This required practical covers Required Practical: Reaction Time (RPA7) within Nervous System for GCSE Biology. Topic 2: Nervous System It is section 8 of 18 in this topic. Revise both the method and the reason for each step, because practical questions often test understanding rather than pure recall.
🧪 Required Practical: Reaction Time (RPA7)
In this practical, you measure reaction time using the ruler-drop method:
- One person holds a ruler vertically at the 0 cm mark between another person's open thumb and forefinger.
- The ruler is dropped without warning — the second person catches it as quickly as possible.
- Read the distance the ruler fell (in cm) and use a conversion table to find the reaction time.
- Repeat at least 5 times and calculate the mean to improve reliability.
Variables:
- Independent variable (what you change): e.g. caffeine intake, practice, distraction
- Dependent variable (what you measure): distance the ruler falls (reaction time)
- Control variables: same ruler, same hand, same starting position, same person dropping
Why repeat and average? Individual readings vary because reaction time is affected by concentration, fatigue, and anticipation. Taking a mean reduces the effect of anomalies and gives a more reliable result.
Practice questions for Nervous System
What are the two organs that make up the central nervous system (CNS)?
Explain how a signal is transmitted across a synapse from one neurone to the next.
Quick recall flashcards
Name four types of sensory receptor.
Photoreceptors (light, in eye), thermoreceptors (temperature, in skin), pressure receptors (touch, in skin), chemoreceptors (chemicals, in tongue and nose).
Name the three types of neurone.
Sensory (receptor → CNS), relay (within CNS), motor (CNS → effector). Remember: SRM — Students Revise Methodically.