Substance A is converted to substance B in a metabolic reaction. Which statement best describes the role of an enzyme during this reaction?
It adjusts the pH of the reaction.
It provides energy to carry out the reaction.
It dissolves substance A in the reaction medium
It speeds up the reaction without being consumed.
Carbohydrates and proteins are two types of macromolecules. Which functional characteristic of proteins distinguishes them from carbohydrates?
Large amount of stored information
Ability to catalyze biochemical reactions
Efficient storage of usable chemical energy
Tendency to make cell membranes hydrophobic
Use the diagram below to answer the question.
Glycolysis
Hydrolysis
Photosynthesis
Dehydration synthesis
The difference between the structures of proteins and carbohydrates is that proteins are made of...
Carbon
Hydrogen
Oxygen
Nitrogen
A scientist observes that, when the pH of the environment surrounding an enzyme is changed, the rate the enzyme catalyzes a reaction greatly decreases. Which statement best describes how a change in pH can affect an enzyme?
A pH change can cause the enzyme to change its shape.
A pH change can remove energy necessary to activate an enzyme.
A pH change can add new molecules to the structure of the enzyme.
A pH change can cause an enzyme to react with a different substrate.
An enzyme speeds up a reaction by...
Lowering the activation energy
Raising the activation energy
Releasing energy
Absorbing energy
Which statement correctly describes how carbon's ability to form four bonds makes it uniquely suited to form macromolecules?
It forms short, simple carbon chains.
It forms large, complex, diverse molecules.
It forms covalent bonds with other carbon atoms.
It forms covalent bonds that can exist in a single plane.
What does the following formula represent?
A sugar
A starch
An amino acid
A fatty acid
Which statement best describes an effect of the low density of frozen water in a lake?
When water freezes, it contracts, decreasing the water level in a lake.
Water in a lake freezes from the bottom up, killing most aquatic organisms
When water in a lake freezes, it floats, providing insulation for organisms below.
Water removes thermal energy from the land around a lake, causing the lake to freeze.
Compared to most other substances, a great deal of heat is needed to raise the temperature of water by a given amount. This is because water...
Is an acid
Readily forms solutions
Has a high heat capacity
Acts as a buffer