AP Biology 2020 Midterm

D. 120 thymine and 120 adenine molecules.

A double-stranded DNA molecule contains a total of 120 purines and 120 pyrimidines. This DNA molecule could be composed of A. 120 adenine and 120 uracil molecules. B. 120 adenine and 120 guanine molecules. C. 120 cytosine and 120 thymine molecules. D. 120 thymine and 120 adenine molecules.

B. three molecules of 9 and one molecule of 10.

A fat (or triacylglycerol) would be formed as a result of a dehydration reaction between A. one molecule of 9 and three molecules of 10. B. three molecules of 9 and one molecule of 10. C. one molecule of 5 and three molecules of 9. D. three molecules of 5 and one molecule of 9.

B. blue and violet

A plant has a unique photosynthetic pigment. The leaves of this plant appear to be reddish yellow. What wavelengths of visible light are being absorbed by this pigment? A. red and yellow B. blue and violet C. green and yellow D. blue, green, and red

B. E. coli bacteria reproduce in liquid media containing either glucose or galactose.

A researcher claims that different metabolic pathways allow bacteria to use different molecules as sources of matter and energy. Which of the following statements best helps justify the researcher's claim by providing a relevant example? A. Rhizobia bacteria form close associations with the roots of bean plants. B. E. coli bacteria reproduce in liquid media containing either glucose or galactose. C. The antibiotic rifampicin inhibits the growth of some bacterial strains but not of others. D. Some viruses that infect bacteria reproduce by either the lysogenic cycle or the lytic cycle.

D. Atmospheric carbon dioxide is the raw material for photosynthesis, which plants rely on for producing sugars and other organic compounds.

A researcher claims that increased atmospheric carbon dioxide levels cause increased growth rates in plants. Which of the following statements best supports the researcher's claim? A. Atmospheric carbon dioxide is produced by the burning of fossil fuels, which are formed from the remains of living organisms such as plants. B. Atmospheric carbon dioxide is a byproduct of cellular respiration, which is a metabolic process that occurs in plants and other living organisms. C. Atmospheric carbon dioxide typically enters plant leaves through the stomata, which plants rely on for regulating gas exchange with the atmosphere. D. Atmospheric carbon dioxide is the raw material for photosynthesis, which plants rely on for producing sugars and other organic compounds.

A. The initial concentration of the substrate

A researcher designs an experiment to investigate the effect of environmental temperature on the function of an enzyme. For each trial included in the experiment, the researcher will add the enzyme and its substrate to an aqueous buffer solution and then measure the amount of product formed over 20 minutes. Which of the following must remain the same for all trials of this experiment? A. The initial concentration of the substrate B. The final concentration of the product C. The three-dimensional structure of the enzyme D. The temperature of the aqueous buffer solution

B. The enzyme's active site binds to and stabilizes the transition state, which decreases the activation energy of the reaction.

A researcher proposes a model of an enzyme-catalyzed reaction in which a reactant is converted to a product. The model is based on the idea that the reactant passes through a transition state within the enzyme-substrate complex before the reactant is converted to the product. Which of the following statements best helps explain how the enzyme speeds up the reaction? A. The enzyme's active site binds to and stabilizes the reactant, which decreases the free-energy change of the reaction. B. The enzyme's active site binds to and stabilizes the transition state, which decreases the activation energy of the reaction. C. The enzyme's active site binds to and stabilizes the product, which increases the amount of energy released by the reaction. D. The enzyme's active site binds to and stabilizes both the reactant and the product at the same time, which increases the reaction's equilibrium constant.

D. The bacterial cell, because it has the largest surface-to-volume ratio.

A spherical bacterial cell has a radius of 3μm. The human egg cell has a radius of 100μm. Which statement correctly indicates the cell that is able to more efficiently exchange materials with the external environment and provides a correct explanation? A. The egg cell, because it has the smallest surface-to-volume ratio. B. The egg cell, because it has the largest surface-to-volume ratio. C. The bacterial cell, because it has the smallest surface-to-volume ratio. D. The bacterial cell, because it has the largest surface-to-volume ratio.

