Under which condition will the metabolic activity in a sea urchin egg most likely be activated even in the absence of sperm?
injection of calcium ions into the cytosol
The formation of the fertilization envelope in a sea urchin egg is most directly stimulated by an increase in the cytosolic concentration of which of the following ions
calcium ions
Contact between signaling molecules on a sperm membrane with receptor molecules on an oocyte membrane will most directly result in which of the following responses?
membrane depolarization
Which of the following answers best describes a feature of the plasma membrane of a sea urchin egg that is required for fertilization?
It has receptor molecules that specifically bind to acrosomal proteins.
Release of the acrosomal contents during fertilization most directly results in which of the following events?
digesting the protective jelly coat on the surface of the egg
Which of the following statements best describes the function of the vitelline layer in a newly fertilized sea urchin egg?
It lifts away from the egg and hardens to form a fertilization envelope.
Treating an oocyte with a chemical that binds calcium and magnesium ions will block ________.
formation of the fertilization envelope
In mammalian eggs, the receptors for sperm are found in which of the following locations
plasma membrane
Which of the following is true about human eggs at the moment of sperm penetration?
They are still surrounded by follicular cells
Which of the following is the largest cell involved in frog reproduction?
egg
Which of the following correctly describes a difference between the vegetal pole of a frog zygote and the animal pole?
The vegetal pole has a higher concentration of yolk.
In which of the following pairs of organisms does holoblastic cleavage typically occur?
sea urchins and humans
Which of the following correctly describes the sequence of developmental milestones in chordates?
cleavage → blastula → gastrula
Which of the following structures is formed before the others during frog development?
blastocoel
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. Given this information, what is the role of sperm in reproduction in this species?
Sperm trigger egg activation
The cortical reaction of sea urchin eggs is required for which of the following events in fertilization
forming a fertilization envelope
Which of the following correctly describes the order of events of early development from earliest to latest?
acrosomal reaction → cortical reaction → synthesis of embryo's DNA begins → first cell division
Which of the following types of embryos displays meroblastic cleavage, extraembryonic membranes, and a primitive streak?
a bird
During which stage of development do cells in a triploblastic embryo move to new positions btestbanks.com to establish the three germ tissue layers
gastrulations
Which of the following options describes the correct outer-to-inner sequence of tissue layers in a post-gastrulation vertebrate embryo
ectoderm → mesoderm → endoderm
Which of the following outcomes would most likely occur if gastrulation was blocked?
embryonic germ layers would not form
What does the archenteron of the developing sea urchin eventually develop into?
digestive tract
Which of the following correctly describes gastrulation in frog embryos?
proceeds by involution as cells roll over the lip of the blastopore
Which of the following correctly matches a structure with the germ layer from which it is derived?
The mesoderm gives rise to the notochord
The primitive streak in a bird embryo is the functional equivalent to which of the following structures
the lip of the blastopore in the frog
Which of the following is required for development in all vertebrate animals
an aqueous environment
The eggs of which of the following organisms contains the least amount of yolk
eutherian mammal
Which of the following structures releases enzymes that initiate implantation of an embryo in the endometrium?
trophoblast
Thalidomide, now banned for use as a sedative during pregnancy, was used in the early 1960s by many women in their first trimester of pregnancy. Some of these women gave birth to children with limb and organ deformities. Which of the following processes did the drug most likely influence?
morphogenesis
The migratory neural crest cells give rise to which of the following structures?
a variety of peripheral neural and non-neural structures
Which of the following is a result of gastrulation in animals?
The archenteron is formed.
The germ layers are formed.
