Deck 44: Animal Development

Question 1

The gray crescent is the region of the egg

A) that is opposite the site of sperm penetration.
B) where gastrulation begins.
C) that was pigmented before cytoplasmic rearrangement.
D) where the dorsal lip of the blastopore develops.
E) All of the above

Answer 1

E

Question 2

Which of the following is part of the embryonic contribution to placenta formation?

A) Amnion
B) Chorion
C) Ectoderm
D) Allantois
E) Zona pellucida

Answer 2

B

Question 3

Fertilization involves all of the following except

A) equal contributions of cell organelles from sperm and egg.
B) joining of sperm and egg haploid nuclei.
C) induction of rearrangements of the egg cytoplasm.
D) sperm binding to specific sites on the egg surface.
E) metabolic activation of the egg.

Answer 3

A

Question 4

Which of the following is true of human development?

A) Most organs begin to form during the second trimester.
B) Gastrulation takes place in the oviducts.
C) Genetic diseases can be detected by sampling cells from the chorion.
D) Implantation occurs through interactions of the zona pellucida with the uterine lining.
E) Exposure to drugs and chemicals is most likely to cause birth defects when it occurs in the third trimester.

Question 5

The gray crescent

A) is observable in the frog zygote.
B) develops at the site of sperm entry.
C) causes rotation of the cortical cytoplasm.
D) induces formation of the optic cup.
E) can be mimicked by retinoic acid.

Question 6

When is the developing human most susceptible to the occurrence of birth defects from radiation or chemical insults?

A) At the time of birth
B) During the third trimester
C) During the first trimester
D) When it is a zygote
E) During the final stages of organ formation

Question 7

The earliest stage of development is called the _______ stage.

A) fetal
B) cleavage
C) gastrula
D) blastula
E) trophoblast

Question 8

Which of the following was a conclusion from the experiments of Spemann and Mangold?

A) Cytoplasmic determinants of development are homogeneously distributed in the amphibian zygote.
B) In the late blastula, certain regions of cells are determined to form skin or nervous tissue.
C) The dorsal lip of the blastopore can be isolated and will form a complete embryo.
D) The dorsal lip of the blastopore can initiate gastrulation.
E) The dorsal lip of the blastopore gives rise to the neural tube.

Question 9

In early cleavage, sea urchins undergo _______ cleavage, whereas insects undergo _______ cleavage.

A) complete; superficial
B) complete; incomplete
C) superficial; incomplete
D) incomplete; complete
E) superficial; complete

Question 10

In organisms such as the chick, in which the egg has extensive yolk, the egg

A) shows complete cleavage.
B) shows incomplete cleavage.
C) forms a blastoderm but no blastocoel.
D) shows even distribution of the yolk.
E) fails to synthesize DNA during cleavage.

Question 11

Which statement about gastrulation is true?

A) In frogs, gastrulation begins in the vegetal hemisphere.
B) In sea urchins, gastrulation produces the notochord.
C) In birds, cells from the surface of the blastodisc move down through the primitive groove to form the hypoblast.
D) In mammals, gastrulation occurs in the hypoblast.
E) In sea urchins, gastrulation produces only two germ layers.

Question 12

Which of the following does not occur during cleavage in frogs?

A) A high rate of mitosis
B) Reduction in the size of cells
C) Expression of genes critical for blastula formation
D) Orientation of cleavage planes at right angles
E) Unequal division of cytoplasmic determinants

Question 13

Which of the following characterizes neurulation?

A) The notochord forms a neural tube.
B) The neural tube is formed from ectoderm.
C) A neural tube forms around the notochord.
D) The neural tube forms somites.
E) In birds, the neural tube forms from the primitive groove.

Question 14

In frogs, the sperm penetrates

A) in the region of the vegetal pole.
B) in the region of the animal pole.
C) in the region of the gray crescent.
D) on the border of the animal and vegetal poles.
E) in the region of either pole or of the gray crescent.

Question 15

Which of the following play a role as cytoplasmic determinants in directing embryonic development?