A. The drug is a small nonpolar molecule.

A team of biologists develop a new drug, and one team member hypothesizes that the drug is incapable of freely passing across the plasma membrane and requires the help of membrane proteins to enter cells. Alternatively, another biologist on the team hypothesizes that the drug can diffuse passively across the plasma membrane like O2 and CO2 can. Which of the following, if true about the drug, best supports the alternative hypothesis that the new drug will exhibit simple diffusion across plasma membranes? A. The drug is a small nonpolar molecule. B. The drug is a small charged molecule. C. The drug is a large polar molecule. D. The drug is a large charged molecule.

A. They can move laterally along the plane of the membrane.

According to the fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids? A. They can move laterally along the plane of the membrane. B. They frequently flip-flop from one side of the membrane to the other. C. They occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane. D. They are free to depart from the membrane and dissolve in the surrounding solution.

A. increased by exposure to light

According to this experiment, germination of tobacco seeds during the first week is A. increased by exposure to light B. unaffected by light intensity C. prevented by paper towels D. accelerate in green-leaved seedlings

A. Enzymatic modification of newly synthesized integral membrane proteins

All eukaryotic cells contain at least one Golgi complex, typically located in the cytoplasm and near the endoplasmic reticulum. Which of the following best describes a process that occurs within the Golgi complex? A. Enzymatic modification of newly synthesized integral membrane proteins B. Synthesis of cytosolic proteins based on the nucleotide sequences of mRNAs C. Degradation of proteins by hydrolytic enzymes contained within the complex D. Synthesis of various types of lipids

D. nuclear envelope

All of the following cell components are found in prokaryotic cells EXCEPT A. DNA B. ribosomes C. cell membrane D. nuclear envelope E. enzymes

B. cholesterol

All of the following contain amino acids *except* A. hemoglobin. B. cholesterol. C. antibodies. D. enzymes. E. insulin.

D. 64-68

Approximately how many molecules of ATP are produced from the complete oxidation of two molecules of glucose (C6H12O6) in aerobic cellular respiration? A. 2 B. 4 C. 32-34 D. 64-68

H3O+ is more polar than glycerol/H3O+ is charged.

Aquaporins exclude passage of hydronium ions (H3O+). Recent research on fat metabolism has shown that some aquaporins allow passage of glycerol, a three-carbon alcohol, as well as H2O. Since H3O+ is much closer in size to water than is glycerol, what do you suppose is the basis of this selectivity?

D. the synthesis of ATP

Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will have the most direct effect on which of the following processes? A. the splitting of water B. the absorption of light energy by chlorophyll C. the flow of electrons from photosystem II to photosystem I D. the synthesis of ATP

C. tertiary

At which level of protein structure are interactions between the side chains (R groups) *most* important? A. primary B. secondary C. tertiary D. quaternary

A. positively charged.

Based on your knowledge of the polarity of water molecules, the solute molecule depicted here is most likely A. positively charged. B. negatively charged. C. nonpolar. D. hydrophobic.

D. Rough ER can synthesize and package proteins for export, and smooth ERER cannot.

Cells contain smaller components called organelles that are necessary for a cell's survival. Organelle functions have often been compared to components of larger systems. Which of the following functional differences between the rough and smooth endoplasmic reticulum (ER) is explained by the structural differences between them? A. Rough ER breaks down toxic substances, and smooth ERER only transports them out of the cell. B. Rough ER can synthesize and package lipids for export, and smooth ER cannot. C. Rough ER can produce ATP, and smooth ER cannot. D. Rough ER can synthesize and package proteins for export, and smooth ER cannot.

D. always alter the primary structure of the protein, sometimes alter the tertiary structure of the protein, and sometimes affect its biological activity.

Changing a simple amino acid in a protein consisting of 325 amino acids would A. alter the primary structure of the protein, but not its tertiary structure or function. B. cause the tertiary structure of the protein to unfold. C. always alter the biological activity or function of the protein. D. always alter the primary structure of the protein, sometimes alter the tertiary structure of the protein, and sometimes affect its biological activity.

