Forensic Science Part II: Serology Quiz

Answer: all of these

In 1875 the main blood test in use was the hematin test. It could not distinguish animal blood from human blood or identify the type of blood.
The guaiacum test then came along.
In the test the suspected blood was put in water. Then guaiacum (a type of tree resin) was added.
Hydrogen peroxide was then put into the container.
If blood was present, a blue color formed.
This test, like the hematin test, could not identify what type of blood it was or tell whether it was human or animal, but it could be applied to small amounts of dried blood.

Answer: Yes

At the beginning of the twentieth century, Karl Landsteiner discovered blood types. He found out that a person's blood cells had an antigen and an antibody.
A person with type A antigen has type A blood and has the type B antibody. Therefore if a person with type A blood is transfused with type B blood their blood cells would clump, causing serious problems.
If a person has both antigens their blood type is AB. If they have neither their blood type is O. This is why O can be transfused into anybody. No antibodies mean no clumping on A or B blood cells.

Answer: False

Most preliminary tests look for an enzyme in blood called peroxidase. Unfortunately peroxidase is also found in many other blood resembling substances like shrimp sauce. For this reason, preliminary tests are called "presumptive" tests.

Answer: Yes

This is an extremely rare occurrence, but it can happen. A blood type can change through an addition or suppression of an antigen through infection or malignancy.

Answer: semen

In criminal cases semen is the second most common fluid that is found at the scene. The first most common is blood. The investigator will usually do a acid phosphatase color test to determine whether or not a fluid is semen.

Answer: False

DNA is always found where white, not red, blood cells are present (DNA is found only in a cell's nucleus, and red blood cells do not have nuclei.) For this reason, it can be found in blood, semen, saliva, hair root follicles, and more.

Answer: CODIS

The Combined DNA Index System (CODIS) has blood samples of offenders and has solved many cases. CODIS solved a 1993 sexual assualt case by linking that suspect to a 1991 rape case.

Answer: True

In addition to having antigens and antibodies in MOST blood types, you can also have the RH protein. That means that a person without the RH protein (meaning they have a negative blood type) cannot be infused with blood from a person with the RH protein (meaning they have a positive blood type), but a person with the RH protein can be infused with negative blood.

Answer: phone

All of these things would help find out who the woman is, but to the forensic serologist, the phone would be the most handy. When you talk on the phone, little bits of saliva go onto the phone when you talk. White blood cells are found in saliva so the woman's DNA would be on the phone.

Answer: False

You are born with your DNA and this isn't "Threshhold". Your DNA cannot change and if someone did try to alter it, you would probably die.