BIO 349 Developmental Biology (K. Kalthoff)

Exams, Fall 1996

First Midterm (3 October 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 of the following cells occupy the outermost position (closest to the wall) in a seminiferous tubule?
a. Primary spermatocytes
b. Secondary spermatocytes
c. Spermatogonia
d. Spermatozoa

2. The direction of coiling in the snail Lymnea peregra is determined by the
a. genome of the embryo
b. maternal genome
c. paternal genome
d. all of the above are correct

3. Discoidal cleavage is characteristic of the eggs of
a. birds
b. insects
c. mammals
d. sea urchins

4. Totipotency, or at least pluripotency, as been demonstrated in
a. differentiated plant cells
b. frog blastomeres at the two-cell stage
c. nuclei from some differentiated frog cells
d. all of the above

5. The activity of a localized cytoplasmic determinant is proven by
a. immunostaining
b. unequal distribution in microscopic sections
c. both of the above are correct
d. none of the above is correct

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.

6/7. Egg activation is a series of events including re-starting of the protein cycle and increasing the rate of cell synthesis.

8/9. In embryos with spiral axis, the orientation of the mitotic spindles is oblique to the animal-vegetal cleavage.

10/11 During gastrulation in Xenopus, the marginal cap undergoes epiboly while the animal zone undergoes convergent extension.

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.

12/13.During frog oocyte maturation, the block in Prophase I is due to the ____________________ of M-phase promoting factor (MPF) whereas the arrest in metaphase II is caused by the ___________________ to break down MPF.

14/15.Xenopus kidney nuclei transplanted into ____________________ will support the synthesis of oocyte-specific but not ___________________ proteins.

16/17.In the Xenopus gastrula, the deep IMZ (involuting marginal zone) forms trunk _____________________ while the superficial IMZ forms the ____________________ roof.

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.

18. Cytoplasmic Control over Nuclear Activity
a. Frog kidney nuclei transplanted into newt oocytes synthesize newt oocyte RNA.
b. Blastula nuclei transplanted into growing oocytes synthesize RNA.
c. Brain cell nuclei transplanted into fertilized eggs synthesize DNA.
d. Blastula or brain nuclei transplanted into maturing oocytes undergo chromosome condensation.

19. Localized Cytoplasmic Determinants (LCDs)
a. LCDs are always associated with visible markers.
b. Local UV irradiation by itself has proven the existence of LCDs.
c. A rescue bioassay can be used to characterize the molecular nature of an LCD.
d. Heterotopic transplantation shows that an LCD is necessary.

20. More about Localized Cytoplasmic Dewterminants (LCDs)
a. LCDs often contain messenger RNA (mRNA).
b. The 3' untranslated regions of localized mRNAs often contain specific binding domains for proteins.
c. LCDs may be transported along microtubules.
d. LCDs often serve as inductive signals between cells.

21-30. SHORT ESSAY (MAX. 10 POINTS) Sea Urchin Bindin

A. What is bindin? Briefly summarize its biochemical nature and location in sea urchin sperm before and after the acrosome reaction.
B. Describe the design of a competitive binding experiment to test whether the adhesion of bindin to eggs is species-specific.
C. Which result would you predict if the adhesion of bindin to eggs were not species-specific?
D. What were the results of actual experiments carried out under the design described in part B ? What do you conclude from these results?

31-40. SHORT ESSAY (MAX. 10 POINTS) Cell Fate and Potency

A. How is cell fate defined?
B. How is the fate of a cell (or group of cells) established?
C. How is cell potency defined?
D. How is the potency of a cell (or group of cells) tested?

41-50. SHORT ESSAY (MAX. 10 POINTS) Patterned Mesoderm Induction

In a key experiment on mesoderm induction in amphibian ambryos, isolated vegetal blastomeres were combined with complete tiers of animal blastomeres ("animal caps").
A. Describe the result of this experiment; how does it depend on the position of the vegetal blastomere in the donor from which it was taken?
B. Summarize how the vegetal blastomeres acquire the differing capabilities they display in the experiment described in part A?

Second Midterm Exam
31 October 1996

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

	1.  ______  adrenal medulla               a.  dermatome

	2.  ______  aorta                         b.  endoderm

	3.  ______  appendicular skeleton         c.  epidermal ectoderm

	4.  ______  blood cells                   d.  intermediate mesoderm

	5.  ______  gonads (somatic portion)      e.  myotome

	6.  ______  hair                          f.  neural crest cells

	7.  ______  lung (inner epithelium)       g.  notochord

	8.  ______  pigment cells                 h.  sclerotome

	9.  ______  skeletal muscles              I.  somatic lateral mesoderm

	10. ______  smooth muscle of intestine    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. Neurulation in amphibian embryos involves
a. cell fusion
b. cell death
c. both of the above are correct
d. none of the above is correct

12. Dorsal blastopore lip from an amphibian gastrula, after transplantation to ventral marginal zone, changes the fate of
a. host ectoderm
b. host mesoderm
c. both of the above are correct
d. none of the above is correct

13. Mechanisms of translational control include
a. polyadenylation of mRNA
b. longevity of mRNA
c. masking of mRNA
d. all of the above

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.