C. 576 glucose molecules.

Consider a polysaccharide consisting of 576 glucose molecules. The total *hydrolysis* of the polysaccharide would result in the production of A. 575 glucose molecules. B. 575 water molecules. C. 576 glucose molecules. D. A and B only. E. B and C only.

B. The phosphodiester bonds between deoxyribose sugars would be broken.

DNAase is an enzyme that catalyzes the hydrolysis of the covalent bonds that join nucleotides together. What would first happen to DNA molecules treated with DNAase? A. The two strands of the double helix would separate. B. The phosphodiester bonds between deoxyribose sugars would be broken. C. The purines would be separated from the deoxyribose sugars. D. The pyrimidines would be separated from the deoxyribose sugars. E. All bases would be separated from the deoxyribose sugars.

rubisco - attaches CO2 to RuBP, thus allowing sugar to be made (from G3P) for cell to use (structure/storage)

Give the name of the Earth's most abundant protein and describe its function in photosynthesis.

C. the stroma to the thylakoid space.

In mitochondria, chemiosmosis translocates protons from the matrix into the intermembrane space, whereas in chloroplasts, chemiosmosis translocates protons from A. the stroma to the photosystem II. B. the matrix to the stroma. C. the stroma to the thylakoid space. D. the intermembrane space to the matrix.

3 Na+ move out of the cell and 2 K+ move into the cell, both via the sodium potassium pump.

How many Na+ and K+ ions are moved across the plasma membrane by the Na+/K+ pump? In which direction(s) are these ions moving?

B. a surface made with carbon and hydrogen atoms covalently bonded together

If a salamander relied on hydrogen bonds to cling to surfaces, what type of surface would cause the most problems for this animal? A. a surface coated with a thin film of water B. a surface made with carbon and hydrogen atoms covalently bonded together C. a surface made with carbon, hydrogen, and oxygen atoms covalently bonded together D. a surface made with carbon, hydrogen, nitrogen, and oxygen atoms covalently bonded together

-9.97 bars

If the molar concentration of a sucrose solution in an open beaker is 0.4 M, calculate the solute potential at 27 degrees Celsius. Round to the nearest hundredth.

D. thylakoid membrane and inner mitochondrial membrane

In a plant cell, where are the ATP synthase complexes located? A. thylakoid membrane only B. plasma membrane only C. inner mitochondrial membrane only D. thylakoid membrane and inner mitochondrial membrane

C. ATP production in mitochondria requires a hydrogen ion gradient that favors movement of protons into the mitochondrial matrix.

In an experiment, a scientist isolates mitochondria from living cells and suspends them in two different buffered solutions. One solution is maintained at pH 4, while the other solution is maintained at pH 9. The scientist finds that mitochondria in the solution at pH 4 continue to produce ATP but those in the pH 9 solution do not. The results of the experiment can be used as evidence in support of which of the following scientific claims about mitochondrial activity? A. Mitochondria in a cell-free environment are unable to convert thermal energy into ATP. B. The electron transport chain pumps electrons from the cytosol to the mitochondrial matrix. C. ATP production in mitochondria requires a hydrogen ion gradient that favors movement of protons into the mitochondrial matrix. D. ATP synthase molecules change their orientation in relation to the proton gradient across the mitochondrial membrane.

C. amphipathic, with at least one hydrophobic region.

In order for a protein to be an integral membrane protein it would have to be A. hydrophilic. B. hydrophobic. C. amphipathic, with at least one hydrophobic region. D. completely covered with phospholipids. E. exposed on only one surface of the membrane.

C. in the plasma membrane.

In prokaryotes, the respiratory electron transport chain is located A. in the mitochondrial inner membrane. B. in the mitochondrial outer membrane. C. in the plasma membrane. D. in the cytoplasm.

