Chapter 5 Mastering Biology
A white blood cell engulfing a bacterium is an example of _____.
phagocytosis Phagocytosis occurs when a cell engulfs a large particle.
Chemical energy is a form of _____ energy.
potential
Most enzymes are _____.
proteins
In a catalyzed reaction, a reactant is often called a(n) ______.
substrate
What name is given to the reactants in an enzymatically catalyzed reaction?
substrate
Utah's Great Salt Lake has an average salinity seven times higher than that of the oceans. Very few multicellular organisms live in this harsh environment. An example is the brine shrimp, which must devote a large portion of its metabolic energy to osmoregulation. These brine shrimp must _____.
actively pump water back into their cells to counter its loss due to osmosis.
Aquaporins
allow water to cross the plasma membrane via facilitated diffusion.
Membrane phospholipids...
are able to drift about in the plasma membrane.
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
exhibit a net movement to the side with lower free water concentration.
Which of these is exhibiting kinetic energy?
a space station orbiting Earth
As a result of its involvement in a reaction, an enzyme _____.
is unchanged
A plant cell surrounded by a(n) ______ solution will be flaccid (limp).
isotonic
The ideal osmotic environment for an animal cell is a(n) ______ environment.
isotonic
In cells, what is usually the immediate source of energy for an endergonic reaction?
ATP
Using the data from the graphs and what you know about membranes and metabolic pathways, predict which of the following is the likely reason why actions of aquaporins in a membrane can change so rapidly.
Aquaporins are inserted into the membrane as needed.
Which of the following is a typical feature of an ATP-driven active transport mechanism?
The solute moves against the concentration gradient.
An enzyme speeds up reactions by lowering the ______.
activation energy
The reaction ADP + P --> ATP is a(n) _____ reaction.
endergonic
Which of these reactions requires a net input of energy from its surroundings?
endergonic The products of endergonic reactions have more potential energy than the reactants.
What name is given to the process by which water crosses a selectively permeable membrane?
osmosis
Diffusion across a biological membrane is called ______.
passive transport
Endocytosis moves materials _____ a cell via _____.
into ... membranous vesicles
An enzyme _____.
is an organic catalyst
In active transport,
molecules move across the plasma membrane against their concentration gradient.
Aspirin and other nonsteroidal anti-inflammatory drugs (NSAID) inhibit inflammation by inhibiting an enzyme in the prostaglandin pathway. However, inhibiting this enzyme also inhibits other pathways that protect the stomach from damage by stomach acid and that form blood clots. What can you conclude from this?
The enzyme is found in many different types of cells.
In the process of osmosis, water displays a net movement from an area of __________ water concentration to an area of __________ water concentration.
higher ... lower
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
In your body, what process converts the chemical energy found in glucose into the chemical energy found in ATP?
cellular respiration
High temperatures or changes in pH can ______ an enzyme, causing it to lose its shape and biological activity.
denature
What type of reaction breaks the bonds that join the phosphate groups in an ATP molecule?
hydrolysis
A molecule moves down its concentration gradient using a transport protein in the plasma membrane. This is an example of
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.
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. 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 ______ between an active site and its substrate often strains bonds and helps the reaction proceed.
induced fit
What is energy coupling?
the use of energy released from an exergonic reaction to drive an endergonic reaction
A(n) ______, which is often a vitamin, binds to an enzyme and plays a role in catalysis.
coenzyme
Which of these are by-products of cellular respiration?
heat and water
An enzyme is specific because the shape of its ______ matches only particular reactants.
active site
"Conservation of energy" refers to the fact that _____.
energy cannot be created or destroyed but can be converted from one form to another
The energy for an endergonic reaction comes from a(n) _____ reaction.
exergonic
The reaction A --> B + C + heat is released in a(n) _____ reaction.
exergonic
When molecules move down their concentration gradient, they move from where they are ______ to where they are ______.
more concentrated; less concentrated
An energy barrier
prevents the spontaneous breakdown of molecules in the cell.
Enzymes work by _____.
reducing activation energy
For an enzyme to catalyze a reaction there must be a specific fit between the __________ and the enzyme's __________.
substrate ... active site
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.
Which of the following statements regarding diffusion is false?
Diffusion occurs when particles spread from areas where they are less concentrated to areas where they are more concentrated. True: --Diffusion is a result of the thermal energy of atoms and molecules. --Diffusion occurs even after equilibrium is reached and no net change is apparent. --Diffusion requires no input of energy into the system.--
What is the fate of the phosphate group that is removed when ATP is converted to ADP?
It is acquired by a reactant in an endergonic reaction.
Which of the following statements about ATP is true?
It releases energy when one phosphate group leaves ATP.
According to the second law of thermodynamics, which of the following is true?
The ordering of one system depends on the disordering of another. The second law of thermodynamics demands a total increase in entropy, but components of the system can increase in order at the expense of other components of the system.
The concentration of solutes in a red blood cell is about 2%. Sucrose cannot pass through the membrane, but water and urea can. Osmosis would cause red blood cells to shrink the most when immersed in which of the following solutions?
a hypertonic sucrose solution
An enzyme is considered a(n) ______because it speeds up a chemical reaction without being used up.
catalyst
A(n) _____ reaction occurs spontaneously.
exergonic In exergonic reactions the products have less potential energy than the reactants.
A plant cell placed in a(n) ______ solution will lose water and plasmolyze.
hypertonic
There is a net diffusion of water out of an animal cell when it is placed in a(n) ______ solution.
hypertonic
An animal cell placed in a(n) ______ solution will gain water, swell, and possibly burst.
hypotonic
The ideal osmotic environment for a plant cell is a(n) ______ environment.
hypotonic
You can recognize the process of pinocytosis when _____.
the cell is engulfing extracellular fluid Pinocytosis is "cell drinking."
In the reaction A → B + C + heat,
the potential energy of the products is less than that of the reactant.
A steer must eat at least 100 pounds of grain to gain less than 10 pounds of muscle tissue. This illustrates
the second law of thermodynamics.
Water crosses the plasma membrane
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.
