Unit 3 AP Biology (Cellular Energetics)

Where does the substrate bind on an enzyme?

• Active site

• Enhancer

• Promoter

• TATA box

Answer explanation

The active site is the location on the enzyme where the substrate binds. Once this binds, it is called the substrate/enzyme complex.

What is a competitive inhibitor?

• Binds to the same site as the substrate.

• Binds to a different site than the substrate.

• Binds to the substrate to inhibit the reaction.

• Binds to the product to inhibit the reaction.

Answer explanation

Competitive inhibitors will bind to the same active site as the substrate. This is why we call them COMPETITIVE because they will COMPETE for the active site.

Which describes light independent reactions?

• Calvin cycle to break bonds to release carbon dioxide

• Calvin cycle to synthesize organic compounds

• Krebs cycle to break bonds to release carbon dioxide

• Krebs cycle to synthesize organic compounds

Answer explanation

Light independent reactions involves a process that does NOT require light. The Calvin Cycle itself does not require the light, but the products of the light reactions.

Tags

NGSS.HS-LS2-5

Any increase in heat will denature an enzyme.

• False

• True

Answer explanation

An increase in heat will increase the kinetic energy of the molecules, but as long as it is within the optimal range of the enzyme, it will not denature. This will speed up the chemical reaction as the molecules absorb the energy increasing collision frequency and collision energy.

Which step of photosynthesis takes place in stroma?

• Calvin Cycle

• Glycolysis

• Krebs Cycle

• Light Reactions

Answer explanation

Calvin cycle takes place in the stroma (cytosol of the chloroplast) while the Light Reactions take place on the thylakoid membrane.

As the product concentration increases, the reaction rate ____?

• Decreases

• Increases

• Stays the Same

Answer explanation

As the product increases, it will be more likely to enter the active site. Since it will enter the active site, it can act as a competitive inhibitor which will decrease the reaction rate. As the product will inhibit the reactant from binding to the enzyme.

Tags

NGSS.HS-PS1-5

Which provided evidence of oxygen generation in the atmosphere?

• Production of ATP without a mitochondria

• Production of fire on earth’s surface

• Production of iron oxide bands in rock layers

• Production of organic compounds

Answer explanation

The iron will oxidize in the presence of oxygen. The fossil evidence shows banding in the rock layers which represents the generation of oxygen by photosynthesis.

How does an enzyme affect activation energy?

• Decrease

• Increase

• Stays the Same

Answer explanation

Enzymes will decrease the activation energy of a reaction by orienting the reactants or straining the bonds.

How can you overcome a competitive inhibitor?

• Add more ATP

• Add more inhibitor

• Add more products

• Add more reactants

Answer explanation

Competitive inhibitors will bind to the active site which is the SAME site as the substrate. In order to overcome this, you can increase the number of reactants (aka substrates) so there’s a higher probability of a substrate binding over an inhibitor.

Enzymes are consumed by the reaction and must be re-added.

• True

• False

Answer explanation

Enzymes are the worker horses of the cell. After they participate in the reaction, their structure returns back which allows for another substrate to bind for another reaction.