The prevention of expression of operons encoding substrate use pathways for substrates other than glucose when glucose is present is called

The answer is : Carbon catabolite repression

Explanation:

Carbon catabolite repression is a vital part of the global control system of the bacteria and other microorganisms. It allows the microorganisms to quickly adapt to the preferred energy and carbon source first. This is generally achieved by the inhibiting the synthesis of the enzymes that are involved in the catabolism of other carbon sources.

This effect was first shown to be initiated by glucose. Therefore, the carbon catabolite repression is also known as glucose effect.            

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.