14/15. Transcriptional control relies on the presence of different factors of gene-specific transcription combinations.

16/17. According to the "masked mRNA" hypothesis, mRNA may be kept in an inhibitory state by association with proteins or other untranslatable components.

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.

18. Phylotypic Stage
a. All vertebrates are very similar to one another after organogenesis (phylotypic stage).
b. Among adult vertebrates, mammals remain closest to the phylotypic organization.
c. The secondary jaw joint of mammals is part of the phylotypic organization of vertebrates.
d. Multiple aortic arches are normal in adult mammals but occur only as atavisms in fish.

19. Control of Transcription
a. Transcription of eukaryotic genes is controlled by promoter and enhancer elements.
b. Promoters and enhancers are bound specifically by transcription factors.
c. Transcription factors position RNA polymerase at the transcription startpoint.
d. All cells of an organism contain the same mixture of transcription factors.

20. Translational Control
a. The availability of initiation factors regulates the overall translation rate.
b. Intracellular pH regulates the translation of specific mRNA sequences.
c. The spectrum of translated proteins may change during egg activation.
d. Mouse protamine is earmarked for delayed translation during spermatogenesis by its trailer sequence.

21-30. SHORT ESSAY (maximum 10 points) Spinal Cord

A. Draw the notochord and the spinal cord of a 6-week-old human embryo in cross section, showing the location of the alar plate, basal plate, floor plate, marginal layer, and neuroepithelial layer.

B. Outline two experiments with chicken embryos (design, results, conclusions) showing that the notochord is necessary and sufficient to induce the ventral structures within the developing spinal cord.

31-40. SHORT ESSAY (maximum 10 points) Transgenic Flies

A. Outline how P elements in Drosophila are used to make transgenic flies.

B. Using the "gene therapy" of rosy (ry/ry) flies as an example, explain how researchers have identified flies that were presumably transgenic. [Remember the phenotype of mutant (ry/ry) flies versus mutant and transgenic flies.]

C. Using the same example, outline how the researchers have demonstrated stable integration of the transgene into the host genome.

41-50. SHORT ESSAY (maximum 10 points) Splicing of doublesex mRNA

A. Outline the splicing of doublesex (dsx) mRNA in Drosophila. Be sure to distinguish the regulated and the default splice patterns. Name the regulatory proteins involved and their way of action.

B. Briefly indicate how the two mRNAs differ from each other and how they function in somatic sex differentiation.

Final Exam
11 December, 1996

MATCH UP (max. 10 points)

The following are a list of key words (1-10) and a list of short descriptions (a-j). Match up by entering the appropriate letters in the spaces behind the numbers.

1.  _____  collagen              a.  abundant molecule in ECM

2.  _____  ecdysone              b.  chromosomal protein in sperm

3.  _____  embryonic field       c.  gill-associated rudiment
                                     occurring in vertebrates

4.  _____  involution            d.  group of cells with size
                                     regulatory properties

5.  _____  nurse cells           e.  insect molting hormone

6.  _____  P element             f.  layer of ECM surrounding
                                     oocyte

7.  _____  pharyngeal arch       g.  morphogenetic movement
                                     occurring in gastrulation

8.  _____  polar lobe            h.  sister cells of insect
                                     oocytes

9.  _____  protamin              i.  transient structure formed
                                     during cleavage of molluscs
	
10. _____  vitelline envelope    j.  transposable section of DNA

EXCHANGE WORDS (Maximum 2 points each)

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

11/12. In mammals, spermatogonia behave as stem cells, being capable of limited self-renewal, whereas the number of oogonia is unlimited.

13/14. By transplanting newt dorsal notochord lip to the ventral side of a gastrula, Spemann and Mangold showed that the transplanted tissue develops into blastopore and induces neighboring host tissues to form other dorsal organs.

15/16. In Drosophila embryos, correct gene products directly control the expression of gap genes while the latter are necessary for the maternal expression of pair rule genes.

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.

17. Which of the following structures is capable of self-assembly?
a. bacteria
b. eukaryotic cells
c. both of the above
d. none of the above

18. Genetic hierarchies are established by
a. monitoring the expression of a given gene in wild-type and various mutant embryos
b. DNase protection assays
c. both of the above are correct
d. none of the above is correct

19. Hox genes are generally most similar
a. within the same chromosome
b. within the same gene
c. within the same homeobox complex
d. within the same subfamilty of corresponding genes from different homeobox complexes

20. Ingressing primary mesenchyme cells in sea urchin gastrulae lose adhesiveness to
a. basal lamina
b. hyaline layer
c. both of the above
d. none of the above

21. Products of proto-oncogenes include
a. growth factors
b. growth factor receptors
c. signal proteins
d. all of the above are correct

FILL IN THE BLANKS (max. 2 points each)

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

22/23 In ________________ , molecules snap together spontaneously, whereas in directed assembly, paragenetic information in the form of _______________ structures is required.

