5 (a) Carrots have different physical characteristics such as colour - Edexcel - GCSE Biology - Question 5 - 2021 - Paper 1

1. Measure the length/width of the carrot sticks to ensure consistent dimensions across samples.
2. Use the same carrot or same part of the carrot for each stick to reduce variability and enhance comparison.

To find the percentage change in mass for carrot stick Q, we can use the formula:

$\text{Percentage Change} = \left( \frac{\text{Final Mass} - \text{Initial Mass}}{\text{Initial Mass}} \right) \times 100$

For Q: Initial Mass = 4.2 g, Final Mass = 5.0 g.

Substituting these values:

$\text{Percentage Change} = \left( \frac{5.0 - 4.2}{4.2} \right) \times 100 = \left( \frac{0.8}{4.2} \right) \times 100 \approx 19.05\%$

Rounded to two significant figures, this gives us 19%.

1. The carrot sticks gained mass because water moved into the carrot (cells) during the process of osmosis.
2. This movement occurred as the carrot sticks were placed in a solution with a lower solute concentration, allowing water to enter the cells of the carrot sticks.