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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

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

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

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November 8, 2025
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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 […]

37. In sea urchins, a group of cells at the vegetal pole become specified as the large micromere cells. These cells are determined to become skeletogenic mesenchyme cells that will leave the blastula epithelium to ingress into the blastocoel. This specification is controlled by the expression of Pmar1 which is a repressor of HesC. HesC represses the genes encoding transcription factors activating skeleton forming genes. The gene regulatory network is given below. Below, column I lists the experiments carried with mRNA/antisense RNA of different genes injected into single-celled sea urchin embryo while column II lists the developmental outcomes: Match the following: Which of the following combinations is correct? (1) A-2, B-1, C-1, D-2 (2) A-1, B-1, C-2, D-2 (3) A-1, B-2, C-2, D-1 (4) A-2, B-2, C-2, D-2

CSIR NET Life Science Previous Year Questions and Solution on Basic Concepts of Development

Gene Regulatory Network Controlling Micromere Specification in Sea Urchin Embryos

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November 8, 2025
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37. In sea urchins, a group of cells at the vegetal pole become specified as the large micromere cells. These cells are determined to become skeletogenic mesenchyme cells that will […]

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

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

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

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November 8, 2025
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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 […]

Given below are few statements regarding the role of Disheveled (Dsh) and β-catenin (β-cat) in the development of sea urchin. A. Dsh is localized in the vegetal cortex of the oocyte before fertilization and in the region of the 16-cell embryo about to become the micromeres. B. Dsh is localized in the cytosol of the oocyte during oogenesis and in the micromere forming blastomeres of a 16- cell embryo. C. β-cat accumulates predominantly in the micromeres and somewhat in the veg2 tier cells. D. Treatment of embryos with lithium chloride does not allow the accumulation of β-cat in the nuclei of all blastula cells, and the animal cells thus become specified as endoderm and mesoderm. E. When β-cat is prevented from entering the nucleus, the embryo develops as a ciliated ectodermal ball. Which one of the following options represents a combination of correct statements? (1) B, C and E (2) A, C and D (3) A, C and E (4) B, D and E

CSIR NET Life Science Previous Year Questions and Solution on Basic Concepts of Development

Understanding the Role of Disheveled and β-Catenin in Early Sea Urchin Embryonic Development

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November 8, 2025
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Given below are few statements regarding the role of Disheveled (Dsh) and β-catenin (β-cat) in the development of sea urchin. A. Dsh is localized in the vegetal cortex of the […]

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

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

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

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November 8, 2025
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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. […]

Following statements with respect to development in sea urchin were put forth: A. The cell fates are determined both by autonomous and conditional modes of specification. B. Large micromeres are conditionally specified. C. Large micromeres produce paracrine and juxtacrine factors that specify the fates of their neighbours. D. B-catenin is not required for the specification of the micromeres. Which one of the following options represents the combination of all correct statements? (1) A and B (2) A and C (3) C and D (4) B and D

CSIR NET Life Science Previous Year Questions and Solution on Basic Concepts of Development

Autonomous and Conditional Cell Fate Specification in Sea Urchin Embryos

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November 8, 2025
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Following statements with respect to development in sea urchin were put forth: A. The cell fates are determined both by autonomous and conditional modes of specification. B. Large micromeres are […]

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

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

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

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November 8, 2025
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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 […]

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

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

Molecular Mechanisms Generating the Dorsal-Ventral Axis in Drosophila Embryogenesis

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November 8, 2025
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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 […]

CSIR NET Life Science Previous Year Questions and Solution on Basic Concepts of Development

Impact of GSK-3 Inhibition on β-Catenin Nuclear Accumulation and Cell Fate in Sea Urchin Embryos

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November 8, 2025
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34. During normal development of sea urchin, β-catenin accumulates predominantly in the micromeres, which are fated to become endoderm and mesoderm. If GSK-3 is blocked in the developing embryo: (1) […]

33. In a given experiment, transplantation o micromeres from the vegetal pole of a 16-cell sea urchin embryo onto the animal pole of a host 16-cell sea Urchin embryo would initiate: (1) The transplanted micromeres to invaginate into the blastocoel to create a new set of skeletogenic mesenchyme cells (2) The transplanted micromeres to ingress into the blastocoel to create a new set of skeletogenic mesenchymal cells (3) The transplanted micromeres will mingle with the host micromeres to ingress into the blastocoel to create skeletogenic mesenchyme cells. (4) The transplanted micromeres will form the secondary archenteron

CSIR NET Life Science Previous Year Questions and Solution on Basic Concepts of Development

Sea Urchin Micromere Transplantation: Formation of Skeletogenic Mesenchyme Cells Through Ingression

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November 8, 2025
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33. In a given experiment, transplantation o micromeres from the vegetal pole of a 16-cell sea urchin embryo onto the animal pole of a host 16-cell sea Urchin embryo would […]

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

Gene Regulatory Network Controlling Micromere Specification in Sea Urchin Embryos

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

Understanding the Role of Disheveled and β-Catenin in Early Sea Urchin Embryonic Development

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

Autonomous and Conditional Cell Fate Specification in Sea Urchin Embryos

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

Molecular Mechanisms Generating the Dorsal-Ventral Axis in Drosophila Embryogenesis

Impact of GSK-3 Inhibition on β-Catenin Nuclear Accumulation and Cell Fate in Sea Urchin Embryos

Sea Urchin Micromere Transplantation: Formation of Skeletogenic Mesenchyme Cells Through Ingression

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