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Nucleic acids are important information-carrying molecules

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Question 3

Scientists investigated the cell cycle in liver cells taken from rats 5 days before their birth and then at 3, 10, and 20 days after their birth.

Their results are shown in Table 1. Age 0 days = day of birth.

Table 1

Age / daysPercentage of liver cells undergoing mitosisPercentage of liver cells undergoing DNA replication
−5-5−516.416.416.410.210.210.2
3339.89.89.84.14.14.1
1010102.52.52.50.50.50.5
2020200.40.40.40.00.00.0
1.

Describe and explain the data in Table 1.

[2]
2.

The scientists determined the percentage of liver cells undergoing DNA replication by using a chemical called IdU. Cells use IdU instead of nucleotides containing thymine during DNA replication.

Describe how IdU would be incorporated into new DNA during semi-conservative replication.

[5]
3.

Cells with IdU in their DNA are detected using an anti-IdU antibody with an enzyme attached.

Use your knowledge of the ELISA test to suggest and explain how the scientists identified the cells that have IdU in their DNA.

[3]
Markscheme

Nucleic acids are important information-carrying molecules Questions

  1. A Level
  2. /Biology
  3. /Nucleic acids are important information-carrying molecules

10 exam-style questions on AQA A Level Biology Nucleic acids are important information-carrying molecules, covering Structure of DNA and RNA and DNA replication. Each one has a worked solution and a mark scheme showing where the marks go.

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