In blue-white screening, what do blue colonies represent?
cells that have not taken up the plasmid vector
cells with recombinant plasmids containing a new insert
cells containing empty plasmid vectors
cells with a non-functional lacz gene

The correct option is : cells containing empty plasmid vectors

Explanation:

The blue-white screen is a technique which involves the rapid identification of the recombinant bacteria in a vector-based molecular cloning experiment. In this method, a DNA ligated vector is inserted in a host cell which is viable for transformation and grown in presence of X-gal.    

The cells that are transformed with the vectors having the recombinant DNA produce the white colonies. Whereas, the cells transformed with empty vector i.e. the non-recombinant plasmids, produce the blue colonies.

photosynthesis makes the glucose that is used in cellular respiration to make atp. the glucose is then turned back into carbon dioxide, which is used in photosynthesis. while water is broken down to form oxygen during photosynthesis, in cellular respiration oxygen is combined with hydrogen to form water.