Category: CSIR NET Life Science Previous Year Questions and Solution on Drosophila Development

Category: CSIR NET Life Science Previous Year Questions and Solution on Drosophila Development

CSIR NET Life Science Previous Year Questions and Solution on Drosophila Development

The change in the state of specification of imaginal disc of Drosophila to that of a different disc type is known as (1) Trans-determination (2) trans-differentiation (3) transformation (4) transduction

Trans-determination in Drosophila Imaginal Discs: Understanding Developmental Plasticity and Cell Fate Switching

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Categorization and Matching of Developmental Genes in Drosophila Embryogenesis

31. What is the observed phenotype when the ultrabithorax gene is deleted in Drosophila? (1) The third thoracic segment is transformed into another second thoracic segment resulting in a fly with four wings. (2) Since it specifics the second thoracic segment, instead of antenna leg grows out of the head socket. (3) Since it specifies the third thoracic segment, a fly with two pairs of halters develop. (4) Since this gene fails to be expressed in the second thoracic segment, the antennae sprout in the leg position.

Ultrabithorax Gene Deletion Phenotype in Drosophila: A Detailed Analysis

30. Antennapedia complex in Drosophila contains five genes, lab, pb, dfd, scr and Antp and they express in parasegments 1 to 5, respectively in a non-overlapping manner. In the larva or in later stages of development, the region of Antp (Antennapedia) expression corresponds to a part of second thoracic segment. A mutation in Antp is known to cause transformation of antenna to leg-like structures. Below are certain statements made in respect to the functions of Antennapedia: A. In the above described Antp mutation, the gene ectopically expresses in the head region B. One of the functions of Antp is torepress genes that induce antenna development C. Antp expresses in thorax and forms a concentration gradient in the posterior-anterior direction, thus affecting head development D. A homozygous recessive mutation of Antp is expected to transform the leg to antenna in the second thoracic segment. Which combination of the above statements correctly describes the function of Antennapedia? (1) A, Band C (2) B and C (3) C and D (4) A, B and D

Function and Mutation Effects of the Antennapedia Gene in Drosophila Development

29. A mutant was experimentally generated which wings had reduced to halter like structure. The following statements are put forward regarding this phenotype: A. ultrabithorax gene ectopically expressed in second thoracic segment B. antennapedia gene ectopically expressed in second thoracic segment C. A homeotic mutation, D. A mutation in gap gene The following combination of statements will be most appropriate explaining the molecular basis of mutant phenotype: (1) A and B (2) B and C (3) C and D (4) A and C

Molecular Basis of Wing-to-Haltere Transformations in Drosophila: The Role of Ultrabithorax and Homeotic Genes

28. Which of the following statements is true about dorso- ventral patterning of drosophila embryo? (A) This is dictated by the location of the nurse cells (B) Dorsal is the default fate (C) The whole process is regulated by preventing the entry of a transcription factor to the nucleus of dorsal cells (D) Homeobox containing genes play a critical role in this process. (1) (A), (B) and (C) (2) (A),(B), (C) and (D) (3) (A) and (D) (4) (B) and (C)

Understanding Dorsal-Ventral Patterning in Drosophila Embryos: Key Molecular Mechanisms

During embryogenesis, a Drosophila embryo with a mutation in a homeotic gene shows (1) changed polarity of each segment. (2) defects in dorso-ventral polarity. (3) deletion of several segments in a row. (4) replacement of one body part by another body part

Impact of Homeotic Gene Mutations on Drosophila Embryonic Development

26. Torpedo, is known to serve as a receptor for Gurken. Deficiencies of the torpedo gene in Drosophila cause ventralization of the embryo. In an experiment, the germ cell precursors from a wild type embryo were transplanted into embryos whose mother carried the torpedo mutation. Also, the reverse experiment, i.e., transplantation of germ cell precursors from torpedo mutants into wild type embryos was done. The torpedo deficient germ cells developed in a wild type female showed normal dorso-ventral axis, while the wild type germ cells developed in a torpedo deficient female showed ventralized egg. Some of the following statements are drawn from the above experiments and some from known facts to understand the functioning of Torpedo. A. Zygotic contribution of Torpedo is essential for the development of dorso- ventral axis. B. Maternal contribution of Torpedo is essential for the development of dorso- ventral axis. C. Since Torpedo is a receptor for Gurken and follicle cells surround the part of the oocyte where Gurken is expressed, it is likely that Torpedo is expressed in follicle cells. D. Gurken signalling initially dorsalizes the follicle cells, which in turn send signal to organize the dorso- ventral polarity in oocyte. E. Gurken signalling initially dorsalizes the nurse cells which help in generation of dorso-ventral polarity in oocyte. Which one of the following combination of statements is most appropriate? (1) B, C and D (2) A, C and D (3) B, C and E (4) A, D and E

