27.3 Embryonic Period

Question 1

Topic: Germ Layers

The _______ forms the epidermis of the skin, the nervous system, and the sense organs.

Answer 1

The ectoderm

Question 2

The _________ forms the skeletal structures, muscles, most other organs (except the epithelial linings), mesenteries, and dermis.

Answer 2

The mesoderm forms the skeletal structures, muscles, most other organs (except the epithelial linings), mesenteries, and dermis.

Question 3

This germ layer forms the gonads, kidneys, and spleen of the developing embryo.

Answer 3

mesoderm

Question 4

The majority of the liver, the gallbladder, and pancreas are formed by this germ layer.

Answer 4

endoderm

Question 5

Along which line of the embryo does the primitive streak form?

right-left

cephalic-caudal

dorsal-ventral

lateral-medial

Answer 5

Along which line of the embryo does the primitive streak form?

right-left

cephalic-caudal

dorsal-ventral

lateral-medial

Question 6

Which of the following is the inner germ layer?

mesoderm

endoderm

ectoderm

epiblast

Answer 6

Which of the following is the inner germ layer?

mesoderm

endoderm

ectoderm

epiblast

Question 7

What is the first major event of organogenesis?

formation of somites

formation of the skin

formation of the endocrine glands

neurulation

Answer 7

What is the first major event of organogenesis?

formation of somites

formation of the skin

formation of the endocrine glands

neurulation

Question 8

A birth defect known as spina bifida results from the incomplete closure of the embryonic neural tube. Which germ layer is affected?

myotome

mesoderm

endoderm

ectoderm

Answer 8

A birth defect known as spina bifida results from the incomplete closure of the embryonic neural tube. Which germ layer is affected?

myotome

mesoderm

endoderm

ectoderm

Question 9

The ________ forms the linings and glands of the digestive and respiratory tracts and several endocrine glands.

Answer 9

The endoderm forms the linings and glands of the digestive and respiratory tracts and several endocrine glands.

Question 10

• At the start of the _________ period, cephalocaudal folding and lateral folding transform the embryo to its cylindrical shape.
• _____________ leads to the development of the three primary germ layers.

Answer 10

• At the start of the embryonic period, cephalocaudal folding and lateral folding transform the embryo to its cylindrical shape.
• Gastrulation leads to the development of the three primary germ layers.

Question 11

____________ involves differentiation of the germ layers into rudimentary organ systems. The three germ layers differentiate into the following:

Answer 11

Organogenesis

The ectoderm forms the epidermis of the skin, the nervous system, and the sense organs.

The mesoderm forms the skeletal structures, muscles, most other organs (except the epithelial linings), mesenteries, and dermis.

The endoderm forms the linings and glands of the digestive and respiratory tracts and several endocrine glands.