24/25 The polar coordinate model is based on two empirical rules, known as the shortest ____________________ rule and the _____________________ rule.

26/27 In newt gastrula, migrating deep zone cells seem to receive contact _____________ by fibers of _______________ located on the underside of the blastocoel roof.

PICK THE ODD STATEMENT (1 point 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 out the one odd statement, be it correct or false, and circle the respective letter.

28. Homeobox Complexes
a. A primordial homeobox gene seems to have duplicated and diverged, giving rise to an ancestral homeobox complex comprising several genes.
b. The ancestral homeobox complex originated before arthropods and vertebrates began to evolve separately.
c. In vertebrates, the homeobox complex was lost and reformed at least four times.
d. The flower beetle, Tribolium castaneum, has only one homeobox complex.

29. Sex Determination in Mammals
a. The crucial sex determinant in mammals is the X/A ratio.
b. An XAA mammal, although it lacks the Y chromosome, develops into a sterile male.
c. The testis determining factor is encoded by a gene located on the X chromosome.
d. In the absence of the testis determining factor, a mammalian embryo develops into a female.

30. Oncogenes
a. Oncogenes are genes causing cancer.
b. Oncogenes can be introduced by viruses or originate by mutation in eukaryotic cells.
c. Most viral and cellular oncogenes are very similar to normal eukayotic genes called proto-oncogenes.
d. Most oncogenes are loss-of-function alleles of proto-oncogenes.

31-40 SHORT ESSAY (max. 10 points) Rescue Criterion for Germ Cell Determinants

A. Describe the "rescue" experiment used to demonstrate the existence of localized germ cell determinants in Drosophila eggs.

B. Which control had to be done in order to make this experiment conclusive?

41-50 SHORT ESSAY (max. 10 points) Oocyte Maturation in Surf Clam

Fertilization in the surf clam Spisula solidissima is associated with changes in the patterns of proteins synthesized: Some proteins made during oogenesis are discontinued while other proteins not made in oocytes are newly synthesized after fertilization.

A. Describe an experiment indicating that the observed changes in protein synthesis are under translational control.

B. Describe another experiment indicating that translational activation in this case is associated with a shift of mRNAs from the subribosomal particle fraction to the polysomal fraction.

51-60 SHORT ESSAY (maximum 10 points) Morphogen Gradient

A. Outline a general model for setting up a spatial pattern of cells with different gene activities by a morphogen gradient.

B. Name an actual gene product that acts as a morphogen in the Drosophila embryo. Draw a diagram showing the morphogen gradient and the approximate expression domains of some of its immediate target genes.

61-70 SHORT ESSAY (max. 10 points) Compartment Hypothesis

A. How are compartments in insect epidermis defined ?

B. Which genetic explanation does the compartment hypothesis provide for the observation that compartment boundaries are remarkably straight?

C. Describe the control of two genes encoding position-specific integrins in Drosophila to illustrate the explanation that you gave in part B.

71-80 SHORT ESSAY (max. 10 points) Androgen Receptor

A. What is the function of the androgen receptor in mammals?

B. Describe the phenotype (external appearance and reproductive organs) of humans who are genetically male (XY) but homozygous for a null allele of the androgen receptor gene.

C. Outline the genetic and hormonal control mechanisms that account for the phenotype described in part B.

EXTRA CREDIT (Max. 5 pts)

The Austin American Statesman recently ran a report attributed to Rick Weiss of the Washington Post. The context was hormone replacement therapy for postmenopausal women, whose own ovaries have stopped producing estrogen. Many of them take a synthetic estrogen orally to ward off osteoporosis and heart disease. However, the prolonged exposure to estrogens may also increase the risk of breast cancer. A new study to explore the ramifications of estrogen replacement was reported as follows.

"A group of women (on replacement therapy with Estrace, a synthetic estrogen) drank pineapple juice mixed with vodka to raise their blood alcohol levels to the equivalent of having drunk two glasses of beer or wine. As alcohol levels climbed, so did their estrogen levels, peaking at about 325 percent of normal. Women not taking (Estrace) showed no increase in estrogen blood levels after drinking." The conclusion of the reporter, and possibly the authors of the study, was given in the newspaper report's headline, which read "Alcohol may radically raise estrogen levels, study shows".

A. Do the data as reported warrant the conclusion as stated? Can you think of an alternative explanation of the data?

B. Design an additional control that would make this experiment more conclusive. Remember a good control needs to duplicate the experiment in every detail except for the one variable that is being tested.


Go back to ZOO 321 Home Page



Website maintained by Dr. Klaus Kalthoff
E mail:
kkalthoff@mail.utexas.edu
Last modified: 16 July 1997