A. ATP, CO2, and ethanol (ethyl alcohol).

In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of A. ATP, CO2, and ethanol (ethyl alcohol). B. ATP, CO2, and lactate (lactic acid). C. ATP, NADH, and pyruvate. D. ATP, pyruvate, and oxygen.

D. The cells do not produce functional motor proteins in flagella and cilia.

Individuals with an inherited autosomal recessive disorder called primary ciliary dyskinesia (PCD) often have severe respiratory problems due to defective cilia. Males with PCD are often sterile because they produce sperm with defective flagella. Which of the following most likely explains the effect of the recessive allele? A. The mitochondria are defective and do not produce sufficient protein to synthesize microtubules in the cilia and flagella. B. The plasma membrane of the alveoli is not permeable to carbon dioxide during respiration because it is too hydrophobic. C. The Golgi bodies secrete an enzyme that destroys the proteins in the flagella and cilia. D. The cells do not produce functional motor proteins in flagella and cilia.

B. oxidative phosphorylation

It is possible to prepare vesicles from portions of the inner mitochondrial membrane. Which one of the following processes could still be performed by this isolated inner membrane? A. the citric acid cycle B. oxidative phosphorylation C. glycolysis and fermentation D. reduction of NAD+

A. Molybdenum atoms can have between 50 and 58 neutrons.

Molybdenum has an atomic number of 42. Several common isotopes exist, with mass numbers of 92, 94, 95, 96, 97, 98, and 100. Therefore, which of the following can be true? A. Molybdenum atoms can have between 50 and 58 neutrons. B. The isotopes of molybdenum have different electron configurations. C. The isotopes of molybdenum can have between 50 and 58 protons. D. The isotopes of molybdenum have between 50 and 58 neutrons and have different electron configurations. E. The isotopes of molybdenum have between 50 and 58 protons and have different electron configurations.

A. The inner membrane of the mitochondria in muscle cells should have more folds to increase the surface area, allowing more ATP to be synthesized.

Muscle cells have high ATP demands. Which of the following is a scientific claim about how the structure of the mitochondria in muscle cells should be different than it is in other cells because of the high energy demands of mitochondria? A. The inner membrane of the mitochondria in muscle cells should have more folds to increase the surface area, allowing more ATP to be synthesized. B. The inner membrane of the mitochondria in muscle cells should be more permeable to large enzymes, allowing the same reactions to occur in both compartments of the mitochondria. C. The outer membrane of the mitochondria in muscle cells should be thicker, allowing more rapid diffusion of molecules into the mitochondria. D. The outer membrane of the mitochondria of muscle cells should have more folds, increasing the surface area for faster diffusion of molecules from the cytoplasm.

A. Each hydrogen atom has a partial positive charge; the nitrogen atom has a partial negative charge.

Nitrogen (N) is much more electronegative than hydrogen (H). Which of the following statements is correct about the atoms in ammonia (NH3)? A. Each hydrogen atom has a partial positive charge; the nitrogen atom has a partial negative charge. B. The nitrogen atom has a full positive charge; each hydrogen atom has a full positive charge. C. Each hydrogen atom has a partial negative charge; the nitrogen atom has a full positive charge. D. The nitrogen atom has a partial positive charge; each hydrogen atom has a partial negative charge.

C. oxidize NADH to NAD+.

One function of both alcohol fermentation and lactic acid fermentation is to A. reduce NAD+ to NADH. B. reduce FAD+ to FADH2 C. oxidize NADH to NAD+. D. reduce FADH2 to FAD+

B. They have highly folded membranes.

Organelles such as mitochondria and the endoplasmic reticulum have membranes that compartmentalize reactions and other metabolic processes. To function properly, the organelles must move substances across their membranes. Which of the following statements describes a feature shared by mitochondria and the endoplasmic reticulum that increases the efficiency of their basic functions? A. They have rigid, non-fluid membranes. B. They have highly folded membranes. C. They have membranes composed of many carbohydrates. D. They have double membranes, with one membrane enclosed within the other.

