Question

Which of the following is not associated with the blastula stage of embryonic development?

• A. It consists of a solid ball of cells
• B. It contains a fluid-filled centre called the blastocoel.
• C. It is the stage of development that precedes the gastrula.
• D. It is a more advanced stage than a morula.
• E. It is a less advanced stage than morula.

Answer 1

The correct option is E It is a less advanced stage than morula.

• The blastula is usually a spherical solid layer of cells surrounding a fluid-filled or yolk-filled cavity (the blastocoel).
• Cells migrate to the interior of the blastula, subsequently forming two (in diploblastic animals) or three (triploblastic) germ layers. The embryo during this process is called a gastrula.
• The zygote undergoes many cleavages (divisions) to develop into a ball of cells called a morula and when the fluid-filled cavity (blastocoele) is formed, the early embryo becomes a blastula.
• So, the correct option is 'It is a less advanced stage than morula'.