Biology Exam 2: Cellular Metabolism, Respiration, Photosynthesis, Cell Signaling, and the Cell Cycle

Comprehensive vocabulary flashcards covering cellular bioenergetics, thermodynamics, cellular respiration, photosynthesis, intercellular and intracellular signaling, and the eukaryotic/prokaryotic cell cycle.

A. Contraction of muscle fibers

Which is an example of kinetic energy in an organism? A. Contraction of muscle fibers B. The sequence of nucleotides in DNA C. Chemical energy stored in fat cells D. An ion concentration gradient across a membrane

D. They evolved early and were preserved because they provide an advantage.

What does the conservation of metabolic pathways across different species suggest? A. They evolved independently in every species B. They constantly change in every species C. They only exist in multicellular organisms D. They evolved early and were preserved because they provide an advantage

D. Catabolism breaks down molecules and releases energy, while anabolism builds molecules using energy.

What is the difference between catabolism and anabolism? A. Both release energy by breaking down molecules B. Catabolism builds molecules, while anabolism breaks them down C. Both are identical processes D. Catabolism breaks down molecules and releases energy, while anabolism builds molecules using energy

D. The total heat content of a system.

What is enthalpy ($H$) in a biological system? A. The amount of disorder in a system B. The energy available to perform work C. The energy needed to start a reaction D. The total heat content of a system

B. More

In an endergonic reaction, the products have _____ free energy than the reactants. A. Less B. More C. The same D. Zero

C. It is converted into heat.

What happens to energy that is "lost" during biological energy transformations? A. It is destroyed B. It is recycled into chemical bonds C. It is converted into heat D. It is always stored as ATP

D. Adenine, ribose, and three phosphate groups.

Which components make up ATP? A. Thymine, ribose, and three phosphates B. Guanine, deoxyribose, and three phosphates C. Ribose, two phosphates, and a lipid D. Adenine, ribose, and three phosphates

A. It strengthens substrate binding and properly positions the substrate

Why is induced fit beneficial for enzyme function? A. It strengthens substrate binding and properly positions the substrate B. It prevents enzymes from releasing products C. It allows all substrates to bind equally D. It makes the enzyme completely rigid

C. Allosteric activation

A small molecule binds to an enzyme's regulatory site and increases its activity. What is this called? A. Feedback inhibition B. Competitive inhibition C. Allosteric activation D. Noncompetitive inhibition

D. Accept electrons and become $NADH$.

What is the primary role of $NAD^+$ during cellular respiration? A. Carry protons across the mitochondrial membrane B. Donate electrons directly to oxygen C. Act as the final electron acceptor D. Accept electrons and become $NADH$

C. It can change the protein's shape and activate or deactivate its function.

How does phosphorylation affect a protein? A. It always increases protein interactions B. It permanently activates proteins C. It can change the protein's shape and activate or deactivate it D. It only increases structural stability

C. The investment phase uses 2 ATP2 ATP, and the payoff phase produces 4 ATP4 ATP$2\text{ ATP}$.

What happens during the two phases of glycolysis? A. Both phases produce $2\text{ ATP}$ B. The investment phase creates $4\text{ ATP}$ C. The investment phase uses $2\text{ ATP}$, and the payoff phase produces $4\text{ ATP}$ D. Neither phase requires ATP

A. They have two membranes, with the inner membrane folded into cristae.

Which statement describes the structure of mitochondria? A. They have two membranes, with the inner membrane folded into cristae B. They have one membrane surrounding the matrix C. They have three membranes D. They have no membrane

D. It begins with one molecule and ends with different products without regenerating the starting molecule.

Why is glycolysis considered a linear metabolic pathway? A. It always produces the same amount of ATP B. One enzyme completes every reaction C. It physically occurs in a straight line D. It begins with one molecule and ends with different products without regenerating the starting molecule

C. It regenerates its starting molecule, oxaloacetate

Why is the citric acid cycle considered circular? A. It is the only pathway that can run backward B. It produces ATP without stopping C. It regenerates its starting molecule, oxaloacetate D. It occurs in a circular organelle

B. The flow of hydrogen ions causes part of the enzyme to rotate and make ATP

Why is ATP synthase compared to a turbine? A. Electrons directly rotate the enzyme B. The flow of hydrogen ions causes part of the enzyme to rotate and make ATP C. It uses heat to generate electricity D. It burns glucose to produce energy

