This required practical covers Required Practical: Measuring Reaction Time (RPA7) within Reflex Arc for GCSE Biology. Topic 3: Reflex Arc It is section 5 of 15 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: Measuring 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 = factor being tested (e.g. caffeine, practice). Dependent = distance ruler falls. Control = same ruler, same hand, same starting position.
Practice questions for Reflex Arc
Which word best describes a reflex action?
State the correct order of the reflex arc pathway from stimulus to response. Name each component.
Quick recall flashcards
What is a reflex action?
A reflex is a rapid, automatic response to a stimulus that does not involve conscious thought. Reflexes protect the body from harm.
What is the reflex arc pathway?
Stimulus → Receptor → Sensory neurone → Relay neurone (in spinal cord) → Motor neurone → Effector → Response.