Which of the following is a function of the protein called ubiquitin?
a.) it attaches to proteins that are marked for destruction in the cell.
b.) it assists in the removal of introns from a eukaryotic pre-mrna.
c.) it initiates the formation of a transcription complex.
d.) it adds the 3' and 5' caps to eukaryotic pre-mrna.

The correct answer is: a) It attaches to proteins that are marked for destruction in the cell.

Ubiquitin is a regulatory protein of eukaryotic cell with the various of function. The mechanism of its action involves the addition of ubiquitin to a substrate protein (ubiquitination). Ubiquitin regulatory roles are:

•marking thee proteins for degradation via the proteasome,  

•alter the cellular location of proteins,  

•promoting or preventing protein interactions.

answer; /// i believe that the correct answer is (50%);

measuring light intensity

light meters can be used to measure light intensity. the meter is held at the soil surface and pointed in the direction of the maximum light intensity, and then the meter is read.

errors can be made when measuring light intensity by accidentally shading the light meter. the reliability of the results can be checked by taking many samples.