Senior Science Essay

Carlingford High School 2008 YEAR 12 2 UNIT SENIOR SCIENCE HALF YEARLY EXAM Time Allowed: 2 hours Instructions: * Attempt all questions * Answer all questions in the spaces provided on this paper. SECTION I: Multiple Choice Questions (Q1-15) (15 marks) SECTION II: Extended Response Questions (Q16-29) (65 marks) Name: __________________________ Class: _____________ SECTION I: 15 Multiple Choice Questions (15 marks) Place a cross in the appropriate space below. | A| B| C| D| 1| | | | | 2| | | | | 3| | | | | 4| | | | | 5| | | | | 6| | | | | 7| | | | | 8| | | | | | | | | | 10| | | | | 11| | | | | 12| | | | | 13| | | | | 14| | | | | 15| | | | | TOTAL=/15 PART A: MULTIPLE CHOICE QUESTIONS (15 marks) Use the Multiple Choice Answer Sheet provided to record your answers for this section. 1. Foam is an example of which type of colloid? A. Liquid in liquid B. Solid in liquid C. Solid in gas D. Gas in liquid 2. What is a solution? E. A uniform mixture that contains dissolved substances. F. A mixture containing particles that settle out, or form layers, quickly. G. A mixture containing particles that remain suspended, for long periods of time. H. A mixture of oil-in-water or water-in-oil. . The diagram below shows Substance X being mixed with substance Y. The following tests were then carried out on this mixture: From these results it is most likely that the mixture of X and Y is a: A. Colloid B. Solution C. Solvent D. Suspension 4. The diagram shows two identical test tubes. One contains some mercury and the other contains a similar volume of water. What conclusions can be reached by observing the shape of each meniscus? I. The surface tension in mercury is greater than the surface tension in water. J. The surface tension in water is greater than the surface tension in mercury.

K. The surface tension in mercury is greater than the forces between mercury particles and the walls of the test tube. L. The surface tension in water is greater than the forces between water particles and the walls of the test tube. 5. What are some factors that affect the validity of a first-hand investigation? M. Tables, Graphs, Safety N. A control group, Accurate measurement, Safety O. Controlled variables, Accurate measurement, Reliability P. Clear instructions, Data in tables, Models to be tested 6. Which is a correct statement about the effect of skin microflora on skin pH? Q.

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Skin microflora increase skin pH R. Skin microflora cause a decrease in skin pH S. Skin microflora have no effect on the pH of skin T. Skin microflora cause the pH of skin to vary from 3 to 11 7. Enteric coated tablets are designed to do which of the following? U. Release medication as quickly as possible into the bloodstream V. Resist being dissolved by acid W. Dissolve quickly in water before being taken X. Dissolve in the stomach 8. Which list contains ONLY fat-soluble vitamins? Y. A B C D Z. A D E K [. B D E K . A B C K 9. The list below shows a range of different information systems used daily.

INTERNETSATELLITEMOBILE PHONETELETEXT TELEMETRY DIGITAL TELEVISION What are TWO things that each of these systems have in common? ]. They are all verbal and electronic ^. They are all non-verbal and short distance _. They are all electronic and long distance `. They are all non-electronic 10. Which of the following is ONE type of wave in the electromagnetic spectrum NOT currently used for communication purposes? a. Visible light b. Microwaves c. Infra-red d. Ultra violet 11. The flow diagram below shows an energy transformation. loudspeaker ? Sound energy electrical energy sound energy

Which communication device is missing from the diagram? e. Microphone f. Sonar g. Radar h. Compact disc 12. A property of electromagnetic waves that makes them useful in communication technologies is: i. They are easily scattered j. They are not easily reflected k. They all travel at very high speed l. They can be bent around natural obstacles, such as mountain ranges 13. A Senior Science student performed a first-hand investigation to compare the quality of reception of AM and FM radio waves. What are the independent and dependent variables in this investigation? | Independent| Dependent|

A| AM & FM signals| Place reception measured| B| AM & FM signals| Quality of reception| C| Quality of reception| Distance to transmission aerial| D| Place reception measured| AM & FM signals| 14. A group of students used a light sensor connected to a data logger to investigate how the brightness of light changes at different distances from an electric light globe. They recorded their results in a table. Distance(m)| Brightness of light (lux)| 1| 417| 2| 104| 3| 45| 4| 25| Which of the properties of electromagnetic waves used in communication systems can be explained by the results of this experiment?

A. Microwaves travel in straight lines B. The signal is stronger closer to the radio transmitter C. Electromagnetic radiation travels faster than sound waves D. Short-wave radio waves can be reflected off the ionosphere and received on the opposite side of the world 15. Binary code is the industry standard used by all major communications throughout the world today. The following is an example of how to convert a number to binary code. Decimal number: 23 22 21 20Binary code:01000001000001000001| Example: The Decimal number 5 = 22 + 20 = 4 + 1 The Binary code is: 00101

Give a reason for your answer. (2 marks) ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. 25. When a television signal reaches your house it passes from the aerial, through the television, to your eye. Construct a flowchart to show the sequence of events in the transfer of this message. On your flowchart, indicate the energy transformation occurring at each stage, and label ONE place where decoding occurs. (3 marks) 26. a) Explain what is meant by a geostationary satellite. (1 mark) ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ) Explain why an Earth based satellite dish must face a fixed direction when receiving information from a geostationary satellite. (2 marks) ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. c) Explain why geostationary satellites stay in orbit. (2 marks) ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. 27. Predict a possible future direction of research into telecommunications, and justify your prediction. 4 marks) ……………………………………………………………………………………………………. ……………………………………………………………………………………………………. ……………………………………………………………………………………………………. ……………………………………………………………………………………………………. ……………………………………………………………………………………………………. ……………………………………………………………………………………………………. ……………………………………………………………………………………………………. ……………………………………………………………………………………………………. ……………………………………………………………………………………………………. 28. Compare the main means of communication between humans 2000 years ago with present-day communication. (3 marks) ……………………………………………………………………………………………………. ……………………………………………………………………………………………………. ……………………………………………………………………………………………………. …………………………………………………………………………………………………. ……………………………………………………………………………………………………. ……………………………………………………………………………………………………. ……………………………………………………………………………………………………. ……………………………………………………………………………………………………. 29. Lee was asked to process and analyse information from secondary sources to compare the properties of copper cables with fibre optics when used in communication systems. She gathered the following information from an internet site. Copper cableThe electrical transmission through a copper cable has a band width of approximately 108 Hz and the transition time for each pulse is 10-8 second.

Due to electromagnetic interference (EMI) and energy loss, the signal loss is greater than 20 dB/km. The cable is large, heavy and expensive, and the signal remains electrical. Fibre opticsThe transmission of a signal through an optic fibre has a bandwidth of 1014 Hz and transition time for each pulse is 10-11 second. The glass used to make the optical fibre is cheaper, smaller and more fragile than copper cable. There is no EMI and little energy loss. The signal loss is approximately 0. 2 dB/km, but the signal must be converted from electrical to optical and then back to electrical. | ) Use the information gathered by Lee to complete the table comparing copper cables with fibre optics in relation to their band width, signal loss and transition time for pulses. (2 marks) Cable| Band Width| Signal loss| Transition time per pulse| Copper cable| | | | Fibre optic cable| | | | b) Using Lee’s gathered data, explain why the fibre optic cable has a faster rate of information transfer than the copper cable. (2 marks) ……………………………………………………………………………………………………. ……………………………………………………………………………………………………. ……………………………………………………………………………………………………. ……………………………………………………………………………………………………. END OF TEST