TEKS 9A&C-Biomolecules/Enzymes

A substance with a pH of 6 is called

• an acid
• a base
• water
• a suspension

What kinds of atoms are bonded to carbon atoms in the molecule shown?

• helium, oxygen, and nitrogen
• calcium, hydrogen, and oxygen
• hydrogen, oxygen, and nitrogen
• helium, carbon, and sodium

Which statement is true about macromolecules?

• Simple sugars are made of polysaccharides.
• Glycerol is made of fatty acids.
• Proteins are made of amino acids.
• Nucleotides are made of nucleic acids.

An enzyme serves as a place where a chemical reaction can occur because-

• the enzyme is a substrate.
• the enzyme is one of the reactants in the reaction.
• the charge on the enzyme's active site is the same as the charge on the substrates.
• the shape of the substrates fits perfectly into the shape of the enzyme's active site.

Most enzymes work best at about 37°C, normal body temperature, and each one

• is usually specific to only one type of chemical reaction in the body.
• serves as a catalyst for several kinds of reactions.
• helps speed up reactions by a factor of 2.
• helps slow down reactions by a factor of 10.

An enzyme acts as a catalyst to a chemical reaction by

• lowering the activation energy needed to get the reaction started.
• making one of the substrates needed for the reaction.
• regulating the temperature at which the reaction takes place.
• regulating the pH at which the reaction takes place.

How do enzymes control chemical reactions in the body?

• Enzymes speed up chemical reactions.
• Enzymes slow down chemical reactions.
• Enzymes increase the activation energy of a reaction.
• Enzymes inhibit the catalysts of a reaction.

In addition to serving as waterproof coverings or as parts of biological membranes, lipids

• store glucose and other sugars.
• store energy.
• transmit hereditary information.
• supply energy for chemical reactions.

The ability of an enzyme to function properly depends on its environment. Unlike most enzymes in the human body, you would expect enzymes produced by the stomach to function best in an environment where

• the temperature is above normal body temperature.
• the acidity is very high.
• there are many other enzymes.
• the salt concentration is very high.

four most common elements that make up all living things are carbon, hydrogen,

• nitrogen, and iron.
• oxygen, and nitrogen.
• calcium, and phosphorus.
• oxygen, and iron.