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Test sobre Biology I - Exam 3, creado por acbridges91 el 10/05/2015.

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Biology I - Exam 3

Pregunta 1 de 100

1

Which of the following is true of metabolism in its entirety in all organisms?

Selecciona una de las siguientes respuestas posibles:

  • Metabolism uses all of an organism's resources.

  • Metabolism manages the increase of entropy in an organism.

  • Metabolism consists of all the energy transformation reactions in an organism.

  • Metabolism depends on a constant supply of energy from food.

Explicación

Pregunta 2 de 100

1

Which of the following is an example of potential rather than kinetic energy?

Selecciona una de las siguientes respuestas posibles:

  • water rushing over Niagara Falls

  • a molecule of glucose

  • a crawling beetle foraging for food

  • light flashes emitted by a firefly

Explicación

Pregunta 3 de 100

1

Most cells cannot harness heat to perform work because _____.

Selecciona una de las siguientes respuestas posibles:

  • heat is not a form of energy

  • heat must remain constant during work

  • heat can never be used to do work

  • temperature is usually uniform throughout a cell

Explicación

Pregunta 4 de 100

1

Which of the following involves a decrease in entropy?

Selecciona una de las siguientes respuestas posibles:

  • reactions that separate monomers

  • hydrolysis reactions

  • depolymerization reactions

  • condensation reactions

Explicación

Pregunta 5 de 100

1

Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?

Selecciona una de las siguientes respuestas posibles:

  • catabolism (catabolic pathways)

  • dehydration

  • metabolism

  • anabolism (anabolic pathways)

Explicación

Pregunta 6 de 100

1

Anabolic pathways _____.

Selecciona una de las siguientes respuestas posibles:

  • are usually highly spontaneous chemical reactions

  • release energy as they degrade polymers to monomers

  • consume energy to build up polymers from monomers

  • consume energy to decrease the entropy of the organism and its environment

Explicación

Pregunta 7 de 100

1

Which of the following is a statement of the first law of thermodynamics?

Selecciona una de las siguientes respuestas posibles:

  • The entropy of the universe is constant.

  • The entropy of the universe is decreasing.

  • Energy cannot be transferred or transformed.

  • Energy cannot be created or destroyed.

Explicación

Pregunta 8 de 100

1

For living organisms, which of the following is an important consequence of the first law of thermodynamics?

Selecciona una de las siguientes respuestas posibles:

  • The organism ultimately must obtain all of the necessary energy for life from its environment.

  • The entropy of an organism decreases with time as the organism grows in complexity.

  • The energy content of an organism is constant.

  • Organisms grow by converting energy into organic matter.

Explicación

Pregunta 9 de 100

1

Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics?

Selecciona una de las siguientes respuestas posibles:

  • As a consequence of growing, organisms cause a greater increase in entropy in their environment than the decrease in entropy associated with their growth.

  • Life obeys the second law of thermodynamics because the decrease in entropy as the organism grows is exactly balanced by an increase in the entropy of the universe.

  • Living organisms do not obey the second law of thermodynamics, which states that entropy must increase with time.

  • Living organisms are able to transform energy into entropy.

Explicación

Pregunta 10 de 100

1

Which of the following statements is representative of the second law of thermodynamics?

Selecciona una de las siguientes respuestas posibles:

  • Cells require a constant input of energy to maintain their high level of organization.

  • Conversion of energy from one form to another is always accompanied by some gain of free energy.

  • Every energy transformation by a cell decreases the entropy of the universe.

  • Without an input of energy, organisms would tend toward decreasing entropy.

Explicación

Pregunta 11 de 100

1

Which of the following types of reactions would decrease the entropy within a cell?

Selecciona una de las siguientes respuestas posibles:

  • digestion

  • hydrolysis

  • catabolic reactions

  • anabolic reactions

Explicación

Pregunta 12 de 100

1

Biological evolution of life on Earth, from simple prokaryote-like cells to large, multicellular eukaryotic organisms, _____.

Selecciona una de las siguientes respuestas posibles:

  • has been made possible by expending Earth's energy resources

  • has caused an increase in the entropy of the planet

  • has occurred in accordance with the laws of thermodynamics

  • has occurred in accordance with the laws of thermodynamics, by expending Earth's energy resources and causing an increase in the entropy of the planet

Explicación

Pregunta 13 de 100

1

A system at chemical equilibrium _____.

