BIO106 Unit 1

What is needed for a cell to recycle ATP? a. ADP + AMP + energy b. ADP + energy + inorganic phosphate cATP + phosphate group dAMP + phosphate ions

ADP + energy + inorganic phosphate This reaction yields ATP. The addition of an inorganic phosphate to an ADP molecule, with an input of energy, gives ATP.

Describe the connection between anabolic and catabolic chemical reactions in a metabolic pathway.

Catabolic reactions produce energy and simpler compounds, whereas anabolic reactions involve the use of energy to make more complex compounds. Anabolic reactions depend on energy to complete their reactions. This energy is obtained as a result of catabolic reactions, so each one leads to the next with the energy coming from one to run the next one.

anabolic pathways

Metabolic pathways that consume energy to build complicated molecules from simpler ones.

catabolic pathways

Metabolic pathways that release energy by breaking down complex molecules into simpler compounds.

We know that the early atmosphere lacked oxygen. Which claim can best be made based on this knowledge and your understanding of how Earth evolved?

Oxygen is a byproduct of photosynthesis, so there was very little oxygen in the atmosphere until photosynthetic organisms evolved.

Microtheme 1: If we hold a match to a small quantity of glucose, a spontaneous reaction occurs and glucose reacts with oxygen to form carbon dioxide and water. Please explain how the carbons initially found in glucose are oxidized in this reaction.

The carbon in glucose is gaining electrons from oxygen (oxidizing agent) as it splits off from oxygen to form carbon dioxide, the gain of oxygen (or loss of electrons) is oxidation. As the free oxygens attach to the hydrogens from carbon, they are reduced to form H2O.

Which of the following are examples of hydrolysis? 1. DNA being broken down into individual nucleotides. 2. Sucrose forming the monosaccharides glucose and fructose. 3. Amino acids forming proteins. a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1 only

a. 1 and 2 Detailed solution: Polymers are broken down into monomers in a process known as hydrolysis. DNA is broken down into individual nucleotides with the addition of water. Sucrose is a polysaccharide that is broken down into glucose and fructose monosaccharides. These are both examples of hydrolysis. Amino acids are monomers that combine to form proteins; therefore, this is an example of dehydration synthesis.

Which of the following reactions is endergonic? a. 6CO2 + 6H2O → C6H12O6 + 6O2 b. C6H12O6 + 6O2 → 6CO2 +6H2O c. C6H12O6 → C3H4O3 + C3H3O3- + 5H+

a. 6CO2 + 6H2O → C6H12O6 + 6O2 Catabolic pathways involve the breakdown of complex molecules into simpler ones; this releases energy stored in the bonds of complex molecules. Reactions that release free energy are called exergonic reactions (reactions 2 and 3). Anabolic pathways synthesize complex molecules from simpler ones using an input of energy. Chemical reactions that require an input of energy are called endergonic reactions (reactions 1 and 4).

What is the role of NADPH in photosynthesis? a. It carries high energy electrons for a reduction reaction. b. It supplies ADP with the energy and phosphate needed to produce ATP. c. It fuels the reaction that reconstitutes RuBP. d. It takes part in Photosystem II.

a. It carries high energy electrons for a reduction reaction. NADPH is produced in the light independent reactions and is found in the stroma. It is used in stage 2 of the Calvin cycle. It carries high energy electrons for a reduction reaction and gets oxidized to NADP+.

Fiber is not really a nutrient, because it passes through our body undigested. Why can't fiber be digested and why is it important to our diet? a. The enzymes required to digest cellulose are not produced in human body; undigested fiber adds bulk to the food easing bowel movements. b. The enzymes that digests cellulose cannot bind to the cellulose due to altered active sites; undigested fiber adds bulk to the food easing bowel movements. c. The enzymes required to digest cellulose are not produced in human body; fiber produces energy for the metabolism. d. Competitive inhibitors are not the reason that fiber is indigestible.

a. The enzymes required to digest cellulose are not produced in human body; undigested fiber adds bulk to the food easing bowel movements. The human body lacks the enzymes required to digest cellulose. Fiber adds bulk to ingested food and eases the food's passage through the colon.

Which of the following statements about carbohydrates is true? a. Disaccharides form when two monosaccharides undergo a hydrolysis reaction. b. A covalent bond formed between two carbohydrate molecules is known as a glycosidic bond. c. A long chain of monosaccharides linked by glycosidic bonds is known as a disaccharide. d. A dehydration synthesis reaction between two glucose molecules can form a polysaccharide.

b. A covalent bond formed between two carbohydrate molecules is known as a glycosidic bond. Yes, monosaccharides are joined by glycosidic linkages.

ATP is made from ___. a. adenosine + high energy electrons b. ADP + pyrophosphate c. AMP + ADP d. the conversion of guanine to adenosine

b. ADP + pyrophosphate ATP molecule is made from addition of pyrophosphate to ADP molecule, which contains two phosphate groups.

Which claim and supporting evidence accurately portray the stability and energy of transitional states? a. Transitional states are stable because molecules have relaxed molecular structure with low energy. b. Transitional states are unstable because molecules have strained molecular structure with high energy. c. Transitional states are unstable because molecules have relaxed molecular structure with high energy. d. Transitional states are stable because molecules have strained molecular structure with low energy.

b. Transitional states are unstable because molecules have strained molecular structure with high energy. Transitional states are the midpoint between reactant and product. These states are unstable, because the molecules are under great strain. During these states, the substance is reaching peak energy, so that it can overcome the activation barrier, which allows for the formation of the product.

An inadequate supply of water can compromise plants' aibility to carry out photosynthesis. How do desert plants prevent such water loss when they are subjected to high heat? a. by using CAM photosynthesis and by closing stomatal pores during the night b. by using CAM photosynthesis and by opening stomatal pores during the night c. by using CAM photosynthesis and by keeping stomatal pores closed at all times d. by bypassing CAM photosynthesis and by keeping stomatal pores closed at night

b. by using CAM photosynthesis and by opening stomatal pores during the night Detailed solution: Desert plants use CAM photosynthesis in order to reduce water loss. In CAM photosynthesis, desert plants open their stomata at night to collect carbon dioxide from the air. At night, temperatures are cooler, preventing a large amount of water loss by transpiration. The collected carbon dioxide is then stored within the leaves as malate. This allows the plants to close their stomata during the day, reducing water loss by evapotranspiration while still having a supply of carbon dioxide to use for photosynthesis.

Enzyme inhibitors play an important part in the control of enzyme functions, allowing them to continue, or inhibiting them for a period of time. Which inhibitor affects the initial rate but do not affect the maximal rate? a. allosteric b. competitive c. non-competitive d. uncompetitive

b. competitive The effect of competitive inhibition is to increase the substrate concentration required to achieve a given reaction speed. So, the rate of the reaction will increase.

