OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What happens to a baby when it is put underwater?

1. Grips stronger

2. Moves arms and legs while holding breath

3. Spreads arms and legs to appear big

4. Stops all movement

The correct answer is: Moves arms and legs while holding breath

When a baby is placed underwater, it instinctively activates the swimming reflex, commonly known as the "bradycardic response." This reflex entails moving its arms and legs in a swimming motion while holding its breath, which demonstrates the innate ability of infants to respond to water. This reflex serves as a protective mechanism, allowing the baby to orient itself and work towards surfacing air while inhibiting inhalation underwater. In contrast, the other responses do not accurately describe the physiological and behavioral responses of infants when submerged. While the baby may grip objects more strongly due to reflexes, this is not the most significant response observed underwater. Spreading arms and legs to appear larger does not occur as a natural reflex when submerged; rather, the body instinctively moves to swim. Lastly, completely stopping all movement would not align with the survival behaviors that infants display in watery environments. Thus, the movement of arms and legs while holding the breath is clearly the accurate and most representative response for a baby underwater.