Selecciona una de las siguientes respuestas posibles:

  • has zero kinetic energy

  • releases energy at a steady rate

  • can do no work

  • consumes energy at a steady rate

Explicación

Pregunta 14 de 100

1

Which of the following is true for all exergonic reactions?

Selecciona una de las siguientes respuestas posibles:

  • The reaction goes only in a forward direction: all reactants will be converted to products, but no products will be converted to reactants.

  • The products have more total energy than the reactants.

  • The reaction proceeds with a net release of free energy.

  • A net input of energy from the surroundings is required for the reactions to proceed.

Explicación

Pregunta 15 de 100

1

A chemical reaction that has a positive ΔG is best described as _____.

Selecciona una de las siguientes respuestas posibles:

  • enthalpic

  • spontaneous

  • endergonic

  • exergonic

Explicación

Pregunta 16 de 100

1

Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as _____ is to _____.

Selecciona una de las siguientes respuestas posibles:

  • work; energy

  • exergonic; endergonic

  • free energy; entropy

  • exergonic; spontaneous

Explicación

Pregunta 17 de 100

1

Why is ATP an important molecule in metabolism?

Selecciona una de las siguientes respuestas posibles:

  • It provides energy coupling between exergonic and endergonic reactions.

  • Its terminal phosphate bond has higher energy than the other two phosphate bonds.

  • Its hydrolysis provides an input of free energy for exergonic reactions.

  • Its terminal phosphate group contains a strong covalent bond that, when hydrolyzed, releases free energy.

Explicación

Pregunta 18 de 100

1

Which of the following is most similar in structure to ATP?

Selecciona una de las siguientes respuestas posibles:

  • a DNA nucleotide

  • a pentose sugar

  • an amino acid with three phosphate groups attached

  • an RNA nucleotide

Explicación

Pregunta 19 de 100

1

Catabolic pathways _____.

Selecciona una de las siguientes respuestas posibles:

  • are endergonic

  • are spontaneous and do not need enzyme catalysis

  • combine molecules into more energy-rich molecules

  • supply energy, primarily in the form of ATP, for the cell's work

Explicación

Pregunta 20 de 100

1

When ATP releases some energy, it also releases inorganic phosphate. What happens to the inorganic phosphate in the cell?

Selecciona una de las siguientes respuestas posibles:

  • It is secreted as waste.

  • It may be used to form a phosphorylated intermediate.

  • It is used only to regenerate more ATP.

  • It enters the nucleus and affects gene expression.

Explicación

Pregunta 21 de 100

1

Which of the following is true of enzymes?

Selecciona una de las siguientes respuestas posibles:

  • Enzyme function is independent of physical and chemical environmental factors such as pH and temperature.

  • Enzymes increase the rate of chemical reaction by providing activation energy to the substrate.

  • Enzymes increase the rate of chemical reaction by lowering activation energy barriers.

  • Enzyme function is increased if the 3- D structure or conformation of an enzyme is altered.

Explicación

Pregunta 22 de 100

1

The lock-and-key analogy for enzymes applies to the specificity of enzymes _____.

Selecciona una de las siguientes respuestas posibles:

  • interacting with water

  • binding to their substrate

  • interacting with ions

  • as they form their tertiary and quaternary structure

Explicación

Pregunta 23 de 100

1

Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's _____.

Selecciona una de las siguientes respuestas posibles:

  • free-energy content

  • entropy

  • activation energy

  • equilibrium point

Explicación

Pregunta 24 de 100

1

The active site of an enzyme is the region that _____.

Selecciona una de las siguientes respuestas posibles:

  • binds allosteric regulators of the enzyme

  • is involved in the catalytic reaction of the enzyme

  • is inhibited by the presence of a coenzyme or a cofactor

  • binds noncompetitive inhibitors of the enzyme

Explicación

Pregunta 25 de 100

1

Increasing the substrate concentration in an enzymatic reaction could overcome which of the following?

Selecciona una de las siguientes respuestas posibles:

  • allosteric inhibition

  • the need for a coenzyme

  • insufficient cofactors

  • competitive inhibition

Explicación

Pregunta 26 de 100

1

A noncompetitive inhibitor decreases the rate of an enzyme reaction by _____.

