species chosen because of their ease to be studied
question
fertilization
answer
the formation of a diploid zygote from a haploid egg and sperm
question
acrosomal reaction
answer
begins with the discharge of hydrolytic enzymes from the acrosome a specialized vesicle at the tip of the sperm
question
fast block to polyspermy
answer
the acrosomal reaction
question
slow block to polyspermy
answer
the cortical reaction
question
cortical reaction
answer
protective fertilization envelope is formed
question
a rise in ca2+ causes:
answer
egg activation
question
zona pellucida
answer
the extracelluar matrix of the egg
question
cleavage
answer
After fertilization, the sperm and egg become a zygote, which then begins a number of cell divisions called cleavage
question
the smaller cells that cleavage creates are called:
answer
blastomeres
question
blastula
answer
hollow ball of cells
question
blastocoel
answer
fluid filled cavity in the blastula
question
holoblastic
answer
A type of cleavage in which there is complete division of the egg, as in eggs having little yolk (sea urchin) or a moderate amount of yolk (frog).
question
meroblastic
answer
a type of cleavage in which there is incomplete division of yolk-rich egg, characteristic of avian development
question
morphogenesis
answer
the cellular and tissue based process by which the animal body takes shape
question
gastrulation
answer
a set of cells at or near the surface of the blastula moves to an interior location, cell layers are established, and a primitive digestive tube is formed
question
organogenesis
answer
further transformation that occurs and forms organs
question
gastrula
answer
2 or 3 layered embryo
question
cell layers produced by gastrulation are called:
answer
germ layers
question
ectoderm
answer
One of the three primary (embryonic) germ layers formed during gastrulation. Ectoderm ultimately forms external structures such as the skin, hair, nails, and inner linings of the mouth and anus, as well as the entire nervous system.
question
endoderm
answer
Germ layer that gives rise to the epithelial lining of the gastrointestinal tract and its outgrowths.
question
mesoderm
answer
between the ectoderm and endoderm, skeletal and muscular systems
question
archenteron
answer
The endoderm-lined cavity, formed during the gastrulation process, that develops into the digestive tract of an animal.
question
blastopore
answer
the open end of the archenteron which will become the anus
question
dorsal lip
answer
The region above the blastopore on the dorsal side of the amphibian embryo.
question
vegetal pole
answer
yolk is concentrated here
question
animal pole
answer
yolk is less concentrated here
question
primitive streak
answer
a thickening produced by the pileup of cells moving inward at the blastoderm's midline, which runs along what will become the birds anterior-posterior axis; functionally equivalent to the dorsal lip in frogs
question
blastocyst
answer
the mammalian version of the blastula
question
4 stages in early embryonic development in humans:
answer
blastocyst is formed with the inner cell mass, then the trophoblast is formed then the extra embryonic membranes are formed, then the 3 germ layers have formed by the end of gastrulation
question
trophoblast
answer
it initiates implantation by secreting enzymes that break down molecules of the endometrium
question
mammals and reptiles and birds are called:
answer
amniotes
question
notochord
answer
A rod of tough, flexible material that runs the length of a creature's body, providing the majority of its support
question
neural tube
answer
runs along the anterior-posterior axis of the embryo, it will become the spinal cord and the brain
question
neural crest
answer
a band of cells that develops along the borders where the neural tube pinches off from the ectoderm
question
somites
answer
Formed in the mesoderm and appear as a bump on the surface of the embryo on either side of the notochord
question
differentiation
answer
the resulting specialization in structure and function
question
totipotent
answer
can each develop into all the different cell types of that species
question
The first stage of embryonic development is _____. This process produces _____.
cleavage ... a cluster of cells
gastrulation ... a three-layered embryo
parturition ... a fetus
ovulation ... a zygote
neurulation ... a neurula
answer
cleavage ... a cluster of cells
question
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 notochord forms from mesoderm and develops into the central nervous system.
The mesoderm gives rise to the epidermis of the frog's skin.
The neural tube forms from ectoderm and develops into the central nervous system.
The endoderm gives rise to the lining of the frog's digestive tract.
Somites form along the length of the notochord and neural tube.
The notochord does not persist in adult frogs.
Some somite cells migrate to other locations in the developing embryo.
answer
The neural tube forms from ectoderm and develops into the central nervous system.
The endoderm gives rise to the lining of the frog's digestive tract.
Somites form along the length of the notochord and neural tube.
The notochord does not persist in adult frogs.
Some somite cells migrate to other locations in the developing embryo.
question
In animal development, which of the following best describes the process of cleavage?
Meiosis
Differentiation
Mitosis
Fertilization
answer
mitosis
question
What are the cells created by cleavage called?
Blastopores
Blastomeres
Blastulas
Blastocoels
answer
Blastomeres
question
Which of the following are the three germ layers contained in the gastrula?
Ectoderm, mesoderm, epidermis
Ectoderm, mesoderm, endoderm
Ectoderm, mesoderm, echinoderm
Ectotherm, mesoderm, endoderm
answer
Ectoderm, mesoderm, endoderm
question
Which of the following stages of development is defined by the three embryonic tissue layers (ectoderm, mesoderm, and endoderm)?
Zygote
Blastula
Gastrula
Yolk
answer
Gastrula
question
What happens to a cell during the process of differentiation?
Material moves across the cell membrane from a region of higher concentration to a region of lower concentration.
It undergoes a change toward a more specialized form or function.
It divides to produce a cell with the same number of chromosomes.
It divides to produce a cell with one-half the number of original chromosomes.
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?
Endoderm formation
Ectoderm formation
Cleavage
Mesoderm formation
answer
Endoderm formation
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.
True
False
answer
false
question
In sea urchins, the process of fertilization produces a(n) _____.
archenteron
morula
gastrula
gamete
zygote
answer
zygote
question
What is the cortical reaction?
the formation of a fertilization envelope that bars additional sperm from entry into the egg
the release of hydrolytic enzymes from the sperm cell
a depolarization of the eggs' plasma membrane so that only one sperm cell can fuse with it
a series of rapid mitotic divisions that follow fertilization
the process that forms a three-layered embryo
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) _____.
endometrium
morula
trophoblast
gastrula
blastula
answer
Morula
question
Several hours after fertilization, cleavage results in the formation of a hollow ball of cells called a _____.
blastomere
morula
trophoblast
gastrula
blastula
answer
Blastula
question
The three-layered embryo is the _____.
archenteron
morula
trophoblast
gastrula
blastula
answer
Gastrula
question
The _____ eventually develops into the sea urchin's digestive tract.
blastocoel
archenteron
blastomere
ectoderm
blastopore
answer
archenteron
question
During gastrulation, invagination occurs at the _____.
archenteron
blastocoel
endometrium
blastopore
trophoblast
answer
blastopore
question
In vertebrates, the ectoderm gives rise to the _____.
skeleton
circulatory system
outer layer of skin
lining of the digestive tract
pancreas
answer
outer layer of skin
question
During gastrulation in frogs, a rod of mesoderm under the dorsal surface forms the _____.
notochord
ectoderm
endoderm
archenteron
blastopore
answer
notochord
question
During gastrulation in frogs, cells from the animal pole spread over the embryo and form the _____.
endoderm
ectoderm
archenteron
blastopore
blastula
answer
ectoderm
question
The notochord functions as a core around which mesodermal cells form the frog's _____.
backbone
blastopore
endometrium
nervous system
archenteron
answer
Backbone
question
An ectodermal thickening above the frog's notochord forms a _____.
pancreas
neural plate
skeleton
liver
lining of the stomach
answer
Neural plate
question
The _____ is(are) formed when the neural folds join and a portion of the neural plate sinks beneath the embryo's surface.
archenteron
anus
back muscles
neural tube
digestive system
answer
neural tube
question
The enlarged anterior portion of the neural tube will develop into a frog's _____.
spinal cord
tongue
reproductive system
outer layer of skin
brain
answer
brain
question
The posterior portion of the neural tube will develop into the frog's _____.
spinal cord
brain
blastocoel
digestive tract
anus
answer
spinal cord
question
The mesoderm gives rise to _____.
the central nervous system
skeletal and muscular systems
the gastrointestinal tract and pancreas
the lining of the lungs
jaws and teeth
answer
skeletal and muscular systems
question
Birds, reptiles, and mammals are called "amniotes" because _____.
