Bio II Quiz I Part II
Terms in this set (51)
Choose the correct developmental sequence of animal development.
fertilization → cleavage → gastrulation → organogenesis
Among the following, the earliest consequence of the acrosomal reaction is _____.
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.
The first stage of embryonic development is _____. This process produces _____.
cleavage ... a cluster of cells
The uneven cleavage of cells early in the development of the yolk-rich embryos of birds is called _____.
Even in the absence of sperm, metabolic activity in an egg can be artificially activated by _____.
injection of calcium ions into the cytosol
Contact of a sea urchin egg with signal molecules on sperm causes the egg to undergo a brief _____.
The plasma membrane of the sea urchin egg _____.
has receptor molecules that are specific for binding acrosomal proteins
During fertilization, the acrosomal contents _____.
digest the protective jelly coat on the surface of the egg
In a newly fertilized egg, the vitelline layer _____.
lifts away from the egg and hardens to form a fertilization envelope
In sea urchins, the "fast block" and the longer lasting "slow block" to polyspermy, respectively, are _____.
membrane depolarization = fast block to polyspermy
cortical reaction = slow block
In a developing frog embryo, most of the yolk is _____.
located near the vegetal pole
The pattern of embryonic development in which only the cells lacking yolk subsequently undergo cleavage is called _____.
meroblastic development, which is typical of birds
As cleavage continues during frog development, the size of the blastomeres _____.
decreases as the number of the blastomeres increases
The vegetal pole of a frog zygote differs from the animal pole in that _____.
the vegetal pole has a higher concentration of yolk
The first cavity formed during frog development is the _____.
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.
the blastopore will develop into
frog's anus -> posterior end of the embryo
molecules, which may be proteins or nucleic acids, that help direct early development, including cell movements during gastrulation.
Cells roll inward through the blastopore and move to the interior of the embryo. enables the formation of the endoderm and mesoderm.
The primitive gut (archenteron) forms from
What is true about organogenesis in a frog embryo?
- 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.
In animal development, which of the following best describes the process of cleavage?
What are the cells created by cleavage called?
What are the three germ layers contained in the gastrula?
Ectoderm, mesoderm, endoderm
Which of the following stages of development is defined by the three embryonic tissue layers (ectoderm, mesoderm, and endoderm)?
What happens to a cell during the process of differentiation?
It undergoes a change toward a more specialized form or function.
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?
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.
During gastrulation in frogs, a rod of mesoderm under the dorsal surface forms the _____.
notochord, a physically supportive structure
During gastrulation in frogs, cells from the animal pole spread over the embryo and form the _____.
The notochord functions as a core around which mesodermal cells form the frog's _____.
An ectodermal thickening above the frog's notochord forms a
The _____ is formed when the neural folds join and a portion of the neural plate sinks beneath the embryo's surface.
The enlarged anterior portion of the neural tube will develop into a frog's _____.
The posterior portion of the neural tube will develop into the frog's
In sea urchins, the process of fertilization produces a _____.
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 _____.
The three-layered embryo is the _____.
The _____ eventually develops into the sea urchin's digestive tract.
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 and the nervous system
The mesoderm gives rise to _____.
skeletal and muscular systems
Cells move to new positions as an embryo establishes its three germ-tissue layers during _____.
The outer-to-inner sequence of tissue layers in a post-gastrulation vertebrate embryo is _____.
ectoderm → mesoderm → endoderm
If gastrulation was blocked by an environmental toxin, then _____.
embryonic germ layers would not form
The archenteron of the developing sea urchin eventually develops into the _____.
In a frog embryo, gastrulation _____.
proceeds by involution as cells roll over the lip of the blastopore