Blood as Evidence

Question 1

What are the 4 components of blood?

Answer 1

1. Red Blood Cells
2. White Blood Cells
3. Platelets
4. Plasma

Question 2

What is a presumptive blood test?

Answer 2

A test to determine if it is blood or not

Question 3

What are some types of presumptive blood types? (4)

Answer 3

1. Kastle-Meyer
2. Luminol
3. Hemastix
4. Benzidine Test

Question 4

What does the Castle-Meyer test mix with to produce a pink color?

Answer 4

Hydrogen peroxide and blood

Question 5

What does the Luminol test mix with in the blood?

Answer 5

Iron reacts with the ingredients in Luminol which can be made visible with a UV light

Question 6

What gives blood its color?

Answer 6

Red blood cells

Question 7

What helps blood to clot?

Answer 7

Platelets

Question 8

What antibodies does A blood type have in plasma?

Answer 8

Anti-B

Question 9

What antibodies does B blood type have in plasma?

Answer 9

Anti- A

Question 10

What antibodies does AB blood type have in plasma?

Answer 10

None

Question 11

What antibodies does O blood type have in plasma?

Answer 11

Anti-B and Anti- A

Question 12

Which blood type is most common?

Answer 12

O Positive

Question 13

Which blood type is least common?

Answer 13

AB Negative

Question 14

What antigens does A blood have on red blood cell?

Answer 14

A antigen

Question 15

What antigens does B blood have on red blood cell?

Answer 15

B antigen

Question 16

What antigens does AB blood have on red blood cell?

Answer 16

A and B antigen

Question 17

What antigens does O blood have on red blood cell?

Answer 17

None

Question 18

What does it mean if your blood type is positive?

Answer 18

If your blood type is positive, then your blood cells have the Rh protein

Question 19

Serology

Answer 19

a broad range of laboratory tests using reactions of blood serum and other body fluids

Question 20

What could a serology section of a forensic lab deal with?

Answer 20

• blood typing
• characterization of unknown blood
• stain patterns for crime reconstruction
• paternity testing
• semen identification in rape cases
• DNA techniques used for identification

Question 21

What are the advantages of using blood typing over DNA profiling?

Answer 21

Cheaper and less time consuming

Question 22

What type of evidence is blood typing considered to be?

Answer 22

Class evidence because it can help narrow the suspect field but cannot directly link to an individual person

Question 23

Test to determine if it is Is it human blood

Answer 23

precipitin test

Question 24

The absence of a tail

Answer 24

indicates that the blood dropped from a 90 degree angle (this is called a passive or gravitational drop)

Question 25

Blood spatter

Answer 25

technique that seeks to piece together the events that caused bleeding

Question 26

What can be determined by measuring the shape of the bloodstain on a surface

Answer 26

it is possible to determine the direction the blood was traveling, the angle of impact and the point of origin of the blood

Question 27

Trajectory

Answer 27

where the blood came from and how it spread over the surface

Question 28

Why does blood form circles?

Answer 28

due to the cohesion properties of blood.

Question 29

Directionality

Answer 29

comes from the tail

Question 30

Method used to find the area of area of convergence

Answer 30

stringing