A) Transcription factors
B) Protein kinases
C) Protein kinase inhibitors
D) $\beta$ -catenin
E) All of the above

Question 16

Which statement about trophoblast cells is true?

A) They are capable of producing monozygotic twins.
B) They are derived from the hypoblast of the blastocyst.
C) They are endodermal cells.
D) They secrete proteolytic enzymes.
E) They prevent the zona pellucida from attaching to the oviduct.

Question 17

The large amount of yolk in birds' eggs results in

A) gradual metamorphosis.
B) complete metamorphosis.
C) incomplete cleavage.
D) incomplete mitosis during cleavage.
E) bicoid larvae.

Question 18

The embryos of complex multicellular animals must establish spatial coordinates if development is to proceed. An important reference coordinate for developing frogs is the

A) location of the vegetal pole.
B) location of the animal pole.
C) point of sperm penetration.
D) location where gastrulation begins.
E) direction of the sun.

Question 19

How does cleavage in mammals differ from cleavage in frogs?

A) Slower rate of cell division
B) Formation of tight junctions
C) Expression of the embryo's genome
D) Early separation of cells that will not contribute to the embryo
E) All of the above

Question 20

The sperm contributes _______ to the zygote.

A) a nucleus
B) half of the mitochondria and a nucleus
C) a centriole and a nucleus
D) cilium and a nucleus
E) All of the above

Question 21

Bottle cells are

A) cells of the mammalian trophoblast.
B) cells of the mammalian inner cell mass.
C) fluid-filled cells used for storage.
D) bottle-shaped cells found around the amphibian blastopore.
E) another name for granulosa cells.

Question 22

Which of the following cells develops into a human embryo?

A) Trophoblast
B) Extraembryonic membrane
C) Inner cell mass
D) Cumulus
E) All of the above

Question 23

Gastrulation is the stage of development

A) when neural tube formation begins.
B) that makes possible the inductive interactions that trigger differentiation and organ formation.
C) that follows the formation of the three germ layers.
D) that precedes cleavage.
E) that is marked by a dramatic increase in the rate of mitosis.

Question 24

If one of the blastomeres is removed from a developing mouse embryo, the remaining cells will still develop into a normal mouse. This is an example of

A) regulative development.
B) determination.
C) mosaic development.
D) involution.
E) ingression.

Question 25

Which of the following statements about animal development is false?

A) Signaling molecules interact to produce different combinations of signals that eventually guide embryonic cells to differentiate along different pathways.
B) $\beta$ -catenin is necessary but not sufficient for the formation of the primary embryonic organizer.
C) Blastomeres are early embryonic cells.
D) The mouth of the sea urchin forms where the archenteron makes contact with the ectoderm.
E) Cells actively migrate during gastrulation.

Question 26

The mesoderm

A) is located on the outside of the embryo.
B) lies between the endoderm and the ectoderm.
C) is found in blastula-stage embryos.
D) gives rise to the linings of the gut.
E) is formed during cleavage.

Question 27

If the blastopore dorsal lip is grafted from one frog embryo onto a second embryo, the second dorsal lip will

A) change the polarity of the adjacent segments.
B) block gastrulation.
C) change the developmental fate of the surrounding cells.
D) change the prospective potency of the surrounding cells.
E) cause rapid cell division.

Question 28

Invagination of the sea urchin blastula

A) is preceded by changes in the shape of individual blastomeres.
B) involves the filopodia of secondary mesenchyme cells.
C) is due to the uneven distribution of various transcriptional regulatory proteins in the egg cytoplasm.
D) forms the archenteron.
E) All of the above

Question 29

If cells from the presumptive neural ectoderm of a frog gastrula are transplanted onto the surface of a second gastrula where skin would normally develop, the transplanted cells will still develop into tissues of the nervous system. This experiment shows that the transplanted cells are

A) differentiated.
B) totipotent.
C) discontinuous.
D) determined.
E) endodermal.

Question 30

After gastrulation, the endodermal cells contribute predominantly to the developing

A) brain, nervous system, and nails.
B) skeletal system and muscles.
C) lining of the digestive and respiratory tracts.
D) sweat glands and milk secretory glands.
E) None of the above

Question 31

The movement of cells toward the blastopore is called

A) mass cellular migration.
B) embryonic cellular integration.
C) cellular destiny.
D) furrowing.
E) epiboly.

