BIOL251 EXAM 3 STUDY POINTS QUESTIONS WITH
CORRECT ANSWERS 2026 RATED A+
1. CH13 START
What are the different types of germicidal chemicals, and what does each
control-ANSWER- Alcohols- Aldehydes- Ethylene oxide- Bisguanides- Halogens- Heavy metals-
Phenolics
2. Alcohols-ANSWER- kills bacteria, fungi. Not endospores or naked viruses- antiseptic on skin-
hand sanitizers 60-90% alcohol
3. Aldehydes-ANSWER- kills bacteria, fungi, endospores, viruses- irritating to skin- 2%
glutaraldehyde: sterilization- Formaldehyde, formalin
4. Ethylene oxide-ANSWER- gaseous sterilization- for fabric, pillows, artificial hips, pacemakers,
petri dishes
5. Bisguanides-ANSWER- antiseptics before surgery, surgeon hand scrub- Chlorhexidine: skin
creams, disinfectants, mouthwash
6. Halogens-ANSWER- Chlorine: pools, disinfects waste liquid- Bleach: kills bacteria and viruses-
Chloramine: disinfects drinking water- Chloride dioxide: fumigation and sterilization of enclosed
areas- Iodine: betadine, surgical hand scrub
7. Heavy metals-ANSWER- kill microbes by binding to proteins- Mercury: not used in US, toxicity
concerns- Silver: antiseptic
Silvadene cream for burn wounds
Silver nitrate drops for ophthalmia neonatorum
BIOL251 EXAM 3 STUDY POINTS
Study online at https://quizlet.com/_i70hiy- Copper, Nickel, Zinc
Copper: algacide
Zinc chloride: mouthwashes
Zinc oxide: topical antiseptic creams
,8. Phenolics-ANSWER- less toxic than phenol, disinfectant for surgical wounds- Listerine, Lysol-
pHisoHex: handwashing in hospitals- Triclosan: banned by FDA because soaps with triclosan
were ineffective
9. Explain how the appropriate chemical means of control is selected-ANSWER- Know where
the chemical will be used
Skin safe?
Surgical equipments- Are we trying to kill everything (incl. Spores, viruses,)
Stronger chemicals
10. Know about each of the categories of chemicals discussed in class (slides
28-36), and the examples of what each might be used-ANSWER- Alcohols- Aldehydes- Ethylene
oxide- Bisguanides- Halogens- Heavy metals- Phenolics
11. Why was Triclosan banned-ANSWER- Not effective as soaps- Bacteria becoming immune to
the chemicals
12. What are the targets in bacterial cells that are affected by germicidal chem
icals: Enzymes and cell membrane
13. Explain the assay for testing the effectiveness of germicidal chemicals-ANSWER- Disk
diffusion assay- Check for zone of inhibition ’ if has = germicide works
14. CH14 START
Understand what antibiotics are and how they work-ANSWER- Meds used to treat bacterial
infections
BIOL251 EXAM 3 STUDY POINTS
Study online at https://quizlet.com/_i70hiy- Bind to cell processes- Narrow or broad spectrum,
bactericidal or bacteriostatic- Ineffective against viruses
15. Distinguish between antibiotics, antifungals, and antivirals-ANSWER- Antibiotics ’ against
bacteria- Antifungals ’ against fungus- Antivirals ’ against virus
16. Explain why antibiotics work to eliminate bacteria and not effective for other
, types of microbes-ANSWER- They target specific things in bacteria- Ex. protein synthesis
inhibitors won't work on viruses because they have no ribosomes
17. Know the history of antibiotics we discussed in class-ANSWER- Plants, fungi, and other
natural
products used as meds for centuries- Antibiotics can be pure natural, semi-synthetic, or
synthetic- Sulfanilamide first synthetic antimicrobial- Penicillin first natural antibiotic
18. Know about the key players we discussed, their contributions, and how the
relevance/significance of those contributions-ANSWER- Paul Ehrlich ’ discovered Salvarsan,
treatment
for syphilis- Fleming ’ discovered penicillin, credited with discovery of antibiotics- Howard Florey
and Ernst Chain ’ purified and sped up penicillin production- Dorothy Hodgkins ’ determined the
structure of penicillin, led to more semi-synthetic antibiotics
19. What are the sources of natural antibiotics-ANSWER- Bacteria
Streptomyces: source of ½ current antibiotics in use; streptomycin, erythromycin, lincomycin,
tetracycline
Bacillus: Bacitracin, polymixin- Fungi
Cephalosporium: Cephalosporins
Penicillum: Penicillins
20. Distinguish between natural, semi-synthetic and synthetic antibiotics, and
examples we discussed in class-ANSWER- Natural ’ found in nature- Semi-synthetic ’ found in
nature and modified in lab- Synthetic ’ made in lab
BIOL251 EXAM 3 STUDY POINTS
Study online at https://quizlet.com/_i70hiy
21. Explain the differences between the various penicillins we discussed in class
-ANSWER- Penicillin G ’ parenteral, kills Gram+, few G-- Penicillin V ’ oral, similar to penicillin G-
Ampicillin ’ parenteral and oral, effective for G+ and G-- Amoxicillin ’ oral, similar to and better
than ampicillin- Methicillin ’ parenteral, only G+ and beta lactamase producers, effective against
