which of the following effects is produced by the high surface tension of water?
A water strider can walk across the surface of a small pond
which type of bond must be broken for water to vaporize?
Polar covalent bonds
the two molecules shown in the figure are best described aas
optical isomers
DNAase is an enzyme that catalyzes the hydrolysis of the covalent bonds that join nucleotides together. What would first happen to DNAmolecules treated withDNAase?
All bases would be separated from the deoxyribose sugars.
A 0.01 M solution of a substance has a pH OF 2 What can you conclude about this substance?
It is neither an acid nor a base.
which of the following solutions would require the greatest amount of base to be added to bring the solution to neutral pH?
tomato juice at pH 4.
There are 20 different amino acids. What makes one amino acid different form another?
Different structural and optical isomers.
If the pH of a solution is decreased from 9 to 8, it means that the
concentration of H+ has increased tenfold (10X) and the concentration of OH- has decreased to one-tenth (1/10) what they were at pH 9.
ONe liter of a solution of pH 2 has how many more hydrogen ions (H+) than 1 L of a solution of pH 6?
40,000 times more
the molecular formula for glucose is C6H12O6 what would be the molecular formula for a molecule made by linkinig three glucose molecules together by dehydration reactions?
C18H36O18
which of the following explains most specifically the attraction of water molecules to one another?
Hydrogen bond
How many electron pairs does carbon share in order to complete its valence shell?
8
Amino acids are acids because they always possess which funtional group?
amino
Misfoldinig of polypeptides is a serious problem in cells. Which of the following diseases is (are) associated with an accumulation of misfolded polypeptides?
Alzheimers and parkinsons only
Which two functional groups are always found in amino acids?
chloride ions
water molecules are able to form hydrogen bonds with
oxygen gas molecules
temperature usually increases when waer condenses. which behavior of water is most dierectly responsible for this phenomenon?
the release of heat by the formation of hydrogen bonds
the element present in all organic molecules is
carbon
which of the following statements about the 5' end of a polynucleotide strand of RNA is correct?
the 5' end is the fifth position on one of the nitrogenous bases
Which of the following best summarizes the relationship between dyhydration reactions and hydrolysis?
Dehydration reactions can occur only after hydrolyssis
Reseasrch indicates that ibuprofen, a drug used to relieve inflammation and paink, is amixture of two enantiomers, that it, molecules that
differ in the arrangement of atoms around their double bonds
A strong acid like HCL
ionizes completely in aqueous solutions
How many molecules of water are needed to completely hydrolyze a polymer that is 11 monomers long?
10
all of the following contain amino acids except
cholesterol
if one strand of a dna molecule has the seuence of bases 5' ATTGCA3' the other complementary strand would have the sequence
5'TGCAAT3'
Humans can digest starch but not cellulose because
humans have enzymes that can hydrolyze the a glycosidic linkages of starch but not the b glycosidic linkages of cellulose
if a solution has a pH of 7, this means that
the concentration of H+ ions in the water equals the concentration of Oh- ions in the water.
The slight negative charge at one end of one water molecules is attracted to the slight positive charge of another water molecule. what is this attraction called?
a hydrophillic bond
which of the following takes place as an ice cube cools a drink?
molecular collisions in the drink increase
which bonds are created during the formation of the primarty structure of a protein?
peptide bonds
which of the following is true of both starch and cellulose?>
they are both polymers of glucose
Hydrophobic substances such as vegetable oil are
nonpolar substances that repel water molecules
liquid water's high specific heat is mainly a consequence of the
small size of water molecules
which chemical group can act as an acid?
methyl
What is the chemical reaction mechanism by which cells make polymers from monomers?
hydrolysis
which of the following is not a monomer/polymer pairing?
deoxyribonuceotide/DNA
which of the following is not a polymer?
glucose
why does ice float in liquid water?
the ionic bonds between the molecules in ice prevent the ice from sinking.
which of the following is a major cause of the size limits for certain types of cells?
the need for sufficient surface area to support the cells metabolic needs
which of the following statements concering cells of bacteria and archaea is correct?
dna is present in both arachaea and bacteria
prokaryotes are classified as belonging to two different domains. what are the domains?
Bacteria and arachea
large numbers of riobosomes are present in cells that specialzie in producing which of the following molecules?
proteins
which structure is the site of the synthesis of proteins that may be exported from the cell?
rough er
ECM proteins are made by riobosomes in which part of a eukaryotic cell?
rough er
the liver is involved in detoxification of many poisons and drugs. which of the following structures is primarily involved in this process and therefore abundant in liver cells?
smooth er
the golgi has a polarity or sidedness to its structure and function. which of the following statements correctly describes this polarity?
alll of the above correctly describe polar characteristics of the golgi function.
