Bio Exam Review
Which of the following statements regarding ATP is correct?
ATP serves as a main energy shuttle inside cells. ATP drives endergonic reactions in the cell by the enzymatic transfer of the phosphate group to specific reactants. The regeneration of ATP from ADP and phosphate is an endergonic reaction.
How can one increase the rate of a chemical reaction?
Add a catalyst.
Which of the following statements is correct about an oxidation-reduction (or redox) reactions?
The molecule that is reduced gains electrons. The molecule that is oxidized loses electrons.
Which of the following statements correctly describes catabolic pathways?
They release energy as they degrade polymers to monomers.
The surface of an integral membrane protein would be best described as
amphipathic
Substance A functions as
an allosteric inhibitor
All of the following are part of a prokaryotic cell except
an endoplasmic reticulum
G proteins and G-protein-linked receptors
are thought to have evolved very early, because of their similar structure and function in a wide variety of modern organisms whose common ancestors diverged billions of years ago
Observe these structures of glucose and fructose. These two molecules differ in the
arrangement of carbon, hydrogen, and oxygen atoms.
Most signal molecules
bind to specific sites on receptor proteins in a membrane and are water soluble
Membrane receptors that attach phosphates to specific amino acids in proteins are
called receptor tyrosine kinases.
A molecule with the chemical formula C₁₆H₃₂O₁₆ is probably a
carbohydrate
A chemical reaction that has a positive ∆G is correctly described as..
endergonic
Desert rabbits are adapted to the warm climate because their large ears aid in the removal of heat due to the...
high heat of vaporization of water.
What maintains the secondary structure of a protein?
hydrogen bonds
An enzyme catalyzes a reaction by
lowering the energy of activation of a reaction
contains hydrolytic enzymes
lysosome
What is one of the functions of cholesterol in animal cell membranes?
maintains membrane fluidity
All of the following are correct matches of the location of a protein and the location of its synthesis EXCEPT
mitochondrial matrix protein-rough ER
Hydrophobic substances such as vegetable oil are
nonpolar substances that repel water molecules.
The α helix and the β pleated sheet are both common polypeptide forms found in which level of protein structure?
secondary
From the perspective of the cell receiving the message, the three stages of cell signaling are
signal reception, signal transduction, cellular response
When biological membranes are frozen and then fractures, they tend to break along the middle of the bilayer. The best explanation for this is that
the hydrophobic interactions that hold the membrane together are weakest at this point
In addition to exporting materials from the cytoplasm of the cell, the process of exocytosis is also important in
the production of cell walls by plant cells
Polymers of polysaccharides, fats, and proteins are all synthesized from monomers by which process?
the removal of water (dehydration synthesis)
The tertiary structure of a protein is the
unique three dimensional shape of the fully folded polypeptide
a compartment that often takes up much of the volume of a plant cell
vacuole
Which of the following signal systems use G-protein linked receptors?
yeast mating factors, epinephrine, neurotransmitters
The mathematical expression for the change in free energy of a system is: ∆G= ∆H- T∆S. Which of the following is incorrect?
∆H is the change in enthalpy, the energy available to do work
A double stranded DNA molecule contains a total of 120 purines and 120 pyrimidines. This DNA molecule could be compromised of...
120 thymine and 120 adenine molecules
Which of the following statements is false?
14 and 15 could be joined together to form a polypeptide.
Which of the following molecules consists of a hydrophilic head region and hyprophobic tail region?
5
Which of the following molecules is a saturated fatty acid?
9
Which statement is NOT correct with regard to redox reactions?
A molecule is reduced if it loses electrons.
What do cohesion, surface tension, and adhesion have in common with reference to water?
All are properties related to hydrogen bonding.
Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics?
As a consequence of growing, organisms create more disorder in their environment than the decrease in entropy associated with their growth.
Which line represents the bag that contained a solution isotonic to the 0.6 molar solution at the beginning of the experiment?
C
Which of the following statements describes the results of this reaction?
C₆H₁₂O₆ is oxidized and O₂ is reduced.
Which of the following best describes the flow of information in eukaryotic cells?
DNA→RNA→proteins
Which of the following best summarizes the relationship between dehydration reactions and hydrolysis?
Dehydration reactions assemble polymers, and hydrolysis breaks down polymers.
Which of the following is a statement of the first law of thermodynamics?
Energy cannot be created or destroyed.
Which of the following statements regarding enzymes is true?
Enzymes increase the rate of the reaction.
Which of the following is NOT true of enzymes?
Enzymes provide activation energy for the reaction they catalyze.
Which of the following statements is a logical consequence of the second law of thermodynamics?
Every chemical reaction must increase the total entropy of the universe.
As temperature decreases, the rate of an enzyme catalyzed reaction also decreases. Which of the following explains why this occurs?
Fewer substrates have sufficient energy to get over the activation energy barrier. Motion in the active site of the enzyme is slowed, thus slowing the catalysis of the enzyme.
Which of the following is a place where both DNA and ribosomes are UNLIKELY to be found in ANY type of cell?
Golgi apparatus
Membranes are a phospholipid bilayer between two layers of hydrophilic proteins.
H. Davson and J. Danielli
Which of the following statements is CORRECT about diffusion?
It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration
Why is ATP an important molecule in metabolism?
It provides energy coupling between exergonic and endergonic reactions.
What would be TRUE for the signaling system in an animal cell that lacks the ability to produce GTP?
It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane.
Which of the following statements correctly describes some aspect of energy in living organisms?
Living organisms can convert energy among several different forms, Living organisms can use energy to do work, Organisms expend energy in order to decrease their entropy.
