BIO 349 Developmental Biology (K. Kalthoff)

Exams Fall 1995

First Midterm Exam (3 October 1995)

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 most adequate.

1. The animal egg pole is characterized by
a. a polar lobe
b. polar bodies
c. polar granules
d. none of the above is correct

2. The part of the mammalian blastocyst that contributes to the placenta is called
a. amnion
b. inner cell mass
c. trophoblast
d. none of the above is correct

3. In species with regulatory development, a normally proportioned larva may develop from
a. an isolated blastomere
b. two early embryos stuck together
c. both of the above are correct
d. none of the above is correct

4. Vitellogenesis and RNA synthesis in oocytes occur during
a. prophase of first meiosis
b. prophase of second meiosis
c. after fertilization
d. none of the above is correct

5. 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

6. The activity of a localized cytoplasmic determinant is proved by
a. the unequal distribution of a visible cytoplasmic component
b. heterotopic transplantation
c. both of the above are correct
d. none of the above is correct

7. Anterior determinants in dipteran embryos are thought to be
a. microtubules
b. mitochondria
c. pigment granules
d. RNA-containing particles

8. Discoidal cleavage is characteristic of
a. birds
b. insects
c. mammals
d. none of the above is correct

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 the one odd statement, be it correct or false, and circle the respective letter.

9. Germ Cell Development
a. The maturation of male and female gametes differs in the number of meiotic divisions.
b. Spermatocytes may form clones of interconnected cells.
c. Histones in oocyte nuclei are replaced by protamines.
d. Insect oocytes receive a rich supply of RNA from follicle cells.

10. Nuclear Transplantation Experiments with Amphibians
a. Blastula nuclei transplanted into oocytes synthesize RNA.
b. Brain cell nuclei transplanted into eggs synthesize DNA.
c. Frog kidney nuclei transplanted into newt oocytes synthesize frog oocyte RNA.
d. Frog kidney nuclei transplanted into newt oocytes synthesize newt oocyte RNA.

11. Lens regeneration
a. Urodeles can regenerate a lens from dorsal iris epithelium.
b. This regeneration is accomplished by reorganizing the iris tissue without cell division and growth.
c. Enzymes in the iris cells transform retina pigment into lens crystallin.
d. Mammals can regenerate eye lenses in a similar way.

12. Primordial germ cells (PGC)
a. PGC are often segregated early in development.
b. PGC give rise to eggs or sperm.
c. PGC in insects are known as polar bodies

12. Primordial germ cells (PGC)
a. PGC are often segregated early in development.
b. PGC give rise to eggs or sperm.
c. PGC in insects are known as polar bodies.
d. PGC often migrate to the mesodermal portion of the gonad.

13. Mitotic Spindle Orientation
a. In small cells, the mitotic spindle is oriented parallel to the longest cell dimension.
b. Maternal factors determine the spindle orientation during the second cleavage of the snail, Lymnea peregra.
c. In sea urchin eggs, the mitotic spindle is parallel to the animal-vegetal axis during the first two cleavages.
d. Spindle poles may be attracted to certain areas of the cell cortex.

14. Clonal Analysis
a. A cell clone is defined as all cells within a compartment.
b. A cell clone can be labeled by somatic crossover.
c. A cell clone can be labeled by injecting fluorescent dye into two neighboring cells.
d. All cells of a clone divide in synchrony.

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.

15/16. In mammals, oogonia behave as stem cells, being capable of unlimited self-renewal, whereas the number of spermatogonia is limited.

17/18. Determination is the potency by which the process of a cell or embryonic region becomes limited to its fate.

19/20. Small transplantation experiments have shown that at least nuclear fractions of differentiated animal cells retain highly pluripotent nuclei.

21-30. SHORT ESSAY (max. 10 points) Mouse Sperm-Egg Adhesion

A. Name the zona pellucida protein to which mouse sperm adheres before the sperm undergoes the acrosome reaction.
B. Describe a competitive bioassay that has been used to identify this zona pellucida protein.
C. Which components of this zona pellucida protein are critical to sperm adhesion as revealed by the bioassay?

31-40. SHORT ESSAY (max. 10 points) String+ Gene

A. Which changes in embryos are covered by the term midblastula transition (MBT)?
B. Describe the role of the string+ gene in the MBT of Drosophila.
C. What do you expect to happen in a Drosophila embryo that has no functioning string gene?

41-50. SHORT ESSAY (max. 10 points) Cortical Reaction

A. Describe the cortical reaction (CR) in amphibian embryos.
B. Outline two experiments showing that some event associated with CR is necessary for establishing dorsoventral polarity.
C. Outline another experiment showing that an event associated with CR is sufficient to establish dorsoventral polarity.

Second Midterm Exam (2 November 1995)

MATCH UP

The following are lists of Xenopus gastrula areas (1-6) and their derivatives (a-f). Match up by entering the appropriate letters in the spaces behind the numbers. The correct answer shows a one-to-one correlation.

1. animal cap and non involuting marginal zone
2. bottle cells
3. deep layer of involuting marginal zone
4. deep zone
5. superficial layer of involuting marginal zone
6. vegetal base


a. CNS and epidermis
b. floor of archenteron
c. head mesoderm
d. roof of archenteron
e. tip and sides of archenteron
f. trunk mesoderm

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.

7/8. During amphibian neurulation, the neural plate shrinks in length and decreases in width while the total surface area increases.

9/10. The cytoplasmic activity of many mRNAs is controlled by translational polyadenylation.

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 most adequate.

11. The inner epithelium of the mammalian lung is derived from
a. intermediate mesoderm
b. lateral somatic (parietal) mesoderm
c. lateral visceral (splanchnic) mesoderm
d. none of the above

12. Differential gene expression can be shown directly by
a. in situ hybridization of a defined labeled cDNA to histological sections
b. digestion with restriction enzymes
c. both of the above
d. none of the above

13. Neurulation in amphibians involves
a. elongation of neural plate cells
b. constriction of the apical surfaces of neural plate cells
c. cells changing their relative positions in the supra-notochordal region of the neural plate
d. all of the above

14. Which of the following structures are NOT derived from neural crest cells?
a. dorsal root ganglia
b. intervertebral discs
c. pigment cells
d. Schwann cells

15. The formation of the floor plate in the spinal cord is induced by the
a. archenteron
b. marginal layer
c. neural crest
d. none of the above

16. A mutant allele that is dominant to the wild-type allele is likely to represent a
a. complete loss of function
b. gain of function
c. maternal effect gene
d. partial loss of function

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 the one odd statement, be it correct or false, and circle the respective letter.

17. Control of Transcription
a. Transcription of eukaryotic DNA 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.

18. Heart and Aortic Arches in Vertebrates
a. The primitive heart pumps blood from posterior to anterior on the ventral side.
b. The blood leaves the heart through the truncus arteriosus, which gives off six pairs of aortic arches.
c. The aortic arches form angiogenetic clusters in adult fish.
d. The ductus arteriosus in mammals is a vestigal part of the sixth aortic arch on the left side.

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

20. 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 fish but occur only sporadically as atavisms in mammals.

21-30. SHORT ESSAY (max. 10 points) Accessory Nipples

It is not uncommon for human males or females to be born with accessory nipples.

A. Offer a developmental explanation of the fact that the supernumerary nipples are almost always located along a line from the armpit to the groin.
B. Name the general phenomenon that is exemplified by accessory nipples. Describe another example of the same general phenomenon.
C. What does the phenomenon discussed under (B) suggest about the evolution of genetic control circuits in development?

31-40. SHORT ESSAY (max. 10 points) Reporter Genes

A. Outline with the aid of a diagram the general features of a reporter gene, or fusion gene.
B. For what purposes are reporter genes used, and why?
C. Diagram a fusion gene used to analyze the interaction between bicoid protein and embryonic hunchback+genes. What results were obtained, and how were they interpreted?

41-50. SHORT ESSAY (max. 10 points) Sex Determination and Splicing of Doublesex pre-mRNA

A. Outline, with the aid of a diagram, the cascade of RNA splicing reactions that control somatic sexual development in Drosphila.
B. Suppose you analyze RNA from Drosophila adults of the following genotypes, using the ³Northern² blotting technique with a probe that hybridizes to both male-specific and female specific doublesex (dsx) mRNA.

1. wild-type males
2. wild-type females
3. transformer­/transformer­; XX
4. transformer-2­/transformer-2­; XX
5. Sexlethala/Sexlethalb; XX

Diagram the results that you expect. Note: male-specific dsx mRNA is longer than female specific dsx mRNA.

Final Exam (Fall 1995)

MATCH UP (1 point each)

The following is 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. _____ bindin

3. _____ cadherin

4. _____ cyclin

5. _____ homeobox

6. _____ hyaluronic acid

7. _____ polar body

8. _____ polar granule

9. _____ polar lobe

10. _____ trophoblast

a. cell adhesion molecule

b. conserved DNA sequence of 180 nucleotide pairs

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

d. extracellular matrix component

e. membranous compartment at tip of sperm

f. outer cells in mammalian blastocyst

g. protein promoting mitosis

h. sea urchin glycoprotein mediating sperm-egg adhesion

i. sister cell of oocyte

j. transient structure formed during cleavage in mollusks

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.

11./12. The midblastula transition in Xenopus is characterized by slow-down of the cell ____________________ and by a transition from ____________________ to embryonic gene expression.

13./14. Cells that fail to receive a specific developmental signal often proceed with a ____________________ program that is well ordered except that it is normally carried out ___________________ in the body or in the opposite sex.

15./16. ____________________ information in the form of structural organization is passed on during cell divisions without being ____________________ in DNA.

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

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 most adequate.

19. Which of the following structures are NOT derived from neural crest cells?
a. dorsal root ganglia
b. intervertebral discs
c. pigment cells
d. Schwann cells

20. The engrailed mutation in Drosophila transforms
a. anterior third thorax into anterior second thorax
b. posterior third thorax into posterior second thorax
c. both of the above are correct
d. none of the above is correct

21. The gray crescent in amphibian eggs is formed near the
a. animal pole
b. equator on the future dorsal side
c. equator on the future ventral side
d. none of the above is correct

22. Imaginal discs are found in
a. adult insects
b. insect larvae
c. mammalian embryos
d. salamander lenses

23. A mutant allele that is homozygous viable, and recessive to the wild-type allele, usually represents
a. a partial loss of function
b. a complete loss of function
c. a gain of function
d. a maternal effect gene

24. Stem cells are found in the
a. male germ line of vertebrates
b. basal layer of the epidermis
c. both of the above
d. none of the above

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 the one odd statement, be it correct or false, and circle the respective letter.

25. RNA and Protein Synthesis in Early Embryos
a. Many animal embryos synthesize RNA actively while protein synthesis is immeasurable.
b. The utilization of maternal mRNA in early embryos is indicated by the existence of maternal effect mutants.
c. Enucleated egg fragments are capable of protein synthesis.
d. The rate of protein synthesis increases after fertilization.

26. Oncogenes
a. Oncogenes are defined as genes causing cancer.
b. The proteins encoded by oncogenes are always localized in the cell nucleus.
c. Some oncogene proteins growth factors.
d. Oncogenes have been isolated from viruses as well as eukaryotic cells.

27. Polytene chromosomes (PC)
a. PC are interphase chromosomes.
b. The puffing pattern of PC is tissue-independent and stage-independent.
c. The stained bands in PC are the sites of highest DNA coiling.
d. The number of PC per cell represents the haploid chromosome number.

28. The Barr body (BB)
a. The BB is an example for gene inactivation by a change in chromosome structure.
b. The BB is observed in male mammals.
c. The BB represents an extra nucleolus.
d. The BB is found outside the nucleus in the cytoplasm.

29. Segmentation Genes in Drosophila Embryos
a. Segment polarity genes have been discovered as maternal effect mutations.
b. Pair rule genes are expressed in two stripes per segment.
c. The expression of gap genes begins after segmentation is complete.
d. Gap genes mutually delimit their expression domains.

30. Recapitulation
a. All vertebrates look alike during gastrulation
b. Pharyngeal pouches extend from the pharyngeal endoderm of all vertebrates
c. The bones that form the middle ear ossicles in reptiles develop into the secondary jaw joint in mammals.
d. Among the adult vertebrates, fish depart furthest from the phylotypic organization.

31-40. SHORT ESSAY (max. 10 points) Polyspermy

A. What is polyspermy?
B. Why are mechanisms preventing polyspermy adaptive?
C. Outline experiments that have revealed a fast block to polyspermy in sea urchins.
D. Summarize three mechanisms that constitute a slow block to polyspermy.

41-50. SHORT ESSAY (max. 10 points) Neurulation

A. Define Neurulation.
B. Outline experiments showing that neurulation in amphibians is independent of epidermis but dependent on axial mesoderm.
C. Outline two cellular behaviors involved in forming the keyhole-shaped neural plate in amphibians.
D. Indicate--on a map of an amphibian embryo at the keyhole stage--where the cellular behaviors mentioned in part C are most prominent.

51-60. SHORT ESSAY (max. 10 points) Compartment Hypothesis

A. How are compartments in the epidermis of Drosophila defined?
B. How does the compartment hypothesis link compartments to the activity of ³selector genes²?
C. Choose an actual Drosophila gene and show that it carries out the functions ascribed to selector genes.

61-70. SHORT ESSAY (max. 10 points) Deep Zone Cells and ECM in Amphibian Gastrulation

A. Outline the movement of deep zone cells in amphibian gastrulation.
B. Describe experiments--including controls--showing that a specific component (which?) of extracellular material is present on the blastocoel roof and necessary for gastrulation in newts.
C. How were the experiments described in part B interpreted?

71-80. SHORT ESSAY (max. 10 points) Estrogen/Androgen Receptors

Do human males have estrogen receptors, and do human females have androgen receptors? Hint: Argue on the basis of the phenotypes displayed by individuals with androgen insensitivity syndrome or congenital adrenal hyperplasia.


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