Define primary electron acceptor in your own words. a. pigment molecule that directly absorbs light and transfers the energy absorbed to other pigment molecules b. pigment or other organic molecule in the reaction center that accepts an energized electron from the reaction center c. complex of chlorophyll molecules and other organic molecules that is assembled around a special pair of chlorophyll molecules and a primary electron acceptor; capable of undergoing oxidation and reduction d. group of proteins between PSII and PSI that pass energized electrons and use the energy released by the electrons to move hydrogen ions against their concentration gradient into the thylakoid lumen

b. pigment or other organic molecule in the reaction center that accepts an energized electron from the reaction center

Dehydration synthesis leads to the formation of what? a. monomers b. polymers c. carbohydrates only d. water only

b. polymers Polymers are formed through dehydration synthesis, during which monomers combine to release a water molecule.

An experiment is set up to determine how light intensity affects the rate of photosynthesis in plants. What measurements can be made to determine the rate of photosynthesis? 1. Measure the production of carbon dioxide 2. Measure the production of oxygen 3. Measure the production of glucose 4. Measure the uptake of carbon dioxide 5. Measure the uptake of oxygen 6. Measure the uptake of glucose a. 1, 2, 6 b. 1, 3, 5 c. 2, 3, 4 d. 2, 4, 6 e. 3, 4, 5

c. 2, 3, 4 Detailed solution: Photosynthesis uses solar energy, carbon dioxide, and water to produce energy-storing carbohydrates (glucose). Oxygen is generated as a waste product of photosynthesis. Therefore, there is an uptake of carbon dioxide, and a production of oxygen and glucose by photosynthesis in plants.

Athletes consume large amounts of energy to meet the needs of their high activity level. Carbohydrates are an excellent choice for delivering calories that quickly fuel the body. Which of the following would be the best source of energy for an athlete? a. 3 carbon chain b. 5 carbon chain c. 6 carbon chain

c. 6 carbon chain (glucose) Detailed solution: ( c ), glucose, is a primary source of energy in humans, especially athletes. ( a ) is glyceraldehyde, ( b ) is ribose, and ( d ) is dihydroxyacetone.

Which of the following is an endergonic reaction that will proceed in a cell? a. Lipids form droplets to sequester their hydrophobic tails b. Proteolysis of incorrectly folded protein c. Addition of Acetyl-CoA to Oxaloacetate during ATP production d. Glucose combustion

c. Addition of Acetyl-CoA to Oxaloacetate during ATP production Detailed solution: An endergonic reaction produces products with a higher free energy value than the reactants. Anabolic processes, such as the addition of Acetyl-CoA to OAA, that make bonds to build larger molecules are generally endergonic reactions that are catalyzed by an enzyme.

Activation energy, EA, is always a positive value regardless of whether the reaction is exergonic or endergonic. Based on your understanding of activation energy, which of these statements best supports this claim? a. Activation energy is independent of the type of reaction. b. Activation energy is supplied in the intermediate stage of the reaction. c. The transition state of a reaction exists at a higher energy state than the reactants. d. The transition state of a reaction exists at a lower energy state than the reactants.

c. The transition state of a reaction exists at a higher energy state than the reactants. The transition state exists at a higher energy state. So, when the reactant gains activation energy, its energy level increases.

What is the relationship between anabolic and catabolic chemical reactions in a metabolic pathway? a. The two types of reactions depend on each other because catabolic reactions utilize the energy released by the anabolic reactions to form complex compounds. b. The two types of reactions work against each other because both utilize energy to form complex compounds. c. The two types of reactions depend on each other because anabolic reactions utilize the energy released by catabolic reactions to form complex compounds. d. The two types of reactions work against each other because catabolic reactions utilize the the reactants of anabolic reactions to form complex compounds.

c. The two types of reactions depend on each other because anabolic reactions utilize the energy released by catabolic reactions to form complex compounds. Anabolic reactions utilize energy which is used by catabolic reactions to form compounds. Detailed solution: Anabolic reactions build up complex chemicals and get the energy to complete this from catabolic reactions. Catabolic reactions provide the building blocks needed for the anabolic reactions.

Evaluate the processes in photosynthesis and respiration that take place as a cycle of reactions. Use your understanding of specific reactions to explain why the process of producing glucose in plants is a cycle. a. Three RuBP molecules get converted to three G3P, and two G3P molecules with the help of three ATPs are converted back to three molecules of RuBP. b. Three RuBP molecules get converted to five G3P, and three G3P molecules with the help of three ATPs are converted back to three molecules of RuBP. c. Three RuBP molecules get converted to six G3P, and five G3P molecules with the help of three ATPs are converted back to three molecules of RuBP. d. Three RuBP molecules get converted to six G3P, and four G3P molecules with the help of five ATPs are converted back to three molecules of RuBP.

c. Three RuBP molecules get converted to six G3P, and five G3P molecules with the help of three ATPs are converted back to three molecules of RuBP. Detailed solution: The Calvin cycle is a process in which molecules are constantly recycled. As shown in the animation, the process begins with three RuBP molecules, which are broken into 3-PGA after the addition of carbon dioxide. NADPH and ATP convert the 3-PGA molecules into six G3P molecules. One of the molecules is used to make glucose, which is used as fuel for the plant. The rest are recycled back to become RuBP molecules, so the cycle can start again.

The fatty acids of triglycerides are classified as saturated, unsaturated, or trans fats. What is it about the structure of these compounds that distinguishes them from each other? a. Saturated fats and trans fats contain the greatest possible number of hydrogen atoms, while unsaturated fats do not. b. Saturated and unsaturated fats have stable configurations, while trans fats are transient. c. Trans fats are a type of unsaturated fat where the hydrogens around the double bond are not in the same plane. Unsaturated fats and trans fats have double bonds whereas saturated fats have only single bonds. d. Trans fats are a type of saturated fat that is produced artificially by hydrogenation.

c. Trans fats are a type of unsaturated fat where the hydrogens around the double bond are not in the same plane. Unsaturated fats and trans fats have double bonds whereas saturated fats have only single bonds.