penicillin resistant bacteria
CORRECT ANSWERS 2026 RATED A+
1. CH13 START
What are the different types of germicidal chemicals, and what does each
control-ANSWER- Alcohols- Aldehydes- Ethylene oxide- Bisguanides- Halogens- Heavy metals-
Phenolics
2. Alcohols-ANSWER- kills bacteria, fungi. Not endospores or naked viruses- antiseptic on skin-
hand sanitizers 60-90% alcohol
3. Aldehydes-ANSWER- kills bacteria, fungi, endospores, viruses- irritating to skin- 2%
glutaraldehyde: sterilization- Formaldehyde, formalin
4. Ethylene oxide-ANSWER- gaseous sterilization- for fabric, pillows, artificial hips, pacemakers,
petri dishes
5. Bisguanides-ANSWER- antiseptics before surgery, surgeon hand scrub- Chlorhexidine: skin
creams, disinfectants, mouthwash
6. Halogens-ANSWER- Chlorine: pools, disinfects waste liquid- Bleach: kills bacteria and viruses-
Chloramine: disinfects drinking water- Chloride dioxide: fumigation and sterilization of enclosed
areas- Iodine: betadine, surgical hand scrub
7. Heavy metals-ANSWER- kill microbes by binding to proteins- Mercury: not used in US, toxicity
concerns- Silver: antiseptic
Silvadene cream for burn wounds
Silver nitrate drops for ophthalmia neonatorum
BIOL251 EXAM 3 STUDY POINTS
Study online at https://quizlet.com/_i70hiy- Copper, Nickel, Zinc
Copper: algacide
Zinc chloride: mouthwashes
Zinc oxide: topical antiseptic creams
,8. Phenolics-ANSWER- less toxic than phenol, disinfectant for surgical wounds- Listerine, Lysol-
pHisoHex: handwashing in hospitals- Triclosan: banned by FDA because soaps with triclosan
were ineffective
9. Explain how the appropriate chemical means of control is selected-ANSWER- Know where
the chemical will be used
Skin safe?
Surgical equipments- Are we trying to kill everything (incl. Spores, viruses,)
Stronger chemicals
10. Know about each of the categories of chemicals discussed in class (slides
28-36), and the examples of what each might be used-ANSWER- Alcohols- Aldehydes- Ethylene
oxide- Bisguanides- Halogens- Heavy metals- Phenolics
11. Why was Triclosan banned-ANSWER- Not effective as soaps- Bacteria becoming immune to
the chemicals
12. What are the targets in bacterial cells that are affected by germicidal chem
icals: Enzymes and cell membrane
13. Explain the assay for testing the effectiveness of germicidal chemicals-ANSWER- Disk
diffusion assay- Check for zone of inhibition ’ if has = germicide works
14. CH14 START
Understand what antibiotics are and how they work-ANSWER- Meds used to treat bacterial
infections
BIOL251 EXAM 3 STUDY POINTS
Study online at https://quizlet.com/_i70hiy- Bind to cell processes- Narrow or broad spectrum,
bactericidal or bacteriostatic- Ineffective against viruses
15. Distinguish between antibiotics, antifungals, and antivirals-ANSWER- Antibiotics ’ against
bacteria- Antifungals ’ against fungus- Antivirals ’ against virus
16. Explain why antibiotics work to eliminate bacteria and not effective for other
, types of microbes-ANSWER- They target specific things in bacteria- Ex. protein synthesis
inhibitors won't work on viruses because they have no ribosomes
17. Know the history of antibiotics we discussed in class-ANSWER- Plants, fungi, and other
natural
products used as meds for centuries- Antibiotics can be pure natural, semi-synthetic, or
synthetic- Sulfanilamide first synthetic antimicrobial- Penicillin first natural antibiotic
18. Know about the key players we discussed, their contributions, and how the
relevance/significance of those contributions-ANSWER- Paul Ehrlich ’ discovered Salvarsan,
treatment
for syphilis- Fleming ’ discovered penicillin, credited with discovery of antibiotics- Howard Florey
and Ernst Chain ’ purified and sped up penicillin production- Dorothy Hodgkins ’ determined the
structure of penicillin, led to more semi-synthetic antibiotics
19. What are the sources of natural antibiotics-ANSWER- Bacteria
Streptomyces: source of ½ current antibiotics in use; streptomycin, erythromycin, lincomycin,
tetracycline
Bacillus: Bacitracin, polymixin- Fungi
Cephalosporium: Cephalosporins
Penicillum: Penicillins
20. Distinguish between natural, semi-synthetic and synthetic antibiotics, and
examples we discussed in class-ANSWER- Natural ’ found in nature- Semi-synthetic ’ found in
nature and modified in lab- Synthetic ’ made in lab
BIOL251 EXAM 3 STUDY POINTS
Study online at https://quizlet.com/_i70hiy
21. Explain the differences between the various penicillins we discussed in class
-ANSWER- Penicillin G ’ parenteral, kills Gram+, few G-- Penicillin V ’ oral, similar to penicillin G-
Ampicillin ’ parenteral and oral, effective for G+ and G-- Amoxicillin ’ oral, similar to and better
than ampicillin- Methicillin ’ parenteral, only G+ and beta lactamase producers, effective against
penicillin resistant bacteria
