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

Which of the following methods is least effective in preventing pregnancy?

1. Barrier methods

2. Natural methods

3. Hormonal methods

4. Surgical methods

The correct answer is: Natural methods

Natural methods are considered the least effective in preventing pregnancy because they typically rely on tracking the menstrual cycle, understanding ovulation patterns, and avoiding intercourse during fertile periods. These methods can be influenced by various factors such as irregular cycles, hormonal fluctuations, and human error in timing, making them less reliable than other contraceptive options. In contrast, barrier methods involve physical devices like condoms that can actively block sperm from reaching an egg. Hormonal methods, such as birth control pills or implants, work by altering hormonal levels to prevent ovulation, while surgical methods (like vasectomy or tubal ligation) provide a permanent solution by physically altering reproductive pathways, making them much more effective at preventing pregnancy. The effectiveness of natural methods varies widely and generally results in higher rates of unplanned pregnancies compared to the other methods mentioned.