Bio Chapter 5 Test
The fluid mosaic model describes the plasma membrane as consisting of
A phospholipid bilayer with embedded proteins
Membrane "ghosts"
Are derived from red blood cells, Are a form of pure plasma membrane, Are a result of breaking open cells and washing away the cytoplasm, Have provided much of our knowledge about plasma
Heating inactivates enzymes by
Breaking the hydrogen bonds that give the molecules its three-dimensional shape
A major function of glycoproteins are glycolipids in the cell membrane is to
Communicate with other cells by sending signals
How does inhibition of n enzyme-catalyzed reaction by a competitive inhibitor differ from inhibition by a noncompetitive inhibitor?
Competitive inhibitors bind to the active binding site; noncompetitive inhibitors bind to a different site
Living systems
Decrease their entropy while they increase the entropy of the universe
Phagocytosis is to eating as pinocytosis is to
Drinking
Cellular metabolism can include
Endergonic reactions, Exergonic reactions, Cellular repiration, Fermintation
When a cell uses chemical energy to perform work, it couples a (n) _____ reaction with a (n) _____ reaction
Exergonic ... Endergonic
What is the basic difference between exergonic and endergonic reactions?
Exergonic reactions release energy; endergonic reactions absorb (store) energy
Certain cells that line the stomach synthesizes a digestive enzyme and secrete it into the stomach. This enzyme is a protein. WHich of the following processes could be responsible for its secretion?
Exocytosis
Enzyme(s)
Function depends on its three-dimensional shape, emerged unchanged from the reactions they catalyze
Organic Cofactors
Include minerals
An "energy barrier"
Is equilavent to the energy of activation of a reaction
A plant cell in a hypotonic solution
Is turgid (or filled)
A cell that neither gains not loses water when it is immersed in a solution is
Isotonic to its enviornment
Which of the following is (are) a true statement about the ATP molecule?
It contains three phosphate molecules, It contains a nitrogenous base molecule called adenine
Which of the following is NOT a function of the plasma membrane?
It is the control center of the cell
When an enzyme catalyzes a reaction,
It lowers the activation energy of the reaction, It acts as a reactant but is not decomposed in the reaction
Which of the following is NOT a true statement about diffusion?
It occurs when particles spread from areas of less concentration to areas of greater concentration
The organ that plays a major role in osmoregulation (Regulates fluid level) in humans is the
Kidney
Which of the following energy transfers is (are) possible in living systems?
Light energy to chemical energy, Chemical energy to kinetic energy, light energy to potential energy
Which of the following substances would have the most trouble crossing a biological membrane by diffusing through the lipid bilayer?
NA+
The production of insulin increases as blood sugar levels increase. The production of insulin decreases as the blood sugar levels decrease. This is an example of
Negative feedback
Diffusion does not require the cell to expend ATP. Therefore, diffusion is considered
Passive Transport
The act of a white blood cell engulfing a bacterium is
Phagocytosis
The transfer of a phosphate group to a molecule or compound is celled
Phosphorulation
Glucose molecules provide energy to power the swimming motion of sperm. In this example, the sperm are changing
Potential energy into kinetic energy
Most of a cells enzymes are
Proteins
The molecules responsible for membrane transport are
Proteins
Anything that prevents ATP formation will
Result to cell death
Relaying a message from a membrane receptor to a molecule that performs a specific function within the cell is called
Signal Transduction
Which of the following can affect the rate of an enzyme-catalyzed reaction?
Temperature, pH, Competitive Inhibitors, Noncompetitive Inhibitors
Which of the following pieces of evidence would prove that a substance enters a cell by active rather then passive transport
The breakdown of ATP is needed for transport to occure
Osmosis can be defined as
The diffusion of water across a membrane
According to _____, energy cannot be created or destroyed
The first law o thermodynamics
Plasma membranes are selectively permeable. This means that
The plasma membrane regulates he passage of material into and out of the cell
The "active site" of an enzyme is
The region of the enzyme that attaches to a substrate
A steer must eat at least 100 pounds of grain to gain less then 10 pounds of muscle tissue. This illustrates
The second law of thermodynamics, the fact that energy transformations are never 100% efficient
Which of the following processes is endergonic?
The synthesis of glucose from carbon dioxide and water
Facilitated diffusion across a biological membrane requires _____.
Transport proteins
Active transpirt
Uses ATP as an energy source, Can move solutes up a concentration gradient, Requires the cell to expend energy, Can involve the coupled passage of soultes