Macromolecules

As food travels through the digestive system, it is exposed to a variety of pH levels. The stomach has a pH of 2 due to the presence of hydrochloride acid (HCl), and the small intestine has a pH ranging from 7 to 9. HCl converts pepsinogen into pepsin, an enzyme that digests proteins in the stomach. Which of the following most likely happens to pepsin as it enters the small intestine?

• A. It becomes inactive.

• B. It begins to replicate.

• C. It's shape changes to engulf large proteins.

• D. It's activity increases to digest more proteins.

You are analyzing a compound in the laboratory. You find that it is made up of carbon, hydrogen, and oxygen in a ratio of two hydrogen atoms for each carbon atom. How will you classify the compound?

• A. lipid

• B. protein

• C. carbohydrate

• D. nucleic acid

Fats, oils and cholesterol are all types of what?

• A. cell membranes

• B. hormones

• C. lipids

• D. fatty acids

What will most likely happen if an appropriate enzyme is added to a chemical reaction?

• A. The reaction rate will increase.

• B. The equilibrium of the reaction will be maintained.

• C. The reaction rate will decrease.

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• D. The reaction will stop.

A sugar, a phosphate group, and a nitrogen base form the building blocks of which organic compound?

• A. carbohydrates

• B. lipids

• C. nucleic acids

• D. proteins

The human body maintains a temperature of around 98.6 degrees at all times. Enzymes are involved in almost every chemical reaction in the body. Which of the following describes the connection between these two statements?

• A. Enzymes function best at a specific temperature.

• B. The body needs to be warm to prevent hypothermia.

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• C. The body is kept relatively warm to prevent too much enzyme action.

• D. There is no connection between the two statements.

The enzyme lactase will break down the sugar lactose into which of the following components?

• A. monosaccharides

• B. nucleic acids

• C. amino acids

• D. phospholipids