How is the energy from the sun transported within chloroplasts? Support your answer with details of the processes involved. a. When photons strike photosystem (PS) I, pigments pass the light energy to chlorophyll, molecules that excite electrons, which are then passed to the electron transport chain. The cytochrome complex then transfers protons across the thylakoid membrane and transfers electrons from PS-II to PS-I. The products of the light-dependent reaction are used to power the Calvin cycle to produce glucose. b. When photons strike photosystem (PS) II, pigments pass the light energy to chlorophyll a molecules that in turn excite electrons, which are then passed to the electron transport chain. The cytochrome complex transfers protons across the thylakoid membrane and transfers electrons from PS-I to PS-II. The products of the light-dependent reaction are used to power the Calvin cycle to produce glucose. c. When photons strike photosystem (PS) II, pigments pass the light energy to chlorophyll a molecules that excite electrons, which are then passed to the electron transport chain. The cytochrome complex transfers protons across the thylakoid membrane and transfers electrons from PS-II to PS-I. The products of the light-dependent reaction are used to power the Calvin cycle to produce glucose. d. When photons strike photosystem (PS) II, pigments pass the light energy to chlorophyll a molecules that excite electrons, which are then passed to the electron transport chain. The cytochrome complex transfers protons across the thylakoid membrane and transfers electrons from PS II to PS I. The products of the light-independent reaction are used to power the Calvin cycle to produce glucose.

c. When photons strike photosystem (PS) II, pigments pass the light energy to chlorophyll a molecules that excite electrons, which are then passed to the electron transport chain. The cytochrome complex transfers protons across the thylakoid membrane and transfers electrons from PS-II to PS-I. The products of the light-dependent reaction are used to power the Calvin cycle to produce glucose. The electron transfer is from photosystem II to photosystem I.

Statins reduce the level of cholesterol in the blood. Based on the everyday connection, which of the following might also reduce cholesterol levels in the blood? a. a drug that increases HMG-CoA reductase levels b. a drug that reduces cyclooxygenase levels c. a drug that reduces lipid levels in the body d. a drug that blocks the action of acetaminophen

c. a drug that reduces lipid levels in the body Cholesterol is made from lipids, so less cholesterol would be made if fewer lipids were present.

An allosteric inhibitor does which of the following? a. binds to an enzyme away from the active site and changes the conformation of the active site, increasing its affinity for substrate binding b. binds to an active site and blocks it from binding substrate c. binds to an enzyme away from the active site and changes the conformation of the active site, decreasing its affinity for the substrate d. binds directly to the active site and mimics the substrate

c. binds to an enzyme away from the active site and changes the conformation of the active site, decreasing its affinity for the substrate An allosteric inhibitor binds to an alternative site to the active site and an alteration of the active site occurs, decreasing the affinity of the enzyme for the substrate.

How can energy be supplied to chemical reactions in living systems? a. condensation b. dehydration synthesis c. hydrolysis d. transcription

c. hydrolysis Hydrolysis reactions typically release energy that can be used to power cellular processes.

What counteracts entropy? a. energy release b. endergonic reactions c. input of energy d. time

c. input of energy Input of energy lowers the entropy of the system and decreases the disorder. Thus, input of energy counteracts high entropy and makes the system stable.

Define electromagnetic spectrum in your own words. a. group of proteins between PSII and PSI that pass energized electrons and use the energy released by the electrons to move hydrogen ions against their concentration gradient into the thylakoid lumen b. range of wavelengths of electromagnetic radiation absorbed by a given substance c. range of all possible frequencies of radiation d. distance between consecutive points of equal position (two crests or two troughs) of a wave in a graphic representation; inversely proportional to the energy of the radiation

c. range of all possible frequencies of radiation

In which compartment of the plant cell do the light-independent reactions of photosynthesis take place?

c. stroma The light independent reactions take place in the stroma of the chloroplast because ATP and NADPH are produced on the stroma side of thylakoid. Also, Calvin cycle enzymes are found in the stroma, so the light independent reaction take place in the stroma.

The difference between saturated and unsaturated fats lies in the ____. a. the number of fatty acids b. the length of the fatty acids c. the number of hydrogen atoms on the triglycerides d. the ester bonds between the fatty acids and glycerol

c. the number of hydrogen atoms on the triglycerides The saturated fat has more hydrogen atoms as it has all single bonds between carbons, versus unsaturated fatty acids, which have fewer hydrogen atoms due to the presence of double bonds between carbons.

Define acid in your own words. a. substance capable of dissolving another substance b. substance that prevents a change in pH by absorbing or releasing hydrogen or hydroxide ions c. molecule that donates hydroxide ions or otherwise binds excess hydrogen ions and decreases the concentration of hydrogen ions in a solution d. molecule that donates hydrogen ions and increases the concentration of hydrogen ions in a solution

d molecule that donates hydrogen ions and increases the concentration of hydrogen ions in a solution

Lock-and-key model of enzyme action

A model for enzyme-substrate interaction that shows an enzyme and substrate having pre-existing complementary shapes. Only the correct size and shape of the substrate will fit into the correct active site.

induced fit model of enzyme action

A substrate binds to an enzyme and changes the enzyme's shape, allowing the enzyme to perform its catalytic function.

Define photosystem II in your own words. a. complex that passes energy from sunlight to the reaction center in each photosystem; it consists of multiple antenna proteins that contain a mixture of 300-400 chlorophyll a and b molecules as well as other pigments like carotenoids b. integral pigment and protein complex in thylakoid membranes that uses light energy to transport electrons from plastocyanin to NADP+ (which becomes reduced to NADPH in the process) c. group of reversibly oxidizable and reducible proteins that forms part of the electron transport chain between photosystem II and photosystem I d. integral protein and pigment complex in thylakoid membranes that transports electrons from water to the electron transport chain; oxygen is a product of PSII

d. integral protein and pigment complex in thylakoid membranes that transports electrons from water to the electron transport chain; oxygen is a product of PSII

All else being equal, endergonic reactions are ____ likely to occur as exergonic ones. a. about equally b. independently c. more d. less

d. less Endergonic reactions are less likely to occur than exergonic reactions. Endergonic reactions require energy while exergonic reactions can occur without any input of energy.

According to the Calvin Cycle: Predict which of the listed conditions would most likely cause a plant to run out of NADP. a. missing the ATP synthase enzyme b. exposure to light c. a lack of water d. not enough CO2

d. not enough CO2

What is a diacylglycerol 3-phosphate? a. phospholipid b. phosphatidylcholine c. phosphatidylserine d. phosphatidate

d. phosphatidate A phosphate group alone attached to a diglycerol does not qualify as a phospholipid; it is phosphatidate, diacylglycerol 3-phosphate, the precursor of phospholipids.

The energy released by the hydrolysis of ATP is ____. a. equal to -57 kJ/mol b. harnessed as heat energy by the cell to perform work c. primarily stored between the alpha and beta phosphates d. providing energy to coupled reactions

d. providing energy to coupled reactions Cells couple the exergonic reaction of ATP hydrolysis with endergonic reactions, allowing them to proceed. Thus, it provides energy to coupled reactions.

Why can water be a good insulator within the body of endothermic (warm-blooded) animals? a. adhesive properties b. surface tension c. heat of vaporization d. specific heat capacity

d. specific heat capacity The specific heat of water is 1 calorie/gram, which is higher than any other common substance.

