Mastering Biology Chapter 5

Which one of the following is TRUE?

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

Water crosses the plasma membrane

through facilitated diffusion or diffusion.

When molecules move down their concentration gradient, they move from where they are __________ to where they are ______________.

more concentrated... less concentrated

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

transport proteins... down

What compound directly provides energy for cellular work?

ATP

In osmosis, water always moves toward the __________ solution, that is, toward the solution with the __________ solute concentration.

hypertonic... greater

You can recognize the process of pinocytosis when __________.

the cell is engulfing extracellular fluid

A(n) _______________ is a molecule that can bind to an enzyme and prevent the enzyme from working. There are two types; a(n) _____________ binds to the active site of the enzyme; a(n) _____________ binds elsewhere on the enzyme.

inhibitor...competitive inhibitor... noncompetitive inhibitor

Endocytosis moves materials __________ a cell via ____________.

into... membranous vesicles

Which one of the following is most similar to the mechanism of an enzyme inhibitor?

keeping someone from parking by parking in their designated spot

Diffusion __________.

proceeds until equilibrium is reached

Structure A is a ____________.

solute

Osmosis can be defined as _____________.

the diffusion of water across a selectively permeable membrane

Some large molecules move into or out of cells by exocytosis or endocytosis. Drag the correct label under each diagram.

a. exocytosis b. endocytosis

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

activation energy

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

diffusion

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

endocytosis

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

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

In active transport

molecules move across the plasma membrane against their concentration gradient

Usually, enzymes are ____________.

proteins

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

shape

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

the relative inelasticity and strength of the plant cell wall

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

metabolism

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

Facilitated diffusion is a type of _____________.

passive 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.

Which one of the following is an example of osmosis?

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

Certain molecules use facilitated diffusion to cross the plasma membrane. Drag the labels to their appropriate locations on the diagram.

a. plasma membrane b. side with higher concentration of molecules c. side with lower concentration of molecules d. facilitated diffusion causes a net movement of molecules down their concentration gradient e. transport protein

Certain molecules use diffusion to cross the plasma membrane. Drag the labels to their appropriate locations on the diagram.

a. side with higher concentration of molecules b. plasma membrane c. side with lower concentration of molecules d. diffusion causes a net movement of molecules down their concentration gradient

Certain molecules cross the plasma membrane through the process of active transport. Active transport requires an input of energy and moves molecules against their concentration gradient. Drag the labels to their appropriate locations on the diagram.

a. side with lower concentration of square molecules b. transport protein c. energy input from the cell d. plasma membrane e. side with higher concentration of square molecules

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

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

enzyme inhibitors

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

phagocytosis

Structure B is a _____________.

transport protein

Diffusion across a biological membrane is called __________.

passive transport

In a hypotonic solution, a plant cell will ____________.

become turgid

Enzymes increase the rate of a reaction by ___________.

decreasing activation energy

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

phagocytosis

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

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

The use of energy to move molecules across a membrane defines ____________.

active transport

Which of the following processes 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

A balloon permeable to water but not to glucose contains a 10% glucose solution. A beaker contains a 5% glucose solution. Which of the following is TRUE?

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

A balloon permeable to water but not to glucose contains a 10% glucose solution. 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.

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

exocytosis

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

facilitated diffusion

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

facilitated diffusion.