C. High-energy electrons donated by $NADH$ and $FADH_2$.

What directly provides the energy used to pump protons across the inner mitochondrial membrane? A. Oxygen entering the cell B. Heat from respiration C. High-energy electrons donated by $NADH$ and $FADH_2$ D. ATP hydrolysis

C. Protons move down their gradient through ATP synthase

Why is chemiosmosis important for ATP production? A. It transfers phosphates directly to ADP B. It moves oxygen into mitochondria C. Protons move down their gradient through ATP synthase D. Electrons directly phosphorylate ATP

B. It produces significantly more ATP

Why is aerobic respiration generally more efficient than fermentation? A. It produces oxygen B. It produces significantly more ATP C. It does not require enzymes D. It is always faster

C. They break down into glycerol and fatty acids that enter energy-producing pathways

How are triglycerides used to produce ATP? A. They are all converted directly into glucose B. They immediately enter the electron transport chain unchanged C. They break down into glycerol and fatty acids that enter energy-producing pathways D. They remain stored until extreme starvation

A. By converting inorganic carbon into organic compounds

How does photosynthesis support the energy needs of heterotrophs? A. By converting inorganic carbon into organic compounds B. By producing heat energy C. By absorbing infrared radiation D. By providing ATP directly through the atmosphere

Stroma

Which part of the chloroplast contains the fluid surrounding the thylakoids and is where the Calvin cycle occurs? A. Lumen B. Matrix C. Cytoplasm D. Stroma

C. The plant could absorb less light in certain wavelengths, reducing photosynthesis.

How would a deficiency in carotenoids affect photosynthesis? A. Chlorophyll alone would completely make up for their absence B. The plant would absorb more total light C. The plant could absorb less light in certain wavelengths, reducing photosynthesis D. The plant would produce more oxygen but less glucose

A. Absorbed light from chlorophyll drives photosynthesis

Why do the action spectrum and chlorophyll absorption spectrum have similar peaks? A. Absorbed light from chlorophyll drives photosynthesis B. Other pigments prevent chlorophyll absorption C. Chlorophyll reflects all wavelengths equally D. Photosynthesis only occurs in green light

C. $CO_2$

What inorganic molecule supplies the carbon used to build sugars during photosynthesis? A. $O_2$ B. $H_2O$ C. $CO_2$ D. $C_6H_{12}O_6$

C. Use light energy to extract electrons from water, releasing $H^+$ and $O_2$.

What is the primary role of Photosystem II (PSII)? A. Fix $CO_2$ into sugars B. Produce photons of light C. Use light energy to extract electrons from water, releasing $H^+$ and $O_2$ D. Directly reduce $NADP^+$ to $NADPH$

D. The proton gradient disappears, preventing chemiosmosis

A chemical makes the thylakoid membrane permeable to protons. Why does ATP production stop? A. The electron transport chain stops immediately B. The membrane blocks electrons C. NADPH prevents ATP synthase from functioning D. The proton gradient disappears, preventing chemiosmosis

B. Photosystem I

Which photosystem receives electrons from plastocyanin and helps move them toward $NADP^+$ reduction? A. Cytochrome $b_6f$ complex B. Photosystem I C. Photosystem II D. ATP synthase

D. RuBisCO attaches it to RuBP, eventually producing three-carbon compounds

What happens to $CO_2$ during carbon fixation in the Calvin cycle? A. It is immediately converted into glucose B. It is converted into oxygen C. It is broken down to release energy D. RuBisCO attaches it to RuBP, eventually producing three-carbon compounds

A. It donates electrons to help reduce molecules involved in G3P production.

What is the role of NADPH during the Calvin cycle? A. It donates electrons to help reduce molecules involved in G3P production B. It forms the structure of the chloroplast membrane C. It provides the carbon backbone of glucose D. It acts as the enzyme for carbon fixation

D. Autocrine

A cell responds to a growth factor that it secreted itself. What type of signaling is this? A. Paracrine B. Gap junction C. Endocrine D. Autocrine

B. Paracrine signaling

A cell releases a signaling molecule that affects nearby cells in the same tissue. What type of signaling is this? A. Endocrine signaling B. Paracrine signaling C. Synaptic signaling D. Autocrine signaling

B. Only cells with the matching receptors can respond.

Why do only certain cells respond to a specific signaling molecule? A. Only certain cells allow signaling molecules through special pores B. Only cells with the matching receptors can respond C. Every cell has every receptor but chooses whether to respond D. Cells closest to the signal always respond

