Cell Biology: Microbes

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1. Name the period of rapid growth in a bacterial culture when the cells divide every few minutes.
(a) mitosis
(b) replication
(c) log phase
(d) apoptosis

2. Which of these must infect a living host to reproduce?
(a) bacteria
(b) viruses

3. Chemotaxis in E. coli depends on what flagellar characteristic?
(a) length
(b) thickness
(c) rotation
(d) number

4. What bacterial structure does penicillin weaken?
(a) nucleosome
(b) ribosome
(c) endospore
(d) cell wall

5. What genus of bacteria has been shown to cause peptic ulcers?
(a) Escherichia
(b) Helicobacter
(c) Salmonella
(d) Enterococcus

6. Given good growing conditions, bacteria in log phase may double as often as every...
(a) 24 hours
(b) 6 hours
(c) 2.5 hours
(d) 20 minutes

7. After passing through the stomach, a cyst of the parasite Cryptosporidium will release how many infective sporozoite(s)?
(a) one
(b) four
(c) twelve
(d) over 100

8. What does the parasite Giardia use to attach to the intestinal wall of its host?
(a) super glue
(b) capsule
(c) flagella
(d) suction cup

9. Some strains of Streptococcus have a toxin on their surface called streptolysin-s. When a white blood cell attacks these bacteria, what happens?
(a) the bacteria paralyze the white cell
(b) the bacteria bounce off the white cell
(c) the bacteria are killed and the white cell self destructs
(d) nothing: white cells avoid these bacteria

10. The T4 bacteriophage, a virus that attacks E. coli bacteria, looks like...
(a) an alien landing pod
(b) my little sister
(c) a coiled rope
(d) a rhinovirus

Answer Grid:
1.(c); 2.(b); 3.(c); 4.(d); 5.(b); 6.(d); 7.(b); 8.(d); 9.(c); 10.(a)

Tutorial for correct answers:

Question 1: Bacteria Divide and Multiply

Bacteria are all around us. Given good growing conditions, a bacterium grows slightly in size or length, a new cell wall grows through the center forming two daughter cells, each with the same genetic material as the parent cell. If the environment is optimum, the two daughter cells may divide into four in 20 minutes. Oh my! 1, 2, 4, 8, 16, 32, 64... Then why isn't the earth covered with bacteria?

The primary reason may be that conditions are rarely optimum. Scientists ...