Exam Questions and CORRECT Answers
What is a preservative? - CORRECT ANSWER - a naturally occurring or synthetically
produced substances that is added to products such as foods, pharmaceuticals, paints, biological
samples, wood and human or biological specimens to prevent decomposition by microbial
growth or by undesirable chemical changes such as autolysis of the body by its own enzymes.
What are some preservatives referred to as? - CORRECT ANSWER - Fixatives
What are fixatives? - CORRECT ANSWER - what some preservatives are referred to as
and is especially true of formaldehyde and glutaraldehyde. The use of these chemicals "fix" the
tissues in place.
What do preservatives do? - CORRECT ANSWER - Inactivate the chemical groups of
proteins and amino acids, inhibits further decomposition, Inactivates enzymes, kills
microorganisms, and destroys and stops production of odors.
What is the reaction of formaldehyde with water? - CORRECT ANSWER - It exists as
methylene glycol and is not a stable compound.
What is the reaction of formaldehyde with methanol? - CORRECT ANSWER - It prevents
the polymerization of formaldehyde to para-formaldehyde ( coagulated formaldehyde)
What is the reaction of formaldehyde with amino acids? - CORRECT ANSWER - It
preserves without coagulation, amino acid strand is not long enough to coagulate. (must have an
amino chain with a peptide bond).
What is the reaction of formaldehyde with proteins? - CORRECT ANSWER - Preserves
and coagulates, it is denatured breaking up 3 dimensional structure, loses its ability to imbibe
(hold water)
, What is the first step in the partial oxidation series for methane (CH4)? - CORRECT
ANSWER - Changes to an alcohol - methyl alcohol (CH3OH)
3 hydrogens attached to a carbon
What is the second step in the partial oxidation series for methane (CH4)? - CORRECT
ANSWER - Changes to an aldehyde HCHO
2 hydrogens attached to a carbon
What is the third step in the partial oxidation series for methane (CH4)? - CORRECT
ANSWER - Changes to formic acid (HCOOH)
1 hydrogen attached to a carbon
What is the fourth step in the partial oxidation series for methane (CH4)? - CORRECT
ANSWER - CO2 + H2O + Energy
0 hydrogens attached to a carbon
What is the definition for oxidation? - CORRECT ANSWER - The removal of hydrogen
from the carbon atom leading to CO2 (no hydrogen)
What is the definition for reduction? - CORRECT ANSWER - The removal of oxygen
from the carbon atom leading to CH4(methane)
What is reversibility of formaldehyde preserved tissue? - CORRECT ANSWER - The
action that formaldehyde has on proteins will be reversed in the presences of an abundance of
water.
What is cross linking action of formaldehyde preserved tissue? - CORRECT ANSWER -
This occurs between the nitrogen containing portions of the proteins.
What is formaldehyde demand? - CORRECT ANSWER - The total amount of
formaldehyde with which protein will combine to be completely preserved.