B. Signals that bind cell-surface receptors need to be relayed inside the cell.

Why do cell-surface receptors need signal transduction pathways? A. Ligands must always cross the membrane first B. Signals that bind cell-surface receptors need to be relayed inside the cell C. Prokaryotic cell walls block signaling D. Receptors are too small to interact with signaling molecules

C. cAMP

Which is a common second messenger in eukaryotic cells? A. DNA polymerase B. Insulin C. cAMP D. ATP

B. Ligand binding activates their kinase activity and phosphorylation of tyrosine residues

How do receptor tyrosine kinases (RTKs) function? A. They only respond to neurotransmitters B. Ligand binding activates their kinase activity and phosphorylation of tyrosine residues C. They bind steroid hormones inside the nucleus D. They activate G proteins to make cAMP

A. It responds to signals such as DAG and $Ca^{2+}$ and phosphorylates target proteins

What is the primary function of protein kinase C (PKC)? A. It responds to signals such as DAG and $Ca^{2+}$ and phosphorylates target proteins B. It removes phosphate groups from RTKs C. It acts as a second messenger that directly binds GPCRs D. It initiates DNA replication by binding ligands

A. Growth factors activate signaling pathways that can trigger cell-cycle progression.

How can signaling pathways regulate cell growth? A. Growth factors activate signaling pathways that can trigger cell-cycle progression B. They always decrease protein synthesis C. They prevent DNA replication D. They increase plasma membrane thickness

D. Apoptosis

During embryonic development, cells between the forming fingers die in a controlled way. What is this called? A. Mitosis B. Necrosis C. Differentiation D. Apoptosis

D. By secreting mating factors that bind to receptors on other yeast cells

How do single-celled yeast cells communicate during mating? A. Through quorum sensing to detect nutrients B. By transferring DNA through plasmodesmata C. By releasing neurotransmitters D. By secreting mating factors that bind to receptors on other yeast cells

Bioenergetics

What is the study of how energy flows and is transformed in living organisms? A. Metabolism B. Bioenergetics C. Chemiosmosis D. Catabolism

Catabolism

Which metabolic process breaks down complex molecules into simpler ones, releasing energy? A. Anabolism B. Photosynthesis C. Catabolism D. Energy coupling

Anabolism

Which process builds complex molecules from simpler ones and requires energy? A. Catabolism B. Anabolism C. Fermentation D. Hydrolysis

Kinetic energy

Which type of energy is associated with motion? A. Potential energy B. Chemical energy C. Kinetic energy D. Stored energy

Potential energy

Which type of energy is stored based on an object's position or structure? A. Thermal energy B. Kinetic energy C. Mechanical energy D. Potential energy

Activation energy

What is the energy required to start a chemical reaction? A. Free energy B. Activation energy C. Enthalpy D. Kinetic energy

Enthalpy

Which term describes the total heat content of a system? A. Entropy B. Activation energy C. Enthalpy D. Free energy

First Law of Thermodynamics

Which law states that energy cannot be created or destroyed, only transferred or transformed? A. Second Law of Thermodynamics B. First Law of Thermodynamics C. Law of Entropy D. Law of Energy Coupling

Enzyme

What biological catalyst speeds up chemical reactions by lowering activation energy without being consumed? A. Substrate B. Coenzyme C. Enzyme D. Inhibitor

Allosteric inhibition

Which type of enzyme inhibition involves a molecule binding somewhere other than the active site and changing the enzyme's shape? A. Competitive inhibition B. Allosteric inhibition C. Enzyme activation D. Substrate binding

Coenzyme

What type of small organic molecule helps enzymes catalyze reactions by providing chemical groups or carrying electrons? A. Substrate B. Coenzyme C. Inhibitor D. Receptor

Metabolism

What term describes the sum of all chemical reactions in an organism, including breaking down and building molecules? A. Metabolism B. Catabolism C. Phosphorylation D. Cellular respiration

Cellular respiration

Which process is an example of catabolism because it breaks down glucose to produce ATP? A. Protein synthesis B. DNA replication C. Cellular respiration D. Glycogen synthesis

C. They evolved early and have been preserved through evolution

What does it mean when similar metabolic pathways are found in many different species? A. They developed independently in every species B. They are only used by multicellular organisms C. They evolved early and have been preserved through evolution D. They change completely with each generation

ATP

Which molecule contains adenine, ribose sugar, and three phosphate groups? A. $NADH$ B. ATP C. $FADH_2$ D. ADP

