Among the following, the earliest consequence of the acrosomal reaction is _____.
answer
the membrane of the egg depolarizing. Fusion of the membranes of the egg and sperm causes membrane depolarization, known as the "fast" block to polyspermy, i.e., the prevention of additional sperm binding to the egg.
question
The first stage of embryonic development is _____. This process produces _____.
answer
cleavage ... a cluster of cells
question
The uneven cleavage of cells early in the development of the yolk-rich embryos of birds is called _____.
answer
meroblastic cleavage
question
Even in the absence of sperm, metabolic activity in an egg can be artificially activated by _____.
answer
injection of calcium ions into the cytosol
question
Contact of a sea urchin egg with signal molecules on sperm causes the egg to undergo a brief _____.
answer
membrane depolarization
question
The plasma membrane of the sea urchin egg _____.
answer
has receptor molecules that are specific for binding acrosomal proteins
question
During fertilization, the acrosomal contents _____.
answer
digest the protective jelly coat on the surface of the egg
question
In a newly fertilized egg, the vitelline layer _____.
answer
lifts away from the egg and hardens to form a fertilization envelope
question
In sea urchins, the "fast block" and the longer lasting "slow block" to polyspermy, respectively, are _____.
answer
membrane depolarization = fast block to polyspermy
cortical reaction = slow block
question
In a developing frog embryo, most of the yolk is _____.
answer
located near the vegetal pole
question
The pattern of embryonic development in which only the cells lacking yolk subsequently undergo cleavage is called _____.
answer
meroblastic development, which is typical of birds
question
As cleavage continues during frog development, the size of the blastomeres _____.
answer
decreases as the number of the blastomeres increases
question
The vegetal pole of a frog zygote differs from the animal pole in that _____.
answer
the vegetal pole has a higher concentration of yolk
question
The first cavity formed during frog development is the _____.
answer
blastocoel
question
cleavage
answer
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.
question
gastrulation
answer
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.
question
organogenesis
answer
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.
question
the blastopore will develop into
answer
frog's anus -> posterior end of the embryo
question
cytoplasmic determinants
answer
molecules, which may be proteins or nucleic acids, that help direct early development, including cell movements during gastrulation.
question
involution
answer
Cells roll inward through the blastopore and move to the interior of the embryo. enables the formation of the endoderm and mesoderm.
question
The primitive gut (archenteron) forms from
answer
endoderm
question
What is true about organogenesis in a frog embryo?
answer
- The neural tube forms from ectoderm and develops into the central nervous system.
- Somites form along the length of the notochord and neural tube.
- The endoderm gives rise to the lining of the frog's digestive tract.
- Some somite cells migrate to other locations in the developing embryo.
- The notochord does not persist in adult frogs.
question
In animal development, which of the following best describes the process of cleavage?
answer
Mitosis
question
What are the cells created by cleavage called?
answer
Blastomeres
question
What are the three germ layers contained in the gastrula?
answer
Ectoderm, mesoderm, endoderm
question
Which of the following stages of development is defined by the three embryonic tissue layers (ectoderm, mesoderm, and endoderm)?
answer
Gastrula
question
What happens to a cell during the process of differentiation?
answer
It undergoes a change toward a more specialized form or function.
question
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?
answer
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.
question
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.
answer
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.
question
During gastrulation in frogs, a rod of mesoderm under the dorsal surface forms the _____.
answer
notochord, a physically supportive structure
question
During gastrulation in frogs, cells from the animal pole spread over the embryo and form the _____.
answer
ectoderm
question
The notochord functions as a core around which mesodermal cells form the frog's _____.
answer
backbone.
question
An ectodermal thickening above the frog's notochord forms a
answer
neural plate.
question
The _____ is formed when the neural folds join and a portion of the neural plate sinks beneath the embryo's surface.
answer
neural tube
question
The enlarged anterior portion of the neural tube will develop into a frog's _____.
answer
brain
question
The posterior portion of the neural tube will develop into the frog's
answer
spinal chord
question
In sea urchins, the process of fertilization produces a _____.
answer
zygote
question
What is the cortical reaction?
answer
the formation of a fertilization envelope that bars additional sperm from entry into the egg
question
As cleavage continues, a zygote forms into a solid multicellular ball called a(n) _____.
answer
morula. The morula is a solid ball of cells produced when the zygote undergoes cleavage.
question
Several hours after fertilization, cleavage results in the formation of a hollow ball of cells called a _____.
answer
blastula
question
The three-layered embryo is the _____.
answer
gastrula
question
The _____ eventually develops into the sea urchin's digestive tract.
answer
archenteron
question
During gastrulation, invagination occurs at the _____.
answer
blastopore, which develops into the sea urchin's anus.
question
In vertebrates, the ectoderm gives rise to the _____.
answer
outer layer of skin and the nervous system
question
The mesoderm gives rise to _____.
answer
skeletal and muscular systems
question
Cells move to new positions as an embryo establishes its three germ-tissue layers during _____.
answer
gastrulation
question
The outer-to-inner sequence of tissue layers in a post-gastrulation vertebrate embryo is _____.
answer
ectoderm → mesoderm → endoderm
question
If gastrulation was blocked by an environmental toxin, then _____.
answer
embryonic germ layers would not form
question
The archenteron of the developing sea urchin eventually develops into the _____.
answer
digestive tract
question
In a frog embryo, gastrulation _____.
answer
proceeds by involution as cells roll over the lip of the blastopore
Haven't found what you need?
Search for quizzes and test answers now
Quizzes.studymoose.com uses cookies. By continuing you agree to our cookie policy
