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Chapter 47 Homework

Terms in this set (29)

The first stage of embryonic development is _____. This process produces _____.
cleavage ... a cluster of cells

Gastrulation and organogenesis are developmental stages that follow cleavage.
In animal development, which of the following best describes the process of cleavage?
Mitosis

Cleavage refers to the rapid cell division that takes place in animals after fertilization. Cleavage partitions the egg cytoplasm without additional cell growth taking place.
What are the cells created by cleavage called?
Blastomeres

A blastomere is a cell created by cleavage division.
Which of the following are the three germ layers contained in the gastrula?
Ectoderm, mesoderm, endoderm

These are the three basic embryonic cell layers of all vertebrate embryos.
Which of the following stages of development is defined by the three embryonic tissue layers (ectoderm, mesoderm, and endoderm)?
Gastrula

Gastrulation is the process that leads to the formation of the gastrula, which contains the three embryonic tissue layers.
What happens to a cell during the process of differentiation?
It undergoes a change toward a more specialized form or function.

During organogenesis, embryonic cells become progressively more specialized as they develop into their specific cell type (brain, muscle, etc.).
A child is born without a fully developed pancreas. He is normal in all other respects, and thus doctors believe that the problem most likely began early in development. During which of the following processes did the original error most likely occur?
Endoderm formation

The endoderm provides the cells that develop into the lining of the digestive and respiratory tracts, as well as the liver and pancreas. Problems with its formation could result in an unformed pancreas.
True or false? Early animal development progresses through distinct stages: first the production of the zygote through fertilization, then cleavage, then the formation of the gastrula, and then the formation of the blastula.
False

The formation of a gastrula is the last stage in early animal development; the zygote undergoes cleavage to form a blastula, which eventually forms a gastrula.
In sea urchins, the process of fertilization produces a(n) _____.
zygote

Fertilization, the combination of haploid sets of chromosomes, results in the formation of a diploid zygote.
What is the cortical reaction?
the formation of a fertilization envelope that bars additional sperm from entry into the egg
As cleavage continues, a zygote forms into a solid multicellular ball called a(n) _____.
morula

The morula is a solid ball of cells produced when the zygote undergoes cleavage.
Several hours after fertilization, cleavage results in the formation of a hollow ball of cells called a _____.
blastula

The blastula is a hollow ball of cells formed as the result of cleavage.
The three-layered embryo is the _____.
gastrula

The gastrula, formed when the blastula undergoes gastrulation, is a ball of cells that consists of the three primary germ layers.
The _____ eventually develops into the sea urchin's digestive tract.
archenteron

The archenteron, formed as a result of gastrulation, develops into the sea urchin's digestive tract.
During gastrulation, invagination occurs at the _____.
blastopore

During gastrulation, invagination occurs at the blastopore, which develops into the sea urchin's anus.
In vertebrates, the ectoderm gives rise to the _____.
outer layer of skin

The ectoderm gives rise to the outer layer of skin and the nervous system
During gastrulation in frogs, a rod of mesoderm under the dorsal surface forms the _____.
notochord

This rod of mesoderm forms the notochord, a physically supportive structure.
During gastrulation in frogs, cells from the animal pole spread over the embryo and form the _____.
ectoderm

Cells from the animal pole form the ectoderm.
The notochord functions as a core around which mesodermal cells form the frog's _____.
backbone

In vertebrates, the notochord functions as a core around which mesodermal cells form the frog's backbone.
An ectodermal thickening above the frog's notochord forms a _____.
neural plate

The ectodermal thickening above the frog's notochord forms the neural plate.
The _____ is(are) formed when the neural folds join and a portion of the neural plate sinks beneath the embryo's surface.
neural tube

The question describes the formation of the neural tube.
The enlarged anterior portion of the neural tube will develop into a frog's _____.
brain

The anterior end of the neural tube develops into the brain.
The posterior portion of the neural tube will develop into the frog's _____.
spinal cord

The posterior portion of the neural tube develops into the spinal cord.
The mesoderm gives rise to _____.
skeletal and muscular systems

The muscles and skeleton are of mesodermal origin.
Birds, reptiles, and mammals are called "amniotes" because _____.
they have extra-embryonic membranes that develop an aqueous environment in which development occurs

These three groups of vertebrates form the amniotes. Fish and amphibians lay their eggs in water and do not require a special water-filled enclosure.
Embryonic cells especially active in assuring nutritional exchange between a pregnant woman and her embryo are found in the _____.
trophoblast

The trophoblast is the outer epithelium of the blastocyst.
Embryonic development proceeds through three stages.
During cleavage, the cytoplasm of the zygote is divided into many different cells called blastomeres. By the end of cleavage, the embryo is called a blastula, which is a ball of cells surrounding a fluid-filled cavity called a blastocoel.

During gastrulation, the embryo is called a gastrula. In this stage, cells undergo dramatic rearrangement, forming the embryonic germ layers and other structures, such as the blastopore. Once gastrulation is complete, the major body axes of the embryo (anterior-posterior and dorsal-ventral) are visible.

During organogenesis, the three embryonic germ layers develop into the rudiments of organs. Structures such as the notochord, the neural tube, and somites form. Somite cells undergo differentiation, giving rise to different body tissues and organs, including the skeleton, muscles, and skin.
Tissue and organ formation begins during the process of organogenesis.
Which five of the following statements are true about organogenesis in a frog embryo?
The neural tube forms from ectoderm and develops into the central nervous system.

The notochord does not persist in adult frogs.

The endoderm gives rise to the lining of the frog's digestive tract.

Some somite cells migrate to other locations in the developing embryo.

Somites form along the length of the notochord and neural tube.
An embryonic cell that is "totipotent" is one that can _____.
by itself, give rise to the entire embryo, as cleavage proceeds

In Sperman's work on frog embryos, he showed that the first two blastomeres can develop into all of the cells of the frog embryo.
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