Selecciona una de las siguientes respuestas posibles:

  • binding at the active site of the enzyme

  • acting as a coenzyme for the reaction

  • changing the shape of the enzyme's active site

  • changing the free energy change of the reaction

Explicación

Pregunta 27 de 100

1

How might a change of one amino acid at a site, distant from the active site of an enzyme, alter an enzyme's substrate specificity?

Selecciona una de las siguientes respuestas posibles:

  • by changing the shape of an enzyme

  • by changing the enzyme's stability

  • by changing the enzyme's pH optimum

  • An amino acid change away from the active site cannot alter the enzyme's substrate specificity.

Explicación

Pregunta 28 de 100

1

HIV is the virus that causes AIDS. In the mid-1990s, researchers discovered an enzyme in HIV called protease. Once the enzyme's structure was known, researchers began looking for drugs that would fit into the active site and block it. If this strategy for stopping HIV infections were successful, it would be an example of what phenomenon?

Selecciona una de las siguientes respuestas posibles:

  • denaturation

  • allosteric regulation

  • competitive inhibition

  • vaccination

Explicación

Pregunta 29 de 100

1

Use the following information to answer the questions below.
A series of enzymes catalyze the reaction X → Y Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme.
What is substance X?

Selecciona una de las siguientes respuestas posibles:

  • the product

  • an allosteric inhibitor

  • an intermediate

  • a substrate

Explicación

Pregunta 30 de 100

1

The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is most precisely described as _____.

Selecciona una de las siguientes respuestas posibles:

  • feedback inhibition

  • noncooperative inhibition

  • allosteric inhibition

  • metabolic inhibition

Explicación

Pregunta 31 de 100

1

Allosteric enzyme regulation is usually associated with _____.

Selecciona una de las siguientes respuestas posibles:

  • the need for cofactors

  • feedback inhibition

  • an enzyme with more than one subunit

  • activating activity

Explicación

Pregunta 32 de 100

1

Besides turning enzymes on or off, what other means does a cell use to control enzymatic activity?

Selecciona una de las siguientes respuestas posibles:

  • hydrophobic interactions

  • connecting enzymes into large aggregates

  • localization of enzymes into specific organelles or membranes

  • exporting enzymes out of the cell

Explicación

Pregunta 33 de 100

1

Protein kinases are enzymes that transfer the terminal phosphate from ATP to an amino acid residue on the target protein. Many are located on the plasma membrane as integral membrane proteins or peripheral membrane proteins. What purpose may be served by their plasma membrane localization?

Selecciona una de las siguientes respuestas posibles:

  • Membrane localization lowers the activation energy of the phosphorylation reaction.

  • ATP is more abundant near the plasma membrane.

  • They can more readily encounter and phosphorylate other membrane proteins.

  • They flip back and forth across the membrane to access target proteins on either side.

Explicación

Pregunta 34 de 100

1

Substrate-level phosphorylation occurs _____.

Selecciona una de las siguientes respuestas posibles:

  • in the citric acid cycle

  • in both glycolysis and the citric acid cycle

  • in glycolysis

  • during oxidative phosphorylation

Explicación

Pregunta 35 de 100

1

The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction _____.

Selecciona una de las siguientes respuestas posibles:

  • gains electrons and loses potential energy

  • loses electrons and gains potential energy

  • loses electrons and loses potential energy

  • gains electrons and gains potential energy

Explicación

Pregunta 36 de 100

1

When electrons move closer to a more electronegative atom, what happens? The more electronegative atom is _____.

Selecciona una de las siguientes respuestas posibles:

  • reduced, and energy is consumed

  • reduced, and energy is released

  • oxidized, and energy is consumed

  • oxidized, and energy is released

Explicación

Pregunta 37 de 100

1

Which of the listed statements describes the results of the following reaction?
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy

Selecciona una de las siguientes respuestas posibles:

  • O2 is reduced and CO2 is oxidized.

  • C6H12O6 is oxidized and O2 is reduced.

  • O2 is oxidized and H2O is reduced.

  • CO2 is reduced and O2 is oxidized.

Explicación

Pregunta 38 de 100

1

When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes _____.

