Biology Study Guide Module 4
For each glucose molecule that begins cellular respiration, the citric acid cycle must turn once.
false
In photosynthesis, the oxygen atoms released as O2 comes from CO2.
false
The cell maintains a ratio of ATP to ADP that is at the equilibrium point.
false
The conversion of polysaccharides to monosaccharides is an example of an anabolic reaction.
false
The stage of cellular respiration in which most of the ATP is produced is the citric acid cycle.
false
Chemical energy is a form of kinetic energy.
false; potential
When an electron returns to its ground state, energy will be released as heat or as an emission of light, known as
fluorescence.
In which of the following reactions is pyruvate degraded and combined with coenzyme A to form acetyl CoA?
formation of acetyl CoA
What is the primary function of the leaf structure labeled as 5 in the accompanying figure?
gas exchange
Why are enzymes considered important biological catalysts?
Enzymes lower the activation energy of a biochemical reaction.
A(n) exergonic reaction results in a net gain of free energy.
False
ATP is generated when protons flow through the cytochrome complex in the thylakoid membrane.
False
According to the Second Law of Thermodynamics, energy cannot be created nor destroyed.
False
After the conversion of pyruvate molecules to acetyl CoA molecules, how many NADH molecules have been produced from one glucose molecule?
Four
In glycolysis, a phosphorylated sugar (fructose-1,6-bisphosphate) is split, forming two molecules of
G3P
Both alcohol fermentation and lactate fermentation are highly ____ because the fuel is only partially ____.
Inefficient ; oxidized
Which class of enzyme can catalyze the conversion of a molecule from one isomeric form to another?
Isomerases
Which of the following is a series of reactions in which glucose is degraded to pyruvate and electrons are transferred to carriers?
glycloysis
What color does chlorophyll reflect?
green
What are the reactants of the light-dependent reactions of photosynthesis?
h2o,ADP, NADP+
The direction of an exergonic reaction can best be described as moving
higer to lower free energy
ATP is formed when __________ the thylakoid lumen.
hydrogen ions leave
An endergonic reaction can proceed only if it absorbs
less free energy than is released by a coupled exergonic reaction
An electron absorbs a photon of light energy and becomes energized; the electron shifts from a ____ atomic orbital to a __________ atomic orbital.
lower energy ; higher energy
At night, CAM plants incorporate CO2 into ____, which is stored in the ____ of their cells.
malate; vacuoles
In C4 plants, reactions that fix CO2 into four-carbon compounds occur in what type of cells?
mesophyll cells
Which best describes a catabolic reaction?
It involves the breakdown of large organic molecules to simple building blocks.
What unit is used to measure thermal energy that flows from an object of higher temperature to an object of lower temperature?
Kilocalories
What are the two phases of photosynthesis?
Light-dependent reactions and carbon fixation reactions
Energy that is usable and organized is classified as having ____.
Low entropy
Which of the following is the common cofactor for enzymes?
Magnesium
Where does the citric acid cycle take place in a eukaryotic cell?
Mitochondria matrix
Which organism would be classified as a chemoautotroph?
Nitrogen-fixing bacteria
An organism can exchange matter and energy with its surroundings. Thus, any change in an organism's energy content must be balanced by a corresponding change in the energy content of the surroundings. As such, an organism is referred to as a(n)
Open system
What is the process by which light energy is converted into the stored chemical energy of organic molecules?
Photosynthesis
Capacity to do work as a result of position or state is known as _______.
Potential energy
Chlorophyll and accessory photosynthetic pigments are associated with which part of the chloroplast?
Thylakoid membranes
Refer to the accompanying figure. The line on the graph labeled B represents the ____.
activation energy with an enzyme
Some enzymes have a receptor site that is other than the active site. This is also referred to as a(n) ____ site.
allosteric
Saturated fatty acids store more energy than unsaturated fatty acids. Based on your knowledge of aerobic respiration, you draw this conclusion because saturated fatty acids Group of answer choices
are highly recuced
How are chlorophyll molecules attached to thylakoid membranes?
by a long hydrocarbon side chain
Because enzymes affect the speed of chemical reactions without being consumed, they are referred to as
catalysts
The action spectrum of photosynthesis best matches the absorption spectrum of
chlorophylls a and b.
What is the series of reactions in which the acetyl portion of acetyl CoA is degraded to CO2 and ATP is synthesized?
citric acid cycle
ATP synthesis during the light-dependent reactions occurs by which process?
cyclic electron transport
In eukaryotes, where does glycolysis occur?
cytoplasm
Amino acids are metabolized by reactions in which the amino group (2NH2) is first removed, this is known as ________.
deamination
What is the reaction in which two hydrogen atoms are removed from the substrate and transferred to NAD+ or FAD?
dehydrogenation
During the citric acid cycle, each acetyl group entering the cycle yields
1 ATP, 3NADH, 1FADH2
Consider the following two chemical equations: A. glucose + fructose → sucrose + H2O, ΔG = +27 kJ/mole (or +6.5 kcal/mole) B. glucose + fructose + ATP → sucrose + ADP + Pi, ΔG = −5 kJ/mole (or −1.2 kcal/mole) What is the overall ΔG?
22 kJ/mole
Which best summarizes the overall reactions of photosynthesis?
6CO2 + 12H2O --> C6H12O6+6O2+^6H2O
The electron transport chain forms a concentration gradient for H+, which diffuses through ATP synthase complexes, producing ____.
ATP
Thylakoid membranes are involved in ____ synthesis.
