LS1.5 BIO1 Review

A student conducts an experiment to study the reaction of the enzyme lactase with the substrates sucrose and lactose. Both sucrose and lactose break down in the presence of an enzyme to form glucose. The table shows the experimental results.

Which conclusion is supported by the results of the experiment?

• The enzyme lactase reacts only with lactose to produce glucose

• The reaction of sucrose with the enzyme lactase depends on the temperature of the solution

• The activity of the enzyme lactase is unaffected by a change in its temperature

• The reaction of the enzyme lactase with a substrate is directly proportional to the amount of substrate present

Tags

BIO1.LS1.5

A student is investigating how substrate concentration affects the rate of an enzyme-catalyzed reaction. Which three variables should be kept constant in the setup of the student’s investigation?

• temperature of the reaction

• amount of substrate

• pH of the reaction

• amount of enzyme

• amount of product

Tags

BIO1.LS1.5

Receptor tyrosine kinases (RTKs) are a class of membrane receptor that, when bound by a specific signaling molecule, will enzymatically phosphorylate itself and initiate a response in the cell. A model representing RTK activation is shown.

A researcher is planning an experiment to engineer a nonfunctional version of an RTK. Which engineered protein will most likely be a nonfunctional RTK?

• an RTK protein with a second enzyme region in the cytosolic portion of the protein

• an RTK protein that is unable to bind to the signaling molecule

• an RTK protein that can phosphorylate itself even in the absence of a signaling molecule

• an RTK portion that has multiple phosphorylation sites

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BIO1.LS1.5

The graph shows the effect of temperature on the rate of an enzyme-catalyzed reaction in the presence of excess substrate.

If the reaction temperature were to increase from 40C to 63C the reaction rate would likely

• decrease, because the enzyme would become denatured

• decrease, because the enzyme would be used up

• increase, because the kinetic energy would increase

• stay the same, because the rate of enzyme-catalyzed reactions is constant

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BIO1.LS1.5

Enzymes are known to work on only one substrate.

Which substrate is correct for the enzyme shown?

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The specificity of an enzyme to its substrate is often compared to a lock and key.

Given the enzyme shown, which would be the correct substrate?

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Amylase is a digestive enzyme that is present in human saliva and the pancreas. It converts starch into simple sugars.

Which table must be true about the relative activity of amylase?

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Examine the pH data in Tables 1 and 2.

What can be inferred about the effectiveness of enzymes?

• Enzymes have specific substrates and work best in any pH.

• Enzymes do not have specific substrates and work best in any pH.

• Enzymes have specific substrates, so they work best within a small range of pH.

• Enzymes do not have specific substrates, so they work best within a small range of pH.

The breakdown of complex carbohydrates into glucose is completed in the small intestine during digestion. What protein acts as a catalyst to speed up the reaction?

• cellulose

• enzyme

• hormone

• steroid

An enzyme (catalase) is found in liver cells. Its function is to break down its substrate (hydrogen peroxide) into harmless water and oxygen.

What will happen to the enzyme (catalase) if the amount of substrate (hydrogen peroxide) keeps increasing?

• It will be used up, and the cells will be poisoned.

• It will be used up, and more of the enzyme will be produced.

• It will be denatured by the hydrogen peroxide.

• It will be reused to break down the hydrogen peroxide.

Tags

NGSS.HS-PS1-2