Which of the following statements about metabolism is INCORRECT?
Metabolism is an emergent property of life at the level of organisms.
The concept of vitalism is based on a belief in a life force outside the jurisdiction of physical and chemical laws. According to this belief, organic compounds can arise only within living organisms. Which of the following did the most to refute the concept of vitalism?
Miller's experiments with ancient atmospheres.
The membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids.
S. Singer and G. Nicolson
What is the reason why hydrocarbons are not soluble in water?
The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages.
Which of the following statements CORRECTLY describes the normal tonicity conditions for typical plant and animal cells?
The animal cell is in an isotonic solution, and the plant cell is in a hypotonic solution.
According to the induced fit hypothesis of enzyme catalysis, which of the following is correct?
The binding of the substrate changes the shape of the enzymes active site.
Which of the following comparisons between prokaryotic and eukaryotic cells is incorrect?
The lack of organelles in prokaryotes means that the basic cellular functions are different in prokaryotes than in eukaryotes.
Which of the following statements is true about enzyme catalyzed reactions?
The reaction is faster than the same reaction in the absence of the enzyme.
Which of the following are true for anabolic pathways?
They are highly regulated sequences of chemical reactions. They consume energy to build up polymers from monomers.
Which of the following are true for the class of large biological molecules known as lipids?
They are insoluble in water. They are an important constituent of cell membranes. they contain twice as much energy as an equivalent weight of polysaccharide.
Which of the following statements is true about buffer solutions?
They maintain a relatively constant pH.
The slight negative charge at one end of one water molecule is attracted to the slight positive charge of another water molecule. What is this attraction called?
a hydrogen bond
Which of the following descriptions best fits the class of molecules known as nucleotides?
a nitrogenous base, a phosphate group, and a pentose sugar
What is the molecule illustrated in the figure below?
a saturated fatty acid
What is substance X?
a substrate
What is the term used for the metabolic pathway in which glucose (C₆H₁₂O₆) is degraded to carbon dioxide (CO₂) and water?
cellular respiration
What is the term used for a protein molecule that assists in the proper folding of other proteins?
chaperonin
What is a nonprotein "helper" of an enzyme molecule called?
coenzyme
What is the term used for a change in a protein's three dimensional shape or conformation due to disruption of hydrogen bonds, disulfide bridges, or ionic bonds?
denaturation
What term is used to describe the transfer of free energy from catabolic pathways to anabolic pathways?
energy coupling
Whenever energy is transformed, there is always an increase in the
entropy of the universe
The main difference between facilitated diffusion and active transport is
facilitated diffusion moves substances down their concentration gradient and active transport moves them against their gradient, and facilitated diffusion does not rely on cellular energy and active transport does.
The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is known as
feedback inhibition
Of the following functions, the major purpose of RNA is to...
function in the synthesis of protein.
Which of the following solutions has the greatest concentration of hydrogen ions [H⁺]?
gastric juice at pH 2
Which of the following is NOT one of the four major groups of macromolecules found in living organisms?
glucose
Which of the following are polysaccharides?
glycogen, starch, chitin
What membrane-surface molecules are thought to be most important as cells recognize each other?
glycoproteins
Saturated fatty acids
have a higher ratio of hydrogen to carbon than do unsaturated fatty acids.
When a membrane is freeze-fractured, the bilayer splits down the middle between the two layers of phospholipids. In an electron micrograph of a freeze-fractured membrane, the bumps seen on the fractured surface of the membranes are
integral proteins
Paracrine signaling
involves secreting cells acting on nearby target cells by discharging a local regulator into the extracellular fluid
The active site of an enzyme is the region that
is involved in the catalytic reaction of an enzyme.
A new organism is discovered in the forests of Costa Rica. Scientists there determine that the polypeptide sequence of hemoglobin from the new organism has 72 amino acid differences from humans, 65 differences from a gibbon, 49 differences from a rate, and 5 differences from a frog. These data suggest that the new organism
is more closely related to frogs than humans.
The lateral mobility (fluidity) of lipids and proteins in membranes is a consequence of
lack of covalent bonds between the lipid and protein components of the membrane, and weak hydrophobic interactions among the components in the interior of the membrane
Triacylglycerol is a
lipid made with three fatty acids and a glycerol
What would be the pH of a solution with a hydroxide ion [OH-] concentration of 10⁻¹² M?
pH 2
Which bonds are created during the formation of the primary structure of a protein?
peptide bonds
In a single molecule of water, the two hydrogen atoms are bonded to a single oxygen atom by
polar covalent bonds
A polypeptide can best be described as a
polymer of amino acids
If 128 molecules of the general type shown in the figure below were covalently joined together in sequence, the single molecule that would result would be a
polysaccharide
Altering which of the following levels of structural organization could change the function of a protein?
primary, secondary, tertiary, quaternary
All of the following are functions of integral membrane proteins EXCEPT
protein synthesis
Large numbers of ribosomes are present in cells that specialize in producing which of the following?
proteins
When a molecule of NAD⁺ gains a hydrogen atom (not a hydrogen ion) the molecule becomes
reduced
The bonding of two amino acid molecules to form a larger molecule requires which of the following?
removal of a water molecule
What kinds of molecules pass through a cell membrane most easily?
small and hydophobic
Observe the structures of glucose and fructose. These two molecules are
structural isomers.
Which of the following describes some aspect of metabolism?
synthesis of macromolecules, breakdown of macromolecules, control of enzyme activity
At which level of protein structure are interactions between the side chains (R groups) most important?
tertiary
