Question 1

During the pre-embryonic period, the zygote undergoes several mitotic divisions called cleavage divisions. If a zygote starts as a single cell and undergoes 5 cleavage divisions, how many cells will be present in the resulting morula?

Accepted Answer

32 cells

Question 2

Which of the following best describes the function of the trophoblast during blastocyst development?

Accepted Answer

Provides nutrients to the developing embryo and forms the chorion

Question 3

Implantation of the blastocyst typically occurs at which time point after fertilization?

Accepted Answer

About 5 days after fertilization

Question 4

Which extraembryonic membrane is responsible for forming the fetal part of the placenta and facilitating the exchange of nutrients and gases between maternal and fetal blood?

Accepted Answer

Chorion

Question 5

During gastrulation, the embryoblast differentiates into three germ layers. Which germ layer gives rise to the muscles, cardiovascular system, and dermis?

Accepted Answer

Mesoderm

Question 6

A patient presents with a congenital defect affecting the epithelial lining of their digestive and respiratory tracts. Which embryonic germ layer was most likely affected during development?

Accepted Answer

Endoderm

Question 7

If the blastocyst fails to implant into the uterine wall, which of the following outcomes is most likely?

Accepted Answer

The blastocyst will be expelled and pregnancy will not occur

Question 8

Which of the following correctly matches the extraembryonic membrane with its primary function?

Accepted Answer

Yolk sac – provides nutrients and forms blood cells

Question 9

During the fetal period, which of the following processes is most prominent?

Accepted Answer

Growth and maturation of organs

Question 10

A researcher is studying the movement of oxygen and carbon dioxide between maternal and fetal blood. Which structure is primarily responsible for this exchange?

Accepted Answer

Chorionic villi

Question 11

If a blastocyst contains 64 cells, how many cleavage divisions have occurred since the zygote stage? Use the formula $$N = 2^n$$, where $$N is $$the number of cells and $$n is $$the number of divisions.

Accepted Answer

7 divisions

Question 12

Which of the following is NOT a function of the amniotic cavity during embryonic development?

Accepted Answer

Nutrient exchange between mother and fetus

Question 13

A genetic mutation prevents the formation of the hypoblast during early embryonic development. Which structure would most likely fail to develop as a result?

Accepted Answer

Yolk sac

Question 14

Which of the following statements about the morula is correct?

Accepted Answer

It consists of a solid ball of 16-32 cells

Question 15

During which developmental period do limb buds first begin to differentiate?

Accepted Answer

Embryonic period

Question 16

Which of the following best explains why the morula remains the same size as the original zygote despite increasing cell number?

Accepted Answer

Cleavage divisions reduce cell size with each division

Question 17

A medical student is asked to identify the germ layer responsible for forming the urinary and reproductive system linings. Which should they choose?

Accepted Answer

Endoderm

Question 18

Which of the following structures is derived from the trophoblast and is essential for implantation and nutrient exchange?

Accepted Answer

Chorion

Question 19

If the embryoblast fails to differentiate into the epiblast and hypoblast, which of the following processes would be directly affected?

Accepted Answer

Development of the amniotic cavity and yolk sac

Question 20

Which of the following best describes the role of the allantois during embryonic development?

Accepted Answer

Collects waste and forms part of the umbilical cord and urinary bladder

Human Embryonic and Fetal Development: Key Stages and Structures

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