Free Embryonic Development MCQs with Answers

31. Cleavage differ from mitosis in that:

• A. It occurs only in zygote
• B. It occurs in all body cells
• C. It results in haploid cells only
• D. It results in identical cells

Explanation: Cytokinesis during cleavage results in identical cells as the parent cell divides into two daughter cells. The other options are incorrect as cleavage is not limited to the zygote stage, does not occur in all body cells, and does not result in haploid cells.

32. Extract embryonic membrane like amnion and chorine appeared for the first time:

• A. Amphibians
• B. Reptiles
• C. Birds
• D. Fish

Explanation: Embryonic membranes like the amnion and chorion first appeared in reptiles, making option B the correct answer. These membranes are part of the amniotic egg, a key adaptation that allowed reptiles to reproduce on land. Birds also have similar adaptations, but they evolved from reptilian ancestors, not the other way around. Options A, C, and D are incorrect because they do not align with the evolutionary development of embryonic membranes in animals.

33. Which germinal layer develops in the digestive system?

• A. Ectoderm
• B. Mesoderm
• C. Epidermis
• D. Endoderm

Explanation: During embryonic development, the digestive system originates from the endoderm, which is one of the three primary germinal layers.

34. During the development of the chick peripheral part of the blastoderm lies unseparated from the yolk and forms:

• A. Area pellucida
• B. Area opaca
• C. Notochord
• D. Primitive streak

Explanation: During the development of a chick embryo, the peripheral part of the blastoderm that remains attached and unseparated from the yolk forms the Area pellucida.

35. Extra embryonic membranes like amnion and chorion appeared for the first time in

• A. Fish
• B. Amphibian
• C. Reptiles
• D. None

Explanation: Extra embryonic membranes like amnion and chorion appeared for the first time in reptiles. The amnion is a membrane that surrounds and protects the embryo, providing a fluid-filled cavity for its development. The chorion is another extra embryonic membrane that allows for gas exchange with the environment.

36. All of the following are derived from mesoderm except:

• A. Muscles
• B. Liver
• C. Gonads
• D. Blood vessels

Explanation: GERM LAYERS: A germ layer is a group of cells in an embryo. There are 3 germ layers: the endoderm (inner layer), the ectoderm (outer layer), and the mesoderm (middle layer). All the parts mentioned are formed by mesoderm except for the liver, which is a product of endoderm.

37. The genetic potential for one type of cell from a multicellular organism to generate a whole new organism is called

• A. unipotent
• B. multipotent
• C. totipotent
• D. pluripotent

Explanation: Totipotent is an immature cell that is capable of giving rise to any cell type or even a complete embryo.

38. Muscles develop from:

• A. ectoderm
• B. mesoderm
• C. endoderm
• D. all of the above

Explanation: Muscles develop from the mesoderm, which is one of the three primary germ layers in the early embryo. The mesoderm also gives rise to the skeletal and reproductive systems. The ectoderm forms the skin and nervous system, while the endoderm develops into the lining of the digestive and respiratory systems. Thus, the correct answer is B: mesoderm.

39. Lungs are _ in srcin.

• A. Ectodermal
• B. Endodermal
• C. Mesodermal
• D. Preformed

Explanation: The correct answer is Endodermal. The endoderm, one of the three primary germ layers formed during embryonic development, is responsible for the formation of the respiratory tract lining, including the lungs. This layer also forms other vital internal organs such as the liver, pancreas, and parts of the digestive system. The ectoderm and mesoderm, while important for forming other bodily structures, do not contribute to the primary functional tissue of the lungs. 'Preformed' is unrelated to germ layer origins and lung development.

40. Implantation of zygote takes place in the:

• A. 2nd week
• B. 3rd week
• C. 7th week
• D. 5th week

Explanation: Implantation is the process of the blastocyst embedding into the endometrial lining of the uterus, which typically occurs in Week 2 of development. For implantation to occur, the blastocyst must completely hatch from the zona pellucida once the conceptus enters the uterine cavity