Energy coupling

What process uses energy released by ATP hydrolysis to drive reactions that require energy? A. Energy coupling B. Fermentation C. Oxidation D. Diffusion

B. The reaction has a high activation energy barrier

Why might a chemical reaction occur very slowly at room temperature? A. The reaction has no reactants B. The reaction has a high activation energy barrier C. The products have no energy D. The reaction is already complete

ATP hydrolysis

Which process releases usable energy when ATP loses its terminal phosphate group? A. ATP synthesis B. Glycolysis C. ATP hydrolysis D. Carbon fixation

Substrate-level phosphorylation

Which process produces ATP by directly transferring a phosphate group from a metabolic intermediate to ADP? A. Oxidative phosphorylation B. Chemiosmosis C. Substrate-level phosphorylation D. Electron transport

Oxidative phosphorylation

Which ATP-producing process uses the electron transport chain and a proton gradient? A. Fermentation B. Oxidative phosphorylation C. Glycolysis D. Substrate-level phosphorylation

Cytosol

Where does glycolysis occur in a cell? A. Mitochondrial matrix B. Inner mitochondrial membrane C. Nucleus D. Cytosol

Pyruvate oxidation

Which process converts pyruvate into acetyl-CoA while producing $NADH$ and releasing $CO_2$? A. Glycolysis B. Pyruvate oxidation C. Fermentation D. Electron transport

Electron transport chain (ETC)

Which system passes electrons through a series of redox reactions and uses their energy to pump protons across a membrane? A. Calvin cycle B. Glycolysis C. Electron transport chain D. Fermentation

Chemiosmosis

Which process uses hydrogen ions moving down their electrochemical gradient through ATP synthase to make ATP? A. Oxidation B. Chemiosmosis C. Fermentation D. Glycolysis

Fermentation

Which process regenerates $NAD^+$ from $NADH$ so glycolysis can continue producing ATP without oxygen? A. Krebs cycle B. Oxidative phosphorylation C. Fermentation D. Electron transport

Redox reaction

Which type of chemical reaction involves electrons being transferred between molecules? A. Hydrolysis B. Condensation C. Redox reaction D. Phosphorylation

NADH and $FADH_2$

Which molecules carry high-energy electrons to the mitochondrial electron transport chain? A. ATP and ADP B. $NADH$ and $FADH_2$ C. Glucose and oxygen D. $CO_2$ and $H_2O$

ATP

Which molecule provides energy to drive cellular activities such as transport, movement, and chemical reactions? A. DNA B. ATP C. Oxygen D. Glucose

Phosphorylation

What is the addition of a phosphate group to a molecule called? A. Oxidation B. Hydrolysis C. Phosphorylation D. Reduction

Glycolysis

Which process breaks one glucose into two pyruvate molecules, producing a net gain of $2\text{ ATP}$ and $2\text{ NADH}$? A. Krebs cycle B. Glycolysis C. Oxidative phosphorylation D. Calvin cycle

Energy investment phase

During which phase of glycolysis are two ATP molecules used to phosphorylate sugar intermediates? A. Energy payoff phase B. Electron transport phase C. Energy investment phase D. Fermentation phase

Mitochondrial matrix

Where does pyruvate oxidation occur in eukaryotic cells? A. Cytosol B. Mitochondrial matrix C. Nucleus D. Thylakoid membrane

Dehydrogenation and decarboxylation

Which two processes occur when pyruvate is converted to acetyl-CoA? A. Fermentation and hydrolysis B. Phosphorylation and reduction C. Dehydrogenation and decarboxylation D. Chemiosmosis and diffusion

C. NADH

Which electron carrier is directly produced during the Krebs cycle and later donates electrons to the ETC? A. Glucose B. Oxygen C. $NADH$ D. ADP

B. Two

How many carbon dioxide molecules are released during one turn of the Krebs cycle? A. One B. Two C. Three D. Four

C. Pyruvate buildup and reduced acetyl-CoA production

What is the likely result when the pyruvate dehydrogenase complex cannot efficiently convert pyruvate into acetyl-CoA? A. Increased Krebs cycle activity B. Faster ATP production C. Pyruvate buildup and reduced acetyl-CoA production D. Increased oxygen production

Cytochromes

Which electron-carrying proteins use redox reactions to help transfer electrons through the mitochondrial electron transport chain? A. ATP synthases B. Cytochromes C. Ribosomes D. Phospholipids

