Chapter 5 Mastering Biology

Which of the following is highest in chemical energy.

One molecule of glucose.

Active Transport

Requires energy from the cell. Molecules move against their concentration gradient.

The hydrolysis of DNA into nucleotides constitutes an exergonic reaction. Yet, DNA is quite stable. Why is this the case?

The activation energy required to initiate this reaction is seldom reached.

Endocytosis

The plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell.

An enzyme speeds up reactions by lowering the _____

activation energy

An enzyme is specific because the shape of its______ matches only particular reactants.

active site

The sodium-potassium pump uses energy from ATP to move sodium ions out of the cell, and potassium ions into the cell. This is an example of:

active transport

High temperature or changes in pH can____ an enzyme, causing it to lose its shape and biological activity.

denature

There is a net diffusion of water out of an animal cell when it is placed in _____ solution

hypertonic

An animal cell placed in a _____ solution will gain water, swell, and possibly burst.

hypotonic

The ideal osmotic environment fro a plant cell is an _____ environment.

hypotonic

The _______ between n active site and its substrate often strains bonds and helps the reaction proceed.

induced fit

A plant cell surrounded by _____ solution will be flaccid( limp)

isotonic

Kinetic Energy is energy in motion. Potential energy is ______ energy

stored

Macrophages are white blood cells that roam the body searching for invading microbes. Inside macrophage vacuoles these invaders are destroyed. How do the microbes get inside the macrophages?

Microbes are engulfed into the macrophage via phagocytosis.

In active transport

Molecules move across the plasma membrane against their concentration gradient.

A plant cell placed in a ____solution will lose water and plasmolyze

hypertonic

The ideal osmotic environment for an animal cell is an ________ environment.

isotonic

In a catalyzed reaction, a reactant is often called _____

substrate

Water cross the plasma membrane....

through facilitated diffusion or diffusion.

Energy is conserved. This means that in any system_______

total energy input equal total energy output.

Exocytosis

A vesicle inside the cell fuses with the plasma membrane and releases its contents outside the cell.

Which statement regarding enzyme function is true?

Excessive salt ions can cause an enzyme to denature.

In cellular respiration, most energy is released and transferred to ATP when

high energy electrons fall to lower energy levels.

Facilitated Diffusion

A form of passive transport. Molecules move across the membrane using a transport protein.

A_____ which is often a vitamin, binds to an enzyme and plays a role in catalysis.

coenzyme

Diffusion

A form of passive transport. Molecules move across the plasma membrane by crossing the lipid bilayer.

Which of the following is an accurate comparison of active transport and facilitated diffusion?

Active transport moves solutes against their concentration gradient; facilitated diffusion moves substances down their concentration gradient.

Frequently, transplanted organs are rejected by the recipient's body. How is this reaction related to plasma membranes?

Each person has a unique set of carbohydrate chains attached to his or her plasma membranes.

An enzyme is considered a ____because it speeds up a chemical reaction without being used up.

catalyst

The plasma membrane forms a pocket that pinches inward, forming vesicle that contains material from outside the cell. This describes the process of

endocytosis

A molecule moves down its concentration gradient using a transport protein in the plasma membrane. This is an example of

facilitated diffusion.

You're on the pilot episode of a new reality show called "The Transport Factor." The host hands you three different amino acids, four different sugars, and two different ions. Then the host shouts, "How many different proteins does the cell need to move these molecules across the plasma membrane using facilitated transport?" Quickly, you correctly respond: _____.

nine

Osmosis is often viewed incorrectly as a process driven directly by differences in solute concentration across a selectively permeable membrane. What really drives osmosis?

the difference in water concentration across a selectively permeable membrane

What controls the direction of a molecule, such as oxygen, involved in passive transport?

the direction of the oxygen concentration gradient