ATP
n glycolysis, glucose receives two phosphate groups from ____, thus forming fructose-1,6-bisphosphate.
ATP
Which is the energy source that drives the Calvin cycle?
ATP and NADPH
What happens in the second phase of the Calvin cycle?
ATP and NADPH are used to convert the PGA molecules to glyceraldehyde-3-phosphate
In a reaction in which the rate of the reverse reaction is equal to the rate of the forward reaction, a state of ____ is attained.
dynamic equilibrium
In which of the following aerobic respiration stages does a chain of several electrons transport molecules and release energy to form a proton gradient?
electron transport and chemiosmosis
Why type of energy is represented by a positive change in G?
endergonic
Which best describes the energy of activation?
energy required to break existing bonds
Every type of chemical bond contains a certain amount of energy. The total bond energy, which is essentially equivalent to the total potential energy of the system, is a quantity known as
enthalpy
Total bond energy is essentially equivalent to the total potential energy of the system, a quantity known as ____________.
enthalpy
The reaction ATP + H2O → ADP + Pi is classified as an
exergonic reaction
Respiration which does not use oxygen as the final electron acceptor and is performed by some prokaryotes that live in anaerobic environments, such as waterlogged soil, stagnant ponds, and animal intestines is called ______.
Anaerobic respiration
How does anaerobic respiration differ from aerobic respiration?
Anaerobic respiration utilizes NO3− as the terminal electron acceptor.
An absorption spectrum indicates the relative effectiveness of different wavelengths of light in powering photosynthesis.
false
Which chemical process occurs in which a substance loses electrons?
oxidation
_____________ is a protein-digesting enzyme in the very acidic stomach juice.
pepsin
The maintenance of a high ATP to ADP ratio within cells ensures that
the hydrolysis of ATP to ADP will be strongly exergonic
What would happen if you were to increase the temperature in an enzyme-catalyzed reaction?
the rate of reaction will increase and then decrease rapidly
Where is the electron transport chain of photosynthesis located?
thylakoid membrane
A cell must expend energy to produce a concentration gradient.
true
A closed system does not exchange energy with its surroundings.
true
Fermentation is an anaerobic process that does not use an electron transport chain.
true
Photorespiration is a wasteful process that could be largely avoided if rubisco would bind only CO2.
true
Some enzymes can only function if an additional chemical component, called a cofactor, is present.
true
The downhill flow of protons through the ATP synthase complex powers the production of ATP.
true
The part of a chlorophyll molecule that absorbs light energy is the porphyrin ring.
true
How many electrons are needed to reduce one molecule of NADP+ to NADPH?
two
In order for a cell to maintain a high degree of order, it must constantly
use energy
What is the role of the oxygen molecules required for aerobic respiration?
To accept the low energy electrons at the end of the electron transport chain
The product of the Calvin cycle that is of greatest practical importance to the plant is carbohydrate.
True
The reactions of the citric acid cycle take place in the matrix of the mitochondrion.
True
What is the function of the oxidoreductases?
catalyze oxidation-reduction reactions
During the first phase of glycolysis, two ____ reactions take place to transfer a phosphate group from ATP to the sugar because glucose is relatively stable and not easily broken down.
phosphorylation
Land plants, algae, and certain prokaryotes are known as _______.
photoautotrophs
The energy of a(n) ____ is inversely proportional to its wavelength.
photon
The energy released during the chain of electron transport molecules is used to create a(n) ____ gradient across the inner mitochondrial membrane for chemiosmosis.
proton
What is it called when a phosphate group is transferred to ADP from a phosphorylated intermediate?
substrate-level phosphorylation
A glucose molecule that is metabolized via aerobic respiration has been completely broken down and released as CO2 by the end of
the citric acid cycle
Which of the following statements about the electron transport chain is true?
the proton gradient established during electron transport is a form of potential energy
What is the ultimate source of energy for almost all living organisms?
the sun
During photosynthesis, ____ is reduced and ____ is oxidized.
CO2 ; H2O
ATP synthesis during light-dependent reactions occurs by which process?
Chemiosmosis
Peter Mitchell demonstrated ATP production by aerobic bacteria to prove what process?
Chemiosmosis
What is the reaction in which part of a carboxyl group (—COOH) is removed from the substrate as a molecule of CO2?
Decarboxylation
In liver cells, each pair NADH produced via glycolysis results in two ATP molecules in the electron transport chain.
False
In the tricarboxylic acid cycle, oxaloacetate reacts with acetyl CoA forming citrate.
False
Phosphofructokinase is stimulated by high levels of ATP.
False
Ribulose phosphate is synthesized from which molecule?
G3P
Which of the following molecules can be used as a substrate for cellular respiration?
Glucose, lipids, proteins, and fatty acids
A group of thylakoid discs make up what part of the chloroplast?
Granum
What is the reaction in which a phosphate group is transferred from ATP to the sugar?
Phosphorylation
Enzyme names are usually derived from the name of its substrate followed by which suffix?
-ase
Which of the following are accessory photosynthetic pigments that expand the spectrum of light to provide energy for photosynthesis?
Carotenoids and chlorophyll b
A nonpolypeptide compound that binds to the apoenzyme and serves as a cofactor is called
Coenzyme
How do competitive inhibitors hinder biochemical reactions?
Competitive inhibitors reduce the concentration of substrate
In which part of the chloroplast do the carbon fixation reactions take place?
Stroma
Which of the following steps in the citric acid cycle directly produces a molecule of ATP (or GTP)?
Succinyl CoA → succinate
The region of the enzyme molecule that interacts with a substrate is called the ______.
The active site