Question

1. when a substance loses electrons it is a reaction.
2. when a substance gains electrons it is a reaction

question 7
an enzyme is which type of organic molecule?
protein
carbohydrate
nucleic acid
lipid
question 8
why are enzymes considered important biological catalysts?
enzymes lower the entropy of a biochemical reaction.
enzymes lower the activation energy of a biochemical reaction.
enzymes supply the energy to initiate a biochemical reaction.
enzymes increase the activation energy of a biochemical reaction.

Explanation:

• Question 7: Enzymes are proteins. Proteins are large, complex molecules made up of amino acids. Many enzymes are globular proteins that can catalyze biochemical reactions in living organisms. Carbohydrates are sugars and starches, nucleic acids (like DNA and RNA) store genetic information, and lipids are fats and oils—none of these are the primary class that enzymes belong to.
• Question 8: Enzymes lower the activation energy of a biochemical reaction. Activation energy is the minimum energy required for a reaction to occur. By lowering this energy barrier, enzymes speed up reactions. They do not supply energy to initiate reactions (that would be like reactants providing energy in some cases, but not enzymes), increasing activation energy would slow reactions (opposite of what enzymes do), and entropy (a measure of disorder) is not directly related to how enzymes act as catalysts in the context of activation energy reduction.

Answer:

• Question 7: Protein
• Question 8: Enzymes lower the activation energy of a biochemical reaction.