When plants were grown from these seeds, it would be reasonable to expect that about A - VCE - SSCE Biology - Question 3 - 2004 - Paper 1

To answer this question, we can use principles of Mendelian genetics, specifically the ratios expected from a dihybrid cross. When crossing two heterozygous plants (AaBb x AaBb), we expect a phenotypic ratio of 9:3:3:1. In this case:

1. Total Offspring Calculation: The total number of seeds collected is 1600.

2. Expected Phenotype Ratios:

   • Solid-coloured, sweet fruit (combined dominant characteristics) = 9 parts out of 16
   • Solid-coloured, bitter fruit = 3 parts out of 16
   • Spotted-coloured, sweet fruit = 3 parts out of 16
   • Spotted-coloured, bitter fruit = 1 part out of 16

3. Calculate each phenotype count:

   • Solid-coloured, sweet fruit: $1600 \times \frac{9}{16} = 900$
   • Solid-coloured, bitter fruit: $1600 \times \frac{3}{16} = 300$
   • Spotted-coloured, sweet fruit: $1600 \times \frac{3}{16} = 300$
   • Spotted-coloured, bitter fruit: $1600 \times \frac{1}{16} = 100$

Based on the calculations, the correct expectation from the given choices is option C: 300 of the plants produced solid-coloured, sweet fruit.