BIO 349 Developmental Biology (K. Kalthoff)

Exams Summer 1996

First Midterm Exam (19 June 1996)

MULTIPLE CHOICE (1 point each)

In the following questions or statements, circle the letter associated with the one answer or version of the statement that you consider to be the correct one.

1. Which two membranes fuse during the acrosomal reaction?
a. acrosomal membrane with egg plasma membrane
b. sperm plasma membrane with egg plasma membrane
c. both of the above are correct
d. none of the above is correct

2. Cells are considered to be determined when
a. their potency equals their fate
b. their potency is larger than their fate
c. both of the above are correctM
d. none of the above is correct

3. Neurulation in amphibians involves
a. elongation of neural plate cells
b. constriction of the apical surfaces of neural plate cells
 c. Cell intercalation
d. all of the above are correct

4. The anteriormost portion of the brain rudiment is called the
a. diencephalon
b. mesencephalon
c. myelencephalon
d. telencephalon

5. Transplantation of the dorsal blastopore lip from an amphibian gastrula to the ventral non-involuting marginal zone of another amphibian gastrula changes the fate of
a. host ectoderm
b. host mesoderm
c. both of the above are correct
d. none of the above is correct

PICK THE ODD STATEMENT (1point each)

For the following questions, either three of the statements are correct and one is false, or three are false and one is correct. Pick the one odd statement, be it correct or false, and circle the respective letter.

6. Cell Determination
a. Cell determination is characterized by the synthesis of abundant proteins.
b. The potency of undetermined cells is identical with their fate.
c. Clonal analysis can be used to assess the degree of cell determination.
d. The determined state of cells is always never reversible.

7. Morphogenetic Movements
a. Delamination is the splitting of one cell layer into two parallel layers.
b. Epiboly is the spreading movement of an epithelial layer over a deeper cell layer.
c. Invagination is the local inward buckling of an epithelium.
d. Involution is the migration of single cells from an epithelial layer into an embryonic cavity.

8. Localized Cytoplasmic Determinants
a. The polar lobe of mollusks shunts vegetal cytoplasm into the D cell lineage.
b. Bicoid mRNA serves as a muscle determinant in Drosophila.
c. The polar granules of insects are located at the anterior egg pole.
d. The yellow myoplasm of ascidians acts as a germ cell determinant.

EXCHANGE WORDS (2 points per pair)

The following statements are erroneous. However, each one can be corrected by exchanging two single words. Circle these two words within each statement.

9/10. By applying the acrosome technique, researchers have shown that bindin is localized on the acrosomal process of sea urchin sperm that have undergone the immunostaining reaction.

11/12. Involution is defined as the flowing of an expanding outer epithelium over the inside of an opening to the edge.

13/14. Neural plate formation relies on vertical signals from the underlying blastopore and on planar signals passing from the dorsal chordamesoderm lip through the blastocoel roof.

FILL IN THE BLANKS (1 point each word)

Complete each of the following sentences by inserting one word into each blank space so that a scientifically and linguistically correct statement results. Hyphenated words count as one word.

15/16. Two operational criteria used to establish the existence of localized cytoplasmic determinants are _______________ and _______________ transplantation.

17/18. According to the principle of ________________ mechanisms, a given developmental step may be supported by more than ________________ cellular or molecular mechanism.

19/20. Organogenesis is followed by __________________ , the last period of embryonic development, during which tissues become _______________, and hence acquire their characteristic appearance in microscopic sections.

21-30. SHORT ESSAY RNA Supply to Oocytes

Most animals store large amounts of RNA in their oocytes. Outline the mechanisms used to provide large amounts of ribosomal RNA and messenger RNA to oocytes
A. in frogs,
B. in flies.
C. With regard to flies, describe a key experiment by which RNA supply to the oocyte has been analyzed.

31-40. SHORT ESSAY Spindle Orientation

During meiosis as well as mitosis, the chromosomes are oriented in a spindle between two centrosomes.
A. Briefly characterize - or draw - the position and orientation of the spindle relative to the animal-vegetal axis in a frog egg (1) during meiosis and (2) during first mitosis. If you don't know the answer directly, infer it from what you know about the plane of cytokinesis during frog meiosis and first cleavage and from the rule that the plane of cytokinesis is perpendicular to the spindle axis.
B. What mechanism could account for the position and orientation of the spindle during meiosis?
C. Describe an experiment (carried out in a non-frog species) indicating that the mechanism proposed in part B does indeed exist.

41-50. SHORT ESSAY Ventral Vegetal Blastomeres

Frog embryos ventralized by UV irradiation can be restored to normal development by replacing - at the 32-cell stage - two of their vegetal blastomeres with dorsal vegetal blastomeres from a normal donor. This result has been interpreted to mean that dorsal vegetal blastomeres or their descendants normally induce the formation of the dorsal set of organ rudiments including notochord, neural tube, etc.
A. Which control experiments should have been carried out to make the above interpretation conclusive? (These controls were carried out by the authors of the experiment, I just did not emphasize them in class.)
B. Summarize an independent experiment that also demonstrates the unique ability of dorsal vegetal blastomeres - as opposed to lateral or ventral vegetal blastomeres - to induce dorsal mesoderm.