Hydrolytic enzymes must be segregated and packaged to prevent general destruction of cellular components. In animal cells, which of the follwoing organelles contains these hydrolytic enzymes?
lysosome
which organelle often takes up much of the volume of a plant cell?
vacuole
which orgnaelle is the primary site of ATP synthesis in eukaryotic cells?
mitochondrion
thylakoids, DNA, and ribosomes are all components found in
chloroplasts
in a plant cell, DNA may be found
in the nucleus, mitochondria, and cholorplasts
the evolution of eukaryotic cells most likely involved
endosymbiosis of an aerobic bacterium in a larger host cell-the endosymbiont evolved into mitochondria.
which organelle or structure is absent in plant cells?
centrosomes
Plasmodesmata in plant cells are most similar in fucntion to which of the follwoing strctures in animal cells?
gap junctions
which structure is not part of the endomembrane system?
choloroplast
which structure-function pair is mismatched?
microtubule; muscle contraction
which of the following types of molecules are the major structural components of the cell membrane?
phospholipids and proteins
the presence of cholesterol in the plasma membranes of some animals
enables the membrane to stay fluid more easily when cell temperature drops
in order for a protein to be an integral membrane protein it would have to be
amphiphatic, with at least one hydrophobic reigion.
which of the following is a reasonable explantion for why unsaturated fatty acids help keep any membrane more fluid at lower temperatures?
the double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly
which of the following is true of integral membrane proteins?>
they are usually transmembrane proteins
which of these are not embedded in the hydrophobic portion of the lipid bilayer?
peripheral proteins
the movement of the hydrophobic gas nitrous oxide into a cell is an example of
diffusion across the lipid bilayer
what kinds of molecules pass through a cell membrane most easily?
small and hydrophobic
which of the follwing is a characteristic feature of a carrier proetins in a plasma membrane?
large and hydrophobic
which of the following is a characteristic feature of a carrier protein in a plasma membrane?
it exhibits a specificity for a particular type of molecule
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 regio of lower concentration.
water passes quickley through cell membranes because
it move through aquaporins in the membrane
celey stalks that are immersed in fresh water for several hours become stiff and har. similar stalks left in a .15 M sal solution become limp and soft. from this we can deduce that
the fresh water is hypotoonic and the salt solution is hypertonic to the cells of the celery stalks.
mammalioan blood contains the equivalent of .15 M NACL. Seawater contains the equivalent of .45 M NACL. what will happen if red blood cells are transferred to seawater?
water will leave the cells, causing them to shrivel and collapse.
when a plant cell, such as one from a peony stem, is submerged in a very hypotonic solution, what is likely to occur?
the cell will become turgid.
glucose diffuses slowly through artificial phopholipid bilayers. the cells lining the small intestine, however, rapidly move large quantities from the glucose rich food into their glocose poor cytoplasm. using this information, which transport menchanism is most probably functioning in the insteninal cells?
facilitated diffusion.
which of the following membrane acitivities requires energy from ATP hydrolysis?
movement of na ions from a lower concentration in a mammmalian cell to a higher concentration in the extracellular fluid
what is the voltage across a membrane called?
membrane potential
a bacterium engulfed by a white blood cell through phagocytosis will be digested by enzyme contained in
lysosomes
familial hypercholesterolemia is characterized by which of the follwoing?
defective LDL recpetors on the cell membranes
the difference between pinocytosis and receptor mediated endocytosis is thaqt
pinocytosis is nonselective in the molecules it brings into the cell, whereas recpetor mediated endocytosis offers more selectivity
which of the follwing is true of steroid recpetors?
the receptor may be inside the nucelar membrane.
which of the follwing characterized by a cell releasing a signal molecule into the environment followed by a number of cells in the immediate vicinity responding?
paracrine signaling
when a neuron responds to a particular neurotransmitter by opening gated ion channels, the neurotransmitter is serving as which part of the signal pathway?
signal molecule
which of the following is true of ranscription facotrs?
they control gene expression
sutherland discovered that the signaling molecule epinephrine
elevates cytosolic concentrations of cyclic AMP
which of the follwoing is the greatest advantage of having multiple steps in a transduction pathway?
having multiple steps provides for greater possible amplification of a signal.
which term most precisely describes the cellular process of breaking down large molecules into smaller ones?
catabolism
which of the following is a statement of the first law of thermodynamics?
energy cannot be created or destroyed
which of the follwoing statements is a logical consequence of the secondlaw of thermodynamics?
every chemical reaction must increase the toatl entropy of the universe.
which of the follwing is an example of potential rather than kinetic energy?
a molecule of glucose
which of the follwing is true of metabolism in its entirety in all organisms?
metabolism consists of all the energy transformation reactions in an organism.
the mathmatical expression for the change infree energy of a system is deltaG=deltaH-TdeltaS. which of the follwoing is correct?
deltaG is the change in free energy
a chemical reaction that has a positive deltaG is best described as
endergonic
which of the following best describes enthalpy (H)?
the heat content of a chemical system.
which of the follwoing statements is true concerning catbolic pathways?
they supply energy, primaritly in the form of ATP for the cells work.