Role of Torpedo Receptor and Gurken Signaling in Dorsal-Ventral Axis Formation in Drosophila

25. Torpedo is a trans-membrane receptor on follicle cells that binds with Gurken protein located in the presumptive dorsal surface of the oocytes and inhibits a cascade leading to nuclear localization of the Dorsal Protein. In an experiment, Drosophila germ line chimeras were made by interchanging pole cells (germ line precursors) between wild type embryos and embryos from mother homozygous for a mutation of torpedo gene. These transplants produced: i) wild type females whose egg came from mutant mother, and ii) torpedo deficient females whose egg came from wild type mother. The possible outcome of this experiment can be: A. Torpedo deficient eggs developed in wild type ovary induced normal embryos. B. Wild type eggs developed in Torpedo deficient ovary produced ventralized embryos. C. Torpedo deficient eggs developed in wild type ovary produced ventralized embryos. D. Dorsal protein enters in the nuclei of dorsal side of embryos which came from wild type eggs developed in Torpedo deficient ovary. E. Dorsal protein remains cytoplasmic in the dorsal side of the embryos which came from Wild type eggs developed in Torpedo deficient ovary. Which of the above combination is correct? (1) A, B and D (2) B, C and E (3) B, D and E (4) A, C and E

Role of Torpedo Receptor and Gurken Protein Interactions in Dorsal-Ventral Axis Formation in Drosophila Germ Line Chimera Experiments

24. The Dorsal protein is involved in generating the dorsal-ventral (DV) polarity in Drosophila. The following statements were made regarding the activity of the Dorsal protein in establishing the DV polarity. A. In embryos that lack Gurken protein, the Dorsal protein is not translocated to the nucleus of the follicle cells which then causes ventralization of the embryo B. Though Dorsal protein acts as a morphogen, it is found throughout the syncytial blastoderm of the early Drosophila embryo. C. In embryos that lack Cactus protein the Dorsal protein can be found in the nucleus of cells with a ventral fate. D. If the Dorsal protein is blocked from entering the nucleus, the genes responsible for specifying dorsal cell types are not transcribed. Which of the above statements are correct? (1) A and B (2) B and C (3) C and D (4) A and C

Role of Dorsal Protein in Establishing Dorsal-Ventral Polarity in Drosophila Embryos

23. Following are the events that might take place during demo-ventral axis specification in early embryonic development of Drosophila: A. 'Torpedo' receptor activation B. 'Pipe' synthesis C. A cascade of protease activity D. 'Cactus' dephosphorylation E. Entry of 'Dorsal' in the nuclei of syncytial blastoderm stage embryo. Which combination of the above events will occur in the presumptive dorsal side of the embryo deficient in maternal gurken? (1) A only (2) B and C only (3) B, C and E only (4) B, C, D and E only

Molecular Events During Dorsal-Ventral Axis Specification in Gurken-Deficient Drosophila Embryos

22. The following statements regarding the generation of dorsal/ventral axis in Drosophila was made: A. Gurken protein moves along with the oocyte nucleus and signals follicle cells to adopt the ventral fate. B. Maternal deficiencies of either the gurken or torpedo gene cause ventralization of the embryo. C. Gurken is active only in the oocytes, Torpedo is active only in the somatic follicle cells. D. The Pipe protein is made in the dorsal follicle cells. E. The highest concentration of Dorsal is in the dorsal cell nuclei, which becomes the mesoderm. Which one of the following combination of the above statements is true? (1) A and E (2) C and D (3) B and C (4) B and E

Molecular Mechanisms Generating the Dorsal-Ventral Axis in Drosophila Embryogenesis

21. The anterior-posterior compartment of each segment of Drosophila is defined by wingless and engrailed genes. The following statements are given towards explaining their regulation: A. Wingless is a secretory factor B. Engrailed is a secretory factor and forms a long-range concentration gradient C. Engrailed regulates Wingless through Hedgehog which forms a short-range concentration gradient D. β-catenin homologue is the signalling molecule upstream of Engrailed, which gets cleaved by GSK3 homologue E. Cubitus interruptus is an intracellular signaling molecule in the Engrailed expressing cells. Which one of the following options has all the correct statements towards the regulation of anterior posterior compartment of segments? (1) B only (2) C only (3) B and E (4) A, C and D

Regulation of Anterior-Posterior Compartments in Drosophila Segments by Wingless and Engrailed Genes

