Deck 38: Animal Development

Question 1

In frogs,the sperm fuses with the egg

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 any region of the egg.

Answer 1

B

Question 2

When zebrafish eggs are laid,they are surrounded by a tough chorion.Sperm are unable to get through this chorion and must find the tiny tunnel called a micropyle that provides a channel to the egg cell membrane.This channel is so tiny that only one sperm is able to fit through at a time.The micropyle most likely

A) aids in preventing polyspermy.
B) prevents sperm from other species from fusing with the egg.
C) evolved from a similar structure found in fruit fly eggs.
D) ensures that the head and not the tail of the sperm fuses with the egg.
E) is a mechanism to ensure that the zygote is diploid and not haploid.

Answer 2

A

Question 3

Which protein is involved in development of the central nervous system and is named after a video game character?

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

Answer 3

B

Question 4

The figure below is

A) a modern scientist's drawing of a sperm.
B) a diagram of a human fetus.
C) a seventeenth-century depiction of a human sperm.
D) a drawing of a frog sperm.
E) a rendering of what early scientists saw when they looked at donkey sperm under the microscope.

Question 5

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 yolk.
D) comes from the vegetal pole.
E) undergoes mitosis.

Question 6

The gray crescent is the region of the amphibian egg

A) corresponding to the site of sperm penetration.
B) where gastrulation begins.
C) that was unpigmented before cytoplasmic rearrangement.
D) where the ventral lip of the blastopore develops.
E) that is formed at ovulation and prior to fertilization.

Question 7

The genome that is used to make the mRNA stored in the egg and to direct cleavage in the zygote is the same genome as that of the

A) female who produced the egg.
B) male whose sperm fertilized the egg.
C) zygote.
D) haploid egg prior to ovulation.
E) haploid sperm that fertilized the egg.

Question 8

The sperm contributes _______ to the zygote.

A) a nucleus only
B) half of the mitochondria and a nucleus
C) a centriole and a nucleus
D) a cilium and a nucleus
E) a nucleus and Golgi apparatus

Question 9

You can artificially activate an unfertilized frog egg to begin developing by pricking it with a needle.That the egg can be induced to undergo cleavage in the absence of sperm indicates that

A) sperm do not contribute a microtubule organizing center to the egg.
B) fertilization can occur in the absence of sperm.
C) microtubule organizing centers are not involved in cleavage.
D) mitosis in the egg does not involve centrioles.
E) the egg can provide a centriole if it doesn't receive one from the sperm.

Question 10

The cleavage pattern shown below would be found in the embryo of a

A) crab.
B) sparrow.
C) human.
D) sea star.
E) zebrafish.

Question 11

The stage an embryo enters following fertilization is called the _______ stage.

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

Question 12

If you shift the position of a fruit fly egg relative to the follicle cells as the egg is developing in the ovary,you can expect that the

A) egg will lack a chorion when it is ovulated.
B) anterior-posterior axis of the future embryo will be shifted.
C) egg will not be released.
D) gray crescent will form in an abnormal place at fertilization.
E) sperm will not be able to find the egg after ovulation.

Question 13

Some animal embryos establish axes early in development.In amphibian embryos,the anterior-posterior axis is determined by the

A) location of the vegetal pole.
B) location of the animal pole.
C) point of sperm penetration.
D) location where cleavage begins.
E) position of external light shining on the embryo.

Question 14

If you treat unfertilized frog eggs with a poison that prevents microtubules from forming and then fertilize the eggs with sperm,the first abnormal event you would notice would most likely be

A) a failure of the cytoplasm to shift and expose the gray crescent.
B) nuclear division but no cytoplasmic division.
C) cytoplasmic division but no nuclear division.
D) the formation of two cells,one of which lacks a nucleus.
E) the formation of the gray crescent on the same side as sperm entry.

Question 15

Which event does not occur during cleavage?

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

Question 16

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) is induced by Sonic hedgehog proteins.

Question 17

Based on what you know about holoprosencephaly,what would you expect to happen if expression of the Sonic hedgehog gene was inhibited during development of the forebrain in humans?

