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 antimicrobial activity was compared by measuring the diameter of the zone of growth inhibition. The greater the diameter, the greater the antimicrobial activity. The diagram shows the zone of growth inhibition. The graph shows the results of this investigation. Evaluate the usefulness of this data when making conclusions about the antimicrobial activity of cinnamon oil and chitosan in this investigation. (4) ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................
Exam No:wbi13-01-que-20240523 Year:2024 Question No:(b)
Answer:
An answer that includes the following points:
- uses \{a range / more than one species\} (of microorganism) / bacteria and fungi\} so conclusion is (more) representative
- uses only four microbes so conclusion is not representative (1)
- no \{data given for uncoated fruit / control\} so do not know if either coating has an (antimicrobial) effect (1)
- no \{error bars / SDs / repeats\} so cannot judge if the \{differences are statistically significant / there is no measure of variability (1)
- measures diameter, direct area measure would be better because zone not always circular (1)
- no indication of concentration of coating substance so may not be \{representative / optimal\} (1)
- uses \{a range / more than one species\} (of microorganism) / bacteria and fungi\} so conclusion is (more) representative
- uses only four microbes so conclusion is not representative (1)
- no \{data given for uncoated fruit / control\} so do not know if either coating has an (antimicrobial) effect (1)
- no \{error bars / SDs / repeats\} so cannot judge if the \{differences are statistically significant / there is no measure of variability (1)
- measures diameter, direct area measure would be better because zone not always circular (1)
- no indication of concentration of coating substance so may not be \{representative / optimal\} (1)
Knowledge points:
CH4 – Plant Structure and Function, Biodiversity and Conservation
Solution:
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