20. What will happen if wingless RNAi is expressed in wingless expressing cells from the stage when this gene initiates its expression in a developing Drosophila embryo? A. The enhanced expression of wingless thus caused will broaden the area of engrailed expression. B. Since wingless protein makes a long range gradient, its effect will not be seen in the same segment. C. The posterior compartment of each future segment will get affected. D. Since engrailed expression is initiated by pair rule genes, the posterior segment will not be affected. Which one of the following will most appropriately answer the question? (1) A and C (2) Only C (3) B and D (4) Only D

Effects of Wingless RNAi Expression in Developing Drosophila Embryos: Implications for Segmental Patterning

19. The continued expression of engrailed and wingless is maintained by interactions between the Engrailed- and Wingless-expressing cells. The following statements are given towards the initiation of the cascade of events that occur for this interaction: A. The engrailed gene is expressed in cells where neither even skipped nor fushi tarazu gene is active. B. The wingless gene is expressed in those cells that contain high concentration of either Even skipped or Fushi tarazu. C. Wingless is a secreted protein, diffuses to the surrounding, binds with the Frizzled and Lrp6 receptor proteins and activates engrailed gene via Armadillo. D. Hedgehog protein activates the transcription of engrailed and also activates its own transcription. E. Hedgehog protein diffuses from cells and binds to Patched receptor on neighbouring cells and enables transcription of wingless gene. Which combination of above statements correctly represent the maintenance of engrailed and wingless expression? (1) A and B (2) B and D (3) A and D (4) C and E

Maintenance of Engrailed and Wingless Expression in Drosophila: Key Molecular Mechanisms

18. The following are statements regarding the development and maintenance of anterior and posterior compartments in each segment of Drosophila: A. Expression of wingless and engrailed is activated by pair-rule genes B. continued expression of wingless and engrailed is maintained by interaction between the cells expressing engrailed and wingless proteins C. Hedgehog is expressed wingless expressing cells and forms short range gradient D. Hedgehog is a transcription factor E. Engrailed is a secretory factor and binds with the patched receptor of the wingless expressing cells. Which one of the following combination of above statements is correct? (1) C and E (2) C, D and E (3) D and E (4) A and B

Understanding Anterior and Posterior Compartment Development in Drosophila Segments

17. Engrailed expression in Drosophila melenogaster defines (1) anterior margin of the segment. (2) anterior compartment of each segment. (3) posterior margin of each para-segment. (4) posterior compartment of each segment

Understanding Engrailed Expression in Drosophila melanogaster: Defining Posterior Compartment of Each Segment

16. Segmentation genes in Drossophila are divided into three groups (gap, pair rule and segment polarity) based on their mutant phenotype. Below are some of the major genes expressed in a sequential manner (with respect to the groups) affecting segmentation pattern. (A) hairy → paired → tailless → patched (B) hunchback → even-skipped → fushi tarazu → wingless (C) odd-skipped → giant → paired → wingless (D) tailless → hairy → fushi tarazu → gooseberry Which of the above sequence(s) of genes expressed from early to late embryo is/are correct? (1) (D) only                                                   (2) (A) and (B) (3) (C) and (B)                                               (4) (B) and (D)

Sequential Expression of Segmentation Genes in Drosophila Embryo Development

15. The homologue of β-catenin in Drosophila is (l) Fushi tarazu (2) Engrailed. (3) Armadillo (4) Cubitus interruptus.

Armadillo: The Drosophila Homolog of β-Catenin and Its Role in Development

14. Antennapedia protein expresses in the thoracic segment of the fly and not in the head region. However, a dominant mutation of Antennapedia replaces antenna with leg-like structure. The following statements were made with reference to Antennapedia: A. In a dominant Antennapedia mutant, the Antennapedia gene is expressed in the head as well as in thorax. B. In the Antennapedia mutants, the Antennapedia gene is expressed in head region only and thus promotes leg-like structure in head socket C. In addition to promoting thoracic structures, Antennapedia protein binds to and represses the enhancer of homothorax and some other genes responsible for antenna specification. D. Antennapedia has no role in thoracic region specification and thus recessive Antennapedia mutants show no phenotypic effect. Which one of the following options represents correct statement(s)? (1) A only (2) A and C (3) B and D (4) B only

Understanding Antennapedia Mutations and Their Impact on Drosophila Development

13. In which one of the following developmental events, the fate of maternal somatic cell is determined first, which then the fate of the developing embryo? (1) 1.The specification of primary organizer in amphibian embryo (2) 2.The specification of dorso-ventral axis in Drosophila (3) 3.The formation of the vulval precursor cells during development of C. elegans (4) 4.Specification of the micromeres in case of sea urchin.

