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

To improve the experiment, the following methods can be considered:

1. Measure the length and width of the carrot sticks before weighing them to ensure consistency in size.
2. Use sticks from the same carrot or the same part of the carrot to standardize conditions.

To calculate the percentage change in mass for carrot stick Q:

1. Use the formula for percentage change:

   ext{Percentage Change} = rac{ ext{Change in Mass}}{ ext{Initial Mass}} imes 100

2. For carrot stick Q:

   • Initial Mass = 4.2 g
   • Final Mass = 5.0 g
   • Change in Mass = 5.0 g - 4.2 g = 0.8 g

3. Plug the values into the formula:

   ext{Percentage Change} = rac{0.8}{4.2} imes 100 \\ = 19.05 \\ ext{(rounded to two significant figures as } 19 ext{)}

The increase in mass of the carrot sticks can be explained as follows:

1. The carrot sticks gained mass because they absorbed water from the distilled water solution.
2. This water moved into the carrot cells by osmosis, which is the process of water moving across a semi-permeable membrane from a region of lower solute concentration to a higher concentration.