In drosophila, the segment polarity genes encode proteins that are constituents of the Wnt and Hedgehog signaling pathways. Which of the following is correct regarding to model for transcription of the segment polarity genes engrailed (en) and wingless (wg).

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#Question id: 5237

#Unit 5. Developmental Biology

Match the following stem cell type (Column I) with their niche location (Column II).

Column I	Column II
A. Intestine	i. Bone marrow
B. Hematopoietic stem cells	ii. Bulge
C. Hair follicle	iii. Testes
D. Sperm	iv. Base of small intestinal crypts

Which of the following is correct?

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#Question id: 5238

#Unit 5. Developmental Biology

all tissue types possess a unique stem cell niche, and despite many differences among the niche architecture of different tissues, several common principles of stem cell regulation can be applied to all environments. These principles involve extracellular mechanisms leading to intracellular changes that regulate stem cell behavior.

Column A	Column B
I. Extracellular regulatory mechanisms	i. Regulation by endocrine, paracrine, or juxtacrine mechanisms
II. Intracellular regulatory mechanisms	ii. Regulation by a network of transcription factors
	iii. Epigenetic regulation
	iv. Regulation by cell-to-cell and cell-to-matrix adhesions
	v. Regulation by cytoplasmic determinants

Match the following regulatory mechanism (column A) with the factors that regulate stem cell behavior (column B).

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#Question id: 5254

#Unit 5. Developmental Biology

Following signal transduction pathways can be grouped into several basic types, based on the sequence of intracellular events.

According to above figure, which of the following correctly represents the basic concepts of all signalling pathway?

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#Question id: 14706

#Unit 5. Developmental Biology

Match the types of cell movement during gastrulation

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#Question id: 14707

#Unit 5. Developmental Biology

Which of the following organ belongs to the internal layer of gastrula?

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#Question id: 14708

#Unit 5. Developmental Biology

Difference between gastrulation in Xenopus and sea urchin;

I. In Xenopus, formation of blastopore: mesoderm and endoderm move inside by involution over blastopore lip.

II. In sea urchin, formation of blastopore: mesodermal cells migrate into the interior; endoderm moves inside by invagination of the epithelial sheet.