In phlox plants (Phlox drummondii) a gene locus produces the enzyme alcohol dehydrogenase - VCE - SSCE Biology - Question 20 - 2005 - Paper 1

The frequency of an allele is calculated using the ratio:

$ext{Frequency of A2} = \frac{ ext{Number of A2 alleles}}{ ext{Total number of alleles}}$

We found earlier that there are 50 A2 alleles. With 50 total plants, there are a total of 100 alleles (2 per plant). Using the formula:

$ext{Frequency of A2} = \frac{50}{100} = 0.5$

Therefore, this statement is incorrect.

For the frequency of the A1 allele, we can use a similar calculation:

• A1A1 contributes 40 A1 alleles (20 plants * 2).
• A1A2 contributes 10 A1 alleles (10 plants * 1).
• A2A2 contributes 0 A1 alleles.

Thus:

Total A1 alleles = 40 + 10 + 0 = 50 A1 alleles.

Calculating the frequency:

$ext{Frequency of A1} = \frac{50}{100} = 0.5$

So this statement is also incorrect.

Each plant contributes 2 alleles, and with 50 plants:

Total alleles = 50 * 2 = 100 alleles.

This means this statement is also incorrect.