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TLS Online TPP Program

#Question id: 2585

Which of the following is the correct sequence that describes the excitation and contraction of a skeletal muscle fiber?

A. Tropomyosin shifts and unblocks the cross-bridge binding sites.

B. Calcium is released and binds to the troponin complex.

C. Transverse tubules depolarize the sarcoplasmic reticulum.

D. The thin filaments are ratcheted across the thick filaments by the heads of the myosin molecules using energy from ATP.

E. An action potential in a motor neuron causes the axon to release acetylcholine, which depolarizes the muscle cell membrane.

#Unit 2. Cellular Organization

  1. A → B → C → D → E

  2. B → A → C → E → D

  3. B → C → D → A → E

  4.  E → C → B → A → D

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TLS Online TPP Program

#Question id: 7243

#Unit 5. Developmental Biology

Match the following:

Column I

       Column II

A. Anterior necrotic zone

I. Rapid apoptosis that occurs when epithelial cells lose their attachment to the extracellular matrix.

B. Anoikis

II. Devoid of any neural innervation.

C. Aneurogenic

III. Mammalian equivalent to the chick hypoblast and similar to the head portion of

the amphibian organizer, it creates an anterior region by secreting antagonists of Nodal.

D. Anterior visceral endoderm

IV. A zone of programmed cell death on the anterior side of the developing tetrapod limb that helps shape the limb.


TLS Online TPP Program

#Question id: 7244

#Unit 5. Developmental Biology

Following statements are regarding to the evolutionary conservation of homeotic gene organization and transcriptional expression in fruit flies and mice.

A. In fruit flies and mice genes with similar structures occupy the same relative positions on each of the four chromosomes, and paralogous gene groups display similar expression patterns.

B. Hom-C cluster on Drosophila chromosome 3 and the four Hox gene clusters in the mouse genome are similar and evolutionary conserved.

C. Those mammalian genes homologous to the Drosophila labial, proboscipedia, and deformed genes are expressed anteriorly and early, whereas those genes homologous to the Drosophila AbdB gene are expressed posteriorly and later.

D. In fruit flies and mice genes are orthologous Hox gene groups.

E. Those mammalian genes homologous to the Drosophila labial, proboscipedia, and deformed genes are expressed posteriorly and later, whereas those genes homologous to the Drosophila AbdB gene are expressed anteriorly and early.

Which of the following combination is correct?
TLS Online TPP Program

#Question id: 7245

#Unit 5. Developmental Biology

Gradients of Wnt are essential for normal regeneration of a head and a tail by planaria. Which one of the following statement is incorrect?
TLS Online TPP Program

#Question id: 7246

#Unit 5. Developmental Biology

Treatment of Xenopus embryos with lithium dorsalizes the embryos by interfering with cell-cell signaling pathways. What, if anything, is the effect of lithium on hydra, and what might we infer about its mechanism of action?
TLS Online TPP Program

#Question id: 7247

#Unit 5. Developmental Biology

Which statement correctly characterizes regeneration in the mammalian nervous system?
TLS Online TPP Program

#Question id: 7248

#Unit 5. Developmental Biology

Planning of the Xenopus mesoderm along the dorso-ventral axis contains an antagonistic relationship between chordin and bmp-4. Is there an analogy here to dorso-ventral patterning in the Drosophila embryo?