Lincoln wants to investigate the effect of different antibiotics on the growth of bacteria. Lincoln is going to use three of the antibiotic discs on the mast ring shown below:All the discs have been dipped in antibiotics at the same concentration.Identify the variables and control in this experiment. Independent variableDependent variableControl variableControl testPossible AnswersThe cross-sectional area of the zones of inhibition.The number of antibiotics used.The type of antibiotic.Paper disc dipped in distilled water.The number of bacteria growing.The concentration of the antibiotics.I DON'T KNOWRESETSUBMIT ANSWERLearning MaterialChoose your materialCENTURY ExplainsSlideshowAim & BackgroundVariablesEquipment IEquipment IIAutoclave & IncubatorSafetyResults TableCalculator FunctionMethod: Clean the Work SurfaceMethod: Bunsen BurnerMethod: Agar Plate LabelsMethod: ControlMethod: Disc 1Method: Disc LocationMethod: Control DiscMethod: Seal with TapeAnalysis: Zone of InhibitionAnalysis: Mean Zone MeasurementsAnalysis: Calculate Mean Cross-sectional AreaConclusionAlternative Method IAlternative Method IIQuestionQuestionQuestionQuestionQuestionQuestionQuestionQuestionQuestionQuestionQuestionQuestionSummary

When investigating the effect of different types of antiseptic on the growth of bacteria, one paper disc is dipped in distilled water and placed on the agar plate, along with discs that have been dipped in the antiseptics.We call the disc dipped in distilled water a control. This is different to a control variable.Match the answers to the sentence starters to explain what a control is and why it is needed.A control is set up to prove that the results obtained are due to changes in the...This means that the control test must be set up......but...For this experiment, the paper disc dipped in distilled water must be set up...The distilled water should have......helping to prove that changes seen around the other disc are due to...Possible Answers...no effect on the growth of bacteria......in exactly the same way as other tests......a significant effect on the growth of bacteria......on the same agar plate as the discs dipped in the antiseptics so that it is exposed to exactly the same conditions....without the independent variable....in an entirely different way to the other tests......independent variable only, and not due to changes in any other variable or condition....the bacteria only, and not due to changes in any other variable or condition....the antiseptics only, and not due to changes in any other variable or condition.I DON'T KNOWRESETSUBMIT ANSWER

A scientist has investigated the effectiveness of different antibiotics on the growth of E. coli.The diameter of the clear area around one of the antibiotic discs above is 8 mm.Calculate its cross-sectional area._____ mm2Write your answer to 1 decimal place.

A scientist investigated the effect of different disinfectants on the growth of the bacterium, Bacillus subtilis.A disinfectant used to clean hospital floors left a zone of inhibition with a diameter of 24 mm.Calculate the cross-sectional area in mm._____ mm2Use the maths keyboard to write your answer in standard form and to three significant figures.

Scientists investigated the effectiveness of different disinfectants on the growth of bacteria.The diameter of the clear area around one of the disinfectants is 9.2 mm.Calculate its cross-sectional area._____ mm2Write your answer to 1 decimal place.

Record zones of growth inhibition in mm around each disc. Antiseptic agent dilutions Staphylococcus aureus Escherichia coli Serratia marcescens Mouth wash neat Mouth wash 1:1 Savlon 1:1 Savlon 1:20 Bleach 1:8 Bleach 1:20 Liquid soap 1:10 Liquid soap 1:20 How effective are these agents in controlling growth? Are they still effective at the highest dilution?