A) Formation of nostrils in place of eyes
B) Formation of a single cerebral hemisphere
C) Development of a duplicate pair of eyes
D) Development of a duplicate pair of ears
E) Abnormally high levels of cholesterol

Question 18

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 19

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 20

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 baby daughter's hair.
D) removing cytoplasm from muscle cells and transplanting it into a fertilized egg.
E) separating the cells of a sea urchin embryo to study their development.

Question 21

Scientists examining a water sample from a small pond find a number of eggs and want to determine the group of animals to which the eggs belong.As the eggs begin to develop,it becomes clear that mitosis is proceeding,but there is no sign of cytoplasmic division.To what group do these eggs most likely belong?

A) Reptiles
B) Frogs
C) Fish
D) Insects
E) Mammals

Question 22

In early cleavage,amphibian embryos _______,whereas insect embryos _______.

A) undergo complete cleavage;form a syncytium
B) undergo complete cleavage;undergo cytoplasmic division in the absence of nuclear division
C) undergo spiral cleavage;form a syncytium
D) form a syncytium;undergo complete cleavage
E) undergo radial cleavage;undergo cytoplasmic division in the absence of nuclear division

Question 23

The human embryo is able to split at the 64-cell stage to produce two viable progeny.This is an indication that human development at this stage is

A) mosaic.
B) determinative.
C) definitive.
D) indeterminate.
E) regulative.

Question 24

The formation of the endoderm during gastrulation in frogs results from

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

Question 25

Genetic testing of an embryo is available to couples who want to avoid passing on a genetic defect to their offspring.One method of testing involves removing a single blastomere from an 8-cell stage embryo and analyzing it to determine if it carries the mutant gene.If no mutation is found,the now 7-cell embryo can be implanted in the woman,and it can go on to develop into a healthy infant.These results indicate that

A) at least one of the cells in the human embryo at the 8-cell stage is not used in development.
B) the embryo can compensate for the loss of a cell.
C) not all cells are equally important.
D) the human embryo at the 8-cell stage has not yet formed an inner-cell mass.
E) the cell that is removed for testing is derived from the trophoblast.

Question 26

The large amount of yolk in birds' eggs results in _______ cleavage.

A) complete
B) spiral
C) incomplete
D) superficial
E) radial

Question 27

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;they exist only in placental mammals.

Question 28

You are presented with an egg that is so rich in yolk that cleavage furrows do not pass entirely through the yolk.As development proceeds,a disc of cells accumulates on top of the yolk to form the embryo.This egg is most likely not the egg of a(n)

A) turtle.
B) bullfrog.
C) goldfish.
D) chicken.
E) alligator.

Question 29

What organism would produce the type of embryo shown in the figure?

A) Salamander
B) Fish
C) Human
D) Fruit fly
E) Sea urchin

Question 30

Refer to the figure below.In the embryo of what organism would you find this pattern of cleavage?

A) Lizard
B) Sparrow
C) Mouse
D) Echidna (monotreme)
E) Sea star

Question 31

In sea urchin embryos,mesenchyme cells are able to elongate the archenteron by using

A) mitotic spindles.
B) lobopodia (lobular cell extensions).
C) filopodia (thin extensions of cell).
D) myofibers.
E) centrioles.

Question 32

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) induced.
D) irreversible.
E) mosaic.

Question 33

The mesoderm

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

Question 34

Invagination in the sea urchin blastula

A) forms the neural tube.
B) involves contractile filopodia extending from the endoderm cells.
C) creates a blastopore that becomes the mouth.
D) forms the archenteron.
E) occurs just prior to the blastula stage.

Question 35

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 36

Which cells develop into the body of a human embryo?

A) Trophoblast
B) Extraembryonic membrane
C) Inner cell mass
D) Cumulus
E) Follicle

Question 37

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 38

Cleavage in human embryos _______,whereas cleavage in frog embryos _______.

A) is incomplete;is complete
B) involves formation of an epiblast;involves formation of a trophoblast
C) involves late expression of the embryo's genome;involves early expression of the embryo's genome
D) involves early segregation of cells that will not contribute to the embryo;does not involve early segregation of cells that will not contribute to the embryo
E) is spiral;is radial

Question 39

The structure in birds 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 40

Which feature(s)characterize(s)gastrulation in both birds and frogs?