What is an example of low entropy? a. ATP → ADP + energy b. exhaust from a car c. rust on a metal can d. substrates in a chemical reaction

d. substrates in a chemical reaction Substrates in a chemical reaction possess low entropy because enzyme is yet to act on it. Once the reaction starts, the system becomes disordered.

Which fat serves as an animal's major form of energy storage? a. cholesterol b. glycerol c. phospholipid d. triglycerides

d. triglycerides Triglycerides, stored in adipose tissue, are a major form of energy storage in animals. Fat cells are designed for continuous synthesis and breakdown of triglycerides in animals.

What is the external source of the electrons that ultimately pass through photosynthetic electron transport chains? a. carbon dioxide b. NADPH c. oxygen d. water

d. water The splitting of water releases electrons that are used in the light reactions of photosynthesis.

free energy

energy that is available to do work

Label each of the following systems as high or low entropy: 1 perfume the instant after it is sprayed into the air, 2 An unmaintained 1950s car compared with a brand new car, and 3 a living cell compared to a dead cell. 1. low, 2. high, 3. low 1. low, 2. high 3. high 1. high, 2. low, 3. high 1 high, 2. low, 3. low

i. low, ii. high, iii. low The entropy in case (i) would be low, since the disorderof the perfume is low immediately after it is sprayed (ii) would be high because over the time the disorder in a 1950s car would increase. The entropy in case (iii) would be low, because a living cell would have less disorder in comparison to dead cell.

kinetic energy

the energy an object has due to its motion

Potential Energy (PE)

the energy stored in an object because of its position or composition

activation energy (Ea)

the initial energy needed to start a chemical reaction

Which of the following terms in the Gibbs free energy equation denotes enthalpy? a. ΔG b. ΔH c. ΔS d. ΔT

ΔH Total energy change in a system is called enthalpy and denoted by ΔH.

Glucose equation

C6 H12 O6

The unique properties of water are important in biological processes. For the following three properties of water, define the property and give one example of how the property affects living organisms: - cohesion - adhesion - high heat of vaporization

Cohesion is the attraction between the water molecules, which helps create surface tension. Insects can walk on water because of cohesion. Adhesion is the attraction between water molecules and other molecules. Water moving up from the roots of plants to the leaves as a result of capillary action is because of adhesion. Heat of vaporization is the amount of energy required to convert liquid into gas. This property helps humans maintain homeostasis of body temperature by evaporation.

Which of the following statements about the laws of thermodynamics is true? a. The first law of thermodynamics states that no energy transfer is completely efficient and tends toward disorder. b. The second law of thermodynamics states that energy can't be created or destroyed, only transferred or transformed. c. Entropy is the energy transferred from one system to another that is not work. d. Thermodynamically, heat energy is defined as the energy transferred from one system to another that is not doing work.

Thermodynamically, heat energy is defined as the energy transferred from one system to another that is not doing work. Detailed solution: The first law of thermodynamics states that energy can't be created or destroyed, only transferred or transformed. The second law of thermodynamics states that that no energy transfer is completely efficient and tends toward disorder. Entropy is the measure of randomness or disorder within a system, whereas heat is the energy transferred from one system to another that is not work.

Carbon, in the form of CO2, must be taken from the atmosphere and attached to an existing organic molecule in the Calvin cycle. Therefore, the carbon is bound to the molecule. The products of the cycle only occur because of the added carbon. What are the products of the Calvin cycle and what is regenerated? a. The product of the Calvin cycle is glyceraldehyde-3 phosphate and RuBP is regenerated. b. The product of the Calvin cycle is glyceraldehyde-3 phosphate and RuBisCO is regenerated. c. The product of the Calvin cycle is a 3-PGA molecule and glyceraldehyde-3 phosphate is regenerated. d. The product of the Calvin cycle is glyceraldehyde-3 phosphate and oxygen is regenerated.

a. The product of the Calvin cycle is glyceraldehyde-3 phosphate and RuBP is regenerated. Detailed solution: The Calvin cycle produces glyceraldehyde-3-phosphate (G3P), adenosine diphosphate (ADP), and nicotinamide adenine dinucleotide phosphate (NADP+). The cycle must be repeated three times to yield the G3P product. Ribulose 1,5-bisphosphate (RuBP) is generated from the G3P molecules that remain in the cycle to fix more CO2.

What is the difference between a spontaneous reaction and one that occurs instantaneously. a. A spontaneous reaction is one which releases free energy and moves to a more stable state. Instantaneous reactions occur rapidly with sudden release of energy. b. A spontaneous reaction is one which utilizes free energy and moves to a more stable state. Instantaneous reactions occur rapidly with sudden release of energy. c. A spontaneous reaction is one which releases free energy and moves to a more stable state. Instantaneous reactions occur rapidly within a system by uptake of energy. d. A spontaneous reaction is one in which the reaction occurs rapidly with sudden release of energy. Instantaneous reaction releases free energy and moves to a more stable state.

a. A spontaneous reaction is one which releases free energy and moves to a more stable state. Instantaneous reactions occur rapidly with sudden release of energy. A spontaneous reaction does not require energy to carry out the reaction. It releases free energy which is used by the system to move to a stable state. An instantaneous reaction occurs rapidly with a sudden release of energy. The difference lies in the duration of the reactions: spontaneous reactions can take seconds to years, while instantaneous reactions occur right away.

Evaluating the diagram shown, how does ATP supply energy to chemical reactions? a. ATP dissociates and the energy released by breaking of a phosphate bond within ATP is used for phosphorylation of another molecule. ATP hydrolysis also provides energy to power coupling reactions. b. ATP utilizes energy to power exergonic reactions by hydrolysis of ATP molecule. The free energy released as a result of ATP breakdown is used to carry out metabolism of products. c. ATP utilizes energy to power endergonic reactions by dehydration of ATP molecule. The free energy released as a result of ATP breakdown is used to carry out metabolism of products. d. ATP utilizes the energy released from the coupling reactions and that energy is used to power the endergonic and exergonic reactions.

a. ATP dissociates and the energy released by breaking of a phosphate bond within ATP is used for phosphorylation of another molecule. ATP hydrolysis also provides energy to power coupling reactions. When ATP is utilized in a reaction, it transfers its third phosphate with energy to the chemical reaction. It phosphorylates another molecule and makes the energy available. Also, ATP hydrolysis is performs work in cells by energy coupling.

Which of the following comparisons or contrasts between endergonic and exergonic reactions is false? a. All endergonic and exergonic reactions require the same amount of energy to overcome an activation barrier. b. Endergonic reactions have a positive ΔG and exergonic reactions have a negative ΔG. c. Endergonic reactions consume energy and exergonic reactions release energy. d. Endergonic reactions are not spontaneous and exergonic reactions are spontaneous.

a. All endergonic and exergonic reactions require the same amount of energy to overcome an activation barrier. Both endergonic and exergonic reactions require a small amount of energy to overcome an activation barrier.

