Deck 47: Animal Development

Question 1

A "human blastomere" is ________.

A) an embryonic cell that is smaller than the ovum
B) an embryonic structure that includes a fluid-filled cavity
C) that part of the acrosome that opens the egg's membrane
D) a cell that contains a (degenerating) second polar body

Answer 1

A

Question 2

The pattern of embryonic development in which only the cells lacking yolk subsequently undergo cleavage is called ________.

A) holoblastic development, which is typical of marsupial mammals
B) meroblastic development, which is typical of humans
C) holoblastic development, which is typical of amphibians
D) meroblastic development, which is typical of birds

Answer 2

D

Question 3

In an egg cell treated with a chemical that binds calcium and magnesium ions, the ________.

A) acrosomal reaction would be blocked
B) fusion of sperm and egg nuclei would be blocked
C) fast block to polyspermy would not occur
D) fertilisation envelope would not be formed

Answer 3

D

Question 4

A reproductive difference between sea urchins and humans is ________.

A) the sea urchin egg completes meiosis prior to fertilisation, but meiosis in humans is completed after fertilisation
B) sea urchin eggs and sperm are of equal size, but human eggs are much bigger than human sperm
C) sea urchins, but not humans, have a need to block polyspermy, because only in sea urchins can there be more than one source of sperm to fertilise the eggs
D) sea urchin zygotes get their mitochondria from the sperm, but human zygotes get their mitochondria from the egg

Question 5

At the moment of sperm penetration, human eggs ________.

A) have used flagellar propulsion to move from the ovary to the oviduct
B) are still located within the ovary
C) have a paper-thin cell of calcium carbonate that prevents desiccation
D) are still surrounded by follicular cells

Question 6

Use the following information to answer the question.
In order to test how sea urchin sperm bind to eggs, scientists isolated the egg receptor protein that binds to the sperm acrosomal protein called bindin. Plastic beads were coated with egg receptor for bindin (ERB1) from eggs of the sea urchin Strongylocentrotus purpuratus, and then the beads mixed with sperm from S. purpuratus or from the related species, S. franciscanus. The researchers counted how many sperm were bound to each bead. The results are shown in the graph below. (Adapted from Kamei and Glabe 2003)
Treatments:
A: S. purpuratus sperm mixed with S. purpuratus ERB1 beads
B: S. purpuratus sperm mixed with beads containing no ERB1 protein
C: S. franciscanus sperm mixed with S. purpuratus ERB1 beads
D: S. franciscanus sperm mixed with beads containing no ERB1 protein
What is a broader implication from the observations of the experiment?

A) In sea urchins, fertilisation of eggs by sperm is dependent upon species-specific protein interactions.
B) Only some species of sea urchins use receptor proteins on their eggs to bind sperm.
C) Protein-coated plastic beads should not be used to test sperm binding to eggs.
D) S. franciscanus is probably not a sea urchin, but must be some other type of organism.

Question 7

Among these choices, the largest cell involved in frog reproduction is ________.

A) an egg
B) a blastomere in the vegetal pole
C) a blastomere in the animal pole
D) one of the products of the first cleavage

Question 8

Use the following information to answer the question.
In order to test how sea urchin sperm bind to eggs, scientists isolated the egg receptor protein that binds to the sperm acrosomal protein called bindin. Plastic beads were coated with egg receptor for bindin (ERB1) from eggs of the sea urchin Strongylocentrotus purpuratus, and then the beads mixed with sperm from S. purpuratus or from the related species, S. franciscanus. The researchers counted how many sperm were bound to each bead. The results are shown in the graph below. (Adapted from Kamei and Glabe 2003)
Treatments:
A: S. purpuratus sperm mixed with S. purpuratus ERB1 beads
B: S. purpuratus sperm mixed with beads containing no ERB1 protein
C: S. franciscanus sperm mixed with S. purpuratus ERB1 beads
D: S. franciscanus sperm mixed with beads containing no ERB1 protein
Based on the data in the graph, which of the following conclusions is supported?

A) Plastic beads will bind to sperm from both species of sea urchin.
B) ERB1 prevents S. franciscanus sperm from binding the beads.
C) Sperm from S. purpuratus bind to beads only if ERB1 is present.
D) S. franciscanus and S. purpuratus are actually the same species.

Question 9

In mammalian eggs, the receptors for sperm are found in the ________.

A) fertilisation membrane
B) egg plasma membrane
C) cytosol of the egg
D) mitochondria of the egg

Question 10

The plasma membrane of the sea urchin egg ________.

