The primary structure of a protein is simply the linear amino acid sequence from which the protein is made. "Secondary structure" refers to the folding and coiling of this single strand as it interacts with itself, forming hydrogen bonds between amino acids of that strand. Alpha helices and beta-pleated sheets are two different types of secondary structures that can be formed by hydrogen-bonding between amino acids of a protein sequence that has folded over onto itself. "Tertiary structure" refers to the final three-dimensional structure of a single protein subunit. "Quaternary structure" refers to the non-covalent interactions between multiple protein subunits which come together to form a larger protein.

This question ultimately hinges on knowing the difference between ribozymes and spliceosomes because transferase, hydrolase, and lyase should all be recognized as proteins that function as enzymes. Transferase catalyzes reactions that facilitate the transfer of functional groups. Hydrolase works to catalyze hydrolysis reactions. Lyase works to catalyze reactions that break down double bonds. Spliceosomes are a unit of proteins and RNA that work to catalyze reactions that splice out introns in RNA to form mature mRNA ready for translation. Ribozymes are important because they also splice RNA into mRNA, but they do not have a protein component to them. The discovery of Ribozymes was a breakthrough in that it was the first evidence that not all enzymes are proteins.

Enzymes have an "optimal temperature," or best temperature that they work at. If that temperature is below or above its optimal temperature, the enzyme will decrease in activity; if the temperature change is great enough, the enzyme could even denature (no longer work).

The questions is asking how enzymes affect reactions. The function of an enzyme is to speed up chemical reactions, which will increase the overall rate of the reaction, thus "increasing the rate of the reaction" is the correct answer. 

The function of an enzyme is to speed up chemical reactions. They do this by lowering the activation energy, which is the minimum energy that must be available for a chemical reaction to occur. If the energy required is lowered, the reaction can go faster. Thus the correct answer is an enzyme changes "the activation energy of the reaction."

A reactant is a substance that undergoes change during a reaction. During an enzyme reaction specifically, the reactant is called the substrate, as a substrate is the substance in which an enzyme acts on and changes. 

Both pH and temperature can affect how productive an enzyme is. If an enzyme is functioning in an environment that is not at its optimal pH or optimal temperature, the enzyme's activity will decrease. 

An enzymes function is to speed up chemical reactions by lowering the activation energy. If our bodies did not have enzymes, the reactions would take place, but too slowly for our cells to adequately function.

DNA helicase is an enzyme that is able to slip between the two strands of DNA and disrupt the hydrogen bonds that keep the DNA in the double helix structure. This disruption opens up the DNA helix, and exposes sections of DNA that can then be transcribed or replicated. As helicase moves down the double helix, the DNA reforms into a double helix since the enzyme is no longer blocking the hydrogen bonds.

These are all definitive traits of an enzyme. Enzymes are proteins which are extremely helpful in speeding up certain reactions without being depleted by the reactions themselves (as such, they are catalysts for these reactions). Enzymes reduce the amount of energy needed for a reaction to occur, generally because they facilitate reactions by recognizing reactants and bringing them into contact with each other. This occurs when the reactants bind to certain parts of the enzyme (active sites), which causes the enzyme to change shape and bring the reactants into contact with each other (and then the reactants can bind to form the product).