What property of carbon makes it essential for organic life? a. Carbon can form up to four covalent bonds, allowing it to form carbon chains. b. Carbon can form more than four covalent bonds, allowing it to form carbon chains. c. Carbon can form more than four covalent bonds, but can only form short chains. d. Carbon can form up to four covalent bonds, but can only form short chains.

a. Carbon can form up to four covalent bonds, allowing it to form carbon chains. Carbon is found in all living things because it can form up to four covalent bonds. These strong covalent bonds allow the formation of carbon chains that combine to form proteins and DNA

How does energy get to a cell, whether it is a single-celled or multicellular organism? a. Catabolism of glucose and other molecules results in the release of energy. That energy is then utilized by cells of single-celled as well as multicellular organisms for cellular activities. b. Anabolism of glucose and other molecules results in the uptake of energy. The energy is then utilized by cells of single-celled as well as multicellular organisms for cellular activities. c. Catabolism of glucose and other molecules results in the uptake of energy. The energy is then utilized by cells of single-celled as well as multicellular organisms for cellular activities. d. Catabolism of starch molecules results in the release of energy. That energy is then utilized by cells of single-celled as well as multicellular organisms for cellular activities.

a. Catabolism of glucose and other molecules results in the release of energy. That energy is then utilized by cells of single-celled as well as multicellular organisms for cellular activities. Detailed solution: Energy for any organism is mostly derived from carbohydrates, especially glucose. A single-celled organism can take it in and metabolize it, while a multicellular organism takes it in and transports it to specific areas in its body for metabolism.

Glucose is the sugar most often used in metabolism by the majority of cells on Earth. It is made and used by plants as well as other organisms. Which of the following describes the chemical breakdown of glucose, and what is the name of the chemical process involved in this breakdown? a. Cellular respiration: C6H12O6 + 6O2→6CO2 + 6H2O + energy b. photosynthesis: 6CO2+6H2O+energy→C6H12O6+6O2 c. Electrolysis: C4H8O4+6O2→6CO2+6H2O+energy d. Krebs cycle: 6CO2+6H2S+energy→C6H12O6+6O2

a. Cellular respiration: C6H12O6+6O2→6CO2+6H2O+energy This describes cellular respiration, the breakdown of glucose.

Estradiol and testosterone are made from ____. a. Cholesterol b. Triglycerides c. Proteins d. Nucleic acids

a. Cholesterol Cholesterol acts as a precursor for the synthesis of estradiol and testosterone, which are steroid molecules.

Why is the conversion of CO2 into an organic compound important in photosynthesis? a. It allows organic compounds to be created from inorganic molecules. b. The capture of CO2 allows oxygen to be released. c. The organic compound produced functions as an enzyme in the cytochrome complex. d. The removal of CO2 as a separate compound helps control the acidity of the chloroplasts.

a. It allows organic compounds to be created from inorganic molecules. In the stage 1 of Calvin cycle, organic G3P is created from inorganic CO2. This step is called carbon fixation and is an important partof photosynthesis.

Why is the conversion of CO2 into an organic compound important in photosynthesis? a. It allows organic compounds to be created from inorganic molecules. b. The capture of CO2 allows oxygen to be released. c. The organic compound that is produced functions as an enzyme in the cytochrome complex. d. The removal of CO2 as a separate compound helps control the acidity of the chloroplasts.

a. It allows organic compounds to be created from inorganic molecules. In the stage 1 of the Calvin cycle, organic G3P is created from inorganic CO2. This step is called carbon fixation and is an important part of photosynthesis.

Apply the relationship between potential and kinetic energy as depicted in the pendulum model to predict changes in energy that occur as a child swings on a swing set. a. Kinetic energy increases when the child swings downward; potential energy increases when the child swings upward. b. Kinetic energy decreases when the child swings downward; potential energy decreases when the child swings upward. c. Kinetic energy increases when the child swings upward; potential energy increases when the child swings downward. d. Kinetic energy increases when the child swings downward; potential energy increases when the child swings downward.

a. Kinetic energy increases when the child swings downward; potential energy increases when the child swings upward. The swing acts like a pendulum. When the parent pulls back on the swing and holds it in midair, the swing has maximum potential energy. When the parent lets go, the swing gains kinetic energy, reaching its peak at the bottom. The kinetic energy decreases as the child swings upward while potential energy increases. When the swing reaches its peak height, it has maximum potential energy. As the child swings back, they gain kinetic energy, and the cycle repeats.

Apply the relationship between potential and kinetic energy as depicted in the pendulum model to predict changes in energy that occur as a child swings on a swing set. a. Kinetic energy increases when the child swings downward; potential energy increases when the child swings upward. b. Kinetic energy decreases when the child swings downward; potential energy decreases when the child swings upward. c. Kinetic energy increases when the child swings upward; potential energy increases when the child swings downward. d. Kinetic energy increases when the child swings downward; potential energy increases when the child swings downward.

a. Kinetic energy increases when the child swings downward; potential energy increases when the child swings upward. The swing acts like a pendulum. When the parent pulls back on the swing and holds it in midair, the swing has maximum potential energy. When the parent lets go, the swing gains kinetic energy, reaching its peak at the bottom. The kinetic energy decreases as the child swings upward while potential energy increases. When the swing reaches its peak height, it has maximum potential energy. As the child swings back, they gain kinetic energy, and the cycle repeats.

What are three functions that lipids serve in plants and/or animals? a. Lipids serve in the storage of energy, as a structural component of hormones, and also as signaling molecules. b. Lipids serve in the storage of energy, as carriers for the transport of proteins across the membrane, and as signaling molecules. c. Lipids serve in the breakdown of stored energy molecules, as signaling molecules, and as structural components of hormones. d. Lipids serve in the breakdown of stored energy molecules, as signaling molecules, and as channels for protein transport.

a. Lipids serve in the storage of energy, as a structural component of hormones, and also as signaling molecules. Lipids serve to store energy in the form of triglycerides in the adipose tissues, and act as structural molecules in the formation of steroid hormones such as testosterone and progesterone that are produced from lipid cholesterol. Lastly, they are an important component of the bilayer plasma membrane.

What is phosphorylation as it occurs in chemical reactions? a. Phosphorylation refers to the attachment of a phosphate to another molecule to facilitate a chemical reaction. b. Phosphorylation is the uptake of a phosphorous molecule by an ATP molecule to power chemical reactions. c. Phosphorylation is the release of a third phosphorous molecule of ATP during hydrolysis. d. Phosphorylation is the breakdown of a pyrophosphate molecule which gives phosphate ions.

a. Phosphorylation refers to the attachment of a phosphate to another molecule to facilitate a chemical reaction. Phosphorylation is the addition of a high energy phosphate group to a protein or organic molecule, which facilitates a chemical reaction.

