Biological evidence

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  • Created by: Ashlee
  • Created on: 04-05-15 19:15
What are the 4 main components of blood?
WBC's, RBC's, platelets, plasma
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What do white blood cells do?
Immune system - fight infection
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What do red blood cells do?
Haemoglobin carries oxygen; carries blood type antigens
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What do platelets do?
Helps blood to clot
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What are the components of plasma?
Hormones; waste; antibodies
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What is plasma called when fibrinogen is removed?
Serum
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What presumptives tests can you do for blood?
Hemastix; oxidation reactions; Kastle Meyer Test (KM) and Leucomalachite green (LMG)
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What happens with a Leucomalachite green test?
When the reagent added to hydrogen peroxide it turns blue/green if positive
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What happens with a Kastle Meyer test?
Chemicals react and if positive it turns pink
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What may happen with presumptive tests?
False positives - further tests required
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What are the advantages of presumptive tests?
Cheap and quick
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How would you visually identify biological evidence?
Colour; texture; light sources
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What different light sources could you use to identify biological evidence?
Fixed wavelenght light source; UV light; strong light source; laser
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What is saliva?
Fluid excreted from salivary glands
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What does saliva consist of?
Salivary amylase (digestive starch) and mucin (lubricates food)
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Why is saliva potentially important?
It can contain skin cells from inside the mouth
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What presumptive tests would you do for saliva?
Starch test - add iodine and if it turns blue there is a positive result
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What is *****?
A suspension of spermatazoa cells
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What components make up *****?
Calcium, zinc, sodium and citric acid
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Where would you look for DNA in *****?
The head of the sperm
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What presumptive tests would you do for *****?
Acid phosphate test and UV light
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Why would you use UV light on *****?
It fluoresces
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What happens with an acid phosphate test?
Acid phosphatase is secreted by prostate gland; if ***** is present when mixed with a dye and sodium it will turn that colour
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What is the viscosity of blood?
3-4 mP.s-1
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What is the density of blood?
1060 kg/m3
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What is the surface tension of blood?
0.058 N.m-1
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What is bloodspatter analysis?
The interpretation of dispersion, shape, volume, number and relationship of bloodstains to reconstruct events
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What are 3 types of bloodstain?
Passive; active and transfer
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What are passive bloodstains?
Blood stains formed by the force of gravity
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What are different types of active blood stain?
Gun shot/high velocity; body/artery/cough; movement; cast off
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What are transfer bloodstains?
Objects that leave a mark/silhuette; footwear/fingermark; direct contatct with contaminated objects
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What are the most important aspects to consider when interpreting bloodspatter?
Angle; location; size; volume; outer ring; dispersion
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Other cards in this set

Card 2

Front

What do white blood cells do?

Back

Immune system - fight infection

Card 3

Front

What do red blood cells do?

Back

Preview of the front of card 3

Card 4

Front

What do platelets do?

Back

Preview of the front of card 4

Card 5

Front

What are the components of plasma?

Back

Preview of the front of card 5
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