Unit 3 Test Review

For the following questions: Graphs I-IV depict the effect of pH on the activity of four different hydrolytic enzymes. Enzymes with their highest activity at an alkaline (basic) pH are represented by which of the following graphs?

• I only

• II only

• III only

• I and III only

• I and IV only

For the following questions: Graphs I-IV depict the effect of pH on the activity of four different hydrolytic enzymes. Graphs representing enzymes sensitive to changes in pH include which of the following?

• I only

• IV only

• II and III only

• III and IV only

• I, II and III

For the following questions: Graphs I-IV depict the effect of pH on the activity of four different hydrolytic enzymes. The most likely explanation for the results shown in Graph I is that

• pH affects the shape of the active site of the enzyme

• pH affects the temperature of the reaction

• the enzyme has a quaternary structure

• the enzyme has disulfide bonds

• pH affects the primary structure of the enzyme

The diagram above shows energy changes in a specific chemical reaction with and without the addition of an enzyme to the reaction. Which of the following questions can best be answered by the diagram?

• Does the addition of an enzyme reduce the activation energy required for a reaction?

• Does the addition of an enzyme result in the formation of covalent bonds?

• Does the addition of an enzyme produce a greater amount of products?

• Does the addition of an enzyme change the pathway for the reaction?

Tags

NGSS.HS-PS1-4

A researcher proposes a model of an enzyme-catalyzed reaction in which a reactant is converted to a product. The model is based on the idea that the reactant passes through a transition state within the enzyme-substrate complex before the reactant is converted to the product.

Which of the following statements best helps explain how the enzyme speeds up the reaction?

• The enzyme’s active site binds to and stabilizes the reactant, which decreases the free-energy change of the reaction.

• The enzyme’s active site binds to and stabilizes the transition state, which decreases the activation energy of the reaction.

• The enzyme’s active site binds to and stabilizes the product, which increases the amount of energy released by the reaction.

• The enzyme’s active site binds to and stabilizes both the reactant and the product at the same time, which increases the reaction’s equilibrium constant.

Tags

NGSS.HS-PS1-5

A researcher claims that the synthesis of ATP from ADP and inorganic phosphate (Pi) is essential to cellular function. Which of the following statements best helps justify the researcher’s claim?

• ADP is a small molecule that some cells release into their environment as a way of communicating with other cells.

• ATP hydrolysis is an energy-releasing reaction that is often coupled with reactions that require an input of energy.

• Inorganic phosphate(Pi) is a substance that cells typically acquire from their environment.

• ATP synthase is a mitochondrial enzyme that catalyzes the conversion of ADP and Pi to ATP.

Tags

NGSS.HS-LS1-7

The figures above illustrate the similarities between ATP synthesis in mitochondria and chloroplasts. The figures can best assist in answering which of the following questions?

• Do electron transport chains create a gradient so that ATP synthase can generate ATP molecules?

• What are the sources of energy that drive mitochondrial and chloroplast electron transport systems?

• What is the optimal temperature at which ATP synthase chemically converts ADP and a phosphate group into one molecule of ATP?

• What is the evolutionary relationship between the ATP synthase in mitochondria and the ATP synthase in chloroplasts?

The energy required to run the Calvin cycle reactions of photosynthesis comes from which two substances produced during the light-dependent reactions?

• ATP and NADPH

• ADP and PO4

• H+ and PO2

• O2 and CO2

• H2O and CO2

A researcher claims that only a portion of the light energy captured by green plants is available for growth and repair. Which of the following observations best helps justify the researcher’s claim?

• Light-capturing pigment molecules in green plants absorb red, blue, and violet light but reflect green light.

• The energy of a photon of light is proportional to its frequency and inversely proportional to its wavelength.

• As light energy is converted to chemical energy by metabolic processes, some of the energy is lost as heat.

• Captured energy is stored in the molecular bonds of organic molecules, including simple sugars and starch.

Tags

NGSS.HS-LS1-5

Which of the following statements about mitochondrial chemiosmosis is NOT true?

• A proton gradient is established across the inner membrane of the mitochondrion.

• The potential energy released from the mitochondrial proton gradient is used to produce ATP.

• The mitochondrial proton gradient provides energy for muscle contraction.

• Proteins embedded in the inner mitochondrial membrane play an important role in ATP synthesis.

• Heat energy is required to establish the electron transport chain.

Tags

NGSS.HS-LS1-7