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A scientist produced transgenic zebrafish - AQA - A-Level Biology - Question 9 - 2020 - Paper 1
Question 9
A scientist produced transgenic zebrafish. She obtained a gene from silverside fish. The gene codes for a growth hormone (GH). She inserted copies of this GH gene ... show full transcript
Worked Solution & Example Answer:A scientist produced transgenic zebrafish - AQA - A-Level Biology - Question 9 - 2020 - Paper 1
Step 1
Describe how enzymes could be used to insert the GH gene into a plasmid.
Answer
To insert the GH gene into a plasmid, specific enzymes known as restriction endonucleases are used. These enzymes cut the plasmid at specific sites, creating 'sticky ends' that can facilitate the attachment of the GH gene. Subsequently, another enzyme called ligase is utilized to join the cut plasmid and the GH gene together, forming a recombinant plasmid.
Step 2
Suggest and explain how delayed insertion of the GH gene could produce offspring of transgenic fish without the desired characteristic.
Answer
Delayed insertion of the GH gene might cause issues because the gene may not be incorporated into the DNA of the embryo during early development. If the GH gene is not integrated before significant cell division occurs, some cells may develop without the gene, leading to a mix of transgenic and non-transgenic cells in the offspring. As a result, these fish may not exhibit the desired trait associated with the GH gene.
Step 3
Using Table 3, what can you conclude about the effectiveness of the GH gene on the growth of zebrafish?
Answer
While I cannot access Table 3 directly, a conclusion drawn would focus on assessing any significant increases in growth or mass of zebrafish with the GH gene compared to the control group. If the data shows notable differences, it would suggest that the GH gene positively influences growth, while lack of significant difference would indicate that the gene does not have a meaningful effect.
Step 4
Explain how two features of the design of this investigation helped to ensure the validity of any conclusions obtained.
Answer
Two important features in designing this investigation include:
- The use of a large sample size, which ensures the results are representative of the population and reduces the impact of anomalies.
- A controlled environment for both the experimental group (with the GH gene) and the control group (without the gene) to rule out external factors that might influence growth, ensuring any observed differences are likely due to the gene itself.