Second Midterm Exam (3 July 1996)

The following are lists of adult structures (1-10) and their embryonic precursors (a-j). Match up by entering one appropriate letter in each of the spaces behind the numbers. Note that some precursors may be used several times and others not at all.

1. _____ adrenal medulla

2. _____ blood vessels

3. _____ dorsal root ganglia

4. _____ heart

5. _____ hypodermis

6. _____ lung (inner epithelium)

7. _____ melanocytes (pigment cells)

8. _____ skeletal muscles of the trunk

9. _____ smooth muscle of intestine

10. _____ vertebra

a. dermatome

b. endoderm

c. epidermal ectoderm

d. myotome

e. nephrotome

f. neural crest cells

g. epidermal placode

h. sclerotome

i. somatic lateral mesoderm

j. visceral lateral mesoderm

MULTIPLE CHOICE (1 point each)

In the following questions or statements, circle the letter associated with the one answer or version of the statement that you consider to be the correct one.

11. A gain-of-function allele in an organism can be mimicked by
a. a transgene transcribed from a promoter that is constitutively (always) active
b. transcribing a "flipped" gene into anti-sense mRNA
c. Both of the above are correct.
d. None of the above is cortrect.

12. Which of the following processes is regulated by RNA-binding proteins?
a. splicing of pre-mRNA
b. RNA translation
c. RNA degradation
d. All of the above are correct.

13. Early sea urchin embryos cultured in the presence of an inhibitor of RNA polymerase II synthesize
a. both mRNA and protein
b. mRNA but no protein
c. protein but no mRNA
d. neither mRNA nor protein

14. The "size invariance" of embryonic fields means that such fields
a. always maintain the same size
b. form similar patterns regardless of experimental size changes
c. Both of the above are correct.
d. None of the above is correct.

PICK THE ODD STATEMENT (1point each)

For the following questions, either three of the statements are correct and one is false, or three are false and one is correct. Pick the one odd statement, be it correct or false, and circle the respective letter.

15. Transgenic Flies
a. Germ line transformation of Drosophila takes advantage of mobile DNA elements known as P elements.
b. P elements have different donor and acceptor sequences and encode RNA
c. Incomplete (or non-autonomous) P elements can be used as vectors for the insertion of transgenes.
d. The insertion sites of a transgene in Drosophila can be revealed by in situ hybridization of a suitable probe to polytene chromosomes.

16. Fields
a. An embryonic field is constituted by all cells in an area that can cooperate in the formation of an organ (or an entire embryo).
b. All cells in a field must be fully determined.
c. A field will form a well-proportioned organ even if its size is experimentally reduced or increased.
d. Vertebrate limbs are formed from embryonic fields.

FILL IN THE BLANKS (1 point each word)

Complete each of the following sentences by inserting one word into each blank space so that a scientifically and linguistically correct statement results. Hyphenated words count as one word.

17/18. For the regulated splicing of transformer pre-mRNA, Sexlethal protein blocks the non-sexspecific splice _______________ site for an exon that contains a premature _______________ codon.

19/20. According to the _______________ mRNA hypothesis, mRNA may be rendered _______________ by the specific binding of regulatory proteins or complementary RNAs.

21-30. SHORT ESSAY (max. 10 points) Recapitulations and Atavisms

A. Define in general terms phylogenetic recapitulations in development and illustrate the phenomenon briefly with one example.
B. Define in general terms atavisms and name two examples.
C. What do transdeterminations and homeotic mutants in Drosophila suggest about the causes of atavisms and recapitulations?

31-40. SHORT ESSAY (max. 10 points) bicoid Protein as Transcription Factor

A. How is bicoid protein distributed in Drosophila embryos, and how does this distribution originate?
B. Characterize in one word the biochemical function of bicoid protein.
C. Describe and interpret one experiment to analyze the effect of bicoid protein on the embryonic expression of the hunchback+ gene.
D. Name one additional target gene of bicoid protein.

41-50. SHORT ESSAY (max. 10 points) Patterning Genes in Drosophila

A. Name the classes of genes are involved in specifying the anteroposterior body pattern of Drosophila, and name one gene as an example. Arrange these names in a diagram with arrows to reflect the hierarchy of controls between the classes of genes.
B. Outline three experimental strategies to find out where a gene fits into a hierarchy with other genes.

Final Exam (11 JULY 1996)

MATCH UP (1 point each line)

The following are a list of developmental terms (1-10) and a list of definitions (a-j). Match up by entering the appropriate letters in the spaces behind the numbers.

1. ________ acrosome

2. ________ archenteron

3. ________ blastocyst

4. ________ contractile ring

5. ________ cortical granule

6. ________ polar body

7. ________ polar granule

8. ________ polar lobe

9. ________ Sertoli cells

10. ________ zona pellucida

a. early mammalian embryo

b. electron-dense material near posterior pole of insect eggs

c. membranous compartment at tip of sperm

d. membranous vesicle beneath egg plasma membrane

e. microtubular array radiating from centrosome

f. primitive gut

g. sister cell of oocyte

h. Somatic testicular cell

i. transient structure formed during cleavage in molluscs

j. vitelline envelope in mammals

MULTIPLE CHOICE (1 point each)

In the following questions or statements, circle the letter associated with the one answer or version of the statement that you consider to be the correct one.