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
reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reactions
activation energy
the active site of an enzyme is the region that
is involved in the catlytic reaction of the enzyme
according to the induced fit hypothesis of enzyme catlyssi, which of the following is correct?
the binding of the substrate changes the shape of the enzymes active site.
increasing the substrate concentration in an enzymatic reaction could overcome which of the following?
competitive inhibition
zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. the zinc most likely functions as a(n)
cofactor necessary for enzyme acitivity
how does a noncompetitive inhibitor decrease the rate of an enzyme reaction?
by changing the shape of the enzymes active site
in experimental tests of enzyme evolution, where a gene encoding an enzyme is subjected to multiple cycles of random mutagenesis and selection for altereed substrate specificity, the resulting enzyme had multiple amino acid changes associated with altereed substrate specificity. where in the enzyme were these amino acid changes located?
only in the dyrophobic inferior of the folded protein
the mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is most precisely described as
feedback inhibition
allosteric enzyme regulation is usually associated with
an enzyme with more than one subunit
for the enzyme catalyzed reaction show in the figure which of these treatments will cause the greatest increase in the rate of reaction, if the intial reactanct concentration is 1.0 micromolar?
doubling the enzyme conentration.
in the figure, why does the reaction rate plateau at higher reactant conectrations?
most enzyme molecules are occupied by substrate at high reactant conetrations
this figure shows the electron transport chain. which of the follwoing is the combination of substances that is intially added to the chain?
nadh, fadh2, and o2
the molecule that functions as the reduction agent (electron donor) in a redox or oxidation reduction reaction
loses electrons and loses potential energy
which of the follwing statements describes the results of this reacition? c6h12o6+6o2---> 6co2 +H2O +energy
c6h1206 is oxidized and 02 is reduced.
when a molecule of nad gains a hydrogen atom the molecule becomes
reduced
where does glycolysis take place in eukaryotic cells?
cytosol
the atp made during glycolysis is generated by
substrate level phosphorylation
the oxygen consumed during cellular respiration is involved directly in which process or event?
accepting electrons at the end of the electron transport chain
during aerobic respiration, electrons travel downhill in which sequence?
food--> nadh--->electron transport chain--> oxygen
even though plants carry on photosynesis plant cells still use their mitochondria for oxidation of pyruvate. when and wehre will this occur?
in all cells all the time
which process in eukaryotic cells will proceed normally whether oxygen is present or absent?
glycolysis
in addtion to atop, what are the end products of glycolysis?
nadh and pyruvate
starting with one molecule of glucose, the energy contating products of glyscolysis are1
2 nad, 2 pyruvate, and 2 atp
a molecule that is phosphorylated
has an increased chemical potential energy it is primed to do cellular work.
which kind of metabolic poison would most directly interfere with glycolysis?
an agent that closely mimics the structure of glucose but isnot metabolized
carbon dioxide is released during which of the following stages of cellular respiration?
oxidation of pyruvate to acetyl coa and citric acid cycle.
a young dog has never had much energy. he is brought ot a veterinarian for help and she decides to conduct several diagnostic tests. she discovers that the dogs mitochondria can use only fatty acids and amino acids for respiration, and his cells produce more lactate than normal. of the following, which is the best explantation of the dogs condtion?
his mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane.
where are the proteins of the electron transport chain located?
mitochondrial inner membrane
in cellular respiration, the energy for most atp synthesis is supplied by
a proton gradient across a membrane
during aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level?
fadh2
the primary role of oxygen in cellular respiration is to
act as an acceptor for electrons and hydrogen, forming water.
in chemiosmosis, what is the most direct source of energy that is used to convert adp+pi to atp?
energy released from movement of protons through atp synthase, down their electrochemical gradient
which of the following produces the most atp when glucose is completely oxidized to carbon dioxide and water?
oxidative phosphorylation (chemiosmosis)
why is glycolysis considereed to be one of the first metabloic pathways to have evolved?
it does not involve organelles or specialized structures, does not reqire oxygen, and is present in most organisms.
in alcohol fermentation, nad is regenerated from nadh by
reduction of acetaldehyde to ethanol (ethyl alcohol).
