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Citrus canker is a disease that affects citrus plants such as lime and orange trees, reducing fruit yield and quality by causing the development of dark spots on the fruit and leaves - VCE - SSCE Biology - Question 5 - 2023 - Paper 1
Question 5
Citrus canker is a disease that affects citrus plants such as lime and orange trees, reducing fruit yield and quality by causing the development of dark spots on the... show full transcript
Worked Solution & Example Answer:Citrus canker is a disease that affects citrus plants such as lime and orange trees, reducing fruit yield and quality by causing the development of dark spots on the fruit and leaves - VCE - SSCE Biology - Question 5 - 2023 - Paper 1
Step 1
Using the information in the flow chart above, explain how CRISPR-Cas9 technology could be used to produce citrus-canker-resistant plants.
Answer
CRISPR-Cas9 technology can be applied to produce citrus-canker-resistant plants by targeting specific genes involved in the disease pathway. The process involves designing a single guide RNA (sgRNA) that is complementary to either the CsWRKY22 or CsLOB1 gene. By combining the sgRNA with Cas9, the Cas9 protein can locate and bind to the targeted gene, leading to its cleavage at a specific site.
If the CsWRKY22 gene is disrupted, the plant would not activate the pathway leading to the production of proteins that cause citrus canker, resulting in a healthier plant. Alternatively, if the CsLOB1 gene transcription is hindered, the subsequent proteins necessary for the development of citrus canker would also not be produced. In this manner, the application of CRISPR-Cas9 could effectively inactivate these genes and provide resistance against the disease.
Step 2
Why did the scientists decide to do each of the following?
Answer
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Use 250 °C: At this temperature, most cells are ruptured, leading to maximal glucose release from the broken cells. This is beneficial for the biofuel production process, allowing for higher yields of usable sugars.
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Lower to 35 °C and add yeast: Lowering to 35 °C is optimal because yeast produces ethanol under these conditions, which is the desired product in biofuel production. This is the suitable temperature range for the yeast's enzymatic activity, ensuring effective anaerobic respiration and ethanol production.