SSCE VCE Biology Scientific Investigation and Research Methods: The platypus (Ornithorhynchus an

Question

The platypus (Ornithorhynchus anatinus) is a semi-aquatic animal, historically present in rivers throughout Victoria.

Platypuses usually occur in areas that have stable banks for burrowing, invertebrates for food, and reliable water flows. The platypus is potentially vulnerable to a range of natural and human-induced threats that degrade aquatic ecosystems, including drought, predators, habitat destruction, poor water quality and altered river flows. The Victorian Government listed the platypus as vulnerable in 2021.

An innovative detection technique using environmental DNA (eDNA) allowed scientists to develop a detailed map of platypus populations across the state. eDNA is comprised of traces of DNA that wildlife shed into their environment. Volunteers were provided with water-sampling kits and collected water samples from over 1500 selected sampling sites on Victorian rivers.

At each sampling site, six water samples were collected and tested in the laboratory using the Polymerase Chain Reaction (PCR) method. The PCR results were analysed using a platypus-specific DNA probe. At least two positive PCR results (out of six water samples) were required to classify the site as positive for the presence of platypus DNA.

a. Give two examples of possible sources of eDNA from the platypus.

b. Explain two factors to consider when sampling the water to reduce sources of error.

c. State why PCR was used in the test of the water samples.

d. Referring to the project, state one difference between predicted occurrences and detection of platypus presence from the eDNA survey results. Justify your response.

The platypus (Ornithorhynchus anatinus) is a semi-aquatic animal, historically present in rivers throughout Victoria - VCE - SSCE Biology - Question 10 - 2023 - Paper 1

Worked Solution & Example Answer:The platypus (Ornithorhynchus anatinus) is a semi-aquatic animal, historically present in rivers throughout Victoria - VCE - SSCE Biology - Question 10 - 2023 - Paper 1

a. Give two examples of possible sources of eDNA from the platypus.

b. Explain two factors to consider when sampling the water to reduce sources of error.

c. State why PCR was used in the test of the water samples.

d. Referring to the project, state one difference between predicted occurrences and detection of platypus presence from the eDNA survey results. Justify your response.

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