Proton gradient

What is created when the electron transport chain pumps hydrogen ions across the inner mitochondrial membrane? A. Glucose gradient B. Proton gradient C. Oxygen gradient D. Carbon dioxide gradient

ATP synthase

Which enzyme uses energy from a proton gradient to produce ATP from ADP and inorganic phosphate? A. DNA polymerase B. ATP synthase C. RuBisCO D. Pyruvate kinase

Aerobic cellular respiration

Which process produces significantly more ATP per glucose molecule than fermentation? A. Lactic acid fermentation B. Alcoholic fermentation C. Aerobic cellular respiration D. Glycolysis alone

Carbon dioxide ($CO_2$)

Which product is released during alcoholic fermentation but not during lactic acid fermentation? A. ATP B. $NAD^+$ C. Carbon dioxide D. Lactate

Beta-oxidation

Which process breaks fatty acids into acetyl-CoA molecules that can enter the Krebs cycle? A. Glycolysis B. Beta-oxidation C. Fermentation D. Photosynthesis

Deamination

What process removes amino groups from amino acids so their carbon skeletons can be used in energy-producing pathways? A. Phosphorylation B. Deamination C. Fermentation D. Carbon fixation

Thylakoid membrane

Which part of the chloroplast is responsible for the light-dependent reactions of photosynthesis? A. Stroma B. Thylakoid membrane C. Outer membrane D. Cytoplasm

Stroma

Which fluid-filled region of the chloroplast contains the enzymes needed for the Calvin cycle? A. Thylakoid lumen B. Cristae C. Stroma D. Mitochondrial matrix

Violet

Which color of visible light has the shortest wavelength? A. Red B. Green C. Blue D. Violet

Absorption spectrum

Which spectrum shows the wavelengths of light absorbed by photosynthetic pigments? A. Action spectrum B. Absorption spectrum C. Emission spectrum D. Energy spectrum

Action spectrum

Which spectrum shows how the rate of photosynthesis changes at different wavelengths of light? A. Absorption spectrum B. Action spectrum C. Reflection spectrum D. Electromagnetic spectrum

Proton gradient

What does the photosynthetic electron transport chain help generate to power ATP synthesis? A. Glucose gradient B. Oxygen gradient C. Proton gradient D. Carbon dioxide gradient

G3P

Which three-carbon molecule is directly produced by the Calvin cycle and can be used to make glucose? A. ATP B. NADPH C. G3P D. RuBP

Light-dependent reactions

Which stage of photosynthesis captures light energy to produce ATP and NADPH? A. Calvin cycle B. Light-dependent reactions C. Glycolysis D. Carbon fixation

NADP⁺

Which molecule is the final electron acceptor in the photosynthetic light-dependent electron transport pathway? A. Oxygen B. Water C. $NADP^+$ D. Carbon dioxide

Chlorophyll a

Which photosynthetic pigment absorbs red and blue light most effectively? A. Carotene B. Chlorophyll a C. Xanthophyll D. Anthocyanin

A. Plant A: absorbs 430 nm and 662 nm

A scientist compares three plants. Which plant most likely contains chlorophyll a as its primary pigment? A. Plant A: absorbs $430\,\text{nm}$ and $662\,\text{nm}$ B. Plant B: absorbs $450\,\text{nm}$ and $640\,\text{nm}$ C. Plant C: absorbs $500\,\text{nm}$ and $680\,\text{nm}$ D. All three equally

Photosystem I (PSI)

Which photosystem absorbs light to re-energize electrons that are eventually used to reduce $NADP^+$ to NADPH? A. Photosystem II B. Photosystem I C. ATP synthase D. Cytochrome complex

Thylakoid lumen

Where do hydrogen ions accumulate during the light-dependent reactions before flowing through ATP synthase? A. Stroma B. Cytoplasm C. Thylakoid lumen D. Mitochondrial matrix

Calvin cycle

Which stage of photosynthesis fixes carbon dioxide into organic molecules that can be used to produce sugars? A. Glycolysis B. Krebs cycle C. Calvin cycle D. Light-dependent reactions

RuBP

Which five-carbon molecule is regenerated during the Calvin cycle so carbon fixation can continue? A. Glucose B. ATP C. RuBP D. NADPH

C. 3-PGA

What is the first stable product formed after carbon dioxide fixation in the Calvin cycle? A. G3P B. Glucose C. 3-PGA D. RuBP

Intercellular communication

What is communication between two or more different cells called? A. Intracellular communication B. Intercellular communication C. Signal transduction D. Phosphorylation