Free Embryonic Development MCQs with Answers

21. In which stage of development, germ layers are formed?

• A. Morulation
• B. Blastulation
• C. Gastrulation
• D. Organogenesis

Explanation: Germ layers that are ectoderm, endoderm, and mesoderm are formed during gastrulation. During gastrulation, the blastoderm splits into two layers: an upper layer of cells called epiblast and a lower layer of cells called hypoblast. The epiblast is the presumptive ectoderm and mesoderm while the hypoblast is the presumptive endoderm.

22. Microcephaly, the small sized skull is due to:

• A. Nutritional Cause
• B. Hormonal Causes
• C. Skeleton Damage
• D. Genetic Defect

Explanation: Explanation: Microcephaly, the small-sized skull, is usually due to a genetic defect. It can also be caused by environmental factors such as infections, exposure to toxic substances, and lack of proper nutrition during fetal development, but genetic causes are the most common. Genetic causes may include mutations in genes involved in brain development, chromosomal abnormalities, or inherited conditions that affect brain growth.

23. At the cephalic end of primitive streak, closely packed cells form a loci thickening known as:

• A. Hensen's Node
• B. Primitive Ridge
• C. Gastrocoel
• D. Primitive Gut

Explanation: Explanation:At the cephalic end of the primitive streak, closely packed cells form a locai thickening known as Hensen's node. It is the site where the gastrulation begins and the 3 germ layers are first formed.This option is not correct. The primitive ridge is a thickened area of the ectoderm that lies above the notochord in the developing embryo. It is formed during neurulation and serves as a signaling center that regulates the patterning of the neural tube.This option is also incorrect. The gastrocoel is a cavity that forms in the developing embryo as the gut tube forms by folding the endodermal layer. It eventually becomes the lumen of the developing digestive tract.This option is also incorrect. The primitive gut is the initial tube-like structure that develops from the endoderm during gastrulation. It later gives rise to the digestive tract and associated organs.

24. Grey equatorial cytoplasm produces:

• A. Muscle cells
• B. Gut
• C. Notochord and neural tube
• D. Larval epidermis

Explanation: [A]Sarcoplasm is the cytoplasm of muscle cell which is yellow in colour[B] Gut is produced by grey vegetal cytoplasm[C] Notochord and neural tubules are produced by Grey editorial cytoplasm[D] Larval epidermis is produced by clear cytoplasm

25. The nervous system develops from which of the following layer during embryonic development of animals?

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

Explanation: Option [A]Mesoderm gives rise to muscular,skeletal and reproductive systemsOption [B] After embryonic development the body layers[ ectoderm, mesoderm and endoderm] in most triploblastic animals are represented by the structures formed from them. The systems such as integumentary and nervous system develop from Option [C] Endoderm forms the lining of the digestive tract and forms other glands of the digestive system, such as the liver.Option [D] Mesoderm and Endoderm [same as above]

26. Which one of the following is the additional function of the embryonic membranes?

• A. Respiration and reproduction
• B. Reproduction and nourishment
• C. Strong of wase products
• D. Respiration and storage of waste products

Explanation: During the development of chick and other vertebrates, there are produced certain tissues or structures that temporarily or permanently do not enter into the formation of the embryo themselves but are external to and devoted in one way or another to the care and maintenance of the developing embryo. Collectively these parts are termed fetal membranes, extra-embryonic sacs, or extra-embryonic membranes. Extra-embryonic membranes developed are: i. Amnion or amniotic sac: which surrounds the embryo and provides a kind of private aquarium to protect it from mechanical shocks (such as pressure, abrasion, irritation) and desiccation. ii. A serosa or chorion: which forms the outermost membrane surrounding the rest of the embryonic system. iii. A yolk sac: which is filled with the yolk of the egg functions as the first respiratory organ and as a digestive organ for the embryo. It also acts as a hemopoietic organ like the liver and at later stages serves as a place of origin for blood cells. iv. An allantois: which is a precocious urinary bladder by origin, accumulates the embryonic nitrogenous wastes (non-toxic uric acid) and also acts as an embryonic respiratory surface. In short, They typically perform roles in nutrition, gas exchange, and waste removal

27. The mesodermal cell which give rise to urinary system in frog are called:

• A. Pincer cells
• B. Blastomers
• C. Nephrotome
• D. Parietal

Explanation: Pincer cells are deformed blood cells which are a characteristic feature of hereditary spherocytosis associated with Protein Band-3 deficiency. Therefore, A is incorrect. A blastomere is a type of cell produced by cell division (cleavage) of the zygote after fertilization; blastomeres are an essential part of blastula formation and blastocyst formation in mammals. Therefore, B is incorrect. The nephrotome is a section of the mesoderm that was thought to give rise to the pronephros and eventually to the rest of the kidney. Therefore, A is the correct answer. However, modern visualizing techniques such as scanning electron microscopy have shown this is not the case. Parietal cells (AKA oxyntic cells) are epithelial cells in the stomach that secrete hydrochloric acid (HCl) and intrinsic factors. These cells are located in the gastric glands found in the lining of the fundus and body regions of the stomach.

28. The transitory stage between cleavage and gastrulation is:

• A. Orgenogenesis
• B. Blastula
• C. Gastrula
• D. Development

Explanation: Zygote develops by a sequence of mitotic division, called cleavage, into a multicellular structure, first a solid ball of cells the module, and then a hollow ball of cells the blastula.

29. The individual with hare-lip shows which of the following condition?

• A. Cleft palate
• B. Polydactyly
• C. Hard-palate
• D. Microcephaly

Explanation: A cleft palate is a congenital condition often associated with a hare lip, involving an opening or split in the upper lip and/or roof of the mouth. This occurs when the developing facial structures in an unborn baby do not completely fuse. The other options are unrelated: Polydactyly involves extra digits; the hard palate is a normal part of the mouth's structure; and microcephaly is a different developmental condition affecting head size.

30. The developing embryo is protected against the physical trauma by :

• A. Pericardial fluid
• B. Allantoic fluid
• C. Amniotic fluid
• D. All of these

Explanation: Amniotic fluid plays a crucial role in protecting the developing embryo/fetus against physical trauma. It is a liquid that surrounds the embryo/fetus within the amniotic sac, which is formed by the amnion membrane. The amniotic fluid acts as a cushion, providing a protective barrier and absorbing shocks or impacts that may occur during movement or external forces.