A) is outside of the fertilisation membrane
B) releases calcium, which initiates the cortical reaction
C) has receptor molecules that are specific for binding acrosomal proteins
D) is a mesh of proteins crossing through the cytosol of the egg

Question 11

The formation of the fertilisation envelope requires an increase in the cytosolic concentration of ________.

A) calcium ions
B) hydrogen ions
C) potassium ions
D) sodium ions

Question 12

In a newly fertilised egg, the vitelline layer ________.

A) lifts away from the egg and hardens to form a fertilisation envelope
B) secretes hormones that enhance steroidogenesis by the ovary
C) reduces the loss of water from the egg and prevents desiccation
D) provides most of the nutrients used by the zygote

Question 13

As cleavage continues during frog development, the size of the blastomeres ________.

A) increases as the number of the blastomeres decreases
B) increases as the number of the blastomeres increases
C) decreases as the number of the blastomeres increases
D) decreases as the number of the blastomeres decreases

Question 14

In sea urchins, the "fast block" and the longer lasting "slow block" to polyspermy, respectively, are ________.

A) the acrosomal reaction and the formation of egg white
B) the cortical reaction and the formation of yolk protein
C) the jelly coat of the egg and the vitelline membrane
D) membrane depolarisation and the cortical reaction

Question 15

Even in the absence of sperm, metabolic activity in an egg can be artificially activated by ________.

A) abnormally high levels of carbonic acid in the cytosol
B) abnormally low levels of extracellular oxygen
C) injection of calcium ions into the cytosol
D) depletion of its ATP supplies

Question 16

During fertilisation, the acrosomal contents ________.

A) block polyspermy
B) help propel more sperm toward the egg
C) digest the protective jelly coat on the surface of the egg
D) trigger the completion of meiosis by the sperm

Question 17

Fertilisation of an egg without activation is most like ________.

A) placing the key in the ignition of a car but not starting the engine
B) resting during halftime of a basketball game
C) preparing a pie from scratch and baking it in the oven
D) walking to the cafeteria and eating lunch

Question 18

Use the following information to answer the question.
In order to test how sea urchin sperm bind to eggs, scientists isolated the egg receptor protein that binds to the sperm acrosomal protein called bindin. Plastic beads were coated with egg receptor for bindin (ERB1) from eggs of the sea urchin Strongylocentrotus purpuratus, and then the beads mixed with sperm from S. purpuratus or from the related species, S. franciscanus. The researchers counted how many sperm were bound to each bead. The results are shown in the graph below. (Adapted from Kamei and Glabe 2003)
Treatments:
A: S. purpuratus sperm mixed with S. purpuratus ERB1 beads
B: S. purpuratus sperm mixed with beads containing no ERB1 protein
C: S. franciscanus sperm mixed with S. purpuratus ERB1 beads
D: S. franciscanus sperm mixed with beads containing no ERB1 protein
Based on the description of the experiment, which of the treatments would be considered a "control" treatment for S. purpuratus sperm binding?

A) Treatment A
B) Treatment B
C) Treatment C
D) Treatment D

Question 19

Contact of a sea urchin egg with signal molecules on sperm causes the egg to undergo a brief ________.

A) mitosis
B) membrane depolarisation
C) vitellogenesis
D) acrosomal reaction

Question 20

The vegetal pole of a frog zygote differs from the animal pole in that ________.

A) the vegetal pole has a higher concentration of yolk
B) the blastomeres originate only in the vegetal pole
C) the vegetal pole cells undergo mitosis, but not cytokinesis
D) the polar bodies bud from this region

Question 21

The archenteron of the developing sea urchin eventually develops into the ________.

A) blastocoel
B) heart and lungs
C) digestive tract
D) brain and spinal cord

Question 22

The outer-to-inner sequence of tissue layers in a post-gastrulation vertebrate embryo is ________.

A) endoderm → ectoderm → mesoderm
B) mesoderm → endoderm → ectoderm
C) ectoderm → mesoderm → endoderm
D) ectoderm → endoderm → mesoderm

Question 23

The migratory neural crest cells ________.

A) form most of the central nervous system
B) form the spinal cord in the frog
C) form a variety of neural and non-neural structures
D) form the lining of the lungs and of the digestive tract

Question 24

In which of the following organisms does holoblastic cleavage typically occur?
I) sea urchins
II) humans
III) birds
IV) fish

A) both II and IV
B) both I and III
C) both I and II
D) I only

Question 25

The primitive streak in a bird is the functional equivalent of ________.

A) the lip of the blastopore in the frog
B) the archenteron in a frog
C) the notochord in a mammal
D) neural crest cells in a mammal

Question 26

The first cavity formed during frog development is the ________.

A) blastopore
B) mouth
C) blastocoel
D) anus

Question 27

At the time of implantation, the human embryo is called a ________.

