1) To isolate DNA, a swab is usually taken by forensic scientists from the a) blood b) mouth c) skin d) urine 2) The best cells to isolate DNA are... a) epithelial cells b) nerve cells c) red blood cells d) muscle cells 3) Epithelial cells are... a) difficult to detach from the mouth surface b) not easy to induce lysis c) dense in nuclei and DNA d) only found in the mouth 4) Cell membranes can be broken down (lysis) using a) chemical means (detergent) b) mechanical means (detergent) c) chemical means (blender) d) mechanical means (blender) 5) Which chemical is used to allow the DNA to precipitate out of solution into a pellet form which we could see? a) detergent b) salt c) water d) ethanol 6) Which gel is used in electrophoresis? a) jelly b) agar c) ethanol d) detergent 7) At which end is the negative electrode attached during gel electrophoresis? a) at the wells b) right side of wells c) furthest from the wells d) left side of wells 8) In gel electrophoresis, DNA fragments are separated on the basis of ... a) volume b) mass c) size d) temperature 9) In gel electrophoresis, the smallest DNA fragments move ... a) furthest away from the wells b) closest to the wells 10) When light passes from air to glass, the light bends towards the ‘normal’ line. This is called a) reflection b) refraction c) transmission d) absorption 11) The higher the refractive index the ... a) slower light travels and less it bends b) slower light travels and more it bends c) faster light travels and less it bends d) faster light travels and more it bends 12) Glass seems to disappear when placed in a solution with _____________ refractive index. a) a lower b) a higher c) the same 13) Density is calculated by.... a) mass / volume b) volume / mass 14) When measring density, volume can be measured using.... a) a balance b) a scale c) displacement of water d) the temperature 15) If an object hits glass, the projectile hole will be ... a) wider at the exit side b) wider at the entry side c) same at the entry and exit side 16) If an object hits glass, the first fractures that form are the... a) radial lines b) concentric lines 17) Radial lines form on the surface on the ____________ side of the applied force. a) opposite b) same 18) A fracture always terminates at an existing fracture line. a) true b) false 19) Which projectile hit first? a) 1 b) 2 20) The secondary lines are... a) radial b) concentric 21) The explosive in a gun is... a) nitroglycerine b) TNT c) ethanol d) fertiliser 22) The test for GSR a) Refractive index b) Benedict's c) Modified Griess d) gel electrophoresis 23) If the modified Griess test is positive for GSR, it will turn... a) blue b) green c) red d) orange 24) Circumstance that could produce a false positive result for GSR a) working with DNA b) working with fertilisers c) working with pesticides d) working with pigeons 25) Which of the following swabs shows a positive results for GSR? a) A b) B c) C d) D

Forensic techniques revision A

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