Mastering biology chapter 5

You can recognize the process of pinocytosis when _____.

the cell is engulfing extracellular fluid

Osmosis can be defined as ________.

the diffusion of water across a selectively permeable membrane

Water crosses the plasma membrane

through facilitated diffusion or diffusion.

Facilitated diffusion across a biological membrane requires ________ and moves a substance ________ its concentration gradient.

transport proteins; down

The sum total of all the chemical reactions that occur in organisms is called ________.

metabolism

If placed in tap water, an animal cell will undergo lysis, whereas a plant cell will not. What accounts for this difference?

relative inelasticity and strength of the plant cell wall

An enzyme's function is most dependent on its ________.

shape

During an enzymatic reaction, a molecule of __________ binds to the enzyme and is broken down into one or more molecules of _________, which are released.

substrate, product

Which statement about an enzyme is TRUE?

An enzyme's function depends on its three-dimensional shape

________ occurs when a white blood cell engulfs a bacterium.

Phagocytosis

Active transport

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

The ________ between an active site and its substrate often strains bonds and helps the reaction proceed.

induced fit

A(n) __________ is a molecule that can bind to an enzyme and prevent the enzyme from working.

inhibitor

Substances that plug up an enzyme's active site are enzyme ________.

inhibitors

Endocytosis moves materials _____ a cell via _____.

into ... membranous vesicles

Exocytosis

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

A cell that neither gains nor loses a net amount of water at equilibrium when it is immersed in a solution is ________.

isotonic to its environment

Diffusion across a biological membrane is called _______________.

passive transport

Facilitated diffusion is a type of _____.

passive transport

A white blood cell engulfing a bacterium is an example of _____.

phagocytosis

Which one of the following terms is sometimes called "cell eating"?

phagocytosis

Diffusion ________.

proceeds until a dynamic equilibrium is reached

Usually, enzymes are ________.

proteins

The region of an enzyme to which a substrate binds is called the ________ site.

active

The specific location within an enzyme molecule where the substrate binds is called the ____________.

active site

"The use of energy to move molecules across a membrane" is the definition of __________.

active transport

The concentration of calcium in a cell is 0.3%. The concentration of calcium in the surrounding fluid is 0.1%. How could the cell obtain more calcium?

active transport

Which process could result in the net movement of a substance into a cell, if the substance is more concentrated in the cell than in the surroundings?

active transport

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.

In a hypotonic solution, a plant cell will ________.

become turgid

An enzyme is considered a(n) _________ because it speeds up a chemical reaction without being used up.

catalyst

High temperatures or changes in pH can _________ an enzyme, causing it to lose its shape and biological activity.

denature

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

endocytosis.

Lactose takes years to break down on its own. But if exposed to the protein lactase, the reaction proceeds very quickly, while lactase itself remains unchanged. Lactase is an example of a(n) ____________.

enzyme

Specialized cells that line the stomach synthesize a digestive enzyme and secrete it into the stomach. Which process could be responsible for its secretion?

exocytosis

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

facilitated diffusion.

In osmosis, water moves across a selectively permeable membrane toward the __________ solution; that is, toward the solution with the __________ solute concentration.

hypertonic ... greater

What compound directly provides energy for cellular work?

ATP

Which is a true statement about the ATP cycle?

A single muscle cell needs only about one minute to recycle all of its ATP.

Diffusion

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

Facilitated diffusion

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

Endocytosis

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

A balloon that is permeable to water but not to glucose contains a 10% glucose solution. A beaker contains a 5% glucose solution. Which statement correctly classifies the solutions?

The solution in the balloon is hypertonic relative to the solution in the beaker.

A balloon contains a 10% glucose solution. The balloon is permeable to water but not to glucose. A beaker contains a 5% glucose solution. What will happen when the balloon is submerged in the beaker?

The volume of water in the beaker will decrease.

Which one of the following is an example of osmosis?

Water enters a plant by passing through the root cell membranes.

Enzymes speed up chemical reactions by lowering the ____________, which allows the reaction to proceed much more quickly.

activation energy

Enzymes increase the rate of a reaction by ________.

decreasing activation energy

When molecules move down their concentration gradient, they move from where they are __________________ to where they are _____________.

more concentrated, less concentrated