A) blastocyst
B) gastrula
C) foetus
D) zygote

Question 28

In all vertebrate animals, development requires ________.

A) a large supply of yolk
B) an aqueous environment
C) extraembryonic membranes
D) a primitive streak

Question 29

In a frog embryo, gastrulation ________.

A) produces a blastocoel displaced into the animal hemisphere
B) occurs along the primitive streak in the animal hemisphere
C) proceeds by involution as cells roll over the lip of the blastopore
D) occurs within the inner cell mass that is embedded in the large amount of yolk

Question 30

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, suggesting that the drug most likely influenced ________.

A) early cleavage divisions
B) differentiation of bone tissue
C) morphogenesis
D) gastrulation

Question 31

If gastrulation was blocked by an environmental toxin, then ________.

A) cleavage would not occur in the zygote
B) embryonic germ layers would not form
C) the blastula would not be formed
D) the blastopore would form above the grey crescent in the animal pole

Question 32

Which of the following is a correct description of the fate of the germ layers?

A) The mesoderm gives rise to the notochord.
B) The endoderm gives rise to the hair follicles.
C) The ectoderm gives rise to the liver.
D) The mesoderm gives rise to the lungs.

Question 33

Cells move to new positions as an embryo establishes its three germ tissue layers during ________.

A) determination
B) cleavage
C) induction
D) gastrulation

Question 34

Uterine implantation due to enzymatic digestion of the endometrium is initiated by the ________.

A) inner cell mass
B) endoderm
C) mesoderm
D) trophoblast

Question 35

From earliest to latest, the overall sequence of early development proceeds in which of the following sequences?

A) first cell division → synthesis of embryo's DNA begins → acrosomal reaction → cortical reaction
B) cortical reaction → synthesis of embryo's DNA begins → acrosomal reaction → first cell division
C) cortical reaction → acrosomal reaction → first cell division → synthesis of embryo's DNA begins
D) acrosomal reaction → cortical reaction → synthesis of embryo's DNA begins → first cell division

Question 36

An embryo with meroblastic cleavage, extraembryonic membranes, and a primitive streak must be that of ________.

A) an insect
B) an amphibian
C) a bird
D) a sea urchin

Question 37

Which of the following correctly displays the sequence of developmental milestones?

A) blastula → gastrula → cleavage
B) cleavage → gastrula → blastula
C) cleavage → blastula → gastrula
D) gastrula → blastula → cleavage

Question 38

The least amount of yolk would be found in the egg of a ________.

A) bird
B) frog
C) eutherian mammal
D) reptile

Question 39

The cortical reaction of sea urchin eggs functions directly in ________.

A) the formation of a fertilisation 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

Question 40

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. Why do you think sperm are necessary for reproduction?

A) The sperm allow morphogenesis to proceed.
B) Sperm trigger egg activation.
C) Cell differentiation is initiated by the sperm.
D) Sperm are necessary to produce a diploid zygote.

Question 41

Select the choice that correctly matches the organ with its embryonic sources.

A) adrenal medulla-endoderm
B) nervous system-mesoderm
C) kidney-mesoderm
D) skin-endoderm and mesoderm

Question 42

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 kidneys

Question 43

One primary factor in shaping the polarity of the body axes in chick embryos is ________.

A) light
B) membrane potential
C) gravity
D) moisture

Question 44

Which of the following is a result of gastrulation in animals?
I) The archenteron is formed.
II) The body axes are established.
III) The germ layers are formed.

A) I
B) III
C) I and II
D) I, II, and III

Question 45

The term applied to a morphogenetic process whereby cells extend themselves, making the mass of the cells narrower and wider, is ________.

A) convergent extension
B) induction
C) invagination
D) involution

Question 46

Cell migration occurs extensively during ________.

A) organogenesis, but not during gastrulation or cleavage
B) cleavage, but not during gastrulation or organogenesis
C) gastrulation and cleavage
D) both gastrulation and organogenesis

Question 47

The developmental precursors to the gonadal tissues of Caenorhabditis elegans uniquely contain ________.

A) proteins of maternal origin
B) high concentrations of potassium ions
C) T tubules for the propagation of action potentials
D) P granules of mRNA and protein

Question 48

If an amphibian zygote is manipulated so that the first cleavage plane fails to divide the grey crescent, then ________.

A) the daughter cell with the entire grey crescent will die
B) both daughter cells will develop normally, because amphibians are totipotent at this stage
C) only the daughter cell with the grey crescent will develop normally
D) both daughter cells will develop abnormally

Question 49

Which of the following is an adult organism that has fewer than 1,000 cells?

