bio 111 test 2

Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis?

100%

Starting with one molecule of glucose, glycolysis results in the net production of which of the following sets of energy-containing products?

2 NADH, 2 pyruvate, and 2 ATP

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

30-32

For each mole of glucose (C6H12O6) oxidized by cellular respiration, how many moles of CO2 are released in the citric acid cycle (see the accompanying figure)?

4

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

ATP and NADPH

Which of the following statements describes a central role that ATP plays in cellular metabolism?

ATP provides energy coupling between exergonic and endergonic reactions.

In the absence of oxygen, yeast cells can obtain energy by fermentation, which results in the production of which of the following sets of molecules?

ATP, CO2, and ethanol (ethyl alcohol)

Which of the following statements describes a key component of the induced fit hypothesis of enzyme catalysis?

Binding of substrate to the active site changes the shape of the active site of an enzyme.

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

C6H12O6 is oxidized and O2 is reduced.

In what way do the membranes of a eukaryotic cell vary?

Certain proteins are unique to each membrane.

Which of the following characteristics is most likely to be associated with an enzyme that catalyzes two different chemical reactions?

Either the enzyme has two distinct active sites or the substrates involved in the two reactions have very similar structures.

Which of the following statements describes the first law of thermodynamics?

Energy cannot be created or destroyed.

Which of the following is a major difference between prokaryotic cells and eukaryotic cells?

Eukaryotic cells have membrane-bound organelles, while prokaryotic cells do not

________ is a regulatory mechanism in which the end product of a metabolic pathway inhibits an enzyme that catalyzes an early step in the pathway.

Feedback inhibition

C

Five dialysis bags, constructed of a type of membrane that is permeable to water and impermeable to sucrose, were filled with various concentrations of sucrose and then placed in separate beakers containing an initial concentration of 0.6 M sucrose solution. At 10-minute intervals, the bags were massed (weighed), and the percent change in mass of each bag was graphed. Which line in the graph represents the bag that contained a solution isotonic to the 0.6 M solution at the beginning of the experiment?

A mutation that disrupts the ability of an animal cell to add polysaccharide modifications to proteins would most likely cause defects in which of the following organelles or structures?

Golgi apparatus and extracellular matrix

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

H2O → NADPH → Calvin cycle

Which of the following statements correctly describes osmosis?

In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration.

Why is glycolysis considered to be one of the first metabolic pathways to have evolved?

It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms.

Which of the following statements about diffusion is true?

It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.

What happens to the free energy released as electrons are passed from photosystem II to photosystem I through a series of electron carriers?

It is used to establish and maintain a proton gradient.

Which of the following statements describes what happens to a molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction?

It loses electrons and loses potential energy.

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

It may be used to form a phosphorylated intermediate.

What is the function of the nuclear pore complex found in eukaryotes?

It regulates the movement of proteins and RNAs into and out of the nucleus.

Which of the following statements best describes the primary role played by oxygen in cellular respiration?

It serves as the final acceptor for electrons from the electron transport chain.

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

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

Which of the following statements about the cytoskeleton is true?

Movement of cilia and flagella is the result of motor proteins causing microtubules to move relative to each other.

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 stored in the form of which of the following molecules?

NADH

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

NADH and FADH2

Which molecule is the final electron acceptor for electrons from photosystem I?

NADP+

Which of the following would likely diffuse through the lipid bilayer of a plasma membrane most rapidly?

O2

If pyruvate oxidation is blocked, what will happen to the levels of oxaloacetate and citric acid in the citric acid cycle shown in the accompanying figure?

Oxaloacetate will accumulate and citric acid will decrease.

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

Photosynthesis stores energy in complex organic molecules; cellular respiration releases energy from complex organic molecules.

When a plant cell, such as one from a tulip leaf, is submerged in a hypertonic solution, what is likely to occur?

Plasmolysis will shrink the interior of the cell.

Most enzyme molecules are occupied by substrate at high reactant concentrations.

Rate of an enzyme-catalyzed reaction as a function of varying reactant concentration, with the concentration of enzyme constant In the figure, why does the reaction rate plateau at higher reactant concentrations?

In a metabolic pathway, succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, a substance that resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the amount of succinate molecules to those of malonic acid reduces the inhibitory effect of malonic acid. Which of the following statements correctly describes the role played by molecules described in the reaction?

Succinate is the substrate, and fumarate is the product in the reaction.

Which of the following statements is a reasonable explanation for why unsaturated fatty acids help keep a membrane more fluid at lower temperatures?

The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly

B

The figure illustrates the energy states associated with the reaction A + B ↔ C + D. Which of the following represents the activation energy required for the enzyme-catalyzed reaction in the figure?

What happens when electrons are passed from one atom to a more electronegative atom?

The more electronegative atom is reduced, and energy is released.