Maternal Somatic Cell Fate Determination Preceding Embryonic Fate: Developmental Events Overview

11. If an early cleavage stage wild type Drosophila embryo is injected with bicoid mRNA at the posterior pole then (1) head structures develop at posterior pole, while the same is inhibited at anterior pole (2) head structures form at both poles (3) head structures are not formed at posterior pole due to presence of posterior morphogens (4) duplication of usual posterior structures occurs

Impact of Posterior Injection of Bicoid mRNA on Drosophila Embryonic Patterning

10. The following statements were made regarding the patterning of anterior-posterior body plan of Drosophila: A. Microinjection of bicoid mRNA in the middle of a bicoid-deficient embryo leads to formation of 'head' in the middle and telson at the two ends. B. Nanos protein inhibits the translation of caudal mRNA at the posterior half of the embryo. C. The Bicoid protein activates the zygotic expression of the hunchback gene. D. The segment polarity genes are expressed in segments of the embryo. Which one of the following options represents all correct statements as made above? (1) A and B only (2) A and C only (3) A, C and D (4) B, C and D

Comprehensive Insight into Anterior-Posterior Patterning Genes in Drosophila Embryo

9. Three embryos, X (wild type), Y (mutant for bicoid) and Z (mutant for nanos) were injected with bicoid mRNA in their posterior pole at early cleavage stage. What would be the phenotypes of the resulting embryos? (1) Embryo X will develop head on both anterior and posterior side, while embryos Y and Z will develop head on posterior side only. (2) Embryos X and Z will develop head on both anterior and posterior side, while embryo Y will develop head on posterior end only. (3) Embryos X, Y and Z will develop head on both anterior as well as posterior side. (4) Embryo X will develop head on anterior side, embryo Y will develop no head, while embryo Z will develop head on anterior as well as posterior side.

Phenotypic Outcomes of Bicoid mRNA Injection in Wild Type and Mutant Drosophila Embryos

8. Cytoplasmic determinants coding for anterior structure of Drosophila embryo if injected elsewhere in the recipient embryo, would lead to (1) normal development. (2) formation of additional ectopic head. (3) degeneration. (4) a phenotype with two heads and two tails.

Effects of Cytoplasmic Determinants on Anterior Structure Formation in Drosophila Embryo

Which of the following maternal effect gene products regulate production of anterior structures in Drosophila embryo? (1) Bicoid and Nanos (2) Bicoid and Hunchback (3) Bicoid and Caudal (4) Nanos and Caudal

Maternal Effect Genes Regulating Anterior Structures in Drosophila Embryo: The Role of Bicoid and Hunchback

6. One of the most important gene, involved in dorsal—ventral axis determination in Drosophila is dorsal. It codes Dorsal protein which (1) is taken up into the nuclei of cells and this side will become the ventral side (2) remains in the cytoplasm of cell and this side will become ventral side. (3) is taken up into the nuclei of cells and this side will become the dorsal side. (4) degraded in one side and that will become dorsal side

Role of the Dorsal Protein in Drosophila Dorsal-Ventral Axis Formation

5. An embryo lacking bicoid is injected with bicoid m-RNA at middle portion. It will result into (1) Two heads and no tarsons (2) Head in middle and tarsons at both end (3) No head and Tarson at both ends (4) Normal phenotype

Effects of Bicoid mRNA Injection in the Middle of a Drosophila Embryo

4. The emergence of polarity of a drosophila embryo is the result of (1) Positive and negative charges interacting in early development. (2) cytoplasmic differences between cells. (3) cytoplasmic determinants within cells. (4) All of the above

Mechanisms Underlying Polarity Emergence in Drosophila Embryos

3. Dorsal mutant in Drosophila will result in (1) Dorsalization of ventral side (2) Ventralization of dorsal side (3) There would be no effect (4) Anterior-posterior pattern formation will be effected

Impact of Dorsal Gene Mutation on Drosophila Embryonic Development

2. Homeotic selector genes are responsible for the specification of Drosophila body parts. Which one of the following identities would you expect if the ultrabithorax gene is deleted? (1) The third thoracic segment is transformed to another second thoracic segment and a fly with four wings. (2) The third thoracic segment develops halteres. (3) The second thoracic segment loses wings. (4) The first and second thoracic segments fuse and wings are formed on the third thoracic segment.

The Role of Ultrabithorax Gene in Drosophila Segment Identity and Phenotypic Outcomes

1. Which of the following phenotypes is obtained upon deletion of the ultrabithorax gene in Drosophila? (1) Fly with four wings (2) Fly with six wings (3) Fly with no wings (4) Fly with two wings

Ultrabithorax Gene Deletion Phenotype in Drosophila: Four Wings Instead of Two

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