A) Establishment of three germ layers
B) Inward migration of ectoderm cells to form the gut
C) Formation of the neural tube from the hypoblast
D) Invagination of cells of the epiblast to form endoderm and mesoderm
E) Both a and c

Question 41

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

A) Vertebrates
B) Jellyfish
C) Sea stars
D) Flatworms
E) Sea urchins

Question 42

Following gastrulation in vertebrates,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) pigment cells.
E) epidermis.

Question 43

If the blastopore dorsal lip is grafted from one salamander 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 44

Following gastrulation in vertebrates,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) heart and blood vessels

Question 45

The major divisions of the brain develop from the

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

Question 46

The epiblast and hypoblast are structures found in _______ development.

A) human but not sparrow
B) frog but not human
C) human and frog
D) frog and sparrow
E) human and sparrow

Question 47

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

Question 48

The segmented characteristic of human embryonic development is evident from the bricklike structures called _______ that form in paired rows lateral to the notochord.

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

Question 49

Which sequence represents the correct chronological order of developmental events,from earliest to latest?

A) Formation of the neural tube,invagination of the neural plate,release of neural crest cells
B) Invagination of the neural plate,formation of the neural tube,release of neural crest cells
C) Release of neural crest cells,formation of the neural tube,invagination of the neural plate
D) Release of neural crest cells,invagination of the neural plate,formation of the neural tube
E) Invagination of the neural plate,release of neural crest cells,formation of the neural tube

Question 50

Which statement 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) Expression of embryonic genes usually begins just before gastrulation.
D) The mouth of the sea urchin forms where the archenteron makes contact with the ectoderm.
E) Cells can actively migrate during gastrulation.

Question 51

The process of neurulation in chick embryos is similar to that of

A) humans.
B) sea urchins.
C) snails.
D) earthworms.
E) fruit flies.

Question 52

Experiments on amphibian embryos have shown that the notochord secretes Chordin and Noggin.If you performed an experiment in which you blocked the production of Chordin and Noggin in the early embryo,the expected result would be an embryo

A) that did not gastrulate.
B) that formed two embryos,joined belly-to-belly.
C) that lacked a developing nervous system.
D) that lacked an outer covering of epidermis.
E) in which the blastopore became the mouth.

Question 53

Which conclusion can be made from the experiments of Hans Spemann and Hilde Mangold in which they transplanted the dorsal lip of one salamander embryo to the ventral side of a second embryo?

A) Cytoplasmic determinants of development are homogeneously distributed in the amphibian zygote.
B) In the late blastula,certain regions of cells are destined to form epidermis or nervous tissue.
C) The dorsal lip of the blastopore,even if isolated from other cells,can 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 54

In amphibian eggs,cells migrate to the interior of the embryo through the blastopore.In mammalian embryos,this migration occurs at the

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

Question 55

Which statement about the neural tube is true?

A) It gives rise to the forebrain,midbrain,and hindbrain.
B) It gives rise to the epidermis.
C) It is formed from the notochord.
D) It develops from endoderm.
E) It forms at the beginning of gastrulation.

Question 56

Following gastrulation in vertebrates,the ectodermal cells contribute predominantly to the developing

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

Question 57

The somites are derived from _______ tissue.

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

Question 58

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) somites.
C) parenchyma.
D) neural crest cells.
E) lateral plate mesoderm.

Question 59

The cells that form the neural tube come from the

A) notochord.
B) mesoderm.
C) endoderm.
D) ectoderm.
E) neural crest.

Question 60

Experimental evidence has shown that when cells from the presumptive neural ectoderm of a newt embryo in the late gastrula stage are transplanted onto the surface of a second late gastrula where epidermis would normally develop,the transplanted cells still develop into tissues of the nervous system.These results show that the transplanted cells are

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

Question 61

In a chick embryo,the processes of gas exchange and waste removal are

A) carried out by structures surrounding the developing embryo.
B) similar to those of frogs.
C) handled by the chick's mother.
D) accomplished by the placenta.
E) similar to those of humans.

Question 62

Which function is not carried out by the placenta?

A) Waste removal for the fetus
B) Exchange of respiratory gases for the fetus
C) Transfer of nutrients to the fetus
D) Bathing of chorionic villi in maternal blood
E) Protection of the fetus in a bag of fluid

Question 63

A birth defect called holoprosencephaly results in the formation of a single central eye.This defect can be caused by environmental factors and mutations in the _______ gene.

