Test 3

Question 0

Describes the pattern of microbial death

Answer 0

The cells in a population die at a constant rate

Question 1

What is the best method in use for the sterilization of heat-labile solutions?

Answer 1

Membrane filtration

Question 2

List the chemical agents used for sterilization

Answer 2

Ethylene oxide

Question 3

List the substances used for surgical hand scrubs

Answer 3

Chlorhexidine

Question 4

What is the antimicrobial activity of chlorine due to?

Answer 4

The formation of hypochlorous acid

Question 5

How is sterilization achieved?

Answer 5

By removing all microbial life. Heating is the most common method used for killing the most resistant forms ex. Endospores

Question 6

Which disinfectants act by disrupting the plasma membrane?

Answer 6

Bisphenols

Question 7

List the oxidizing agents

Answer 7

• O3
• H2O2
• Peracetic acid

Question 8

Which substances are effective against non enveloped viruses?

Answer 8

Chlorine
Ethylene oxide
Ozone

Question 9

Which method is used to preserve food by slowing the metabolic processes of food borne microbes?

Answer 9

Freezing

Question 10

When is the concentration of ethanol the most effective bactericide?

Answer 10

70%

Question 11

State the factors contributing to hospital acquired infections

Answer 11

1) some bacteria metabolize disinfectants, gram negative bacteria are often resistant to disinfectants
2) invasive procedures can provide a portal of entry for bacteria
3) may be present in commercial products

Question 12

What is the thermal death time?

Answer 12

The minimal length of time for all bacteria on a particular liquid culture to be killed at a given temperature

Question 13

What is the thermal death point

Answer 13

The lowest temperature at which all microorganisms in a particular liquid suspension will be killed in 10 minute

Question 14

What is the decimal reduction time?

Answer 14

The time (in minutes) in which 90% of a population of bacteria at a given temperature will be killed

Question 15

Describe the zone of inhibition

Answer 15

An area around the antibiotic where the bacteria doesn’t grow

Question 16

What is an iodophor?

Answer 16

A combination of iodine and an organic molecule from which the iodine is released slowly

Question 17

If you were preparing nutrient agar at home and did not have an autoclave what could you use to sterilize the nutrient agar?

Answer 17

Pressure cooker at 121 degrees C for 15 minutes

Question 18

Using your knowledge of the gram stain, which organisms are the most resistant to chemical biocides?

Answer 18

Mycobacteria

Question 19

Describe the functioning of antimicrobial control agents

Answer 19

1) alteration of membrane permeability
2) damage to proteins
3) damage to nucleic acids

Question 20

What is the best definition of a gene

Answer 20

Gene codes for either a polypeptide or an RNA molecule

Question 21

What is the role of RNA polymerase?

Answer 21

It’s an enzyme that binds to DNA during transcription an separates or unwinds the DNA strands

Question 22

How is DNA constructed?

Answer 22

Polymers of nucleotides running anti parallel

Question 23

What is an enzyme produced in response to the presence of a substrate called?

Answer 23

Inducible enzyme

Question 24

When glucose is high, cAMP is ______

Answer 24

Low

Question 25

CAP ______ bind the lac operator

Answer 25

Doesn't

Question 26

RNA polymerase ______ bind the lac promotor

Answer 26

Doesn't

Question 27

What is transformation ?

Answer 27

Transfer of DNA from a donor to a recipient cell as naked DNA in a solution

Question 28

How can genetic change in bacteria be brought about?

Answer 28

Conjugation, transduction, transformation, and mutation

Question 29

According to the operon model, what should happen for the synthesis of an inducible enzyme to occur?

Answer 29

Substrate must bind to the repressor

Question 30

How is the synthesis of a repressible enzyme stopped?

Answer 30

By the compressor- repressor binding to the operator

Question 31

Describe complementary base pairing

Answer 31

The base sequence of one DNA strand determines the case sequence of the other strand, thus making them complementary

Question 32

Describe a frame shift mutation

Answer 32

One or a few nucleotide pairs are deleted or inserted in the DNA. Almost always result in a long stretch of altered amino acids and the production of an inactive protein from the mutated gene

Question 33

Describe feedback inhibition

Answer 33

Feedback inhibition inhibits the action or preexisting enzymes

Question 34

How does conjugation differ from reproduction?

Answer 34

Conjugation transfer DNA horizontally to cells in the same generation

Question 35

Describe a nonsense mutation

Answer 35

Causes a premature stop codon

Question 36

Which process can be prevented if the antibiotic chloramphenicol binds the 50S ribosome?

Answer 36

The formation of peptide bonds in the growing polypeptide chain

Question 37

If you knew the sequence of nucleotides within a gene which structure (level of organization) could you determine with the most accuracy?

Answer 37

The primary structure of the protein

Question 38

Which enzyme copies DNA to make a molecule of RNA

Answer 38

RNA polymerase

Question 39

Describe the functioning of the lac operon

Answer 39

Cluster or series of genes responsible for the metabolism of lactose

Question 40

How is protein synthesis in eukaryotes similar to the process in prokaryotes?

Answer 40

Use codons to determine polypeptide sequences