Selecciona una de las siguientes respuestas posibles:

  • an oxidizing agent

  • hydrolyzed

  • reduced

  • oxidized

Explicación

Pregunta 39 de 100

1

When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a proton), the molecule becomes _____.

Selecciona una de las siguientes respuestas posibles:

  • reduced

  • redoxed

  • dehydrogenated

  • oxidized

Explicación

Pregunta 40 de 100

1

Which of the following statements about NAD+ is true?

Selecciona una de las siguientes respuestas posibles:

  • NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle.

  • NAD+ can donate electrons for use in oxidative phosphorylation.

  • NAD+ has more chemical energy than NADH.

  • In the absence of NAD+, glycolysis can still function.

Explicación

Pregunta 41 de 100

1

The oxygen consumed during cellular respiration is involved directly in which process or event?

Selecciona una de las siguientes respuestas posibles:

  • glycolysis

  • the oxidation of pyruvate to acetyl CoA

  • the citric acid cycle

  • accepting electrons at the end of the electron transport chain

Explicación

Pregunta 42 de 100

1

Carbohydrates and fats are considered high-energy foods because they _____.

Selecciona una de las siguientes respuestas posibles:

  • have a lot of oxygen atoms.

  • are easily reduced.

  • have a lot of electrons associated with hydrogen.

  • have no nitrogen in their makeup.

Explicación

Pregunta 43 de 100

1

A cell has enough available ATP to meet its needs for about 30 seconds. What is likely to happen when an athlete exhausts his or her ATP supply?

Selecciona una de las siguientes respuestas posibles:

  • He or she has to sit down and rest.

  • Other cells take over, and the muscle cells that have used up their ATP cease to function.

  • ATP is transported into the cell from the circulatory system.

  • Catabolic processes are activated that generate more ATP.

Explicación

Pregunta 44 de 100

1

Starting with one molecule of glucose, the energy-containing products of glycolysis are _____.

Selecciona una de las siguientes respuestas posibles:

  • 6 CO2, 2 pyruvate, and 2 ATP

  • 2 FADH2, 2 pyruvate, and 4 ATP

  • 2 NADH, 2 pyruvate, and 2 ATP

  • 2 NAD+, 2 pyruvate, and 2 ATP

Explicación

Pregunta 45 de 100

1

In glycolysis, for each molecule of glucose oxidized to pyruvate _____.

Selecciona una de las siguientes respuestas posibles:

  • four molecules of ATP are used and two molecules of ATP are produced.

  • two molecules of ATP are used and six molecules of ATP are produced.

  • two molecules of ATP are used and four molecules of ATP are produced.

  • two molecules of ATP are used and two molecules of ATP are produced.

Explicación

Pregunta 46 de 100

1

Most of the CO2 from the catabolism of glucose is released during _____.

Selecciona una de las siguientes respuestas posibles:

  • glycolysis

  • chemiosmosis

  • the citric acid cycle

  • electron transport

Explicación

Pregunta 47 de 100

1

Following glycolysis and the citric acid cycle, but before the electron transport chain and oxidative phosphorylation, the carbon skeleton of glucose has been broken down to CO2 with some net gain of ATP. Most of the energy from the original glucose molecule at that point in the process, however, is in the form of _____.

Selecciona una de las siguientes respuestas posibles:

  • NADH

  • acetyl-CoA

  • pyruvate

  • glucose

Explicación

Pregunta 48 de 100

1

Which electron carrier(s) function in the citric acid cycle?

Selecciona una de las siguientes respuestas posibles:

  • ADP and ATP

  • NAD+ only

  • the electron transport chain

  • NADH and FADH2

Explicación

Pregunta 49 de 100

1

Which one of the following is formed by the removal of a carbon (as CO2) from a molecule of pyruvate?

Selecciona una de las siguientes respuestas posibles:

  • acetyl CoA

  • glyceraldehyde 3-phosphate

  • citrate

  • oxaloacetate

Explicación

Pregunta 50 de 100

1

Which of the following events takes place in the electron transport chain?

Selecciona una de las siguientes respuestas posibles:

  • substrate-level phosphorylation

  • the extraction of energy from high-energy electrons remaining from glycolysis and the citric acid cycle

  • the breakdown of glucose into two pyruvate molecules

  • the breakdown of an acetyl group to carbon dioxide

Explicación

Pregunta 51 de 100

1

The electron transport chain _____.

