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Title: Action Of Antibiotic On Bacteria
Aim: To study the effects of an antibiotics onbacteria
Hypothesis: Antibiotics produce clear areas
on the surface of agar
Constant variable: Quantity of nutrient/ type of
bacteria
Manipulated variable: The presence on an
antibiotics
Responding variable: Clear area on the surface
of the agar
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Materials: sterile nutrient agar, two penicilin
discs (2 units and 5 units), cellophonetape, label paper,
bacteria culture
solution (Bacillus subtilis)
Apparatus: Sterile petri dish and cover, sterile
forceps, sterile syringe
----diagram----
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Procedure:
1. Two sterile Petri dishes labelled A and B are
prepared
2. Petri dishes A and B are filled with dampnutrient agar
3. 1 cm3of bacteria culture solution is added toeach Petri
dish
4. Penicillin discs 2 units and 5 units are placedon the surface
of the nutrient agar in Petri
dish B using a sterile forcep
5. Petri dishes A and B are covered and sealedwith cellophane
tape.
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Analysis:
1. The bacteria is killed in the clear area2. Antibiotics are
substances that are extracted
from organisms such as fungi and bacteria
that can kill bacteria or slow down their
growth without harming the body cell
3. Hypothesis is accepted
4. Antibiotics are taken orally or injected into
persons body to fight against the diseases
causing the by bacteria
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5. Some antibiotics such as penicillin can fight
the diseases into the gonorrhea and syphilis.
Higher concentration of penicillin can kill more
bacteria compared to lower concentration of
penicillin. Bacteria are killed and form clear
areas6. Petri dishes A functions as a control
Conclusion: Antibiotics can kill bacteria andformed clear area
around penicillin
disc