Differences: photosynthesis in chloroplasts, CR in mitochondria; photosynthesis is endergonic, CR is exergonic. Similarities: both use ATP synthase to make ATP; both have an ETC.

State two differences and two similarities between photosynthesis and cellular respiration.

C. side chains (R groups).

The 20 different amino acids found in polypeptides exhibit different chemical and physical properties because of different A. carboxyl groups attached to an alpha (α) carbon B. amino groups attached to an alpha (α) carbon C. side chains (R groups). D. alpha (α) carbons

B. H2O

The O2 released during photosynthesis comes from A. CO2 B. H2O C. NADPH D. RuBP

B. B

The ester bond in figure 8 is labeled (I can't get the right picture) A. A B. B C. C D. D

A. cells of the tail dying and the nutrients being absorbed and reused by the body

The last part of the metamorphosis of a tadpole to an adult frog results in the disappearance of the tail. This stage of development most likely occurs by A. cells of the tail dying and the nutrients being absorbed and reused by the body B. shedding of the tail so energy is not spent on maintenance of an unneeded part C. bilateral division of the tail and fusion with the developing hind limbs D. individual cells of the tail migrating to the developing gonads

B. C18H32O16

The molecular formula for glucose is C6H12O6. What would be the molecular formula for a molecule made by linking three glucose molecules together by dehydration reactions? A. C18H36O18 B. C18H32O16 C. C6H10O5 D. C18H10O15

A. enables the membrane to stay fluid more easily when cell temperature drops.

The presence of cholesterol in the plasma membranes of some animals A. enables the membrane to stay fluid more easily when cell temperature dropls. B. enables the animal to remove hydrogen atoms from saturated phospholipids C. enables the animal to add hydrogen to unsaturated phospholipids. D. makes the membrane less flexible, allowing it to sustain greater pressure from within the cell.

E. to mediate cell-to-cell recognition.

The primary function of polysaccharides attached to the glycoproteins and glycolipids of animal cell membranes is A. to facilitate diffusion of molecules down their concentration gradients. B. to actively transport molecules against their concentration gradients. C. to maintain the integrity of a fluid mosaic membrane. D. to maintain membrane fluidity at low temperatures. E. to mediate cell-to-cell recognition.

D. J to K

The rate of oxygen consumption equaled the rate of oxygen production during which of the following time periods? A. G to H B. H to I C. I to J D. J to K

A. It will be on the cytoplasmic side of the ER.

The sodium-potassium pump in animal cells requires cytoplasmic ATP to pump ions across the plasma membrane. When the proteins of the pump are first synthesized in the rough ER, what side of the ER membrane will the ATP binding site be on? A. It will be on the cytoplasmic side of the ER. B. It will be on the side facing the interior of the ER. C. It could be facing in either direction because proteins are properly reoriented in the Golgi apparatus. D. It doesn't matter, because the pump is not active in the ER.

D. the relationship between wavelengths of light and the rate of photosynthesis.

Theodore W. Engelmann illuminated a filament of algae with light that passed through a prism, thus exposing different segments of algae to different wavelengths of light. He added aerobic bacteria and then noted in which areas the bacteria congregated. He noted that the largest groups were found in the areas illuminated by the red and blue light. An outcome of this experiment was to help determine A. the relationship between heterotrophic and autotrophic organisms. B. the relationship between wavelengths of light and the rate of aerobic respiration. C. the relationship between wavelengths of light and the amount of heat released. D. the relationship between wavelengths of light and the rate of photosynthesis.

