#Question id: 4156

#Section 3: Genetics, Cellular and Molecular Biology

The reading frame of DNA is fixed by

#Question id: 1861

#Section 2: General Biology

Paroxysmal nocturnal hemoglobulinuria results from deficiency in:

#Question id: 3278

#Section 3: Genetics, Cellular and Molecular Biology

What does the biological species concept use as the primary criterion for determining species boundaries?

#Question id: 11800

#Section 6: Plant, Animal and Microbial Biotechnology

There are at least three different types of companion cells in the minor veins of mature, exporting leaves. Which of the following statements about these companion cells is CORRECT?

 a.) transfer cells are transport sugars enter the apoplast during the movement of sugars from mesophyll cells to sieve elements. Transfer cells transport sugars from the apoplast to the symplast of the sieve elements and companion cells in the source.

 b.) the numerous mitochondria in companion cells may supply energy as ATP to the sieve elements

 c.) Ordinary companion cells can function in either symplastic or apoplastic short-distance transport in source leaves, depending in part on plasmodesmatal frequencies

 d.) Intermediary cells, by contrast, function in symplastic transport of sugars from mesophyll cells to sieve elements

#Question id: 619

#Section 2: General Biology

The benefit of measuring the initial rate of a reaction V0 is that at the beginning of a reaction: