Some students investigated the effect of drinking caffeine on reaction time - AQA - GCSE Biology Combined Science - Question 1 - 2019 - Paper 2

To find the mass of caffeine consumed by group D, we first note that group D drank 600 cm³ of the caffeine drink. Given that the drink contains 32.25 mg of caffeine per 100 cm³, the calculation is as follows:

$X = 600 imes \frac{32.25}{100} = 193.5 \text{ mg}$

Group A drank water instead of the caffeine drink to serve as a control group. This allows a comparison of the effects of caffeine on reaction times, ensuring any observed changes can be attributed specifically to caffeine intake.

To estimate the reaction time for a distance of 23 cm, we can interpolate between the values given in Table 2. Since 23 cm falls between 20 cm (0.212 s) and 26 cm (0.221 s), we may approximate the reaction time at this distance to be around:

$0.217 \text{ s}$

The data indicate that as the mass of caffeine consumed increases, the decrease in reaction time tends to become greater. This suggests that higher caffeine intake may enhance alertness and improve reaction time.

The decrease in reaction time being negative indicates that the reaction time after caffeine consumption was slower than before. This can occur due to various factors, such as individual variability in response to caffeine or lack of adequate stimulation from the drink.

To determine the range of results for group C, we find the difference between the maximum and minimum reaction times recorded. Assuming the recorded reaction times for group C are 0.166 s and 0.182 s, the range is:

$\text{Range} = \text{Max} - \text{Min} = 0.182 - 0.166 = 0.016 ext{ s}$

1. The time of day when the reaction tests were conducted - to ensure consistent environmental conditions.
2. The amount of sleep prior to the experiment for all participants - as fatigue can influence reaction times.

The ruler-drop test does not involve a reflex action because it requires a voluntary response to catch the ruler, which involves cognitive processing. Reflex actions occur without conscious thought, while this test necessitates awareness and decision-making.