Midterm Review KEY
1. What are the different parts of an experiment?
a. Control group
b. independent variable
c. dependent variable
d. all of the above
2. Match the following terms to the correct statement.
a. Independent Variable b. Control Group c. Dependent Variable
The control group is the part of the experiment where the independent variable being tested is not so that it may serve as a standard for comparison.
In an experiment it is the independent variable that is manipulated by the researcher.
The dependent variable in the experiment is the measured effect, outcome, or response.
3. How do the clues found at a scene of a mysterious death help investigators determine what might have occurred and help identify or exonerate potential suspects?
Evidence at a crime scene, such as blood, DNA, fingerprints, or shoeprints all help forensic investigators determine what might have occurred and help identify or exonerate potential suspects.
4. How can bloodstain patterns left at a crime scene be useful to investigators?
Bloodstain patterns can help investigators distinguish between an accident and foul play. If two similar-sized blood droplets fall from different heights, the resulting stains will have different sizes. Therefore, the height from which a blood droplet falls can be determined based on the size of the bloodstain. This is called blood stain analysis. The bigger the splatter the greater the height. The smaller the droplet, the lower the height.
5. What are keys points in determining differences between two fingerprints?
No two people have the same fingerprints, even twins. Main types of ridge patterns are plain arch, tented arch, whorl, and radial loop. Minutiae are the tiny fingerprint ridge details. Looking for these very small differences can eliminate a suspect from a case.
6. What are the different search methods? Explain how they work.
Link method- a method seeking to find associations between evidence.
Line(strip)method- used on large, outdoor crime scenes. Members of search team search along straight lines. Typically used to look for bodies or an abduction.
Grid method- Used on large, outdoor crime scenes. Searchers follow the first line pattern and search in the same manner as the line method. Once the first line pattern is complete, searchers realign on the other line pattern. Typically used to look for a weapon.
Zone method- Used in crimes scenes with zones such as a house or buildings. Teams are assigned small zones for searching.
Spiral method (inward or outward)- Used on areas with no physical barriers such as open water. Can begin at a critical point of the crime scene (outward spiral) or the outer edge of the crime scene (inward spiral).
Wheel or Ray method- Used on small, circular crime scenes. Investigators start from a critical point and travel outward along many straight lines from this point. Typically used when there has been an explosion.
7. Explain how Gel Electrophoresis works.
Restriction enzymes act as scissors that can cut DNA in a specific location. An individual’s code determines the number of times the restriction enzymes will cut and the number and size of DNA pieces that will result. These pieces can then be separated and compared using a process called gel electrophoresis. The DNA moves from the negative end to the positive end. As the fragments move, their varying lengths propel them through an agarose gel at different speeds. Short strands move through the holes in the gel more quickly than long strands and will over time move farther away from the starting point. Staining the sorted groups of DNA makes them visible to the naked eye (show up as bands in the gel).
8. What is an autopsy and what does it entail?
Autopsy: procedure that is completed in order to determine the cause of someone’s death. An autopsy includes identifying the person, cause of death, manner of death,...
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