A patient was involved in a serious accident and lost a large quantity of blood. In an attempt to replenish body fluids, distilled water equal to the volume of blood lost is added to the blood directly via one of his veins. What will be the most probable result of this transfusion?

The patient's red blood cells will swell and possibly burst because the blood has become hypotonic compared to the cells.

Which of the following statements is true for a system at chemical equilibrium?

The system can do no work.

Which of the following statements describes a common characteristic of catabolic pathways?

They are exergonic and provide energy that can be used to produce ATP from ADP and Pi.

Which of the following statements about anabolic pathways is true?

They consume energy to build up polymers from monomers.

D

Which component in the accompanying figure is hydrophilic?

curves 3 and 5

Which curves on the graphs may represent the temperature and pH profiles of an enzyme taken from a bacterium that lives in a mildly alkaline hot springs at temperatures of 70°C or higher?

C

Which of the following graphs most likely describes the effect of pH on the function of the enzyme catalase in human cells? Note: The x-axis is pH and the y-axis is enzyme activity.

curves 1 and 4

Which temperature and pH profile curves on the graphs are most likely associated with an enzyme isolated from a human stomach where conditions are strongly acid?

Chemical equilibrium is relatively rare in living cells because metabolic pathways are interconnected. Which of the following statements describes an example of a reaction that may be at chemical equilibrium in a cell?

a chemical reaction in which neither the reactants nor the products are being produced or consumed in any metabolic pathway at that time in the cell

Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as _____.

a cofactor necessary for enzyme activity

The force driving simple diffusion is ________, while the energy source for active transport is ________.

a concentration gradient; ATP hydrolysis

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

a molecule of glucose

Spherocytosis is a human blood disorder associated with a defective cytoskeletal protein in the red blood cells (RBCs). What do you suspect is the consequence of such a defect?

abnormally shaped RBCs

The oxygen consumed during cellular respiration is directly involved in which of the following processes or events?

accepting electrons at the end of the electron transport chain

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

acetyl CoA

In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate (1) loses a carbon, which is given off as a molecule of CO2, (2) is oxidized to form a two-carbon compound called acetate, and (3) is bonded to coenzyme A. Which of the following sets of products result from these reactions?

acetyl CoA, NADH, and CO2

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

an RNA nucleotide

Which kind of metabolic poison would most directly interfere with glycolysis?

an agent that closely mimics the structure of glucose but is not metabolized

A series of enzymes catalyze the reactions in the metabolic pathway 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. With respect to the enzyme that converts X to Y, substance A functions as ________.

an allosteric inhibitor

Which of the following statements correctly describes the normal tonicity conditions for typical plant and animal cells? The animal cell is in _____.

an isotonic solution, and the plant cell is in a hypotonic solution

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

anabolic reactions

Which of the following molecules dramatically increases the rate of diffusion of water across cell membranes?

aquaporins

How does a noncompetitive inhibitor decrease the rate of an enzyme-catalyzed reaction?

by binding to an allosteric site, thus changing the shape of the active site of the enzyme

In an HIV-infected cell producing HIV virus particles, the viral glycoprotein is expressed on the plasma membrane. How do the viral glycoproteins get to the plasma membrane? They are synthesized ________.

by ribosomes in the rough ER and arrive at the plasma membrane in the membrane of secretory vesicles

According to the fluid mosaic model of cell membranes, phospholipids _____.

can move laterally along the plane of the membrane

Which structure below is independent of the endomembrane system?

chloroplast

Thylakoids, DNA, and ribosomes are all components found in _____.

chloroplasts

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?

competitive inhibition

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 which of the following processes?

coupling of an endergonic reaction to an exergonic reaction

Familial hypercholesterolemia is characterized by _____.

defective LDL receptors on the cell membranes

The evolution of eukaryotic cells most likely involved ________.

endosymbiosis of an oxygen-using bacterium in a larger bacterial host cell-the endosymbiont evolved into mitochondria

The relationship between catabolism and anabolism is most similar to the relationship between which of the following pairs of terms?

exergonic; endergonic

Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through _____.

gap junctions

Which of the following sequences describes the path by which electrons travel downhill energetically in aerobic respiration?

glucose → NADH → electron transport chain → oxygen

Amoebae move by crawling over a surface (cell crawling), which involves ________.

growth of actin filaments to form bulges in the plasma membrane

The membranes of winter wheat are able to remain fluid when it is extremely cold by ________.

increasing the proportion of unsaturated phospholipids in the membrane

According to the fluid mosaic model, a membrane ________.

is composed of a fluid bilayer of phospholipids with embedded amphipathic proteins

Celery stalks that are immersed in fresh water for several hours become stiff. Similar stalks left in a 0.15 M salt solution become limp. From this we can deduce that the fresh water_____.

is hypotonic and the salt solution is hypertonic to the cells of the celery stalks