In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of
atp, co2, and ethanol (ethyl alcohol)
if photosynthesisizing green algae are provided with co2 containg heavy oxygen, later analysis will show that all of the follwoing molecules produced by the algae contain heavy oxygen except
electrons and H+
which of the following are products of the light reactions of photosynthesis that are utilized in the calvin cycle?
atp and nadph
where does the calvin cycle take place?
stroma of the chloroplast
when oxygen is released as a result of photosyntehsis, it is a direct by-product of
splitting water molecules
a plant has a unique phtosynthetic pigment. the leaves of this plant appear to be reddish yellow. what wavelengths of visible light are being absorbed by this pegment?
blue and violet
in the thylakoid membranes, what is the main role of the pigment molecules in a light harvesting complex?
transfer light energy to the reaction center cholorphyll
which of the following events occurs in the light reactions of photosynthesis?
light is absorbed and funneled to reaction center cholorphylll a.
which statement describes the functioning of photosystem II?
the electron vacancies in p680 are filled by electrons derived from water.
which of the following are directly associated with photosystem I?
receiving electrons from the thylakoid membrane electron transport chian
some photosynthetic organisms contain chloroplasts that lack photosystem II, yet are able to survive. the best way to detect the lack of photosytem II in these orgainsims would be
to test for liberation of O2 in the light
what are the products of linear electron flow?
atp and nadph
as a research scientist you mesure the amount of atp and nadph consumed by the calvin cycle in 1 hour. you find 30000 molecules of atp consumed, but only 20000 molecules of nadph. where did the extra atop molecules come from?
cyclic electron flow
what does the chemiosmotic process in chloroplasts involve?
establishment of a proton gradient across the thylakoid membrane
in a plant cell, where are the atp synthase complexes located?
thylakoid membrane only
in mitochondria, chemiosmosis translocates protons from the matrix into the intermembrane space, whereas in choloroplasts, chemiosomsis translocates protons from
the stroma to the thylakoid space
which of the follwoing statements best describes the relationship bewtween photosynthesis and repiration?
photosynthesis stores energy in complex organic molecules, whereas respiration releases it.
where are the molecules of the elctron transport chain found in plant cells?
thylakoid membranes of chloroplasts.
in photosynthetic cells, syntesis of atp by the chemiosomotic mechanism occurs during
both photosynthesis and respiration
reduction of oxygen to form water occurs during
respiration only
what is the relationship between wavelength of light and the quantity of energy per photon?
they are inversely related.
some photosynthetic bacteria have only photosystem I, whereas others have both photosystem I and photosystem II. which of the follwoing might this observation imply?
photosynthesis with only photosystem I is more ancestral.
In thylakoids, protons travel through atp synthse from the thylakoid space to the stroma. therefore, the catalytic knobs of atp synthase would be located
on the stromal side of the membrane
the reactions that produce molecular oxygen take place in
the light reactions alone
a flask containing photosynthetic green algae and a control flask containing water with no algae are both placed under a bank of lights, which are set to cycle between 12 hours of light and 12 hours of dark. The dossolved oxygen concentrations in both flasks are monitored. Predict what the relative dissovled oxgen concentrations will be in the flask with algae compared to the the control flask.
the dissolved oxygen in the flask with algae will be higher in the light, but lower in the dar.
what is the primarty function of the calvin cycle?
synthesize simple sugars from carbon dioxide
the nadph required for the calvin cycle comes from
reactiions intitiated in photosystem I
reactions that require co2 take place in
the calvin cycle alone.
which of the following statements best represents the relationships between the light reactions and the calvin cycle?
the light reactions provide atp and nadph to the calvin cycle, and the cycle returns ADP, pi, and nadp to the light reactions
this figure shows the absorption for cholorphyll a and the action spectrum for photosynthesis. why are they different?
other pigments absorb light in addtion to chlorphyll a.
what wavelenght of light in the figure is most effective in driving photosynthesis?
420 mm
a spaceship is designed to support animal life for a multiyear voyage to the outer planets of the solar system. plants will be grown to provide oxygen and to recycle coarbon dioxoide. because the spaceship will be too far from the sun for photosynthesis, an artificial light source will be needed. what wavelenths of light sould be used to maximaze plant growth with a minimum of energy expenditure?
a mixture of blue and red light
A gardener is oncerned that her green house is getting too hot from too much light, and seeks to shade her plants with colored translucent plastic sheets, the color which alllows passage of only that wavelength. what color should she use to reduce overall light energy, but still maximize plant growth?
blue