biology test 2
the oxygen consumed during cellular respiration is involved directly in which process or event?
accepting electrons at the end of the electron transport chain
in most exergonic reactions, before products can be formed, the reactants must first overcome a thermodynamic barrier known as the
activation energy of the reaction
an integral membrane protein would have to be
amphipathic, with at least one hydrophobic and one hydrophobic region
the cellular process of synthesizing large molecules from smaller ones is defined as
anabolism
the fluid mosaic model of membrane structure suggest that membranes
are composed of protein molecules embedded in a fluid bilayer of phospholipids
signal transduction pathways that include a phosphorylation cascade
are generally initiated by a phosphorylase enzymes
cooperatively is a form of allosteric activation in which
binding of a substrate molecule to one active site in a multisubunit enzyme stimulates the binding of substrate molecules to the active sites of other subunits
the active site of an enzyme is the region that
binds substrates for the enzyme
which of the following terms describes metabolic pathways that break down complex molecules to release stored energy
catabolic pathways
the cellular process of breaking down large molecules into smaller ones is defined as
catabolism
which of the following state is a logical consequence of the second law of thermodynamics?
cells require a constant put of energy to maintain heir high level of organization
which of the following statements about the relationships between photosynthesis and cellular respiration is correct?
cellular respiration is catabolic and photosynthesis is anabolic
a noncompetitive inhibitor decreases the rate of an enzymatic reaction by
changing the shape of the enzyme active site
proteins that allow the diffusion of ions across membranes in the direction of their concentration gradients are most likely
channel proteins
zinc, an essential trace element for most organisms, is required in the active site of the enzyme carboxypeptidase in order for the enzyme to function properly. the since most likely function as a(n)
cofactor necessary for enzyme activity
where does glycolysis occur in animal cells?
cytosol
the movement of hydrophobic gas nitrous oxide (N20) (laughing gas) into a cell is an example of
diffusion through the lipid bilayer
a chemical reactions that has a positive ∆G is best describe as
endergonic
which of the following is a statement of the first law of thermodynamics?
energy cannot be created or destroyed
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 down their electrochemical gradient through ATP synthase
which of the following statements regarding enzymes is true?
enzymes must increase the rate of a reaction by lowering the activation energy barrier
the mechanism by which the end product of a metabolic pathway inhibits an enzyme that catalyzes an earlier step in the pathway is most precisely described as
feedback inhibition
CAM plants keep stomata closed in daytime, thus reducing loss of water. they can do this because they
fix CO2 into organic acids during the night when temperatures are cooler
in chemiosmosis it mitochondria, protons flow from the intermemebrane space into the matrix
from the thylakoid space to into the stroma
under anaerobic conditions, what carbon sources can be metabolized by yeast cells to produce ATP from ADP?
glucose
which of the following sequences represents the correct order in which metabolic reactions occur during the complete oxidation of glucose though aerobic respiration
glucose-glycolysis-pyruvate oxidation-citric acid cycle-electron transport chain
which of the following metabolic processes in eukaryotic cells will proceed normally whether oxygen (02) is present or absent?
glycolysis
in autotrophic bacteria, where are chlorophyll- like pigments located
in unfolded regions fo the plasma membrane
cell membranes in plants that thrive in extremes cold are able to remain fluid by
increasing the percentage of unsaturated phospholipids in the membrane
where are the proteins of the electron transport chain located in a eukaryotic cell?
inner mitochondrial membrane
why is glycolysis considered to be one of the first metabolic pathways to have evolved?
it does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms
which of the following statements about diffusion is correct?
it is a passive process in which molecules move from a region of higher concentration to a region of lower concentration
hydrolysis of ATP releases energy, which ultimately results in the production of ADP and inorganic phosphate. what is commonly the immediate fate of the phosphate released by ATP hydrolysis in the cell?
it is attached to a substrate to form a phosphorylated intermediate
when chemical, transport, or mechanical work is performed by an organisms, what happens to the heat that is generated?
it is released to the environment
why might a severe fever result in death if it is not brought under control?
it may alter the tertiary and quaternary structures of cellular enzymes
water can move quickly through the plasma membrane of some cells because
it moves through aquaporin channel proteins
summering a red blood cell in distilled water will result in
lysis of the cell
the cytoplasmic side of a cell membrane is negative in charge relative to the extracellular side. what is the voltage across a cell membrane called?