One primary advantage of light microscopy over electron microscopy is that ________.

light microscopy allows the visualization of dynamic processes in living cells

A bacterium engulfed by a white blood cell through phagocytosis will be digested by enzymes contained in _____.

lysosomes

Asbestos is a material that was once used extensively in construction. One risk from working in a building that contains asbestos is the development of asbestosis caused by the inhalation of asbestos fibers. Cells will take up asbestos by phagocytosis, but are not able to degrade it. As a result, asbestos fibers accumulate in ________.

lysosomes

Which of the following macromolecules leaves the nucleus of a eukaryotic cell through pores in the nuclear membrane?

mRNA

The voltage across a membrane is called the _____.

membrane potential

Suppose a young boy is always tired and fatigued, suffering from a metabolic disease. Which of the following organelles is most likely malfunctioning in this disease?

mitochondria

Where are the proteins of the electron transport chain located?

mitochondrial inner membrane

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

mitochondrial intermembrane space

Which of the following is the smallest structure that would most likely be visible with a standard (not super-resolution) research-grade light microscope?

mitochondrion

Which structure is common to plant and animal cells?

mitochondrion

Researchers investigating the mechanism of vesicular transport assembled a cell-free system that included microtubule tracks, vesicles, and ATP. However, they observed no movement of transport of vesicles in this system. What were they missing?

motor proteins

Suppose a cell has the following molecules and structures: enzymes, DNA, ribosomes, plasma membrane, and mitochondria. It could be a cell from ________.

nearly any eukaryotic organism

Carbon dioxide is split to form oxygen gas and carbon compounds in which of the following metabolic pathways?

neither photosynthesis nor respiration

In receptor-mediated endocytosis, receptor molecules initially project to the outside of the cell. Where do they end up after endocytosis?

on the inside surface of the vesicle

Carbon dioxide (CO2) is released during which of the following stages of cellular respiration?

oxidation of pyruvate to acetyl CoA and the citric acid cycle

White blood cells engulf bacteria using _____.

phagocytosis

In photosynthetic cells, synthesis of ATP by chemiosmosis occurs during ________.

photosynthesis and respiration

The difference between pinocytosis and receptor-mediated endocytosis is that _____.

pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis offers more selectivity.

A cell with a predominance of rough endoplasmic reticulum is most likely ________.

producing large quantities of proteins for secretion

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

reduced

In the initial step in carbon fixation, a molecule of CO2 is attached to RuBP to produce a six-carbon molecule, which is immediately split to produce two molecules of 3-phosphoglycerate. After phosphorylation and reduction produces glyceraldehyde 3-phosphate (G3P), what more needs to occur to complete the Calvin cycle?

regeneration of RuBP

Which of the following processes occurs during the Calvin cycle?

regeneration of the CO2 acceptor

Which of the following processes is most directly driven by light energy?

removal of electrons from chlorophyll molecules

Which of the following are found in plant, animal, and bacterial cells?

ribosomes

Vinblastine, a drug that inhibits microtubule polymerization, is used to treat some forms of cancer. Cancer cells given vinblastine would be unable to _____.

separate chromosomes during cell division

A research team is working on the design of a new drug for the treatment of lung cancer. To be most effective, this drug must specifically enter the cytoplasm of lung cells while not entering the cells of other tissues. Which of the following characteristics would likely enhance the specificity of this drug?

similarity of the drug molecule to other molecules normally transported lung cells

What kinds of molecules pass through a cell membrane most easily?

small and hydrophobic

The liver is involved in detoxification of many poisons and drugs. Which of the following structures is primarily involved in this process and, therefore, abundant in liver cells?

smooth endoplasmic reticulum

The oxygen released by photosynthesis is produced by which of the following processes?

splitting water molecules

Which of the following would be the most appropriate method to observe the movements of condensed chromosomes during cell division?

standard light microscopy

Where in a plant cell does the Calvin cycle take place?

stroma of the chloroplast

In mitochondria, an electron transport chain pumps protons from the matrix into the intermembrane space, whereas in chloroplasts, an electron transport chain pumps protons from the ________.

stroma to the thylakoid space

A cell with a predominance of smooth endoplasmic reticulum is likely specialized to ________.

synthesize large quantities of lipids

During which of the following metabolic processes is most of the CO2 from the catabolism of glucose is released?

the citric acid cycle

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

the harnessing of energy from high-energy electrons derived from glycolysis and the citric acid cycle

In a plant, which of the following reactions produce molecular oxygen (O2)?

the light reactions alone

Tay-Sachs disease is a human genetic abnormality that results in cells accumulating and becoming clogged with very large, complex, undigested lipids. Which cellular organelle is most likely defective in this condition

the lysosome

Where are ATP synthase complexes located in plant cells?

thylakoid membrane and inner mitochondrial membrane