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

During what stage do organs begin to grow in an embryo?

1. Stage 4

2. Stage 5

3. Stage 6

4. Stage 3

The correct answer is: Stage 6

In the context of embryonic development, the stage at which organs begin to grow is typically referred to as organogenesis, which occurs during the later stages of embryonic development. In a standardized embryological timeline, this is generally recognized to happen in stage 6, marking significant differentiation and development of the major organ systems. During this stage, the embryo undergoes crucial processes such as the formation of the heart, development of the nervous system, and the establishment of other vital organs. These changes lay the foundation for further growth and functional development as the embryo progresses toward becoming a fetus. Understanding the timeline of embryonic development is critical, as it highlights the rapid and complex processes that occur even in the early stages of life.