Enzymes

Enzymes are proteins that act as catalysts to speed up chemical reactions within cells. The specific shape at the opening of an enzyme is called the active site. Only a specific molecule fits into an active site and binds to the enzyme. The molecule is then converted into products and released from the enzyme. Digestive enzymes help to break food down into nutrients that the body needs. The diagram shows the amino acids that are found in a digestive enzyme.

Notice the two other digestive enzymes are shown below....

Which statement best describes all three enzymes?

• The enzymes have different structures because they have a different sequence of amino acids.

• The enzymes have the same sequence of amino acids because they are all digestive enzymes.

• The enzymes perform different functions because they have the same sequence of amino acids.

• The enzymes break down the same molecules because they have a different sequence of amino acids.

Hormones are proteins that act as chemical-signaling molecules in the body. Each hormone plays a unique role in regulating processes such as growth, development, and reproduction. The diagram shows the hormones oxytocin and vasopressin.

Using the diagram, which three sentences correctly describe the hormones?

• The hormones have the same amino acids.

• The hormones have two unique amino acids.

• The hormones perform different functions.

• The hormones have the same number of amino acids.

• The hormones perform the same function.

The balanced equation below summarizes the decomposition of hydrogen peroxide when the enzyme catalase is added:

2H₂O₂ 2H₂O + O_2(g)

Over time it was observed that the production of bubbles decreased. Why did this most likely occur?

• The concentration of the water decreased.

• The concentration of the water increased.

• The concentration of the hydrogen peroxide (H₂O₂) increased.

• The concentration of the hydrogen peroxide (H₂O₂) decreased.

A group of students conducts research on enzyme activity and collects the data shown in the graphs.

Which statement is supported by the evidence in the graphs?

• The enzyme is very active at approximately 42°C and within a pH range of 2 to 6.

• The enzyme functions well at a temperature of 35°C and would be active at any pH value.

• The enzyme works best in a pH of 7 and at a temperature of approximately 38° C.

• he enzyme's activity is greatest at pH 7 and would not be affected by a change in temperature.

Biological catalysts are involved in many processes that occur in the human body. The illustration represents a series of reactions that occurs in the body.

High temperatures can cause bonds between amino acids to permanently change. If the bonds between amino acids change, the shape of the catalyst will also change. This can cause the reaction to slow. Which of the following arguments is supported by this information?

• Altering the bonds of amino acids will cause a reaction to lose energy.

• The heat in a reaction can misshapen the original molecules to the point where they cannot bond.

• Adding heat to a reaction will slow the rate of the reaction.

• The shape of a biological catalyst will affect its ability to help connect or break apart the original molecules.

Which equation represents an enzyme’s function in chemical reactions?​ ​ (a)  

• substrate + enzyme → product + enzyme
• substrate + enzyme → product
• product + substrate → enzyme