they digest yolk and form a network of blood vessels to distribute nutrients to the embryo
their embryos lack an allantois to collect and store metabolic wastes
they transport oxygen to the embryo
they have extra-embryonic membranes that develop an aqueous environment in which development occurs
they give rise to cells that form the nervous system
answer
they have extra-embryonic membranes that develop an aqueous environment in which development occurs
question
Embryonic cells especially active in assuring nutritional exchange between a pregnant woman and her embryo are found in the _____.
epiblast
hypoblast
trophoblast
ectoderm
inner cell mass
answer
Trophoblast
question
An embryonic cell that is "totipotent" is one that can _____.
organize the blastula
redistribute yolk from the vegetal to the animal pole of the frog embryo
move mesoderm cells in the blastocoel
migrate into the center of the blastula during gastrulation
by itself, give rise to the entire embryo, as cleavage proceeds
answer
by itself, give rise to the entire embryo, as cleavage proceeds
Among the following, the earliest consequence of the acrosomal reaction is _____.
the membrane of the egg depolarizing
the development of the fertilization envelope
the slow block to polyspermy
cleavage
the cortical reaction
answer
the membrane of the egg depolarizing
question
The uneven cleavage of cells early in the development of the yolk-rich embryos of birds is called _____.
gastrulation
holoblastic cleavage
meroblastic cleavage
neurulation
organogenesis
answer
meroblastic cleavage
question
Even in the absence of sperm, metabolic activity in an egg can be artificially activated by _____.
depletion of its ATP supplies
abnormally high levels of carbonic acid in the cytosol
abnormally low levels of extracellular oxygen
injection of calcium ions into the cytosol
answer
injection of calcium ions into the cytosol
question
The formation of the fertilization envelope requires an increase in the availability of _____.
sodium ions
potassium ions
hydrogen ions
calcium ions
answer
calcium ions
question
Contact of a sea urchin egg with signal molecules on sperm causes the egg to undergo a brief _____.
membrane depolarization
mitosis
vitellogenesis
acrosomal reaction
answer
membrane depolarization
question
The plasma membrane of the sea urchin egg _____.
releases calcium, which initiates the cortical reaction
is a mesh of proteins crossing through the cytosol of the egg
is outside of the fertilization membrane
has receptor molecules that are specific for binding acrosomal proteins
answer
has receptor molecules that are specific for binding acrosomal proteins
question
Fertilization of an egg without activation is most like _____.
preparing a pie from scratch and baking it in the oven
placing the key in the ignition of a car but not starting the engine
resting during halftime of a basketball game
walking to the cafeteria and eating lunch
answer
placing the key in the ignition of a car but not starting the engine
question
A reproductive difference between sea urchins and humans is _____.
sea urchins, but not humans, have a need to block polyspermy, because only in sea urchins can there be more than one source of sperm to fertilize the eggs
the sea urchin egg completes meiosis prior to fertilization, but meiosis in humans is completed after fertilization
sea urchin eggs and sperm are of equal size, but human eggs are much bigger than human sperm
sea urchin zygotes get their mitochondria from the sperm, but human zygotes get their mitochondria from the egg
answer
the sea urchin egg completes meiosis prior to fertilization, but meiosis in humans is completed after fertilization
question
During fertilization, the acrosomal contents _____.
block polyspermy
help propel more sperm toward the egg
digest the protective jelly coat on the surface of the egg
trigger the completion of meiosis by the sperm
answer
digest the protective jelly coat on the surface of the egg
question
In a newly fertilized egg, the vitelline layer _____.
reduces the loss of water from the egg and prevents desiccation
provides most of the nutrients used by the zygote
lifts away from the egg and hardens to form a fertilization envelope
secretes hormones that enhance steroidogenesis by the ovary
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 _____.
membrane depolarization and the cortical reaction
the jelly coat of the egg and the vitelline membrane
the acrosomal reaction and the formation of egg white
the cortical reaction and the formation of yolk protein
answer
membrane depolarization and the cortical reaction
question
In an egg cell treated with a chemical that binds calcium and magnesium ions, the _____.
fertilization envelope would not be formed
acrosomal reaction would be blocked
fusion of sperm and egg nuclei would be blocked
fast block to polyspermy would not occur
answer
fertilization envelope would not be formed
question
In mammalian eggs, the receptors for sperm are found in the _____.
cytosol of the egg
fertilization membrane
mitochondria of the egg
egg plasma membrane
answer
egg plasma membrane
question
A human blastomere is _____.
a cell that contains a (degenerating) second polar body
an embryonic cell that is smaller than the ovum
that part of the acrosome that opens the egg's membrane
an embryonic structure that includes a fluid-filled cavity
answer
an embryonic cell that is smaller than the ovum
question
At the moment of sperm penetration, human eggs _____.
are still surrounded by follicular cells
have a paper-thin cell of calcium carbonate that prevents desiccation
have used flagellar propulsion to move from the ovary to the oviduct
are still located within the ovary
answer
are still surrounded by follicular cells
question
In a developing frog embryo, most of the yolk is _____.
found within the cleavage furrow
located near the animal pole
distributed equally throughout the embryo
located near the vegetal pole
answer
located near the vegetal pole
question
Among these choices, the largest cell involved in frog reproduction is _____.
one of the products of the first cleavage
a blastomere in the animal pole
an egg
a blastomere in the vegetal pole
answer
an egg
question
The pattern of embryonic development in which only the cells lacking yolk subsequently undergo cleavage is called _____.
meroblastic development, which is typical of birds
holoblastic development, which is typical of marsupial mammals
holoblastic development, which is typical of amphibians
meroblastic development, which is typical of humans
answer
meroblastic development, which is typical of birds
question
As cleavage continues during frog development, the size of the blastomeres _____.
decreases as the number of the blastomeres decreases
increases as the number of the blastomeres decreases
increases as the number of the blastomeres increases
decreases as the number of the blastomeres increases
answer
decreases as the number of the blastomeres increases
question
The vegetal pole of a frog zygote differs from the animal pole in that _____.
the vegetal pole cells undergo mitosis, but not cytokinesis
the polar bodies bud from this region
the blastomeres originate only in the vegetal pole
the vegetal pole has a higher concentration of yolk
answer
the vegetal pole has a higher concentration of yolk
question
Meroblastic cleavage occurs in _____.
humans, but not in sea urchins or birds
sea urchins, but not in humans or birds
both sea urchins and birds, but not in humans
birds, but not in sea urchins or humans
answer
birds, but not in sea urchins or humans
question
h of the following correctly displays the sequence of developmental milestones?
cleavage ? blastula ? gastrula
gastrula ? blastula ? cleavage
cleavage ? gastrula ? blastula
blastula ? gastrula ? cleavage
answer
cleavage ? blastula ? gastrula
question
The first cavity formed during frog development is the _____.
anus
mouth
blastopore
blastocoel
answer
Blastocoel
question
In some rare salamander species, all individuals are females. Reproduction relies on those females having access to sperm from males of another species. However, the resulting embryos receive no genetic contribution from the males. In this case, the sperm appear to be used only for _____.
egg activation
the creation of a diploid cell
cell differentiation
morphogenesis
answer
egg activation
question
The cortical reaction of sea urchin eggs functions directly in _____.
the release of hydrolytic enzymes from the sperm
the generation of an electrical impulse by the egg
the formation of a fertilization envelope
the production of a fast block to polyspermy
answer
the formation of a fertilization envelope
question
The structure of the Drosophila gene, called Tinman, is similar to a gene in humans that also _____.
specifies the location of the heart
specifies limb elongation points
promotes ear development
determines structures in the eyes
answer
specifies the location of the heart
question
From earliest to latest, the overall sequence of early development proceeds in which of the following sequences?
cortical reaction ? acrosomal reaction ? first cell division synthesis of embryo's DNA begins
cortical reaction ? synthesis of embryo's DNA begins ? acrosomal reaction ? first cell division
acrosomal reaction ? cortical reaction ? synthesis of embryo's DNA begins ? first cell division
first cell division ? synthesis of embryo's DNA begins ? acrosomal reaction ? cortical reaction
answer
acrosomal reaction ? cortical reaction ? synthesis of embryo's DNA begins ? first cell division
question
During the early development of a human embryo, the _____ eventually forms the _____.
epiblast ... ectodermal, mesodermal, and endodermal tissues
blastocoel ... archenteron
trophoblast ... embryo proper
epiblast ... placenta
hypoblast ... amniotic cavity
answer
epiblast ... ectodermal, mesodermal, and endodermal tissues
question
Cells move to new positions as an embryo establishes its three germ-tissue layers during _____.
gastrulation
induction
cleavage
determination
answer
gastrulation
question
Which of the following is a correct description of the fate of the germ layers?
