Topics 3.1 - 3.3 Enzymes

Which of the following correctly describes how enzymes work?  

• they lower the energy of the reactants to increase the rxn rate

• they supply energy to the reaction to increase the rxn rate

• they lower the energy of the products to increase the rxn rate

• they lower the activation energy of the reaction to increase the rxn rate

Answer explanation

Enzymes work by lowering the activation energy of a reaction, which increases the reaction rate. This allows the reactants to convert to products more easily without altering the energy of the reactants or products.

Tags

NGSS.HS-PS1-5

What type of macromolecule are enzymes?

• Protein

• Carbohydrate

• Lipid

• Nucleic Acid

Answer explanation

Enzymes are biological catalysts that speed up chemical reactions in the body. They are primarily made of proteins, which are macromolecules composed of amino acids. Therefore, the correct answer is Protein.

Tags

NGSS.HS-LS1-1

NGSS.HS-LS1-6

Enzymes are made up of these repeating monomers.

• monosaccharides

• amino acids

• nucleotides

• phospholipids

Answer explanation

Enzymes are biological catalysts composed of amino acids, which are the repeating monomers that link together to form proteins. Other options like monosaccharides and nucleotides are not involved in enzyme structure.

Tags

NGSS.HS-LS1-1

NGSS.HS-LS1-6

The part of the enzyme that the substrate bonds to is called the _____.

• active site

• activation energy

• bond site

• peptide bond

Answer explanation

The part of the enzyme that the substrate bonds to is called the active site. This region is specifically shaped to fit the substrate, facilitating the biochemical reaction.

The energy needed to start a reaction

• activation energy

• adhesion energy

• chemical energy

• cohesion energy

Answer explanation

The energy needed to start a reaction is called activation energy. It is the minimum energy required for reactants to undergo a chemical reaction, making it essential for initiating the process.

Tags

NGSS.HS-PS1-4

Which of these is NOT true?

• Enzymes can denature (change shape) when the temperature gets too high.

• Enzymes can only be used once in a chemical reaction. 

• Extreme pH can denature enzymes.

• Enzymes speed up chemical reactions. 

Answer explanation

The statement "Enzymes can only be used once in a chemical reaction" is NOT true. Enzymes can be reused multiple times after catalyzing a reaction, which distinguishes them from other catalysts.

Tags

NGSS.HS-PS1-5

Which of the following is directly responsible for the shape of an enzyme/protein?

• The amino acid sequence of the protein and the properties of the amino acids that make up the protein.

• The temperature of the surrounding environment.

• The pH of the surrounding environment.

• The amount of substrate present.

Answer explanation

The shape of an enzyme/protein is determined by its amino acid sequence and the properties of those amino acids, which dictate how the protein folds. Other factors like temperature and pH can affect stability but not the inherent shape.

Energy is released from ATP when

• a phosphate group is added

• adenine bonds to ribose

• ATP is exposed to sunlight

• a phosphate group is removed

Answer explanation

Energy is released from ATP when a phosphate group is removed. This process, known as hydrolysis, breaks the bond between the second and third phosphate groups, releasing energy for cellular activities.

Tags

NGSS.HS-LS1-7

Cyanide is a toxin that stops the mitochondria from producing ATP. If cyanide were introduced into your cells, it is probably acting as a(n)

• activator

• coenzyme

• inhibitor

• substrate

Answer explanation

Cyanide inhibits the function of mitochondria, preventing ATP production. Therefore, it acts as an inhibitor, blocking the normal biochemical processes necessary for energy production in cells.

Tags

NGSS.HS-LS1-7

NGSS.HS-LS2-5

Whenever energy is transformed, there is always an increase in the ______________

• free energy and enthalpy of the universe

• free energy of the universe

• entropy of the universe

• enthalpy of the univers

Answer explanation

The correct answer is 'entropy of the universe' because, according to the second law of thermodynamics, whenever energy is transformed, the total entropy of the universe always increases, indicating a tendency towards disorder.