Selecciona una de las siguientes respuestas posibles:

  • is a series of substitution reactions

  • takes place in the cytoplasm of prokaryotic cells

  • is driven by ATP consumption

  • is a series of redox reactions

Explicación

Pregunta 52 de 100

1

The chemiosmotic hypothesis is an important concept in our understanding of cellular metabolism in general because it explains _____.

Selecciona una de las siguientes respuestas posibles:

  • the reduction of oxygen to water in the final steps of oxidative metabolism

  • the sequence of the electron transport chain molecules

  • how electron transport can fuel substrate-level phosphorylation

  • how ATP is synthesized by a proton motive force

Explicación

Pregunta 53 de 100

1

During aerobic respiration, electrons travel downhill in which sequence?

Selecciona una de las siguientes respuestas posibles:

  • glucose → pyruvate → ATP → oxygen

  • food → glycolysis → citric acid cycle → NADH → ATP

  • glucose → NADH → electron transport chain oxygen

  • glucose → ATP → electron transport chain NADH

Explicación

Pregunta 54 de 100

1

Where are the proteins of the electron transport chain located?

Selecciona una de las siguientes respuestas posibles:

  • mitochondrial matrix

  • mitochondrial outer membrane

  • mitochondrial inner membrane

  • mitochondrial intermembrane space

Explicación

Pregunta 55 de 100

1

During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level?

Selecciona una de las siguientes respuestas posibles:

  • ADP + Pi

  • NADH

  • ATP

  • FADH2

Explicación

Pregunta 56 de 100

1

The primary role of oxygen in cellular respiration is to _____.

Selecciona una de las siguientes respuestas posibles:

  • yield energy in the form of ATP as it is passed down the respiratory chain

  • combine with carbon, forming CO2

  • combine with lactate, forming pyruvate

  • act as an acceptor for electrons and hydrogen, forming water

Explicación

Pregunta 57 de 100

1

During aerobic respiration, H2O is formed. Where does the oxygen atom for the formation of the water come from?

Selecciona una de las siguientes respuestas posibles:

  • molecular oxygen (O2)

  • carbon dioxide (CO2)

  • pyruvate (C3H3O3-)

  • glucose (C6H12O6)

Explicación

Pregunta 58 de 100

1

Energy released by the electron transport chain is used to pump H+ into which location in eukaryotic cells?

Selecciona una de las siguientes respuestas posibles:

  • mitochondrial matrix

  • mitochondrial inner membrane

  • mitochondrial outer membrane

  • mitochondrial intermembrane space

Explicación

Pregunta 59 de 100

1

When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the _____.

Selecciona una de las siguientes respuestas posibles:

  • reduction of NAD+

  • creation of a proton-motive force

  • lowering of pH in the mitochondrial matrix

  • formation of ATP

Explicación

Pregunta 60 de 100

1

Approximately how many molecules of ATP are produced from the complete oxidation of one molecule of glucose (C6H12O6) in aerobic cellular respiration?

Selecciona una de las siguientes respuestas posibles:

  • 2

  • 4

  • 30-32

  • 18-24

Explicación

Pregunta 61 de 100

1

The synthesis of ATP by oxidative phosphorylation, using the energy released by movement of protons across the membrane down their electrochemical gradient, is an example of _____.

Selecciona una de las siguientes respuestas posibles:

  • a reaction with a positive ΔG

  • an endergonic reaction coupled to an exergonic reaction

  • allosteric regulation

  • active transport

Explicación

Pregunta 62 de 100

1

In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve?

Selecciona una de las siguientes respuestas posibles:

  • It allows for an increased rate of the citric acid cycle.

  • It allows for an increased rate of glycolysis.

  • It increases the surface for substrate-level phosphorylation.

  • It increases the surface for oxidative phosphorylation.

Explicación

Pregunta 63 de 100

1

Chemiosmotic ATP synthesis (oxidative phosphorylation) occurs in _____.

Selecciona una de las siguientes respuestas posibles:

  • all cells, but only in the presence of oxygen

  • only eukaryotic cells, in the presence of oxygen

  • all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors

  • only in mitochondria, using either oxygen or other electron acceptors

Explicación

Pregunta 64 de 100

1

Which of the following normally occurs regardless of whether or not oxygen (O2) is present?

