BIO Chapter 5 Q's

reducing activation energy-

1. Enzymes work by _____.

facilitated diffusion- In facilitated diffusion, molecules use a transport protein to move across the plasma membrane. There is a net movement of molecules down the concentration gradient -- that is, there is a net movement of molecules from where they are more concentrated to where they are less concentrated.

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

hypertonic

A plant cell placed in a _________ solution will lose water and plasmolyze.

isotonic

A plant cell surrounded by a _______ solution will be flaccid (limp).

hypotonic

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

is an organic catalyst-Enzymes are proteins that behave as catalysts.

An enzyme _____.

allow water to cross the plasma membrane via facilitated diffusion.

Aquaporins...

is unchanged- Enzymes are not changed as a result of their participation in a reaction.

As a result of its involvement in a reaction, an enzyme _____.

arrangement of atoms within molecules. The bonds holding atoms together also contain potential energy, energy the cell harnesses when bonds are broken during metabolism.

Cells store energy that they use for work in the _____.

Passive Transport

Diffusion across a biological membrane is called

passive transport-During facilitated diffusion, the cell is not expending energy to move the particles across the membrane; therefore, facilitated diffusion is a form of passive transport.

Facilitated diffusion is a type of _____.

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

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

Bacteria can't survive in a hypertonic solution because they lose water-If a cell is placed in a hypertonic solution, it will lose water to its environment, shrivel, and probably die.

Green olives may be preserved in brine, which is a 20-30% salt solution. How does this method prevent contamination by microorganisms?

glycoprotein- Structure A is composed of both a carbohydrate and a protein.

Identify Structure A

phospholipid bilayer of membrane-Phospholipids can be recognized by the presence of a head and two tails.

Identify Structure D

molecules move across the plasma membrane against their concentration gradient.-Molecules move against their concentration gradient in active transport.

In active transport,

Water will leave the balloon.

In the lab, you use a special balloon that is permeable to water but not sucrose to make an "artificial cell." The balloon is filled with a solution of 20% sucrose and 80% water and is immersed in a beaker containing a solution of 40% sucrose and 60% water. Which of the following will occur?

covalent bonds form between inhibitor and enzyme

Inhibition of an enzyme is irreversible when

kinetic energy is the energy of a moving object, whereas chemical energy is the potential energy of molecules.

Kinetic energy differs from chemical energy in that:

kinetic ... chemical Light is kinetic energy, and molecules possess chemical energy. Chemical energy refers to the potential energy that can be released during chemical reactions.

Light is _____ energy, which is converted by plants into molecules, which possess _____ energy.

are able to drift about in the plasma membrane.

Membrane phospholipids...

Proteins

Most enzymes are _____.

Proteins

Most of a cell's enzymes are

Proteins

Most of the functions of a cell membrane, including transport and enzymatic function, are performed by

the difference in water concentration across a selectively permeable membrane-The driving force for osmosis is water's concentration gradient across a selectively permeable membrane. Differences in solute concentration across a membrane create water concentration differences, but solute concentration differences do not directly drive osmosis.

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 plasma membrane allows some substances to enter or leave a cell more easily than others.

Plasma membranes are selectively permeable. This means that:

easily pass through a membrane's lipid bilayer.

Small, nonpolar, hydrophobic molecules such as fatty acids

transport protein-The protein is allowing solute molecules to enter the cell.

Structure A in the figure is a

active

Substrates bind to an enzyme's ________ site.

helps to keep phospholipids from being too close to one another.

The cholesterol associated with animal cell membranes...

diverse proteins embedded in a phospholipid bilayer

The fluid mosaic model describes the plasma membrane as consisting of

hypotonic

The ideal osmotic environment for a plant cell is a __________ environment.

isotonic environment

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

so that the nonpolar parts of two lipids point toward each other-A phospholipid bilayer can exist as a stable boundary between two aqueous compartments because the molecular arrangement shelters the hydrophobic tails of the phospholipids from water while exposing the hydrophilic heads to water.

The lipids in a cell membrane are arranged _____.

Diffusion-Diffusion is the tendency of molecules to spread out in the available space. A substance will diffuse from an area of high concentration to an area of lower concentration.

The movement of atoms, ions, or molecules from a region of higher concentration to regions of lower concentration is called _____.

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

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

oxygen and carbon dioxide-Oxygen and carbon dioxide, as well as other small, hydrophobic molecules, can move freely across the membrane.

The plasma membrane is selectively permeable. Which of the following can pass freely through the membrane with no assistance?

active transport-The sodium-potassium pump moves ions across the plasma membrane against their concentration gradients. This requires energy and is an example of 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

hypertonic

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

through facilitated diffusion or diffusion-Water can cross the plasma membrane through the process of facilitated diffusion. However, water molecules can also cross the lipid bilayer directly.

Water crosses the plasma membrane

Exergonic reactions release energy; endergonic reactions absorb it.

What is the basic difference between exergonic and endergonic reactions?

energy of activation-The energy of activation must be overcome in order for a reaction to proceed.

What is the correct label for "A"?

stabilization of the phospholipids-Cholesterol helps to stabilize the structure of the plasma membrane.

What is the function of Structure E?

substrate-this is the name given to the reactants in an enzymatically catalyzed reaction.

What name is given to the reactants in an enzymatically catalyzed reaction?

it lowers the activation energy of the reaction.

When an enzyme catalyzes a reaction,

More concentrated; less concentrated - Diffusion is the movement of particles down their concentration gradient.

When molecules move down their concentration gradient, they move from where they are ___________ to where they are_____________

exhibit a net movement to the side with lower free water concentration.

When two aqueous solutions that differ in solute concentration are placed on either side of a semipermeable membrane and osmosis is allowed to take place, the water will

Active transport moves solutes against their concentration gradient; facilitated diffusion moves substances down their concentration gradient-Active transport involves moving solutes against their concentration gradient. Facilitated diffusion moves solutes down their concentration gradient. Active transport requires the use of ATP, whereas facilitated diffusion does not.

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

active transport

Which of the following processes can move a solute against its concentration gradient?

Active transport is driven by the concentration gradient.

Which of the following statements regarding active transport is false?

Na+

Which of the following substances would have the most trouble crossing a biological membrane by diffusing through the lipid bilayer?

A cell engulfs a particle by wrapping pseudopodia around it and packaging it within a vacuole-After entry, the vacuole usually fuses with a lysosome, whose hydrolytic enzymes digest the contents of the vacuole.

Which statement best describes phagocytosis?

You dehydrate yourself

You are adrift in the Atlantic Ocean and, being thirsty, drink the surrounding seawater. As a result,