MCB 2010 – Assume 109 E. coli cells/ml

10 Jun MCB 2010 – Assume 109 E. coli cells/ml

Question
Figure 7.2

Assume 109 E. coli cells/ml are in a flask.

27) Which graph in Figure 7.2 best depicts the effect of placing the culture in an autoclave for 15 minutes at time x?

A) a

B) b

C) c

D) d

E) e

28) Which graph in Figure 7.2 best depicts the effect of placing the culture at 7°C at time x?

A) a

B) b

C) c

D) d

E) e

Table 7.1

A disk-diffusion test using Staphylococcus gave the following results:

Disinfectant Zone of inhibition (mm)

A 0

B 2.5

C 10

D 5

29) In Table 7.1, which compound was the most effective against Staphylococcus?

A) A

B) B

C) C

D) D

E) The answer cannot be determined based on the information provided.

30) In Table 7.1, which compound was the most effective against E. coli?

A) A

B) B

C) C

D) D

E) The answer cannot be determined based on the information provided.

31) In Table 7.1, which compound was bactericidal?

A) A

B) B

C) C

D) D

E) The answer cannot be determined based on the information provided.

32) Table 7.2

The fate of E. coli O157:H7 in apple cider held at 8°C for 2 weeks,

with and without preservatives, is shown below:

Bacteria/ml

Cider only 2.2

Cider with potassium sorbate 2.0

Sodium benzoate 0

Potassium sorbate + sodium benzoate 0

In Table 7.2, which preservative is most effective?

A) potassium sorbate

B) sodium benzoate

C) potassium sorbate + sodium benzoate

D) no preservative

33) An iodophor is a(n)

A) phenol.

B) agent that reduces oxygen.

C) quaternary ammonium compound.

D) form of formaldehyde.

E) iodine mixed with a surfactant.

34) Ethylene oxide

A) is a good antiseptic.

B) is not sporicidal.

C) requires high heat to be effective.

D) is a sterilizing agent.

E) is the active chemical in household bleach.

35) All of the following substances are used to preserve foods EXCEPT

A) biguanides.

B) nisin.

C) potassium sorbate.

D) sodium nitrite.

E) calcium propionate.

36) All of the following are effective for destroying prions EXCEPT

A) boiling.

B) incineration.

C) NaOH + autoclaving at 134°C.

D) proteases.

E) None of the answers are correct; each of these will destroy prions.

37) Which of the following pairs is mismatched?

A) ionizing radiation — hydroxyl radicals

B) ozone — takes electrons from substances

C) plasma sterilization — free radicals

D) supercritical fluids — CO2

E) ultraviolet radiation — desiccation

38) All of the following are methods of food preservation EXCEPT

A) desiccation.

B) high pressure.

C) ionizing radiation.

D) microwaves.

E) osmotic pressure.

Homework Chapter 12 The Eukaryotes: Fungi, Algae, Protozoa, and Helminths

39) Which of the following statements regarding fungi is FALSE?

A) Most fungi are pathogenic for humans.

B) Fungi are eukaryotic heterotrophs.

C) Fungi reproduce by forming asexual or sexual spores.

D) Most fungi grow well in acidic culture condition.

E) Fungi tolerate low moisture conditions.

40) Which of the following statements about helminths is FALSE?

A) They are heterotrophic.

B) They are multicellular animals.

C) They have eukaryotic cells.

D) All are parasites.

E) Some have male and female reproductive organs in one animal.

41) Which of the following statements about the oomycote algae is FALSE?

A) They form hyphae.

B) They produce zoospores in a sporangium.

C) They cause plant diseases.

D) They have chlorophyll.

E) They reproduce sexually.

42) Seventeen patients in ten hospitals had cutaneous infections caused by Rhizopus. In all seventeen patients, Elastoplast bandages were placed over sterile gauze pads to cover wounds. Fourteen of the patients had surgical wounds, two had venous line insertion sites, and one had a bite wound. Lesions present when the bandages were removed ranged from vesiculopustular eruptions to ulcerations and skin necrosis requiring debridement. Fungi are more likely than bacteria to contaminate bandages because they

A) are aerobic.

B) can tolerate low-moisture conditions.

C) prefer a neutral environment (pH 7).

D) have a fermentative metabolism.

E) cannot tolerate high osmotic pressure.

43) Which of the following statements regarding lichens is FALSE?

A) Lichens are a mutualistic relationship between a fungus and a protozoan.

B) Lichens represent a mutualistic relationship between a fungus and an alga.

C) Lichens are often the first life form to colonize rock or soil.

D) The algal partner produces carbohydrates that are absorbed by the fungal partner.

E) The fungal partner provides a means of attachment and protects the algal partner from desiccation.

44) Which of the following pairs is mismatched?

A) Basidiomycota — basidiospores

B) Ascomycota — conidiospores

C) Zygomycota — sporangiospores

D) microsporidia — lack mitochondria

E) anamorphs — lack spores

Table 12.1

1-Arthroconidium 5-Chlamydoconidium

2-Ascospore 6-Conidiospore

3-Basidiospore 7-Sporangiospore

4-Blastoconidium 8-Zygospore

45) In Table 12.1, which of these spores are characteristic of Penicillium?

A) 1 and 2

B) 3 and 4

C) 2 and 6

D) 1 and 4

E) 4 and 6

46) In Table 12.1, which of these spores are characteristic of Rhizopus?

A) 1 and 2

B) 6 and 7

C) 2 and 8

D) 1 and 4

E) 7 and 8

47) In Table 12.1, which is a thick-walled spore formed as a segment within a hypha?

A) 1

B) 3

C) 5

D) 7