What happens when potential energy is turned into kinetic energy? a. Potential energy will be expressed in the form of heat, movement or work. b. Potential energy will be expressed in the form of chemical reaction. c. Potential energy will be converted into hydrothermal energy. d. Potential energy will be converted into mechanical energy.

a. Potential energy will be expressed in the form of heat, movement or work. Detailed solution: The energy inherent in potential energy is expressed in some form, as heat, movement, or, most basically, as work.

On a hot, dry day, plants close their stomata to conserve water. What impact will this have on photosynthesis? a. Rate of photosynthesis will be inhibited as the level of carbon dioxide decreases. b. Rate of photosynthesis will be inhibited as the level of oxygen decreases. c. The rate of photosynthesis will increase as the level of carbon dioxide increases. d. Rate of photosynthesis will increase as the level of oxygen increases.

a. Rate of photosynthesis will be inhibited as the level of carbon dioxide decreases. Carbon dioxide as a reactant is required to carry out the photosynthesis reaction. Stomata present at the surface of the leaf are involved in gas exchange. On a hot and dry day, when stomata close in order to conserve water, gas exchange would also stop. Therefore, if there won't be any uptake of carbon dioxide from the environment, the photosynthesis reaction would inhibited.

Explain how the light reactions and light independent reactions (Calvin cycle) of photosynthesis are interdependent on each other. a. The light reactions produces ATP and NADPH, which are then used in the Calvin cycle. b. The light reactions produces NADP+ and ADP, which are then used in the Calvin cycle. c. The light reactions uses NADPH and ATP, which are produced by the Calvin cycle. d. The light reactions produce only NADPH, which is produced by the Calvin cycle.

a. The light reactions produces ATP and NADPH, which are then used in the Calvin cycle. Detailed solution: The light stage, so called because it requires light, produces NADPH and ATP, which are needed for the dark cycle. The dark stage, also known as the Calvin cycle, takes place in the stroma in the chloroplast. During the dark stage, the plant uses the NADPH and ATP produced in the light stage to break down CO2 into glucose. This results in ADP and NADP+, which are recycled to use during the light stage.

How do phospholipids contribute flexibility to cell membrane structure? a. The phospholipids containing unsaturated fatty acids cannot be tightly packed which provides membrane flexibility. b. The phospholipids containing saturated fatty acids cannot be tightly packed which provides membrane rigidity. c. The two fatty acid chains are flexible as they are unsaturated and provide the flexibility. d. The two fatty acid chains are saturated. Embedded cholesterol and proteins provide the flexibility.

a. The phospholipids containing unsaturated fatty acids cannot be tightly packed which provides membrane flexibility. Phospholipids have two fatty acid chains, one saturated and one unsaturated. The saturated chain is stiff and straight, while the unsaturated one has a bend in it that pushes other molecules aside. This creates space between the membrane molecules and allows the membrane to be flexible and behave as though it were a liquid.

DNA replication involves unwinding two strands of parent DNA, copying each strand to synthesize complementary strands, and releasing the resulting two semi-conserved strands of DNA. Which of the following accurately describes this process? a. This is an anabolic process. b. This is a catabolic process. c. This is both an anabolic and a catabolic process. d. This is a metabolic process, but is neither anabolic nor catabolic.

a. This is an anabolic process. An anabolic process is the one in which simpler molecules combine together to form complex molecules with input of energy. Synthesis of new DNA strands from nucleic acid building blocks is an anabolic process.

What is combined with ADP to form ATP? a. a single inorganic phosphate b. AMP c. a covalently bonded phosphate d. phosphate ions

a. a single inorganic phosphate A single inorganic phosphate molecule, when added to the ADP molecule, yields an ATP molecule.

The synthesis of sucrose is an example of what process? a. anabolic b. catabolic c. hydrolysis d. transcription

a. anabolic An anabolic process is one in which simpler molecules combine to form complex molecules by using energy. Sucrose is a complex molecule formed by the polymerization of glucose and fructose, which are simple molecules.

Where are ββ-1,4 glycosidic linkages found? a. cellulose b. sucrose c. RNA d. starch

a. cellulose Cellulose is made up of glucose monomers that are linked by ββ-1,4 glycosidic bonds. There are no αα or 1,6 glycosidic linkages in cellulose.

When the air temperature drops and rain turns to snow, which law of thermodynamics is exhibited? a. first law of thermodynamics b. second law of thermodynamics c. third law of thermodynamics d. zeroth law of thermodynamics

a. first law of thermodynamics The first law of thermodynamics states that energy can neither be created nor destroyed. It is transferred from one state to the other, so energy is being transferred as the atmosphere gets colder and the rainwater solidifies into snow.

What is the source of energy for chemoautotrophic organisms? a. inorganic molecules b. organic molecules from captured microorganisms c. the ultraviolet wavelengths of light d. the visible wavelengths of light

a. inorganic molecules Chemoautotrophic organisms use inorganic molecules as energy sources to synthesize their own food instead of sunlight. They are mostly bacteria and archaea that live in hostile sea environments where they are the primary producers.

Which of the following metabolic reactions is catabolic? a. 6CO2 + 6H2O → C6H12O6 + 6O2 b. C6H12O6 + 6O2 → 6CO2 + 6H2O c. C3H4O3 + C3H3O3- + 5H+ → C6H12O6 d. C6H12O6 + C6H12O6 → C12H22O11 + H2O

b. C6H12O6 + 6O2 → 6CO2 + 6H2O Catabolic pathways involve the breakdown of complex molecules into simpler ones; as seen in reactions 2 and 3. Anabolic pathways synthesize complex molecules from simpler ones; as seen in reactions 1 and 4.

Which of the following is the best way to judge the relative activation energies between two given chemical reactions? a. Compare the Δ⁢G values between the two reactions. b. Compare their reaction rates. c. Compare their ideal environmental conditions. d. Compare the spontaneity between the two reactions

b. Compare their reaction rates. The activation energy of a particular reaction determines the rate at which it will proceed. The higher the activation energy, the slower the chemical reaction will be. Thus, relative activation energies between two chemical reactions can be judged by comparing their reaction rates.

Which of the following statements about enzymes is false? a. Feedback inhibition results when a product of a reaction decreases its further production by inhibiting the activity of the first enzyme in the pathway that produces it. b. Competitive inhibition is the inhibition by a binding event at a site different from the active site, which induces a conformational change and reduces the affinity of the enzyme for its substrate. c. A coenzyme is a small organic molecule, such as a vitamin or its derivative, which is required to enhance the activity of an enzyme. d. A cofactor is an inorganic ion, such as iron and magnesium ions, required for optimal regulation of enzyme activity.

b. Competitive inhibition is the inhibition by a binding event at a site different from the active site, which induces a conformational change and reduces the affinity of the enzyme for its substrate. Detailed solution: Competitive inhibition is a type of inhibition in which the inhibitor competes with the substrate molecule by binding to the active site of the enzyme; whereas allosteric inhibition is inhibition by a binding event at a site different from the active site, which induces a conformational change and reduces the affinity of the enzyme for its substrate.

