Aim for FiveBiology

Analyze data

Allele frequencies in island lizards

  • Unit 7
  • 4 points
  • About 10 minutes

You can use a calculator on this question, just like on exam day.

A short question with data in a table or graph. You describe what the data show, use the data to judge a hypothesis, and explain how the results connect to biology you know. On the exam: Question 6 of 6 in Section II; about 10 minutes suggested.

The question and its sources

A gene in a population of lizards on a small island has two codominant alleles, F and S. Researchers can identify each lizard's genotype from a blood sample. A severe drought struck the island in 2014, killing many lizards. Earlier studies found that this gene does not affect survival during droughts. In 2010, the frequency of the S allele was 0.40.

Table 1. Number of lizards of each genotype

YearFFFSSSTotal
201018024080500
202098182120400

Source: Hypothetical data

Suggested time: 10 minutes

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Part (a)

1 point

Based on Table 1, identify the genotype whose frequency in the population increased from 2010 to 2020.

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Part (b)

1 point

Calculate the frequency of the S allele in 2020.

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Part (c)

1 point

The researchers hypothesize that the population was not evolving at this gene between 2010 and 2020. Use the data to evaluate this hypothesis.

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Part (d)

1 point

Explain how the 2014 drought could have changed the allele frequencies of this gene, even though the gene does not affect survival during droughts.

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