Adecrease in entropy is associated with which type of reaction

A decrease in entropy is associated with Anabolic reactions. 
Anabolic reactions are powered by catabolism where large molecules are broken down into smaller parts and then used up in cellular respiration. Many anabolic processes are powered by the hydrolysis of ATP. Living organisms are able to make highly ordered structures by coupling free energy- yielding catabolic processes ( increase in entropy) with energy requiring anabolic processes (decrease entropy).

Mass is the amount of matter in an object.  weight is the measurement of the pull of gravity on an object.  say for example, you travel to the moon which has a different gravitational field compared to the gravitational field of earth. (gravitational fields: earth = 1, moon = 0.165)  now when you are on the moon, the pull of gravity on you is different than on the earth. and as weight is the measurement of the pull of gravity on an object, that means yes, your weight can and will change on the moon.  however, on the moon, on earth or even on jupiter, the amount of mass inside of you remains the same. meaning your physical mass remains constant.  in conclusion it is possible for your weight to change as your mass remains constant.