Question

One of the human embryonic developmental stages has been shown in the diagram. What do the A and B indicate?

• A. Inner mass of cells; B - Blastocoel
• B. Inner mass of cells; B - Antrum
• C. Trophoblasts; B - Yolk sac
• D. Ectoderm; B - Amniotic cavity

Hint:

The inner mass of cells forms the embryo, while the blastocoel is the fluid-filled cavity in the early blastula stage.

Answer 1

The Correct Option is A

Step 1: Understanding the developmental stages of the embryo.
In early embryonic development, the inner mass of cells forms the embryo, while the blastocoel is the fluid-filled cavity in the blastula stage.
Step 2: Analyzing the options.
(A) Inner mass of cells; B - Blastocoel: Correct. The inner mass of cells forms the embryo, and the blastocoel is the cavity within the blastula.
(B) Inner mass of cells; B - Antrum: Incorrect. The antrum is associated with ovarian follicles, not embryonic development.
(C) Trophoblasts; B - Yolk sac: Incorrect. The trophoblast forms the placenta, and the yolk sac is involved in early blood cell production, but this is not the correct labeling.
(D) Ectoderm; B - Amniotic cavity: Incorrect. The ectoderm is a germ layer, and the amniotic cavity surrounds the developing embryo, but this option does not match the labeling.
Step 3: Conclusion.
The correct answer is (A) Inner mass of cells; B - Blastocoel, as this corresponds to the typical structure of early embryonic development.