Question 32

During cleavage, the cytoplasm of new cells in a developing frog embryo

A) comes from the egg cytoplasm.
B) is synthesized by the blastomeres.
C) does not contain any yolk.
D) is the vegetal pole.
E) undergoes mitosis.

Question 33

After gastrulation, the ectodermal cells contribute predominantly to the developing

A) brain, nervous system, and sweat glands.
B) skeletal system and muscles.
C) inner lining of the gut and respiratory tract.
D) liver and pancreas.
E) None of the above

Question 34

After gastrulation, the mesodermal cells contribute to the developing

A) brain and nervous system.
B) skeletal system and muscles.
C) inner lining of the gut and respiratory tract.
D) sweat glands.
E) liver and pancreas.

Question 35

The formation of the endoderm during gastrulation in frogs results from

A) movement of cells from the surface layer to the interior.
B) migration of cells within the blastocoel.
C) formation of columnar cells at the vegetal pole.
D) rapid cell division.
E) migration of secondary mesenchyme cells.

Question 36

Because the human embryo is able to split at the 64-cell level of organization to produce two viable progeny, it is said to exhibit _______ development.

A) mosaic
B) determinative
C) definitive
D) classical vertebrate
E) regulative

Question 37

The trophoblast cells in frogs

A) are important to placenta formation.
B) protect the egg from sunlight.
C) carry out gas exchange.
D) help with implantation.
E) do not exist.

Question 38

If a cell is removed from an eight-cell embryo, and a particular portion of the organism fails to form, the development is termed

A) regulative.
B) controlled.
C) banished.
D) irreversible.
E) mosaic.

Question 39

Which of the following does not occur during cleavage?

A) Rapid DNA synthesis
B) Cell growth
C) Differential distribution of nutrients and information molecules
D) A rapid series of cell divisions
E) Formation of the blastula

Question 40

Mesenchyme cells are able to move along extracellular matrix molecules by means of

A) amoeboids.
B) "walking feet."
C) filopodia.
D) sliding cell receptors.
E) None of the above

Question 41

The vertebral column is derived, via the notochord, from

A) ectoderm.
B) neuromesoderm.
C) chordamesoderm.
D) endoderm.
E) None of the above

Question 42

In humans, the amnion forms from the

A) hypoblast.
B) epiblast.
C) chorion.
D) trophoblast.
E) yolk sac.

Question 43

The major divisions of the brain develop from

A) the anterior end of the neural tube.
B) the posterior end of the neural tube.
C) the anterior portion of the notochord.
D) the posterior portion of the notochord.
E) several of the somites.

Question 44

A recent public health campaign in Australia called for the mandatory inclusion of folic acid in bread. Which of the following would be a likely result of this measure?

A) Since folic acid increases the probability that sperm will initiate an acrosome reaction and thereby fertilize eggs, a long-term population decline in the country would be reversed.
B) Since folic acid aids in the fusion of folds of the neural tube, birth defects would be reduced.
C) Since folic acid stiffens the zona pellucida, thereby selecting for the strongest sperm, birth defects would be reduced.
D) It would accelerate weight gain in chickens, thereby increasing their market availability.
E) All of the above

Question 45

Which of the following is a feature of gastrulation in both birds and frogs?

A) Three germ layers are established.
B) Cells from the surface of the blastocyst migrate to form the gut.
C) The neural tube forms from the hypoblast.
D) Gastrulation occurs as some cells of the epiblast invaginate to form endoderm and mesoderm.
E) All of the above

Question 46

Once development has proceeded to the point that three germ layers are in place within the embryo, the next phase of development, called _______, can begin.

A) organogenesis
B) gastrulation
C) hypoblasty
D) epiblasty
E) transcription

Question 47

Neural tube defects during development

A) can lead to spina bifida.
B) include failure of the tube's folds to fuse in the posterior end.
C) are linked to deficiency of folic acid in the diets of pregnant women.
D) have declined significantly in the United States in the last 100 years.
E) All of the above

Question 48

Which of the following represents the correct chronological sequence of developmental events?