A) chooks, Gallus domesticus
B) African clawed frogs, Xenopus laevis
C) fruit flies, Drosophila melanogaster
D) nematodes, Caenorhabditis elegans

Question 50

Which of the following is common to the development of birds and mammals?

A) the formation of an embryonic epiblast and hypoblast
B) the formation of an embryonic trophoblast
C) the formation of an embryonic yolk plug
D) the formation of an embryonic grey crescent

Question 51

Changes in the shape of a cell usually involve a reorganisation of the ________.

A) nucleus
B) cytoskeleton
C) extracellular matrix
D) transport proteins

Question 52

During metamorphosis, a tadpole's tail is reduced in size by the process of ________.

A) regeneration
B) apoptosis
C) oxidative phosphorylation
D) redifferentiation

Question 53

Which of the following correctly matches the extraembryonic membrane with its function?

A) amnion-waste disposal
B) chorion-nutrient storage
C) allantois-waste storage
D) yolk sac-gas exchange

Question 54

The nematode Caenorhabditis elegans ________.

A) is composed of about 1,000 cells, in which the developmental origin of each cell has been mapped
B) has only a single chromosome, which has been fully sequenced
C) has about 1,000 genes, each of which has been fully sequenced
D) uniquely, among animals, utilises programmed cell death during normal development

Question 55

During frog development, the blastocoel ________.

A) becomes the archenteron
B) gives rise to the endoderm
C) gives rise to the placenta
D) is replaced by the expanding archenteron

Question 56

The embryonic precursor to the human spinal cord is the ________.

A) notochord
B) neural tube
C) mesoderm
D) archenteron

Question 57

In humans, identical twins are possible because ________.

A) cytoplasmic determinants are distributed unevenly in unfertilised eggs
B) extraembryonic cells interact with the zygote nucleus
C) early blastomeres can form a complete embryo if isolated
D) the grey crescent divides the dorsal-ventral axis into new cells

Question 58

The arrangement of organs and tissues in their characteristic places in 3-D space defines ________.

A) pattern formation
B) differentiation
C) determination
D) organogenesis

Question 59

Hans Spemann and colleagues (1938) developed the concept of the "organiser" 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) dorsal lip of the blastopore

Question 60

Why was the evolution of the extraembryonic membranes crucial for colonisation of land by the vertebrates? Extraembryonic membranes ________.

A) provide an aqueous environment for embryo development
B) provide nutrients that produce energy for development
C) direct morphogenesis within the embryo
D) give rise to crucial organ systems, like the heart and brain

Question 61

Which of the following is common to the development of both birds and mammals?

A) holoblastic cleavage
B) epiblast and hypoblast
C) trophoblast
D) grey crescent

Question 62

In humans, identical twins are possible because

A) extraembryonic cells interact with the zygote nucleus.
B) convergent extension occurs.
C) early blastomeres can form a complete embryo if isolated.
D) the grey crescent divides the dorsal-ventral axis into new cells.

Question 63

Just prior to the onset of gastrulation in an embryo, the "organiser" cells are specified. If you were to experimentally block the specification of these cells, what would you expect the result to be in the developing embryo?

A) There would be no effect on development.
B) Gastrulation would not occur, and normal development would cease.
C) The body axes would develop normally, but the embryo would not grow appendages.
D) The embryo would not develop an intestine, but all other organs and tissues would develop normally.

Question 64

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

Question 65

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.

Question 66

If an egg cell were 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 fertilisation envelope would not form.

Question 67

The archenteron develops into

A) the mesoderm.
B) the endoderm.
C) the placenta.
D) the lumen of the digestive tract.

Question 68

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

Question 69

The cortical reaction of sea urchin eggs functions directly in

A) the formation of a fertilisation envelope.
B) the production of a fast block to polyspermy.
C) the generation of an electrical impulse by the egg.
D) the fusion of egg and sperm nuclei.

Question 70

Embryonic induction, the influence of one group of cells on another group of cells, plays a critical role in embryonic development. In 1924, Hans Spemann and Hilde Mangold transplanted a piece of tissue that influences the formation of the notochord and neural tube, from the dorsal lip of an amphibian embryo to the ventral side of another amphibian embryo. If embryonic induction occurred, which of the following observations justifies the claim of embryonic induction?

A) The transplanted tissue induced multiple limbs to develop on the ventral side of the recipient embryo.
B) The transplanted tissue inhibited normal cell division on the dorsal side of the recipient embryo that lead to its death.
C) The transplanted tissue had no effect on either the ventral or dorsal side of the recipient embryo so it continued to develop normally.
D) The transplanted tissue induced the formation of a second notochord and neural tube on the ventral side of the developing embryo.