Question 1

Which of the following best describes the embryonic period in human development?

Accepted Answer

It is the first 8-10 weeks post-fertilization, during which the basic body plan and primary germ layers form.

Question 2

During which week does the notochord first appear, and what is its primary function?

Accepted Answer

Week 3; it defines the longitudinal axis and signals the formation of the neural tube.

Question 3

Which germ layer gives rise to the epidermis, brain, and spinal cord?

Accepted Answer

Ectoderm

Question 4

A deficiency in maternal folate (vitamin B9) during early pregnancy most directly increases the risk of which developmental defect?

Accepted Answer

Neural tube defects such as spina bifida

Question 5

Which extraembryonic membrane is primarily responsible for forming the umbilical arteries and draining nitrogenous wastes?

Accepted Answer

Allantois

Question 6

What is the correct sequence of events during the first week of embryonic development?

Accepted Answer

Cleavage → Morula → Blastocyst → Implantation

Question 7

Which structure is formed by the migration of epiblast cells through the primitive streak during gastrulation?

Accepted Answer

Mesoderm

Question 8

The somites, derived from paraxial mesoderm, differentiate into which of the following adult structures?

Accepted Answer

Vertebrae, rib cage, and segmented trunk muscles

Question 9

Which of the following equations best represents the time from conception to a normal birth in weeks?

Accepted Answer

$T_{birth} = 38$

Question 10

A researcher observes a cell population migrating from the yolk sac endoderm to the gonadal ridge during week 5. What type of cells are these most likely to become?

Accepted Answer

Primordial germ cells

Question 11

Which of the following is a direct derivative of the endoderm?

Accepted Answer

Inner epithelial lining of the gut tube

Question 12

Neural crest cells are sometimes referred to as the 'fourth germ layer.' Which of the following is NOT a derivative of neural crest cells?

Accepted Answer

Kidneys

Question 13

During lateral folding of the embryo in week 4, which structure is formed from the dorsal part of the yolk sac?

Accepted Answer

Primitive gut

Question 14

Which of the following best explains the concept of induction in embryology?

Accepted Answer

The process by which one group of cells influences the developmental fate of another group.

Question 15

Which of the following is a function of the amniotic fluid?

Accepted Answer

Acts as a shock absorber to protect the embryo

Question 16

A patient is born with a defect in the sclerotome. Which of the following structures is most likely affected?

Accepted Answer

Vertebrae and rib cage

Question 17

Which of the following best describes the role of the chorion during development?

Accepted Answer

It surrounds all extraembryonic membranes and, with the uterine endometrium, forms the placenta.

Question 18

Which equation correctly represents the number of somite pairs formed during embryonic development?

Accepted Answer

$N_{somites} = 40$

Question 19

Which of the following is a derivative of splanchnic (visceral) mesoderm?

Accepted Answer

Musculature and connective tissue of digestive and respiratory structures

Question 20

A fetus is born at 35 weeks gestation. According to the study materials, how is this birth classified?

Accepted Answer

Premature birth

Basic Embryology: Stages of Prenatal Development and the Basic Body Plan

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