B. 14C-labeled CO2, because atmospheric carbon is fixed to carbohydrates by photosynthesis

To test the hypothesis that a particular plant synthesizes storage lipids by using glyceraldehyde 3-phosphate (G3P) from photosynthesis, a researched plants to use radiolabeled precursors to track the molecules through the biosynthetic pathway. Which of the following radiolabeled precursors is most appropriate for the researcher to use? A. 15N-labeled N2, because atmospheric nitrogen is fixed to amino acids by photosynthesis B. 14C-labeled CO2, because atmospheric carbon is fixed to carbohydrates by photosynthesis C. 35S-labeled methionine, because amino acids are incorporated into lipids during photosynthesis D. 32P-labeled phosphate, because lipids are stored in plants as phospholipids

A. pH 2

What is the pH of a solution with a hydroxyl ion [OH-] concentration of 10^-12 *M*? A. pH 2 B. pH 4 C. pH 10 D. pH 12 E. pH 14

D. synthesize simple sugars from carbon dioxide

What is the primary function of the Calvin cycle? A. use ATP to release carbon dioxide B. use NADPH to release carbon dioxide C. split water and release oxygen D. synthesize simple sugars from carbon dioxide

as λ (wavelength) increases, energy increases; as λ (wavelength) decrease, energy increases; (related indirectly)

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

C. steroid molecule

What is the structure shown in the figure below? A. starch molecule B. protein molecule C. steroid molecule D. phospholipid molecule

B. chaperonin

What is the term used for a protein molecule that assists in the proper folding of other proteins? A. tertiary protein B. chaperonin C. enzyme protein D. renaturing protein

C. membrane potential

What is the voltage across a membrane called? A. water potential B. chemical gradient C. membrane potential D. osmotic potential E. electrochemical gradient

B. small and hydrophobic

What kinds of molecules pass through a cell membrane most easily? A. large and hydrophobic B. small and hydrophobic C. large polar D. ionic E. monosaccharides such as glucose

A. 420 mm

What wavelength of light in the figure is most effective in driving photosynthesis? A. 420 mm B. 475 mm C. 575 mm D. 625 mm

A. The pH of the matrix increases.

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs? A. The pH of the matrix increases. B. ATP synthase pumps protons by active transport. C. The electrons gain free energy. D. NAD+ is oxidized.

D. nonpolar covalent bonds.

When two atoms are equally electronegative, they will interact to form A. hydrogen bonds. B. van der Waals interactions. C. polar covalent bonds. D. nonpolar covalent bonds.

A. stroma of the chloroplast

Where does the Calvin cycle take place? A. stroma of the chloroplast B. thylakoid membrane C. cytoplasm surrounding the chloroplast D. interior of the thylakoid (thylakoid space)

B. receiving electrons from the thylakoid membrane electron transport chain

Which of the following are directly associated with photosystem I? A. harvesting of light energy by ATP B. receiving electrons from the thylakoid membrane electron transport chain C. generation of molecular oxygen D. extraction of hydrogen electrons from the splitting of water.

D. ATP and NADPH

Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle? A. CO2 and glucose B. H2O and O2 C. ADP, P-, and NADP+ D. ATP and NADPH

C. release of oxygen

Which of the following does not occur during the Calvin cycle? A. carbon fixation B. oxidation of NADPH C. release of oxygen D. regeneration of the CO2 acceptor

B. A water strider can walk across the surface of a small pond.

Which of the following effects is produced by the high surface tension of water? A. Lakes don't freeze solid in winter, despite low temperatures. B. A water strider can walk across the surface of a small pond. C. Organisms resist temperature changes, although they give off heat due to chemical reactions. D. Evaporation of sweat from the skin helps to keep people from overheating.

D. An endoplasmic reticulum, mitochondria, and a nucleus

Which of the following groups of cellular components are found in eukaryotic cells but not prokaryotic cells? A. Ribosomes, a nucleus, and chloroplasts B. Circular chromosomes, mitochondria, and an endoplasmic reticulum C. A nucleus, ribosomes, and cell walls D. An endoplasmic reticulum, mitochondria, and a nucleus

B. It moves substances against a concentration gradient.

Which of the following is *not* characteristic of facilitated diffusion? A. It requires a carrier protein. B. It moves substances against a concentration gradient. C. It requires non energy input. D. It involves a change in the shape of its carrier.

