Describe difference between dehydration reaction and hydrolysis. how do these reactions relate to macromolecules?

Dehydration reaction includes removal of water molecule from compounds to facilitate formation of bonds between them while hydrolysis reactions break the compounds by breaking the bonds.

Dehydration reactions form the complex macromolecules while hydrolysis reactions break them down into the simpler elements.

Explanation:

During dehydration reactions, removal of a water molecule from two compounds leads to the formation of a covalent bond between them. These reactions are mainly part of anabolic pathways. Two amino acids are joined together by peptide bond and a water molecule is released during the reaction.

Hydrolysis reactions are the opposite of dehydration reactions and are involved in catabolic pathways of macromolecules. The peptide bonds between amino acids are broken down by hydrolysis.  

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.