A) Formation of the neural tube, movement of neural folds, thickening of neural ectoderm
B) Movement of neural folds, formation of the neural tube, thickening of neural ectoderm
C) Thickening of neural ectoderm, formation of the neural tube, movement of neural folds
D) Thickening of neural ectoderm, movement of neural folds, formation of the neural tube
E) None of the above

Question 49

The cells that form the neural tube come from the

A) notochord.
B) mesoderm.
C) endoderm.
D) ectoderm.
E) neuroderm.

Question 50

The epiblast and the hypoblast are structures found in _______ development.

A) human
B) frog
C) human and frog
D) chicken
E) human and chicken

Question 51

In amphibian eggs, cells migrate to the interior of the embryo through the blastopore. In mammalian embryos with small amounts of yolk, this involution occurs at the

A) archenteron.
B) primitive groove.
C) notochord.
D) blastopore.
E) gray crescent.

Question 52

Which of the following statements about neural tube defects during development is false?

A) The tube's folds may fail to fuse in the posterior end.
B) They are linked to deficiency of folic acid in the diets of pregnant women.
C) Spina bifida is one possible result.
D) They can lead to the absence of a forebrain in infants.
E) All of the above are true; none is false.

Question 53

The process of neurulation in amphibians is similar to that of

A) birds.
B) reptiles.
C) mammals.
D) All of the above
E) None of the above

Question 54

Chordamesoderm converts some ectoderm into neural ectoderm by

A) increasing the flow of nutrients into those cells.
B) hyperexpression of three homeobox genes.
C) sequestering folic acid in those cells.
D) the first expression of inhibitory hormones in the developing embryo.
E) expressing signaling molecules called Noggin and Chordin.

Question 55

Which of the following feature a body plan with re­peating segments (somites) that are modified during development into structures such as nerves, ribs, and muscles?

A) Vertebrates
B) Jellyfish
C) Arthropods
D) Flatworms
E) Both a and c

Question 56

A body plan consisting of repeating segments, which are modified during development into structures such as vertebrae, ribs, and muscles, depends on modification of early developmental structures called

A) interneurons.
B) neural crest cells.
C) parenchyma.
D) somites.
E) None of the above

Question 57

In mammals and birds, the _______ is the structure from which the embryo is derived.

A) trophoblast
B) cumulus cell
C) blastocyst
D) epiblast
E) hypoblast

Question 58

Once the neural tube is formed, it and the other components of the central nervous system must be connected to the rest of the body. The development of those connections is led by _______ cells.

A) mesothelioma
B) neural crest
C) Leydig
D) somite
E) trophoblastic

Question 59

The structure in birds and mammals that is most analogous to the dorsal lip of the frog blastopore is

A) the primitive streak.
B) the archenteron.
C) the yolk plug.
D) Hensen's node.
E) the notochord.

Question 60

One of Hans Spemann's important experiments involved

A) dividing human embryos into equal halves.
B) killing a single cell in a sea urchin embryo to study the effects.
C) dividing a frog embryo in two using a strand of his daughter's hair.
D) removing cytoplasm from muscle cells and transplanting it into a fertilized egg.
E) All of the above

Question 61

Which of the following statements about neurulation is false?

A) Neural crest cells give rise to peripheral nerves.
B) Body segmentation develops during neurulation.
C) Hox genes control differentiation along the anterior-posterior body axis.
D) Neural crest cells are migratory.
E) Neural crest cells break loose from the neural tube adjacent to the line of closure and remain there to contribute to a number of structures.

Question 62

Roughly how many Hox genes are there in mammals?

A) 4
B) 10
C) 40
D) 3,100
E) An unknown number; they have been studied in amphibians only.

Question 63

Which of the following statements about gestation is false?

A) In comparison to large mammals, small mammals have shorter gestation periods.
B) Thalidomide, administered during pregnancy, alters the skin tone of the fetus.
C) Chorionic villus sampling can detect genetic diseases as early as 8 weeks of gestation.
D) Human pregnancy has a duration of about 9 months.
E) All of the above are true; none is false.

