The cells of  posterior marginal zone act as the equivalent of the amphibian Nieuwkoop center because:

A. once the PMZ has formed, it controls the other regions of the margin.

B. Cells of PMZ initiate other regions of the margin from forming their own primitive streaks.

C. the entire marginal zone produces Wnt8c (capable of inducing the accumulation of -catenin) and secrete Vg1, a member of the TGF-family.

D. The PMZ cells secretes nodal protein and Nodal activity is needed to initiate the primitive streak.

E. When placed in the anterior region of the marginal zone, a graft of PMZ tissue (posterior to and including Koller’s sickle) is able to induce wnt signaling.

Which of the following option is correct?

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#Question id: 1200

#Unit 4. Cell Communication and Cell Signaling

Glucagon binds to the glucagon receptor, which interacts with a membrane-bound G protein, whose α subunit releases GDP and binds GTP. The α subunit then dissociates from the G protein and diffuses to a membrane-bound adenylyl cyclase which produces cAMP. In this scenario, name the

(1) transducer,

(2) effector,

(3) first messenger, and

(4) second messenger.

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#Question id: 32714

#Unit 1. Molecules and their Interaction Relevant to Biology

The existence of an enzyme-substrate complex can be experimentally demonstrated by

a. X-ray crystallography

b. ESR

c. NMR

d. Fluorimetery

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#Question id: 10471

#Unit 6. System Physiology – Plant

Under temperate conditions, which one of the two major factors that are involved with light-dependent stomatal opening are,

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#Question id: 23785

#Unit 7. System Physiology – Animal

What happens when rod cells hyperpolarize? 

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#Question id: 28858

#Unit 2. Cellular Organization

Which of the following kinesin is a C-terminal kinesin & travel toward the microtubule minus end?