Bio 1A ch 6 questions
Describe a catabolic pathway?
*Glycolysis converts one molecule of glucose to two pyruvates. *A lipid molecule is broken down into fatty acid subunits.
Describe an anabolic pathway?
*Photosynthesis generates storage carbohydrates from CO2 and H2O. * A nucleic acid is constructed from nucleotide subunits.
Which of the following examples describes an energy transformation?
-An oven uses electrical energy to generate heat to bake a cake. -A plant uses solar energy to construct carbohydrates in photosynthesis. -An individual uses energy obtained from eating a sandwich to ride a bike.
Both photosynthesis and cellular respiration are cellular processes that involve glucose. How do these two processes differently affect the metabolism of glucose?
-Glucose is produced during photosynthesis to hold the energy gathered from light, whereas glucose is broken down during cellular respiration to release stored cellular energy.
5) The 3 types of energy and def?
-Kinetic energy: Energy associated with objects in motion. -Potential Energy: The potential to do work -Chemical Energy: The potential energy that exists within chemical bond, and is released when those bonds are broken.
6) Consider a pendulum swinging. Which type(s) of energy is/are associated with the pendulum in the following instances: i. the moment at which it completes one cycle, just before it begins to fall back towards the other end, ii. the moment that it is in the middle between the two ends, iii. just before it reaches the end of one cycle (just before instant i.)? A) i. potential and kinetic, ii. potential and kinetic, iii. kinetic B)i. potential, ii. potential and kinetic, iii. potential and kinetic C) i. potential, ii. kinetic, iii. potential and kinetic D) i. potential and kinetic, ii. kinetic iii. kinetic
C) i. potential, ii. kinetic, iii. potential and kinetic
Which of the following is an example of the chemical potential energy in adenosine triphosphate (ATP) being turned into work? A)ATP synthase transfers a phosphate to ADP B)ATP is bound by an enzyme but is not hydrolyzed C)ATP hydrolosys induces a conformational change in a protein that moves ions across a membrane D)A phosphate group is transferred from ATP to glucose during glycolysis
C)ATP hydrolosys induces a conformational change in a protein that moves ions across a membrane *D)A phosphate group is transferred from ATP to glucose during glycolysis
What is entropy? A)a measure of the energy available for work in a thermodynamic system B)a measure of the kinetic energy in the random movement of molecules C)a measure of the disorder or energy dispersal in a system D)a measure of the energy stored in the chemical bonds of molecules
C)a measure of the disorder or energy dispersal in a system
7) Which of the following comparisons or contrasts between endergonic and exergonic reactions is false? A) Endergonic reactions have a positive ∆G and exergonic reactions have a negative ∆G B) Endergonic reactions consume energy and exergonic reactions release energy C) Both endergonic and exergonic reactions require a small amount of energy to overcome an activation barrier D) Endergonic reactions take place slowly and exergonic reactions take place quickly
D) Endergonic reactions take place slowly and exergonic reactions take place quickly
15) The energy released by the hydrolysis of ATP is? A) primarily stored between the alpha and beta phosphates B) equal to −57 kcal/mol C) harnessed as heat energy by the cell to perform work D) providing energy to coupled reactions
D) providing energy to coupled reactions
why does the body use chemical energy? A)Chemical energy produces less heat than other forms of energy when used by the body. B)Energy stored in chemical bonds is difficult to convert to other forms of energy. C)Energy stored in chemical bonds is useful for long-term, but not short-term, energy storage. D)The potential energy stored in chemical bonds can be released to perform work within a cell.
D)The potential energy stored in chemical bonds can be released to perform work within a cell.
14) Energy transfers take place constantly in everyday activities. Think of two scenarios: cooking on a stove and driving. Explain how the second law of thermodynamics applies to these two scenarios.?
While cooking, food is heating up on the stove, but not all of the heat goes to cooking the food, some of it is lost as heat energy to the surrounding air, increasing entropy. While driving, cars burn gasoline to run the engine and move the car. This reaction is not completely efficient, as some energy during this process is lost as heat energy, which is why the hood and the components underneath it heat up while the engine is turned on. The tires also heat up because of friction with the pavement, which is additional energy loss. This energy transfer, like all others, also increases entropy.
13) 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 or lower entropy?
The ant farm had lower entropy before the earthquake because it was a highly ordered system. After the earthquake, the system became much more disordered and had higher entropy.
10) Describe the position of the transition state on a vertical energy scale, from low to high, relative to the position of the reactants and products, for both endergonic and exergonic reactions.?
The transition state is always higher in energy than the reactants and the products of a reaction (therefore, above), regardless of whether the reaction is endergonic or exergonic.
9) Explain in your own words the difference between a spontaneous reaction and one that occurs instantaneously, and what causes this difference.?