Question 64

The somites are derived from _______ tissue.

A) mesoderm
B) parenchyma
C) ectoderm
D) endoderm
E) neural

Question 65

Which of the following statements about events during the neurulation stage of development is false?

A) Neurulation initiates the nervous system.
B) The notochord gives structural support to the embryo.
C) Bulges at the posterior end of the neural tube become the brain.
D) The likelihood of a neural tube defect is lowered if a pregnant woman takes folic acid.
E) Both a and b

Question 66

The protein that induces cells in the neural tube to develop into motor neurons is named after which video-game character?

A) Donkey Kong
B) Sonic hedgehog
C) Mario
D) Pac Man
E) Galaga

Question 67

One function of the allantois is

A) waste storage.
B) exchange of respiratory gases.
C) the transfer of nutrients.
D) control of the pace of development.
E) All of the above are functions of the allantois.

Question 68

Peripheral nerves are derived from

A) mesodermal tissue.
B) neural crest cells.
C) somites.
D) microtubules.
E) organelles contributed by the sperm only.

Question 69

The segmented characteristic of human embryonic development is evident from the bricklike structures called _______ that form along the notochord.

A) neural tubes
B) mesoderm
C) ectoderm
D) somites
E) somatomeres

Question 70

The trophoblast helps an early human embryo embed itself in the mother's endometrium

A) after the somites have appeared.
B) by secreting enzymes that break down proteins and allow it to enter.
C) using cilia extending from the zona pellucida.
D) by excreting hydrophobic lipids that cause it to drop out of the uterine fluid and press against the uterine wall.
E) None of the above

Question 71

The order in which mammalian Hox genes are expressed during development

A) varies between males and females.
B) depends on circulating hormone levels.
C) proceeds from the posterior to the anterior parts of the embryo.
D) reflects the order in which they appear on their chromosomes.
E) is the same order in which they were described by biologists.

Question 72

Which of the following is not a name or term used by developmental biologists?

A) Sonic Hedgehog
B) Noggin
C) Goosecoid
D) Mario
E) Siamois

Question 73

The mesoderm of the vertebrate embryo is programmed to produce forelegs rather than hind legs by

A) Noggin.
B) progestin levels.
C) Hox genes.
D) the spacing of somites in the embryo.
E) None of the above

Question 74

Which of the following statements about the umbilical cord is false?

A) It contains blood vessels from the embryo.
B) It contains blood vessels from the mother.
C) It is derived from the allantois.
D) It joins the placenta and the embryo.
E) It carries nutrients and wastes.

Question 75

Which of the following is the distinction between a fetus and an embryo?

A) The term "fetus" applies only to birds.
B) The fetus is a mammalian embryo carried longer than 200 days.
C) A fetus is the legal term applied to human embryos only.
D) By definition, a human fetus becomes an embryo in the second trimester.
E) An embryo becomes a fetus at birth.

Question 76

The _______ is an important structure for waste storage in birds and some mammals, but not in humans.

A) allantois
B) yolk sac
C) placenta
D) umbilical cord
E) amnion

Question 77

Which of the following is not a function of the placenta?

A) Waste removal
B) Exchange of respiratory gases
C) Transfer of nutrients
D) Control of the pace of development
E) All of the above are functions of the placenta.

Question 78

Which of the following statements about the allantois is false?

A) It is formed from the extraembryonic endoderm.
B) It functions in storing metabolic waste.
C) It plays a minor role in humans.
D) It is not part of the embryo.
E) All of the above are true; none is false.

Question 79

Gas exchange and waste removal for a chicken embryo are

A) handled by structures surrounding the developing embryo.
B) handled in a manner similar to that in reptiles.
C) carried out by the chick's mother.
D) accomplished by the placenta.
E) Both a and b

Question 80

Gene duplications during vertebrate evolution have led to

A) the control of body segmentation in mice by four copies of Hox genes.
B) the abundance of somites in vertebrate embryos.
C) the loss of other genes.
D) a long development period of feathers in the chicken embryo.
E) All of the above