Get your research papers, homework and online exams done from just $8 per page

We also have verified textbook solutions at just $3 per answer; No subscription needed

Do my Homework

C H A P T E R 3 Growth

Category:
« Back to Previous Page
▲
0
▼
♥ 0
  1. Figure 3–1 depicts a bacterial growth curve divided into phases

a, b, c, and d. In which one of the phases are antibiotics such as

penicillin most likely to kill bacteria?

(A) Phase a

(B) Phase b

(C) Phase c

(D) Phase d

 

  1. Some bacteria are obligate anaerobes. Which of the following

statements best explains this phenomenon?

(A) They can produce energy both by fermentation (i.e., glycolysis)

and by respiration using the Krebs cycle and cytochromes.

(B) They cannot produce their own ATP.

(C) They do not form spores.

(D) They lack superoxide dismutase and catalase.

(E) They do not have a capsule.

✅ Answers (1)

▲
0
▼
✔
Private answer
  1. (B)

During exponential phase

The earliest studies on the mechanism of action of penicillin showed that the bactericidal

activity of /I-lactam antibiotics depends on bacterial growth (Hobby et al., 1942; Hobby &

Dawson, 1944). This is best illustrated by the inability of penicillin to kill nongrowing bacteria in

contrast to the rapid killing and lysis of the same cells during exponential growth. The

insensitivity of nongrowing cells to the bactericidal and lytic effect of antibiotics is a property

shared by all bacteria and has been termed phenotypic tolerance (Tuomanen, 1986).

 

 

  1. (D)

(D) They lack superoxide dismutase and catalase.

Obligate anaerobes lack superoxide dismutase and catalase and/or peroxidase, and therefore undergo lethal oxidations by various oxygen radicals when they are exposed to O2.

Marked as spam
Answered on June 24, 2020 5:02 pm
« Back to Previous Page

Professional Essay Helpers Online

Get your papers written by online essay writers available 24/7. Submit your assignments and get a quality plagiarism-free paper via email.

Write My Paper For Me