Question 64

Which statement about the allantois is true?

A) It is formed from the extraembryonic ectoderm.
B) It functions in storing metabolic waste.
C) It plays a major role in humans.
D) It becomes part of the body of the embryo.
E) It contains both ectoderm and mesoderm.

Question 65

A fish embryo forms a yolk sac that

A) is made of the same germ layers as the yolk sac in a chick embryo.
B) is vascularized,similar to the yolk sac of a chick embryo.
C) is constructed of ectoderm and mesoderm.
D) is similar in origin to the yolk sac in mammals.
E) surrounds the body of the embryo.

Question 66

What is the difference between a human fetus and embryo?

A) The term "fetus" applies only to the earliest stages of embryonic development.
B) A fetus is an embryo carried longer than 200 days.
C) A fetus is the medical and legal term for a human embryo after the first trimester.
D) An embryo becomes a fetus when the internal organs are completely developed.
E) An embryo becomes a fetus at birth.

Question 67

We say that the birth of a human child is imminent when the pregnant mother's "water breaks." That "water" is produced by which extraembryonic membrane?

A) Allantoic membrane
B) Chorion
C) Amnion
D) Yolk sac
E) Placenta

Question 68

Use the following to answer question 78:
Refer to the figure below.
The figure shows that in humans,development _______ and growth _______.

A) is direct;is isometric
B) is indirect;is allometric
C) is direct;shows a 1:1 size increase
D) involves a larval stage;is isometric
E) is direct;is allometric

Question 69

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

A) at the time of birth.
B) during the third trimester of gestation.
C) during the first trimester of gestation.
D) when it is a zygote.
E) during the final stages of organ formation.

Question 70

The amniote egg

A) first appeared in fish.
B) allowed amphibians to lay moderately yolky eggs.
C) freed the first reptiles from needing to return to a body of water for reproduction.
D) is found in all vertebrates.
E) is a feature characteristic of chordates.

Question 71

Using the figure of the vertebrate embryo below,list in order the structures that the arrow passes through,starting from the tail of the arrow and ending at its tip.

A) Epidermal ectoderm,neural tube,endoderm,archenteron
B) Endoderm,ectoderm,notochord,archenteron
C) Neural ectoderm,notochord,gut endoderm,archenteron
D) Neural crest,neural tube,gut endoderm,coelom
E) Epidermal ectoderm,neural tube,mesoderm,coelom

Question 72

One function of the allantois is the

A) storage of nitrogenous wastes.
B) prevention of fluid loss.
C) transfer of nutrients.
D) control of the pace of development.
E) production of fluid for the embryo.

Question 73

In humans,the amnion forms from the

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

Question 74

Exposure to toxins is particularly dangerous to the embryo in the first trimester of pregnancy because

A) induction of organ systems is occurring during this period.
B) rapid cell division is taking place during this period.
C) tissue differentiation is occurring at its highest levels during this period.
D) organs are beginning to form during this period.
E) All of the above

Question 75

The skin of adult humans serves in part as waterproofing.Which extraembryonic membrane serves an analogous function?

A) Amnion
B) Chorion
C) Allantoic membrane
D) Yolk sac
E) Placenta

Question 76

Which statement about the umbilical cord is true?

A) It contains blood vessels from the embryo and mother.
B) It contains blood vessels just from the mother.
C) It is derived from the inner cell mass.
D) It is derived from the endometrium of the uterus.
E) It carries nutrients and wastes.

Question 77

Sensory neurons are derived from

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

Question 78

The period of human gestation

A) lasts about 360 days.
B) is the time between implantation and organogenesis.
C) can be divided into three trimesters of roughly three months each.
D) is the time between a woman's last period and the occurrence of implantation.
E) ends several days before birth.

Question 79

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

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

Question 80

The figure shows that,relative to the rest of the body,the _______ in a newborn baby is/are larger than in an adult.

A) It would have a notochord.
B) It would lack a tail.
C) It would have a ventral nerve chord.
D) Its body would be much smaller than that of an adult but with the same proportions,because a tunicate goes through direct development.
E) Its body would have different proportions from that of an adult,because tunicate growth is allometric.