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

What begins to occur during stage 6 of embryonic development?

1. The zygote forms into a single cell

2. Embryonic stem cells start to differentiate into various tissue types

3. The embryo is ready for implantation

4. Twins begin to form

The correct answer is: Embryonic stem cells start to differentiate into various tissue types

During stage 6 of embryonic development, embryonic stem cells begin to differentiate into various tissue types. This is a crucial phase in development, as stem cells have the potential to develop into any cell type in the body, which is essential for forming the organs and tissues that will enable the developing organism to function properly. Differentiation is a complex process where the stem cells receive signals that trigger them to develop into specific types of cells, such as muscle cells, nerve cells, or skin cells. While the formation of twins occurs during an earlier stage when the zygote divides, the implantation of the embryo typically happens after the embryo has developed further. The early single-cell zygote stage is also part of earlier development and does not represent stage 6. Thus, the correct context highlights the significance of cellular differentiation at this stage in laying down the foundation for the organism’s structure and function.