Which of the following statements about energy in living systems is false? a. Chemiosmosis is the process in which there is a production of ATP in cellular metabolism by the involvement of a proton gradient across a membrane. b. Dephosphorylation is the production of ATP from ADP using the excess energy from a chemical reaction and a phosphate group from a reactant. c. A redox reaction is a chemical reaction that consists of the coupling of an oxidation reaction and a reduction reaction. d. Oxidative phosphorylation is the production of ATP using the process of chemiosmosis and oxygen using the electron transport chain, chemiosmosis, and oxygen.

b. Dephosphorylation is the production of ATP from ADP using the excess energy from a chemical reaction and a phosphate group from a reactant. Detailed solution: Dephosphorylation is the removal of a phosphate group from a molecule, whereas substrate-level phosphorylation is the production of ATP from ADP using the excess energy from a chemical reaction and a phosphate group from a reactant.

If a chemical reaction could occur without an enzyme, provide the reasoning to explain why it is important to have an enzyme to catalyze that reaction. a. Enzymes are important because they ensure that only the desired products are produced by the reaction. b. Enzymes are important because they ensure that the reaction products are obtained consistently with time. c. Enzymes are important because they ensure that energy remains conserved and no loss of energy occurs. d. Enzymes are important because they do not alter the concentration of the reaction products.

b. Enzymes are important because they ensure that the reaction products are obtained consistently with time. Enzymes provide the products consistently with life. The products are needed for an organism's growth and maintenance, thus they should be available in timely manner.

Which of the following statements about photosynthesis is true? a. Chlorophyll in the outer membrane of chloroplasts is responsible for the initial interaction between light and plant material. b. In the light-dependent reactions, energy from sunlight is absorbed by chlorophyll and that energy is converted into stored chemical energy. c. In the light-dependent reactions, the chemical energy harvested during the light-independent reactions drive the assembly of sugar molecules from carbon dioxide. d. In the light-independent reaction, glucose is broken down to form pyruvate and ATP.

b. In the light-dependent reactions, energy from sunlight is absorbed by chlorophyll and that energy is converted into stored chemical energy. Detailed solution: Chlorophyll in the thylakoid membrane is responsible for the initial interaction between light and plant material. In the light-dependent reactions, energy from sunlight is absorbed by chlorophyll and that energy is converted into stored chemical energy. In the light-independent reactions, the chemical energy harvested during the light-dependent reactions drive the assembly of sugar molecules from carbon dioxide.

What is a difference between saturated and unsaturated fats? a. Saturated fats have at least one double bond between carbon atoms but unsaturated fats have no double bonds. b. Saturated fats are solid at room temperature and unsaturated fats are liquid at room temperature c. Saturated fats are liquid at room temperature and unsaturated fats are solid at room temperature. d. Saturated fats are solid at room temperature and have at least one double bond unlike unsaturated fats.

b. Saturated fats are solid at room temperature and unsaturated fats are liquid at room temperature Saturated fats are solid at room temperature unlike unsaturated fats.

Animals cannot digest cellulose due to the type of bonding between the glucose monomers. The glucose monomers are there for an energy source but are unattainable. Yet ruminants such as cows and sheep, and termites eat cellulose in the form of grasses and wood. How do they do it? a. Specialized glands in the digestive tracts of these animals secrete digestive enzymes that affect cellulose. b. Specialized bacteria and protists are found in the digestive tracts of these animals making cellulase that result in cellulose breakdown. c. These animals make a specialized type of amylase that digests cellulose. d. The saliva of these animals initiates the breakdown of cellulose and it is completed in their stomach.

b. Specialized bacteria and protists are found in the digestive tracts of these animals making cellulase that result in cellulose breakdown. Herbivores and termites contain certain specialized bacteria and protists in their digestive tract that help in the breakdown of cellulose.

Imagine an elaborate ant farm with tunnels and passageways through the sand where ants live in a large community. Now imagine that an earthquake shook the ground and demolished the ant farm. In which of these two scenarios, before or after the earthquake, was the ant farm system in a state of higher entropy? Justify your answer by explaining your reasoning. a. The ant farm is in the state of lower entropy after the earthquake because of the increased disorder, and energy must be spent to bring the system to higher entropy. b. The ant farm is in the state of higher entropy after the earthquake because of the increased disorder, and energy must be spent to bring the system to lower entropy. c. The ant farm is in the state of higher entropy before the earthquake because of the reduced disorder, and energy is given out of the system after the earthquake. d. The ant farm is in the state of lower entropy before the earthquake because of the higher degree of randomness, and energy is given out of the system after the earthquake.

b. The ant farm is in the state of higher entropy after the earthquake because of the increased disorder, and energy must be spent to bring the system to lower entropy. The system is in state of higher entropy after the earthquake which causes disorder.

Dehydration is a word usually used to mean the removal of water. How does this apply to macromolecules? a. Each monomer releases one water molecule when forming a polymer, thereby causing dehydration. b. The hydroxyl groups of two monomers are used to form a bond by removing a hydrogen from one monomer and a hydroxyl group from the second forming a molecule of water. c. The diffusion of a water molecule occurs out of the cell, whenever the polymerization occurs. This provides the required energy to the process. d. Two hydrogen atoms from one monomer and an oxygen from the phosphate group releases water when producing a polymer.

b. The hydroxyl groups of two monomers are used to form a bond by removing a hydrogen from one monomer and a hydroxyl group from the second forming a molecule of water. Both monomers had hydroxyl groups at the point of attachment for monomers. Hydrogen is removed from one and the hydroxyl group from the second. These are combined to make a water molecule, causing the dehydration of the monomers. The oxygen from the hydroxyl group that lost hydrogen is used to link the monomers.

Which of the following apply to both FAD and NAD+? a. They are oxidizing agents and donate electrons. b. They are oxidizing agents and accept electrons. c. They are reducing agents and donate electrons. d. They are reducing agents and accept electrons.

b. They are oxidizing agents and accept electrons. Detailed solution: NAD+ and FAD+ can accept electrons from organic molecules; in this way they act as oxidizing agents. When they accept electrons, they are reduced to NADH and FADH respectively.

