Which of the following occurred first during the separation of the elements of Pangaea through continental drift? 

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#Question id: 15280

#Unit 5. Developmental Biology

The mechanisms governing cell fate specification involves gradients of paracrine factors that regulate gene expression; such factors are called:

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#Question id: 5535

#Unit 5. Developmental Biology

What type of animal forms a trophoblast for the duration of its early development?

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#Question id: 13062

#Unit 13. Methods in Biology

Precision will be reduced, but yield will be increased

Optimisation of a PCR reaction is often a compromise between the competing demands for precision, efficiency and yield. Although the specific effects may vary, generally, increasing the annealing temperature will increase non-specific primer binding and reduce precision. Increasing the length of the elongation phase will reduce the proportion of incomplete newly-synthesised strands and therefore increase yield. In this case, the potential effect on efficiency is unclear. Increasing the elongation phase would increase the reaction time, but the time taken to ramp down to a lower annealing temperature would be reduced.

A restriction enzyme cleaves a circular plasmid vector to produce fragments : 1kb, 0.3kb, 2kb, 1kb and 0.3kb. How many bands will be visible on agarose gel?

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#Question id: 33986

#Unit 2. Cellular Organization

What is the relationship between the chromosome scaffold of dividing cells and the matrix of interphase cells

A. The same DNA fragments that are found within the nuclear matrix in vivo can be retrieved from the metaphase scaffold

B. Fragments containing MAR sequences can bind to a metaphase scaffold; it is likely that DNA contains a single type of attachment site.

C. In interphase cells the attachment site is connected to the nuclear matrix, whereas in mitotic cells it is connected to the chromosome scaffold.

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#Question id: 28850

#Unit 2. Cellular Organization

Kinesin-13 bind and curve the end of the tubulin protofilaments into which conformation?