Selecciona una de las siguientes respuestas posibles:

  • oxidative phosphorylation (chemiosmosis)

  • citric acid cycle

  • fermentation

  • glycolysis

Explicación

Pregunta 65 de 100

1

Which of the following occurs in the cytosol of a eukaryotic cell?

Selecciona una de las siguientes respuestas posibles:

  • glycolysis and fermentation

  • citric acid cycle

  • fermentation and chemiosmosis

  • oxidation of pyruvate to acetyl CoA

Explicación

Pregunta 66 de 100

1

The process of photosynthesis probably originated _____.

Selecciona una de las siguientes respuestas posibles:

  • three separate times during evolution

  • in plants

  • in prokaryotes

  • in fungi

Explicación

Pregunta 67 de 100

1

Plants photosynthesize _____.

Selecciona una de las siguientes respuestas posibles:

  • only in the light but respire only in the dark

  • only in the dark but respire only in the light

  • only in the light but respire in light and dark

  • and respire only in the light

Explicación

Pregunta 68 de 100

1

Every ecosystem must have _____.

Selecciona una de las siguientes respuestas posibles:

  • autotrophs and heterotrophs

  • photosynthesizers

  • producers and primary consumers

  • autotrophs

Explicación

Pregunta 69 de 100

1

When oxygen is released as a result of photosynthesis, it is a direct by-product of _____.

Selecciona una de las siguientes respuestas posibles:

  • chemiosmosis

  • the electron transfer system of photosystem II

  • the electron transfer system of photosystem I

  • splitting water molecules

Explicación

Pregunta 70 de 100

1

Which of the following statements is a correct distinction between autotrophs and heterotrophs?

Selecciona una de las siguientes respuestas posibles:

  • Cellular respiration is unique to heterotrophs.

  • Only heterotrophs have mitochondria.

  • Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2 and other nutrients that are inorganic.

  • Only heterotrophs require oxygen.

Explicación

Pregunta 71 de 100

1

A spaceship is designed to support animal life for a multiyear voyage to the outer planets of the solar system. Plants will be grown to provide oxygen and to recycle carbon dioxide. Since the spaceship will be too far from the sun for photosynthesis, an artificial light source will be needed.
What wavelengths of light should be used to maximize plant growth with a minimum of energy expenditure?

Selecciona una de las siguientes respuestas posibles:

  • green light

  • a mixture of blue and red light

  • full-spectrum white light

  • UV light

Explicación

Pregunta 72 de 100

1

Why are there several structurally different pigments in the reaction centers of photosystems?

Selecciona una de las siguientes respuestas posibles:

  • This arrangement enables the plant to absorb light energy of a variety of wavelengths.

  • They enable the reaction center to excite electrons to a higher energy level.

  • They enable the plant to absorb more photons from light energy, all of which are at the same wavelength.

  • Excited electrons must pass through several pigments before they can be transferred to electron acceptors of the electron transport chain.

Explicación

Pregunta 73 de 100

1

If pigments from a particular species of plant are extracted and subjected to paper chromatography, which of the following is most likely?

Selecciona una de las siguientes respuestas posibles:

  • Paper chromatography would isolate only the pigments that reflect green light.

  • Paper chromatography for the plant would isolate a single band of pigment that is characteristic of that particular plant.

  • The isolated pigments would be some shade of green.

  • Paper chromatography would separate the pigments from a particular plant into several bands.

Explicación

Pregunta 74 de 100

1

In autumn, the leaves of deciduous trees change colors. This is because chlorophyll is degraded and _____.

Selecciona una de las siguientes respuestas posibles:

  • the degraded chlorophyll changes into many other colors

  • water supply to the leaves has been reduced

  • carotenoids and other pigments are still present in the leaves

  • sugars are sent to most of the cells of the leaves

Explicación

Pregunta 75 de 100

1

What event accompanies energy absorption by chlorophyll (or other pigment molecules of the antenna complex)?

Selecciona una de las siguientes respuestas posibles:

  • An electron is excited.

  • ATP is synthesized from the energy absorbed.

  • A carboxylation reaction of the Calvin cycle occurs.

  • Electrons are stripped from NADPH.

Explicación

Pregunta 76 de 100

1

As electrons are passed through the system of electron carriers associated with photosystem II, they lose energy. What happens to this energy?

Selecciona una de las siguientes respuestas posibles:

  • It is lost as heat.

  • It excites electrons of the reaction center of photosystem I.

  • It is used to phosphorylate NAD+ to NADPH, the molecule that accepts electrons from photosystem I.

  • It is used to establish and maintain a proton gradient.

Explicación

Pregunta 77 de 100

1

The final electron acceptor associated with photosystem I is _____.

Selecciona una de las siguientes respuestas posibles:

  • water

  • NADPH

  • oxygen

  • NADP

Explicación

Pregunta 78 de 100

1

The electrons of photosystem II are excited and transferred to electron carriers. From which molecule or structure do the photosystem II replacement electrons come?

Selecciona una de las siguientes respuestas posibles:

  • oxygen

  • the electron carrier, plastocyanin

  • water

  • photosystem I

Explicación

Pregunta 79 de 100

1

In the thylakoid membranes, the pigment molecules in a light-harvesting complex _____.

Selecciona una de las siguientes respuestas posibles:

  • synthesize ATP from ADP and Pi

  • split water and release oxygen from the reaction-center chlorophyll

  • absorb and transfer light energy to the reaction-center chlorophyll

  • transfer electrons to ferredoxin and then NADPH

Explicación

Pregunta 80 de 100

1

Which of the following are directly associated with photosystem I?

Selecciona una de las siguientes respuestas posibles:

  • passing electrons to the cytochrome complex

  • extraction of hydrogen electrons from the splitting of water

  • generation of molecular oxygen

  • receiving electrons from the thylakoid membrane electron transport chain

Explicación

Pregunta 81 de 100

1

Some photosynthetic organisms contain chloroplasts that lack photosystem II, yet are able to survive. The best way to detect the lack of photosystem II in these organisms would be to _____.

Selecciona una de las siguientes respuestas posibles:

  • test for CO2 fixation in the dark

  • test for liberation of O2 in the light

  • do experiments to generate an action spectrum

  • determine if they have thylakoids in the chloroplasts

Explicación

Pregunta 82 de 100

1

What are the products of linear electron flow?

Selecciona una de las siguientes respuestas posibles:

  • ADP and NADP+

  • ATP and NADPH

  • heat and fluorescence

  • ATP and P700

Explicación

Pregunta 83 de 100

1

Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will most directly affect the _____.

Selecciona una de las siguientes respuestas posibles:

  • splitting of water

  • reduction of NADP+

  • synthesis of ATP

  • flow of electrons from photosystem II to photosystem I

Explicación

Pregunta 84 de 100

1

In a plant cell, where are the ATP synthase complexes located?

Selecciona una de las siguientes respuestas posibles:

  • inner mitochondrial membrane only

  • thylakoid membrane and plasma membrane

  • thylakoid membrane only

  • thylakoid membrane and inner mitochondrial membrane

Explicación

Pregunta 85 de 100

1

In mitochondria, chemiosmosis moves protons from the intermembrane space into the matrix, whereas in chloroplasts, chemiosmosis moves protons from the _____.

Selecciona una de las siguientes respuestas posibles:

  • thylakoid space to the stroma

  • matrix to the stroma

  • stroma to the thylakoid space

  • intermembrane space to the matrix

Explicación

Pregunta 86 de 100

1

Which of the following statements best describes the relationship between photosynthesis and respiration?

Selecciona una de las siguientes respuestas posibles:

  • Photosynthesis is catabolic; respiration is anabolic.

  • Photosynthesis occurs only in plants; respiration occurs only in animals.

  • Respiration runs the biochemical pathways of photosynthesis in reverse.

  • Photosynthesis stores energy in complex organic molecules; respiration releases energy from complex organic molecules

Explicación

Pregunta 87 de 100

1

In photosynthetic cells, synthesis of ATP by the chemiosmotic mechanism occurs during _____.

Selecciona una de las siguientes respuestas posibles:

  • photosynthesis only

  • neither photosynthesis nor respiration

  • photosynthesis and respiration

  • respiration only

Explicación

Pregunta 88 de 100

1

Carbon dioxide is split to form oxygen gas and carbon compounds _____.

