BIO160 CH5
Aquaporins allow for the active transport of water. are found in all cells. allow water to cross the plasma membrane against its concentration gradient. allow water to cross the plasma membrane via facilitated diffusion.
allow water to cross the plasma membrane via facilitated diffusion.
Which of the following substances could be a cofactor? a protein a ribosome a zinc atom a polypeptide
a zinc atom
Which of the following statements regarding enzymes is true? All enzymes depend on protein cofactors to function. Enzymes are inorganic. An enzyme's function is unaffected by changes in pH. Enzymes catalyze specific reactions.
Enzymes catalyze specific reactions.
What is the basic difference between exergonic and endergonic reactions? Exergonic reactions release energy; endergonic reactions absorb it. Exergonic reactions involve ionic bonds; endergonic reactions involve covalent bonds. Exergonic reactions involve the breaking of bonds; endergonic reactions involve the formation of bonds. In exergonic reactions, the reactants have less chemical energy than the products; in endergonic reactions, the opposite is true.
Exergonic reactions release energy; endergonic reactions absorb it.
Which of the following statements about the ATP molecule is true? It contains the sugar glucose. Extremely stable bonds link the second and third phosphate groups. It contains five phosphate groups. It releases energy when one phosphate group leaves ATP.
It releases energy when one phosphate group leaves ATP.
Which of the following statements is true among all types of passive transport? Proteins are needed to transport molecules across the membrane. The concentration gradient is the driving force. Only small polar molecules are able to cross the plasma membrane. Ions never cross the plasma membrane by passive transport.
The concentration gradient is the driving force.
Which of the following is a typical feature of an ATP-driven active transport mechanism? The transport protein catalyzes the conversion of ADP to ATP. The transport protein is irreversibly phosphorylated as transport takes place. The transport protein must cross to the correct side of the membrane before the solute can bind to it. The solute moves against the concentration gradient.
The solute moves against the concentration gradient.
Phagocytosis is to eating as pinocytosis is to osmosis. drinking. chewing. lysis.
drinking
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. The solution in the balloon is ________ relative to the solution in the beaker. hypotonic hypertonic isotonic hydrophilic
hypotonic
Many of the enzymes that control a deep-sea firefly squid's ability to produce light energy from chemical energy are located in membranes. within chloroplasts. within mitochondria. outside of cells.
in membranes.
When an enzyme catalyzes a reaction, it raises the activation energy of the reaction. it is used once and discarded. it acts as a reactant. it lowers the activation energy of the reaction.
it lowers the activation energy of the reaction.
The transfer of a phosphate group to a molecule or compound is called carboxylation. ionization. phosphorylation. hydrogenation.
phosphorylation.
Which of the following examples is classified as a metabolic pathway? protein synthesis osmosis cell lysis passive diffusion
protein synthesis
Most of a cell's enzymes are amino acids. proteins. lipids. carbohydrates.
proteins.
Anything that prevents ATP formation will most likely result in cell death. force the cell to rely on ADP for energy. force the cell to rely on lipids for energy. have no effect on the cell.
result in cell death.
Which characteristic promoted the utilization of lipids as the first cell membrane? formation of a semi-solid membrane self-assembly into a simple membrane ability to form an impermeable membrane spontaneous degradation of the intracellular environment
self-assembly into a simple membrane
All cells are enclosed by a plasma membrane that is similar in ________ and ________. thickness . . . composition lucidity . . . texture structure . . . function permeability . . . content
structure . . . function
Osmosis can be defined as the diffusion of water. the diffusion of nonpolar molecules. active transport. the diffusion of a solute.
the diffusion of water.
According to ________, energy cannot be created or destroyed. the second law of thermodynamics the first law of thermodynamics the third law of thermodynamics Aristotle's first principle
the first law of thermodynamics
In the reaction A → B + C + heat, entropy has decreased. the potential energy of the products is greater than that of the reactant. there is a net input of energy. the potential energy of the products is less than that of the reactant.
the potential energy of the products is less than that of the reactant.
If placed in tap water, an animal cell will undergo lysis, whereas a plant cell will not. What accounts for this difference? the fact that plant cells are isotonic to tap water the relative impermeability of the plant cell wall to water the expulsion of water by the plant cell's central vacuole the relative inelasticity and strength of the plant cell wall
the relative inelasticity and strength of the plant cell wall
A steer must eat at least 100 pounds of grain to gain less than 10 pounds of muscle tissue. This illustrates that some energy is destroyed in every energy conversion. that energy transformations are typically 100% efficient. the first law of thermodynamics. the second law of thermodynamics.
the second law of thermodynamics.
Facilitated diffusion across a biological membrane requires ________ and moves a substance ________ its concentration gradient. energy and transport proteins . . . down energy and transport proteins . . . against transport proteins . . . down transport proteins . . . against
transport proteins . . . down
Which of the following is a coenzyme? iron zinc iodine vitamin B6
vitamin B6