Some enzymes may be used to stop a reaction from moving forward true or false a chemical reaction producing energy for a cell is a. embden-meyerhof pathway b. glycolysis c. production of atp occurs in the mitochondria in eukaryotes or on the plasma membrane of bacteria d. all of the above

1. The statement above is TRUE. 
There are different types of enzymes which perform different functions. Some enzymes are capable of limiting chemical reaction, stopping the reaction from moving forward, such type of enzymes are called REGULATORY ENZYMES. This type of enzyme regulate the activities of other enzymes. The use of regulatory enzymes is one of the means which the body used to control biochemical reactions. 

2. A chemical reaction producing energy for the cell is GLYCOLYSIS.
Glycolysis is the biochemical process by which the glucose molecules are broken down in order to produce energy for the body. Embden-Meyerhof Pathway is one of the major pathway of glycolysis but it is not the only one, there are other glycolytic pathways in living organisms. Glycolysis is the principal way by which energy is supplied to the cells.

True statement gravity force is more on bigger mass, less on smaller mass.all mass fall on planet with same acceleration and speeds

If it doesn't have a nucleus its a prokaryote