The ectoderm gives rise to the liver.
The mesoderm gives rise to the notochord.
The mesoderm gives rise to the lungs.
The endoderm gives rise to the hair follicles.
answer
The mesoderm gives rise to the notochord.
question
The outer-to-inner sequence of tissue layers in a post-gastrulation vertebrate embryo is _____.
ectoderm ? mesoderm ? endoderm
ectoderm ? endoderm ? mesoderm
mesoderm ? endoderm ? ectoderm
endoderm ? ectoderm ? mesoderm
answer
ectoderm ? mesoderm ? endoderm
question
If gastrulation was blocked by an environmental toxin, then _____.
cleavage would not occur in the zygote
the blastula would not be formed
embryonic germ layers would not form
the blastopore would form above the gray crescent in the animal pole
answer
embryonic germ layers would not form
question
In a frog embryo, gastrulation _____.
proceeds by involution as cells roll over the lip of the blastopore
occurs along the primitive streak in the animal hemisphere
produces a blastocoel displaced into the animal hemisphere
occurs within the inner cell mass that is embedded in the large amount of yolk
answer
proceeds by involution as cells roll over the lip of the blastopore
question
The primitive streak in a bird is the functional equivalent of _____.
the notochord in a mammal
the lip of the blastopore in the frog
the archenteron in a frog
neural crest cells in a mammal
answer
the lip of the blastopore in the frog
question
In all vertebrate animals, development requires _____.
extraembryonic membranes
a large supply of yolk
an aqueous environment
a primitive streak
answer
an aqueous environment
question
At the time of implantation, the human embryo is called a _____.
gastrula
blastocyst
zygote
fetus
answer
Blastocyst
question
Uterine implantation due to enzymatic digestion of the endometrium is initiated by the _____.
endoderm
mesoderm
inner cell mass
trophoblast
answer
trophoblast
question
From earliest to latest, the overall sequence of early development proceeds in which of the following sequences?
preformation ? morphogenesis ? neurulation
gastrulation ? organogenesis ? cleavage
gastrulation ? blastulation ? neurulation
cleavage ? gastrulation ? organogenesis
answer
cleavage ? gastrulation ? organogenesis
question
Changes in cell position occur extensively during _____.
cleavage, but not during gastrulation or organogenesis
organogenesis, but not during gastrulation or cleavage
gastrulation and cleavage
gastrulation
answer
gastrulation
question
The embryonic precursor to the human spinal cord is the _____.
notochord
neural tube
mesoderm
archenteron
answer
neural tube
question
Which of the following is common to the development of birds and mammals?
the formation of an embryonic epiblast and hypoblast
the formation of an embryonic yolk plug
the formation of an embryonic trophoblast
the formation of an embryonic gray crescent
answer
the formation of an embryonic epiblast and hypoblast
question
The archenteron of a frog develops into the _____.
placenta
blastocoel
endoderm
lumen of the digestive tract
answer
lumen of the digestive tract
question
The cortical reaction of sea urchin eggs functions directly in
the release of hydrolytic enzymes from the sperm.
the fusion of egg and sperm nuclei.
the generation of an electrical impulse by the egg.
the production of a fast block to polyspermy.
the formation of a fertilization envelope.
answer
the formation of a fertilization envelope.
question
Select the correct statement about embryonic development in a frog.
The reorganization of cell layers during gastrulation allows the layers to interact with each other in new ways.
The blastocoel of a developing frog embryo develops into the digestive tract.
Development from zygote to blastula involves mitotic division, cell movement, and cell growth.
answer
The reorganization of cell layers during gastrulation allows the layers to interact with each other in new ways.
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