If D, E and F are the mid–points of the sides of an equilateral triangle ABC, then the ratio of the area of triangle DEF and DCF is :

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#Question id: 1567

#Unit 4. Cell Communication and Cell Signaling

Which of the following cell types are responsible for initiating a secondary immune response?

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#Question id: 10560

#Unit 6. System Physiology – Plant

If a tiny gas bubble forms in a column of water under tension, the gas bubble may expand indefinitely, with the result that the tension in the liquid phase collapses, it can have a devastating effect on water transport through the xylem a phenomenon known as

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#Question id: 15637

#Unit 13. Methods in Biology

You have isolated two mutations in the Lac operon that cause constitutive expression of Lac genes. You designate these mutants Lac1– and Lac2–. Making use of an F' that carries the Lac operon with the LacY gene mutated, you construct strains that you test for both ß-galactosidase activity and Lac permease activity with results shown below.

     

Classify each mutation as dominant or recessive and as cis- or trans-acting, giving the experimental result that allows you to arrive at each conclusion. Finally, deduce what type of Lac mutation best fits the properties of Lac 1– and of Lac 2–.

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#Question id: 4479

#Unit 3. Fundamental Processes

The stepwise assembly of the Pol II preinitiation complex

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#Question id: 3648

#Unit 3. Fundamental Processes

The initiation of DNA replication within a replicon always occurs at a fixed point known as: