The photograph shows jujube fruits. (Source: © Aneeta Benwan-edam/Alamy Stock Photo) Jujube fruits are edible and are native to China. Jujube fruits do not store well. An investigation compared the effect of covering the fruit with an edible coating. One coating was made from chitosan, a polysaccharide obtained from the outer skeleton of shellfish. Another coating was made from cinnamon oil. Samples from stored fruit were tested for vitamin C content and antimicrobial activity. The antimicrobial activity of the coatings was investigated using the agar diffusion method. Agar plates were spread with a suspension of bacteria containing $$\(5 \times 10^{5}\)$$ bacteria per $$\(\mathrm{cm}^{3}\)$$. Two suspensions of bacteria were made, one with E. coli and one with S. aureus. Discs of filter paper were soaked in either the chitosan or the cinnamon oil and placed on top of the agar. The agar plates were then incubated. Agar plates were also prepared that had two types of fungi grown on them: A. flavus and P. citrinum. The diagram shows a graduated pipette. The pipette was used to prepare the suspension of bacteria. Describe how to use a graduated pipette to measure an accurate volume. (2) ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................

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