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51) At the time of implantation, the human embryo is called a
A) blastocyst.
B) gastrula.
C) fetus.
D) somite.
E) zygote.
52) Uterine implantation due to enzymatic digestion of the endometrium is initiated by the
A) inner cell mass.
B) endoderm.
C) chorion.
D) mesoderm.
E) trophoblast.
53) In placental mammals, the yolk sac
A) transfers nutrients from the yolk to the embryo.
B) differentiates into the placenta.
C) becomes a fluid-filled sac that surrounds and protects the embryo.
D) produces blood cells that then migrate into the embryo.
E) stores waste products from the embryo until the placenta develops.
54) Gases are exchanged in a mammalian embryo in the
A) amnion.
B) hypoblast.
C) chorion.
D) trophoblast.
E) yolk sac.
55) Thalidomide, now banned for use as a sedative in 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 arm and
leg deformities, suggesting that the drug most likely influenced
A) early cleavage divisions.
B) determination of the polarity of the zygote.
C) differentiation of bone tissue.
D) morphogenesis.
E) organogenesis.
56) The migratory neural crest cells
A) form most of the central nervous system.
B) serve as precursor cells for the notochord.
C) form the spinal cord in the frog.
D) form neural and non-neural structures in the periphery.
E) form the lining of the lungs and of the digestive tract.
57) From earliest to latest, the overall sequence of early development proceeds in which of the following
sequences?
A) gastrulation → organogenesis → cleavage
B) ovulation → gastrulation → fertilization
C) cleavage → gastrulation → organogenesis
D) gastrulation → blastulation → neurulation
E) preformation → morphogenesis → neurulation
58) Changes in both cell shape and cell position occur extensively during
A) gastrulation, but not organogenesis or cleavage.
B) organogenesis, but not gastrulation or cleavage.
C) cleavage, but not gastrulation or organogenesis.
D) gastrulation and organogenesis, but not cleavage.
E) gastrulation, organogenesis, and cleavage.
59) Changes in the shape of a cell usually involve a reorganization of the
A) nucleus.
B) cytoskeleton.
C) extracellular matrix.
D) transport proteins.
E) nucleolus.
60) Animal development compares to plant development in that
A) plant cells, but not animal cells, migrate during morphogenesis.
B) animal cells, but not plant cells, migrate during morphogenesis.
C) plant cells and animal cells migrate extensively during morphogenesis.
D) neither plant cells nor animal cells migrate during morphogenesis.
E) plant cells, but not animal cells, undergo convergent extension.
61) Cadherins and other cell-adhesion molecules that guide cell migration are
A) steroid hormones.
B) glycoproteins.
C) fatty acids.
D) prostacyclins.
E) ribonucleic acids.
62) To meet a zygote's metabolic and developmental requirements,
A) maternal RNA and maternal proteins must be present.
B) paternal RNA and maternal proteins must be present.
C) the haploid DNA in the nucleus must be transcribed.
D) the nucleus must have hundreds of copies of every gene, allowing a high rate of gene expression.
E) the zygote must continuously undergo endocytosis of proteins to take them from its environment.
63) Select the choice that correctly associates the organ with its embryonic sources.
A) anterior pituitary gland mesoderm and endoderm
B) thyroid gland mesoderm and ectoderm
C) adrenal gland ectoderm and mesoderm
D) skin endoderm and mesoderm
E) brain mesoderm and endoderm
64) The first cavity formed during sea urchin development is the
A) blastopore.
B) mouth.
C) blastocoel.
D) anus.
65) Human trophoblasts
A) form the inner cell mass.
B) form from ectoderm.
C) are the precursors of the mesoderm.
D) are of embryonic origin and function in embryo nutrition.
E) are of maternal origin and function in embryo gas exchange.
66) The embryonic precursor to the human spinal cord is the
A) notochord.
B) neural tube.
C) mesoderm.
D) archenteron.
E) set of bilateral somites.
67) Animal cells that are present only for a brief developmental phase will, following completion of that
phase, undergo
A) diapause.
B) apoptosis
C) meiosis.
D) oxidative phosphorylation.
E) re-differentiation.
68) The term applied to a morphogenetic process whereby cells extend themselves, making the mass of
the cells narrower and longer, is
A) convergent extension.
B) induction.
C) elongational streaming.
D) bi-axial elongation.
E) blastomere formation.
69) During gastrulation in frog embryos, fibronectin
A) provides an extracellular anchorage for migrating cells.
B) regulates actin-myosin interactions in the cytosol of migrating cells.
C) reduces the entry of calcium ions into migrating cells.
D) regulates mRNA movement out of the nucleus of a moving cell.
E) provides the pigment that accumulates in the primitive streak.
70) Which of the following is the anatomical axis that is largely symmetrical in both frogs and humans?
A) medial to lateral
B) dorsal to ventral
C) anterior to posterior
D) animal to vegetal
E) rostral to caudal
71) If an amphibian zygote is manipulated so that the first cleavage plane fails to divide the gray
crescent, then
A) the daughter cell with the entire gray crescent will die.
B) both daughter cells will develop normally because amphibians are totipotent at this stage.
C) only the daughter cell with the gray crescent will develop normally.
D) both daughter cells will develop abnormally.
E) both daughter cells will die immediately.
72) In humans, identical twins are possible because
A) of the heterogeneous distribution of cytoplasmic determinants in unfertilized eggs.
B) of interactions between extraembryonic cells and the zygote nucleus.
C) of convergent extension.
D) early blastomeres can form a complete embryo if isolated.
E) the gray crescent divides the dorsal-ventral axis into new cells.
73) Hans Spemann and colleagues developed the concept of the primary organizer in amphibian
embryos while studying the
A) medial cells between the optic cups.
B) anterior terminus of the notochord.
C) lateral margins of the neural tube.
D) posterior edge of the dorsal ectoderm.
E) dorsal lip of the blastopore.
74) In frogs, formation of the eye lens is induced by chemical signals from
A) cells that will become the neural plate.
B) cells that are forming the inner ear.
C) an outgrowth of the developing brain.
D) both cells that will become the neural plate and cells that are forming the inner ear.
E) both cells that will become the neural plate and an outgrowth of the developing brain.
75) Which of the following is an adult organism that has fewer than 1,000 cells?
A) chickens, Gallus domesticus
B) African clawed frogs, Xenopus laevis
C) humans, Homo sapiens
D) fruit flies, Drosophila melanogaster
E) nematodes, Caenorhabditis elegans
76) The developmental precursors to the gonadal tissues of C. elegans uniquely contain
A) proteins of maternal origin.
B) high concentrations of potassium ions.
C) haploid proteins.
D) T tubules for the propagation of action potentials.
E) P granules of mRNA and protein.
77) Two primary factors in shaping the polarity of the body axes in chick embryos are
A) light and temperature.
B) salt gradients and membrane potentials.
C) gravity and pH.
D) moisture and mucus.
E) location of sperm penetration and cortical reaction.
78) The arrangement of organs and tissues in their characteristic places in 3-D space defines
A) pattern formation.
B) induction.
C) differentiation.
D) determination.
E) organogenesis.
79) If the apical ectodermal ridge is surgically removed from an embryo, it will lose
A) positional information for limb-bud pattern formation.
B) guidance signals needed for correct gastrulation.
C) unequal cytokinesis of blastomeres.
D) the developmental substrate for the gonads.
E) the developmental substrate for the kidneys.
80) The nematode Caenorhabditis elegans
A) is composed of a single cell, in which the developmental origin of each protein has been mapped.
B) is composed of about 1,000 cells, in which the developmental origin of each cell has been mapped.
C) has only a single chromosome, which has been fully sequenced.
D) has about 1,000 genes, each of which has been fully sequenced.
E) uniquely, among animals, utilizes programmed cell death during normal development.
Art Questions
Use the following information to answer the next few questions.
In a study of the development of frog embryos, researchers stained several early gastrulas with vital dyes
and noted the locations of the dyes after gastrulation. The results are shown in the following table.
Tissue
Stain
Brain
red
Notochord
yellow
Liver
green
Lens of the eye
blue
Lining of the digestive tract
purple
81) The ectoderm should give rise to tissues containing
A) yellow and purple colors.
B) purple and green colors.
C) green and red colors.
D) red and blue colors.
E) red and yellow colors.
82) The mesoderm was probably stained with a
A) blue color.
B) yellow color.
C) red color.
D) purple color.
E) green color.
83) The endoderm was probably stained with
A) red and yellow colors.
B) yellow and green colors.
C) green and purple colors.
D) blue and yellow colors.
E) purple and red colors.
Scenario Questions
84) When you slice up a pie that contains a swirled mixture of chocolate and vanilla filling, you notice
that some slices have more chocolate than vanilla and that other slices have more vanilla than chocolate.
This uneven distribution of chocolate and vanilla is most like the uneven distribution of
A) nuclei in a zygote.
B) nuclei in an early embryo.
C) nuclei in an egg prior to fertilization.
D) cytoplasmic determinants in a newly formed zygote.
E) cytoplasmic determinants in a baby just prior to birth.
85) Assume that successful reproduction in a rare salamander species, wherein all individuals are
females, relies on those females having access to sperm from males of another species but that the
resulting embryos show no signs of a genetic contribution from the sperm. In this case, the sperm appear
to be used only for
A) morphogenesis.
B) epigenesis.
C) egg activation.
D) cell differentiation.
E) the creation of a diploid cell.
End-of-Chapter Questions
The following questions are from the end-of-chapter “Test Your Understanding” section in Chapter 47
of the textbook.
86) The cortical reaction of sea urchin eggs functions directly in
A) the formation of a fertilization envelope.
B) the production of a fast block to polyspermy.
C) the release of hydrolytic enzymes from the sperm.
D) the generation of an electrical impulse by the egg.
E) the fusion of egg and sperm nuclei.
87) Which of the following is common to the development of both birds and mammals?
A) holoblastic cleavage
B) epiblast and hypoblast
C) trophoblast
D) yolk plug
E) gray crescent
88) The archenteron develops into
A) the mesoderm.
B) the blastocoel.
C) the endoderm.
D) the placenta.
E) the lumen of the digestive tract.
89) What structural adaptation in chickens allows them to lay their eggs in arid environments rather than
in water?
A) extraembryonic membranes
B) yolk
C) cleavage
D) gastrulation
E) development of the brain from ectoderm
90) In an egg cell treated with EDTA, a chemical that binds calcium and magnesium ions,
A) the acrosomal reaction would be blocked.
B) the fusion of sperm and egg nuclei would be blocked.
C) the fast block to polyspermy would not occur.
D) the fertilization envelope would not form.
E) the zygote would not contain maternal and paternal chromosomes.
91) In humans, identical twins are possible because
A) cytoplasmic determinants are distributed unevenly in unfertilized eggs.
B) extraembryonic cells interact with the zygote nucleus.
C) convergent extension occurs.
D) early blastomeres can form a complete embryo if isolated.
E) the gray crescent divides the dorsal-ventral axis into new cells.
92) 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
A) totipotent.
B) determined.
C) differentiated.
D) mesenchymal.
E) apoptotic.
