Question 1:
Figure 1 shows the result of an experiment to study the effect of different concentrations of an antibiotic on bacteria growth.



(a) State one hypothesis for this experiment. [1 mark]

(b) State the variables in this experiment.
(i) Manipulated variable [1 mark]
(ii) Responding variable [1 mark]

(c) Write down one observation for this experiment. [1 mark]

(d) What is meant by antibiotic based on this experiment (operational definition). [1 mark]


Answer:
(a) A higher concentration of an antibiotic will kill more bacteria.

(b)(i) Concentration of an antibiotic.

(b)(ii) Clear area

(c) The clear area that surrounds the antibiotic disc of high concentration is larger/ wider than the clear area that surrounds the antibiotic disc of low concentration.

(d) Antibiotic is a substance that produces a clear area around the nutrient agar that contains bacteria.