Applying your understanding of how processes of photosynthesis are connected, select the best description of the electron transfer pathway from photosynthesis II to photosynthesis I in the light-dependent reactions. a. After splitting water in PS-I, high-energy electrons are delivered through the chloroplast electron transport chain to PS-II. b. After the photosynthesis reaction, released products like glucose help in the transfer of electrons from PS-II to PS-I. c. After splitting water in PS-II, high-energy electrons are delivered through the chloroplast electron transport chain to PS-I. d. After the completion of the light-dependent reactions, the electrons are transferred from PS-II to PS-I.

c. After splitting water in PS-II, high-energy electrons are delivered through the chloroplast electron transport chain to PS-I. Detailed solution: The excited electron removed from the photosystem must then be replaced. In photosystem II, the electron comes from the splitting of water, which releases oxygen as a waste product. In photosystem I, the electron comes from the chloroplast electron transport chain. The reaction center of PSII (called P680) delivers its high energy electrons one at a time to the primary electron acceptor and through the electron transport chain to PSI.

Cyanide is highly toxic as it prevents the production of ATP. Which of the following metabolic reactions will most rapidly be disrupted by cyanide? a. 6CO2 + 6H2O → C6H12O6 + 6O2 b. C6H12O6 → C3H4O3 + C3H3O3- + 5H+ c. C6H12O6 + 6O2 → 6CO2 +6H2O

c. C6H12O6 + 6O2 → 6CO2 +6H2O The reaction that produces ATP will be most affected. However, the lack of ATP production will then rapidly affect reactions that require an input of ATP.

Based on your understanding of activation energy EA, is the EA for ATP hydrolysis relatively low or high? Explain your reasoning. a. EA for ATP hydrolysis is high because considerable energy is released. b. EA for ATP hydrolysis is high because a low amount of energy is released. c. EA for ATP hydrolysis is low because considerable energy is released. EA for hydrolysis of ATP is low. d. EA for ATP hydrolysis is intermediate because considerable energy is released.

c. EA for ATP hydrolysis is low because considerable energy is released. EA for hydrolysis of ATP is low.

Which excited electrons play a role in the formation of NADPH? a. Electrons from PS I cause the reduction of NADPH to NADP+. b. Electrons from PSII cause the reduction of NADP+ to NADPH. c. Electrons from PS I cause the reduction of NADP+ to NADPH. d. Electrons are gained which causes the oxidation of NADP+.

c. Electrons from PS I cause the reduction of NADP+ to NADPH. Detailed Solution: Electrons required for the formation of NADPH are obtained from PS I.

A scientist wants to invent a new device that can convert macromolecules into energy to power an engine. She does not want it to use of any fossil fuels and it should be completely renewable. During her experimentation, she tests all four classes of macromolecules. She finally decided on the best one to power the device. Which one did she select and why? a. Carbohydrates because they can produce a quick burst of energy. b. Proteins because the nitrogen within them produces a lot of energy. c. Lipids were selected because they have the highest amount of energy in their bonds. d. Nucleic acids because their helical structures can be used to form energy bonds with other molecules.

c. Lipids were selected because they have the highest amount of energy in their bonds. Lipids have many carbon-hydrogen bonds that, when broken, release enormous amount of energy.

How does the formation of nucleic acid polymers differ from the formation of polysaccharides? a. Carbon is removed from nucleic acids, but not polysaccharides. b. They differ in the presence of hydroxyl groups c. Phosphates are removed from nucleic acids, but not polysaccharides. d. They differ in whether or not water is removed

c. Phosphates are removed from nucleic acids, but not polysaccharides. Monosaccharides, the building blocks of polysaccharides, bond together through the removal of water, not phosphates. Nucleotides, on the other hand, are the building blocks of nucleic acids and require a phosphate to be removed before they bond with another nucleotide.

Which order of molecular conversions is correct for the Calvin cycle? a. RuBP+G3P → 3-PGA→ sugar b. RuBisCO→ CO2→ RuBP→ G3P c. RuBP+CO2→ [RuBisCO]3-PGA→ G3P d. CO2→ 3-PGA→ RuBP→ G3P

c. RuBP+CO2→ [RuBisCO]3-PGA→ G3P Detailed Solution: RuBP and CO2 are needed with the enzyme RuBisCO to produce 3-PGA molecules. ATP and NADPH are used to convert 3-PGA molecules into G3P.

What role do electrons play in dehydration synthesis and hydrolysis? a. Sharing of electrons between monomers occurs in both dehydration synthesis and hydrolysis. b. The sharing of electrons between monomers occurs in hydrolysis only. c. H+ and OH− ions share electrons with the respective monomers in dehydration synthesis. d. H+ and OH− ions share electrons with the respective monomers in hydrolysis.

d. H+ and OH− ions share electrons with the respective monomers in hydrolysis. Hydrolysis involves the addition of water molecules where H+ and OH− ions share electrons with the respective monomers.

Why does the lock and key analogy fit the linkage between an enzyme and its substrate? a. The structures cannot be altered, so they always work together. b. The enzyme is the lock that is structured to the key, which is the substrate. c. The reaction cannot proceed without both. d. The key only fits one configuration of the lock, as the enzyme does with the substrate.

d. The key only fits one configuration of the lock, as the enzyme does with the substrate. The enzyme changes its configuration to bind to the transition state of the substrate. This validates the lock and key analogy.

If a cell's metabolism continues to produce a product, eventually that product may reach toxic levels in the cell. Provide the biological reasoning to predict how the process can be prevented. a. The reactant of the reaction binds to the allosteric site of the enzyme catalyzing the reaction, thus changing the configuration of the enzyme. The reaction will then stop and when the reactant concentration drops, then the reaction starts again. b. The product of the reaction binds to the primary binding site of the enzyme catalyzing the reaction, thus changing the configuration of the enzyme. The reaction will then stop, and when the product concentration drops, then the reaction will start again. c. The product of the reaction binds to the allosteric site of the enzyme catalyzing the reaction, thus oxidizing the enzyme. The reaction will then stop, and when the concentration drops, then the reaction will start again. d. The product of the reaction binds to the allosteric site of the enzyme catalyzing the reaction, thus changing the configuration of the enzyme. The reaction will then stop, and when the product concentration drops, then the reaction will start again.

d. The product of the reaction binds to the allosteric site of the enzyme catalyzing the reaction, thus changing the configuration of the enzyme. The reaction will then stop, and when the product concentration drops, then the reaction will start again. The configuration of the enzyme is changed and is not oxidized.

Define endergonic a. pathways that require an input of energy to synthesize complex molecules from simpler ones b. pathways in which complex molecules are broken down into simpler ones c. describes chemical reactions that release free energy d. describes chemical reactions that require energy input

d. describes chemical reactions that require energy input

Which chemical reaction is more likely to occur? a. dehydration synthesis b. endergonic c. endothermic d. exergonic

d. exergonic Exergonic reactions can occur spontaneously and free energy is released from the reaction.