Cell migration occurs extensively as part of which of the following processes?
gastrulation and organogenesis
Which of the following cellular structures is usually reorganized when a cell changes shape?
cytoskeleton
Which correctly matches the organ with its embryonic source
kidney–mesoderm
Which of the following structures is the embryonic precursor to the human spinal cord?
neural tube
Which of the following processes reduces the size of a tadpole's tail during metamorphosis?
apoptosis
Which of the following terms applies to a morphogenetic process whereby cells extend themselves, making the mass of the cells narrower and wider
convergent extension
Which of the following is common to the development of birds and mammals?
the formation of an embryonic epiblast and hypoblast
Which of the following occurs to the blastocoel during frog development?
is replaced by the expanding archenteron
Which of the following correctly matches an extraembryonic membrane with its function
allantois–waste storage
Which of the following contributions of the extra embryonic membranes was crucial for the colonization of land by vertebrate organisms?
extraembryonic membranes provide an aqueous environment for embryo developmen
Which of the following is most likely to occur if an amphibian zygote is manipulated so that the first cleavage plane fails to divide the gray crescent?
only the daughter cell with the gray crescent will develop normally
Which of the following were Hans Spemann and colleagues studying when they developed the concept of the "organizer" in amphibian embryos?
dorsal lip of the blastopore
Which of the following is an adult organism that has fewer than 1,000 cells?
nematodes, Caenorhabditis elegans
Which of the following is a primary external factor in determining the polarity of the body axes in chick embryos
gravity
Which of the following processes will be disrupted if the apical ectodermal ridge is surgically removed from an embryo?
positional information for limb-bud pattern formation
Identical twins are possible in humans because ________
early blastomeres can form a complete embryo if isolated
Cells transplanted from the neural tube of a frog embryo to the ventral part of another embryo develop into nervous system tissues. Which of the following claims about the transplanted cells is most consistent with the results?
the cells were determined
Just prior to the onset of gastrulation in an embryo, the "organizer" cells are specified. What would you expect in the developing embryo if the specification of these cells were experimentally blocked?
Gastrulation would not occur, and normal development would cease.
Researchers were investigating the effects of bicoid in fruit fly development. The gene bicoid controls normal development of anterior structures in flies. In one experiment, they took a normally developing embryo and injected bicoid mRNA into the posterior end of the embryo. What result would they most likely observe?
The embryo would develop with a normal anterior end and anterior structures on the posterior end
In addition to maternal effect genes, paternal effect genes are important for fruit fly development. One such paternal effect gene codes for Sneaky, a protein required for breakdown of the fruit fly sperm plasma membrane that is a critical step for normal embryo development. Suppose that a female fruit fly's oocyte (egg) with a mutation in the bicoid gene is fertilized by a male fruit fly's sperm with a mutation in the Sneaky gene. Both mutations yield nonfunctional proteins. What would be the most likely outcome of this fertilization?
an embryo would not be able to develop
Retinoic acid (a metabolite of vitamin A) plays a key role in vertebrate development, differentiation, and organogenesis. Retinoic acid normally binds to the RAR receptor to initiate changes in gene expression. Researchers have determined that one type of RAR receptor is found at high levels in muscles, but is not found at all in neurons. How can you explain these findings?
The RAR receptor gene is expressed in muscle cells but not neurons.
In C. elegans, P granules act as cytoplasmic determinants to assist with the development of the posterior end of the organism. Suppose that P granules were abnormally found in both the anterior and posterior ends of a developing C. elegans organism. What would you expect to observe?
The embryo would develop with a normal posterior end and posterior structures on the anterior end.
The cortical reaction of sea urchin eggs functions directly in _____
the formation of a fertilization envelope
Which of the following is common to the development of both birds and mammals
epiblast and hypoblast
The archenteron develops into ________
the lumen of the digestive tract
What structural adaptation in chickens allows them to lay their eggs in arid environments rather than in water
extraembryonic membranes
If an egg cell were treated with EDTA, a chemical that binds calcium and magnesium ions, ________.
the fertilization envelope would not form
In humans, identical twins are possible because ________
early blastomeres can form a complete embryo if isolated
Cells transplanted from the neural tube of a frog embryo to the ventral part of another embryo develop into nervous system tissues. This result indicates that the transplanted cells were ________.
determined