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