membrane potential
which of the following is the most comprehensive definition of metabolism in living organisms?
metabolism consists of all the energy transformation reaction in an organism
which of the following metabolic processes produces the most ATP when glucose (C₆h₁₂O₆) is completely oxidized to carbon dioxide (CO₂) and water?
oxidative phosphorylation (chemisomosis)
which of the following membranes proteins tend to lack hydrophobic regions on their surfaces
peripheral membrane proteins
which of the following molecules are localized on the exterior of a phospholipid bilayer
phosphate groups
the primary structural components of the cell membrane are
phospholipids and protein
the difference between pinocytosis and receptor-mediated endocytosis is that
pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor mediated endocytosis is highly selective
an enzyme catalyzed reaction is conducted in a test tube with a fixed amount enzyme. increasing the substrate concentration in the test tube may overcome the effect of which of the following conditions?
presence of a fixed amount of a competitive inhibitor
the sugars associated with glycoproteins and glycolipids of animal cell membranes
serve as markers that distinguish one cell from another
submerging a red blood cell in a hypersonic solution will result in
shriveling of the cell
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
what kinds of molecules pass through a cell membrane most easily?
small hydrophobic
which of the following reactions produces the oxygen released by photosynthesis
splitting of water molecules
where does the Calvin cycle take place?
storm of the chloroplast
which chemical process generates the ATP produced in glycolysis
substrate level phosphorylation
which of the following processes is responsible for the ATP made during fermentation?
substrate-level phosphorylation
wich chemical process generates the ATP produced in the citric acid cycle?
substrate-level phosphorylation
in most plants the carbohydrates produced by photosynthesis are transported out of the leaves to the rest of the plant as which of the following moelcules
sucrose
in C₃ photosynthesis, the reactions that require ATP take place in
the Calvin cycle alone
which of the following metabolic processes consume(s) CO₂
the Calvin cycle only
submerging a plant cell in distilled water will result in
the cell becoming turgid
which of the following descriptions would be an example of potential energy
the chemical bonds in a molecule of sucrose
how do unsaturated fatty acids help keep any membrane more fluid at lower temperatures
the double bonds form kinks in the fatty acids tail that prevent adjacent lipids from packing tightly together
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 Calvin cycle returns to ADP Pi and NADP+ to the light reactions
immediately after a membrane receptor protein binds to its ligand, which of the following process occurs?
the membrane receptor protein undergoes a conformational change
which of the following statements about enzyme-catalyzed reactions is true
the rate of the reaction is greater than when the same reaction occurs in the absence of an enzyme
which of the following statements is true for all exergonic reactions?
the reaction proceeds with a net release of free energy
which of the following statements about a system a chemical equilibrium is true?
the system can do no work
the protein, lipid and carbohydrate compositions of the cytoplasmic and extracellular sides off membranes are different from one another. why is this case?
the two sides of a cell membrane face different environments and carry out different functions
why are C₄ plants able to photosynthesize with no apparent photorespiration
they do not use rubisco to fix CO2
what is the primary function of the Calvin cycle
to produce simple sugars from carbon dioxide
what is the primary role of oxygen in cellular respiration
to serve as an acceptor for electrons and protons forming water
what is the primary function of the pigment molecules in a light harvest complex
to transfer light energy to the reaction center chlorophyll
mammalian blood contains the equivalent of 0.15 M Nacl sea water contains equivalent of 0.45 M NaCl. what will happen if red blood cells are transferred to seawater
water will leave the cells, causing them to shrivel and collapse
glycolysis results in a net production of which fo the following molecules form each molecule fo glucose?
2 NADH, 2 pyruvate, and 2 ATP
which of the following molecule are products of the light reactions of photosynthesis that are utilized in the Calvin cycle
ATP and NADPH
which of the following statements best describes the critical role that ATP plays in cellular metabolism
ATP serves as an energy shuttle in the cell, coupling exergonic and endergonic reactions
the enzyme rubisco plays a critical role in carbon fixation in which of the following types of plants
C3 plants only
which of the following statements about NAD+ is true?
NAD+ is reduced to NADH during glycolysis
what compound provides the reducing power for the Calvin cycle?
NADPH
photorespiration occurs when rubisco combines RubBP with which of the following molecules
O2
in the complete reactions of aerobic respiration, the energy for most of the ATP produced is provided by
a proton gradient across a membrane
a protein that spans the phospholipids bilayer one or more time is
a transmembrane protein