracy in this estimate. [4 marks] 3. (a) State, and briefly discuss the tasks that skin has to perform and what properties are required to perform them. [8 marks] (b) Discuss the basic structure of skin, explaining which part of the skin is most important in performing the functions that you have identified. [6 marks] (c) Typical values for the ultimate tensile strength and maximum elongation of skin are 7.6 MPa and 78% respectively. The analogous values for a tendon are 53 MPa and 9.4%. Discuss the reasons for the differences in these numbers in terms of the mechanical functions that the two organs must perform. [6 marks] 4. (a) What is the specific function of enzymes? Give a detailed description of how enzymes perform their function. [6 marks] (b) Current tooth filling materials can be either metallic or a composite. Give an example and a short description of one metallic and one composite tooth filling material. Include in your answer how the material is applied to the tooth cavity, how it hardens and how it is shaped. State one advantage of a composite tooth filling material over a metallic filler. [8 marks] (c) Give a definition of a pH buffer and explain what a pH buffer achieves. Use the Henderson-Hasselbalch equation to construct a plot of the pH of a solution versus the Base to Acid ratio, with the solution being a weak acid with a pKa of 4.76. Calculate and plot the points representing 10%, 25%, 50%, 75% and 90% base. [6 marks] SECTION B continued over page - CONTINUED
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