A spontaneous reaction is one that has a negative ∆G and thus releases energy. However, a spontaneous reaction need not occur quickly or suddenly like an instantaneous reaction. It may occur over long periods due to a large energy of activation, which prevents the reaction from occurring quickly.
Which of the following analogies best describe the induced-fit model of enzyme-substrate binding? A) A hug between two people B) A key fitting into a lock C) A square peg fitting through the square hole and a round peg fitting through the round hole of a children's toy D) The fitting together of two jigsaw puzzle pieces.
A) A hug between two people
18) Which of the following is not true about enzymes:? A) They increase ∆G of reactions B) They are usually made of amino acids C) They lower the activation energy of chemical reactions D) Each one is specific to the particular substrate(s) to which it binds
A) They increase ∆G of reactions
2) DNA replication involves unwinding two strands of parent DNA, copying each strand to synthesize complementary strands, and releasing the parent and daughter 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 anabolic and catabolic D)This is a metabolic process but is neither anabolic nor catabolic
A) This is an anabolic process
11) Which of the following is not an example of an energy transformation? A) Turning on a light switch B) Solar panels at work C) Formation of static electricity D) None of the above
A) Turning on a light switch
12) Label each of the following systems as high or low entropy: i. the instant that a perfume bottle is sprayed compared with 30 seconds later, ii. an old 1950s car compared with a brand new car, and iii. a living cell compared with a dead cell. A) i. low, ii. high, iii. low B) i. low, ii. high, iii. high C) i. high, ii. low, iii. high D) i. high, ii. low, iii. Low
A) i. low, ii. high, iii. low
16) Which of the following molecules is likely to have the most potential energy? A) sucrose B) ATP C) glucose D) ADP
A) sucrose
8)Which of the following is the best way to judge the relative activation energies between two given chemical reactions? A) Compare the ∆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
Which of the following describes a catabolic? A) a pathway that consumes energy B) a pathway that breaks down molecules into smaller subunits C) a pathway that transmits a signal within a cell D) a pathway that constructs molecules from smaller subunits.
B) a pathway that breaks down molecules into smaller subunits
Activation energy is best defined as the energy that? A)is transferred to the products at the end of the reaction. B)is required to bring the reactant molecules to a transition state. C)is required to form products that are at a higher energy than the reactants. D)is used to make new chemical bonds and form products.
B)is required to bring the reactant molecules to a transition state.
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 the 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
1) Energy is stored long-term in the bonds of _____ and used short-term to perform work from a(n) _____ molecule. A) ATP : glucose B) an anabolic molecule : catabolic molecule C) glucose : ATP D) a catabolic molecule : anabolic molecule
C) glucose : ATP
17) Do you think that the EA for ATP hydrolysis is relatively low or high? Explain your reasoning.?
The activation energy for hydrolysis is very low. Not only is ATP hydrolysis an exergonic process with a large −∆G, but ATP is also a very unstable molecule that rapidly breaks down into ADP + Pi if not utilized quickly. This suggests a very low EA since it hydrolyzes so quickly.
4) Name two different cellular functions that require energy that parallel human energy-requiring functions
Energy is required for cellular motion, through beating of cilia or flagella, as well as human motion, produced by muscle contraction. Cells also need energy to perform digestion, as humans require energy to digest food.
Explain in your own words how enzyme feedback inhibition benefits a cell.
Feedback inhibition allows cells to control the amounts of metabolic products produced. If there is too much of a particular product relative to what the cell's needs, feedback inhibition effectively causes the cell to decrease production of that particular product. In general, this reduces the production of superfluous products and conserves energy, maximizing energy efficiency.
With regard to enzymes, why are vitamins necessary for good health? Give examples.
Most vitamins and minerals act as coenzymes and cofactors for enzyme action. Many enzymes require the binding of certain cofactors or coenzymes to be able to catalyze their reactions. Since enzymes catalyze many important reactions, it is critical to obtain sufficient vitamins and minerals from the diet and from supplements. Vitamin C (ascorbic acid) is a coenzyme necessary for the action of enzymes that build collagen, an important protein component of connective tissue throughout the body. Magnesium ion (Mg++) is an important cofactor that is necessary for the enzyme pyruvate dehydrogenase to catalyze part of the pathway that breaks down sugar to produce energy. Vitamins cannot be produced in the human body and therefore must be obtained in the diet.
3) Does physical exercise involve anabolic and/or catabolic processes? Give evidence for your answer.
Physical exercise involves both anabolic and catabolic processes. Body cells break down sugars to provide ATP to do the work necessary for exercise, such as muscle contractions. This is catabolism. Muscle cells also must repair muscle tissue damaged by exercise by building new muscle. This is anabolism.