A. a covalent bond

Which of the following is *not* considered to be a weak molecular interaction? A. a covalent bond B. a van der Waals interaction C. an ionic bond in the presence of water D. a hydrogen bond

D. It is a major structural component of plant cell walls.

Which of the following is *true* of cellulose? A. It is a polymer composed of sucrose monomers. B. It is a storage polysaccharide for energy in plant cells. C. It is a storage polysaccharide for energy in animal cells. D. It is a major structural component of plant cell walls.

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

Which of the following is a reasonable explanation for why unsaturated fatty acids help keep any membrane more fluid at lower temperatures? A. The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly. B. Unsaturated fatty acids have a higher cholesterol content and therefore more cholesterol in membranes. C. Unsaturated fatty acids are more polar than saturated fatty acids. D. The double bonds block interaction among the hydrophilic head group of the lipids.

C. Lysosomes will release digestive enzymes into the cytosol.

Which of the following processes is most likely to occur as a result of an animal cell receiving a signal to initiate apoptosis? A. Ribosomes will translate mRNA to produce proteins. B. Vesicles will release extracellular growth factors via exocytosis. C. Lysosomes will release digestive enzymes into the cytosol. D. Vacuoles will fuse with the cellular membrane.

B. H2O --> NADPH --> Calvin cycle

Which of the following sequences correctly represents the flow of electrons during photosynthesis? A. NADPH --> O2 --> CO2 B. H2O --> NADPH --> Calvin cycle C. NADPH --> chlorophyll --> Calvin cycle D. H2O --> photosystem I --> photosystem II

A. The light reactions provide ATP and NADPH to the Calvin cycle, and the cycle returns ADP, P-, and NADP+ to the light reactions.

Which of the following statements best represents the relationships between the light reactions and the Calvin cycle? A. The light reactions provide ATP and NADPH to the Calvin cycle, and the cycle returns ADP, P-, and NADP+ to the light reactions. B. The light reactions provide ATP and NADPH to the carbon fixation step of the Calvin cycle, and the cycle provides water and electrons to the light reactions. C. The light reactions supply the Calvin cycle with CO2 to produce sugars, and the Calvin cycle provides the light reactions with sugars to produce ATP. D. The light reactions provide the Calvin cycle with oxygen for electron flow, and the Calvin cycle provides the light reactions with water to split.

D. Some organelles contain their own DNA that is more similar to prokaryotic DNA in structure and function than to the eukaryotic DNA found in the cell's nucleus.

Which of the following statements best supports the claim that certain organelles within eukaryotic cells evolved from free-living prokaryotic cells? A. The cytoplasm of both eukaryotes and prokaryotes is surrounded by a plasma membrane. B. Eukaryotes and prokaryotes both contain ribosomes, but the ribosomes of eukaryotes are more complex in structure than those of prokaryotes. C. Eukaryotes exchange segments of internal membranes between the endoplasmic reticulum and Golgi apparatus, but prokaryotes have no such internal membranes. D. Some organelles contain their own DNA that is more similar to prokaryotic DNA in structure and function than to the eukaryotic DNA found in the cell's nucleus.

A. C6H12O6 is oxidized and O2 is reduced.

Which of the following statements describes the results of this reaction? C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy A. C6H12O6 is oxidized and O2 is reduced. B. O2 is oxidized and H2O is reduced. C. CO2 is reduced and O2 is oxidized. D. C6H12O6 is reduced and CO2 is oxidized.

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

Which of the following statements is a correct distinction between autotrophs and heterotrophs? A. Only heterotrophs require chemical compounds from the environment. B. Cellular respiration is unique to heterotrophs. C. Only heterotrophs have mitochondria. D. Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2 and other nutrients that are inorganic.

A. CO2

Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly? A. CO2 B. an amino acid C. glucose D. K+ E. starch

D. hydrogen bonds

Which type of bonds must be broken for water to vaporize? A. ionic bonds B. both hydrogen bonds and ionic bonds C. polar covalent bonds D. hydrogen bonds

D. hydrogen bonds

Which type of interaction stabilizes the α helix and the β pleated sheet structures of proteins? A. hydrophobic interactions B. disulfide bonds C. ionic bonds D. hydrogen bonds