11. Polyspermy in sea urchins is prevented by b. the cortical reaction
c. both of the above are correct
d. none of the above is correct

12. Localized cytoplasmic determinants control the development of
a. Entire body regions
b. Specific cell types
c. both of the above are correct
d. none of the above is correct

13. Gastrulation in amphibians involves
a. convergent extension
b. epiboly
c. involution
d. all of the above are correct

14. Alternative splicing may be regulated by
a. blockage of a splice-acceptor site
b. capping
c. both of the above are correct
d. none of the above is correct

15. The delayed translation of protamine mRNA in mouse sperm is controlled by nucleotide sequences in
a. the first exon
b. the first intron
c. both of the above are correct.
d. none of the above is correct.

16. Sea urchin development along the animal-vegetal axis has been modeled by
a. morphogen gradients
b. sequential induction
c. both of the above are correct.
d. none of the above is correct.

PICK THE ODD STATEMENT (1point each)

For the following questions, either three of the statements are correct and one is false, or three are false and one is correct. Pick the one odd statement, be it correct or false, and circle the respective letter.

17. Regeneration
a. Regeneration always restores the missing parts.
b. Regeneration may cause duplication of the regenerating part.
c. Intercalary regeneration restores the missing intermediates between unlike parts.
d. Misaligned regeneration blastemas may cause supernumerary limb regeneration.

18. Compartments in Insect Epidermis
a. Compartments in insect epidermis have been defined by clonal analysis.
b. Each compartment is filled by a single clone.
c. Compartment boundaries originate at the sites of greatest epithelial folding.
d. Each compartment is characterized by a unique combination of active pair-rule genes.

19. Hormonal Control of Insect Metamorphosis
a. Insect molts are controlled by ecdysone and juvenile hormone.
b. Ecdysone is a steroid hormone.
c. All cells in an insect have the same type of ecdysone receptor.
d. The ecdysone-receptor complex acts as a transcription factor.

20. Proto-Oncogenes
a. Proto-oncogenes were first discovered in bacteria.
b. Proto-oncogenes inhibit transcription factors that would otherwise promote the expression of cyclin genes.
c. Proto-oncogenes may encode growth factors or growth factor receptors.
d. Proto-oncogenes have no introns.

FILL IN THE BLANKS (1 point each word)

Complete each of the following sentences by inserting one word into each blank space so that a scientifically and linguistically correct statement results. Hyphenated words count as one word.

21/22. The midblastula transition (MBT) is thought to be triggered when embryonic cells reach a certain _______________ ratio. In accord with this hypothesis, MBT occurs one cell cycle _______________ than normal if half of the egg cytoplasm is removed after fertilization.

23/24. A saturation _______________ screen can reveal virtually all _______________ involved in a biological process of interest.

25/26. According to the compartment hypothesis, each epidermal compartment is characterized by a unique _______________ of active selector genes, which affect cell surfaces so as prevent the mixing of cells from _______________ compartments.

27/28. Human XY individuals without functioning _______________ receptors develop the secondary sex characteristics of females but lack all derivatives of the _______________ duct.

29/30. Many tumors are caused by gain-of-function alleles of _______________ and by loss-of-function alleles of tumor _______________ genes.

31-40.SHORT ESSAY (MAX. 10 POINTS) Potency of Embryonic Cells

A. How is the potency of an embryonic cell, or group of cells, defined?
B. Which operational criteria are commonly used to assay the potency of (groups of) cells?
C. Describe an example showing that different methods of assaying the potency of blastomeres may yield different results.

41-50.SHORT ESSAY (MAX. 10 POINTS) Neural Crest Cells

A. Where do neural crest cells originate in vertebrate embryos?
B. Name three major derivatives of neural crest cells and their locations in the adult.
C. Describe an experiment (design, results, interpretation) to establish whether at least some neural crest cells are pluripotent.

51-60.SHORT ESSAY (MAX. 10 POINTS) Homeobox and Homeobox Complexes

A. Define the homeobox and the homeobox complexes found in insects and in mice.
B. Which features are NOT shared between the homeobox complexes of Drosophila and mice?
C. What is the current hypothesis on the evolution of homeobox complexes?
D. Outline evidence supporting the hypothesis proposed in part C.

61-70.SHORT ESSAY (MAX. 10 POINTS) Mapping TDF

A. What are sex-reversed human males and females?
B. Outline a genetic model that explains the occurrence of sex-reversed human males and females.
C. Explain how this model, in conjunction with molecular data from sex-reversed males, has been used to map the testis-determining factor (TDF) in humans.

71-80.SHORT ESSAY (MAX. 10 POINTS) Principle of Epigenesis

A. State the principle of epigenesis in general terms.
B. Relate basic features of (1) embryonic induction OR (2) genetic control of pattern formation OR (3) hormonal control to the principle of epigenesis.


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