BIO.1B.2 Enzymes Review

Examine the pH data table. What can be inferred about the enzymes from this table?

• Enzymes can work with any substrate and any pH.

• Enzymes have specific substrates and can work with any pH.

• Enzymes have specific substrates and work best at a certain pH.

• Enzymes do not have a specific substrate but they do work best at a certain pH.

Match the following numbers to the correct label

• Neutral

• 0 - 6 on the pH scale is

• Base/Basic

• 7 on the pH scale is

• Acid/Acidic

• 8 - 14 on the pH scale is

Students are learning how different enzymes function at different pH levels. The pH in the intestines is basic. Which enzyme is most likely active in the intestines?

• Amylase because its optimum pH is 7

• Trypsin because its optimum pH is 9

• Pepsin because its optimum pH is 2

• Amylase because its optimum pH is 10

The table above shows the results of an experiment done by Juan and Cindy. Juan and Cindy placed hydrogen peroxide on several food samples and recorded the relative amount of fizz that each produced. The fizz was produced by oxygen bubbles released by the action of the enzyme catalase, which is found in almost every living cell. Which of these is a valid conclusion from their data?

• Plant cells produce more oxygen bubbles than animal cells.

• Boiled potato and cooked liver produced the most oxygen bubbles.

• Raw liver produced the most oxygen bubbles, followed by raw potato.

• Cooking the foods seems to increase the activity of the catalase enzyme.

What is another word for base?

• Acid

• Alkaline

• Neutral

• pH

How does an enzyme work as a catalyst to speed up chemical reactions?

• It changes the shape of the active site

• It increases the temperature of the reaction

• It increases the concentration of the substrate

• It lowers the activation energy needed to start the reaction

Look at the picture. What is label B pointing to?

• The enzyme

• The substrate

• The products

• The active site

The graph illustrates the activity level of three common digestive enzymes, across a range of pH values. Which enzyme is likely to be the most active in the acidic environment of the stomach?

• Pepsin

• Trypsin

• Amylase

• Pepsin & amylase

Trypsin and pepsin are both enzymes in the digestive system which catalyze the breakdown of proteins in food into smaller peptide chains or into individual amino acids. However, like other enzymes, they differ in their substrate and optimal conditions. Analyze the graph and select ALL of the statements that accurately describe the action of trypsin and pepsin.

• Trypsin has an optimal pH of 8.

• Pepsin works best at a pH of 3.

• Both enzymes have an optimal pH of 7.

• Pepsin works best in more acidic conditions.

• Trypsin works best in more acidic conditions.

Catalase is an enzyme found in the liver that breaks down hydrogen peroxide (H₂CO₃) into water (H₂O) and oxygen gas (O₂). Students in biology class performed an experiment to test the activity of catalase at different pH levels. When the enzyme is working, oxygen gas bubbles are formed. The diagram below shows the students’ results. Based on the diagrams, catalase works best in…

• A strongly acidic solution

• A neutral solution

• A weakly acidic solution

• A strongly basic solution