Selecciona una de las siguientes respuestas posibles:

  • during photosynthesis and respiration

  • in neither photosynthesis nor respiration

  • during photosynthesis

  • during respiration

Explicación

Pregunta 89 de 100

1

What is the relationship between the wavelength of light and the quantity of energy per photon?

Selecciona una de las siguientes respuestas posibles:

  • They are separate phenomena.

  • They are inversely related.

  • They are logarithmically related.

  • They have a direct, linear relationship.

Explicación

Pregunta 90 de 100

1

P680+ is said to be the strongest biological oxidizing agent. Given its function, why is this necessary?

Selecciona una de las siguientes respuestas posibles:

  • It obtains electrons from the oxygen atom in a water molecule, so it must have a stronger attraction for electrons than oxygen has.

  • It is the molecule that transfers electrons to plastoquinone (Pq) of the electron transfer system.

  • It is the receptor for the most excited electron in either photosystem of photosynthesis.

  • It transfers its electrons to reduce NADP+ to NADPH.

Explicación

Pregunta 91 de 100

1

Carotenoids are often found in foods that are considered to have antioxidant properties in human nutrition. What related function do they have in plants?

Selecciona una de las siguientes respuestas posibles:

  • They shield the sensitive chromosomes of the plant from harmful ultraviolet radiation.

  • They protect against oxidative damage from excessive light energy.

  • They serve as accessory pigments to increase light absorption.

  • They reflect orange light and enhance red light absorption by chlorophyll.

Explicación

Pregunta 92 de 100

1

In a plant, the reactions that produce molecular oxygen (O2) take place in _____.

Selecciona una de las siguientes respuestas posibles:

  • neither the light reactions nor the Calvin cycle

  • the Calvin cycle alone

  • the light reactions alone

  • the light reactions and the Calvin cycle

Explicación

Pregunta 93 de 100

1

The accumulation of free oxygen in Earth's atmosphere began with the origin of _____.

Selecciona una de las siguientes respuestas posibles:

  • land plants

  • chloroplasts in photosynthetic eukaryotic algae

  • life and respiratory metabolism

  • cyanobacteria using photosystem II

Explicación

Pregunta 94 de 100

1

In its mechanism, photophosphorylation is most similar to _____.

Selecciona una de las siguientes respuestas posibles:

  • reduction of NADP+

  • substrate-level phosphorylation in glycolysis

  • the Calvin cycle

  • oxidative phosphorylation in cellular respiration

Explicación

Pregunta 95 de 100

1

Which process is most directly driven by light energy?

Selecciona una de las siguientes respuestas posibles:

  • creation of a pH gradient by pumping protons across the thylakoid membrane

  • carbon fixation in the stroma

  • reduction

  • removal of electrons from chlorophyll molecules

Explicación

Pregunta 96 de 100

1

Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?

Selecciona una de las siguientes respuestas posibles:

  • ATP and NADPH

  • H2O and O2

  • ADP, Pi, and NADP+

  • CO2 and glucose

Explicación

Pregunta 97 de 100

1

Where does the Calvin cycle take place?

Selecciona una de las siguientes respuestas posibles:

  • thylakoid membrane

  • interior of the thylakoid (thylakoid space)

  • outer membrane of the chloroplast

  • stroma of the chloroplast

Explicación

Pregunta 98 de 100

1

What is the primary function of the Calvin cycle?

Selecciona una de las siguientes respuestas posibles:

  • use NADPH to release carbon dioxide

  • synthesize simple sugars from carbon dioxide

  • split water and release oxygen

  • transport RuBP out of the chloroplast

Explicación

Pregunta 99 de 100

1

Which of the following sequences correctly represents the flow of electrons during photosynthesis?

Selecciona una de las siguientes respuestas posibles:

  • NADPH → O2 → C O2

  • NADPH → electron transport chain → O2

  • H2O → NADPH → Calvin cycle

  • NADPH → chlorophyll → Calvin cycle

Explicación

Pregunta 100 de 100

1

Which of the following does NOT occur during the Calvin cycle?

Selecciona una de las siguientes respuestas posibles:

  • oxidation of NADPH

  • release of oxygen

  • consumption of ATP

  • regeneration of the CO2 acceptor

Explicación

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