Biology discussion, revision, testing and homework help. 58 Minutes ago: 1 October 2011 14: 13 a study was carried out, the effectiveness of the four different antibacterial mouthwash, P, Q, R and S. using compare aseptic technique, an identical filter paper disc was soaked in each of the four mouthwashes and on a lawn of Staphylococcus Epidermidis in a Petri dish. The Court was sealed and incubated for 48 hours at 30 C. The diagram shows the appearance of the Petri dish after incubation.

(a) explain why there is a clear zone around each of the paper discs. (1)

(b) there was no control in this investigation. Propose a suitable control, and explain why it would be necessary. (2)

(c) has been concluded that this brand of P to kill the most effective mouthwash was bacteria from the mouth. Two explain reasons why this no valid conclusion from this test.
1............................... ................................ ................................ ................................ .
2............................... ................................ ................................ .............................
(2)
(A total of 5 marks)

Thank you very much

52 Minutes ago: 1 October 2011 14: 19 you will answer not even the questions?

It would be nice, if you came with your own ideas then asked for help instead of just questions, for answers to develop.

Before 44 minutes: 1 October 2011 14: 27 OK, then:

(a) because they all have prevented the entry of bacteria in clear zones.

(c) 1, which was carried out only once.
2 We do not know whether to kill it, the most effective bacteria as it to kill was effective only a kind - Staphylococcus Epidermidis

Last edited by Ghijk; Ago at 14: 30 39 minutes ago: 1 October 2011 14: 32, then in order:

(a) because they all have prevented the entry of bacteria in clear zones.

(c) 1, which was carried out only once.
2 We do not know whether to kill it, the most effective bacteria as it to kill was effective only a kind - Staphylococcus Epidermidis

And part B? 24 Hours: 1 October 2011 14: 47, then in order:

(a) because they all have prevented the entry of bacteria in clear zones.

(c) 1, which was carried out only once.
2 We do not know whether to kill it, the most effective bacteria as it to kill was effective only a kind - Staphylococcus Epidermidis

(a) almost, they have prevented the growth of bacteria within these zones.
(c) they sound like reasonable answers, but these questions can sometimes so stupid and have so many answers, no one will ever think one of the many joys that are a level biology.

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