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Worksheets5.1 What Is Energy?
Total questions: 92
Worksheet time: 46mins
Which statement best defines potential energy in the context of plants shown in the diagram?
Energy of motion used by animals during movement
Stored energy captured from solar radiation in plant parts such as fruits, stems, and leaves
Heat energy released to the environment during respiration
Chemical energy only found in animal muscles
According to the figure, what form of energy does a person primarily use when walking from one location to another after eating fruit?
Potential energy
Kinetic energy
Nuclear energy
Thermal energy
What happens to some energy at every stage of energy flow in the biosphere, as indicated in the figure?
It is completely stored as chemical bonds
It cycles back to the Sun
Some is lost as heat
It is converted entirely to potential energy
Which sequence correctly illustrates the energy transformations depicted?
Kinetic energy in plants → solar energy → heat
Solar energy → potential energy in plant → kinetic energy in person
Heat → potential energy in plant → solar energy
Potential energy in person → solar energy → kinetic energy in plant
Food energy is measured in which unit according to the material?
Joules
Calories
Kelvins
Newtons
A kilocalorie (Calorie on food labels) is equal to how many calories?
10
100
1,000
10,000
Which statement accurately describes a calorie as defined in the material?
The amount of heat needed to raise the temperature of 1 g of water by 1°C
The energy required to move a 1-kg mass 1 meter
The heat released when 1 g of sugar is burned completely
The energy stored in 1 mL of water at 25°C
Why is a portion of energy not available for biological work during energy transfers depicted in the figure?
It is used to create matter
It becomes heat that dissipates into the environment
It converts back to solar energy
It remains trapped as potential energy in plants indefinitely
Which statement best defines a kilocalorie in the context of food energy measurement?
The amount of energy required to raise the temperature of 1 gram of water by 1°C
One thousand calories, commonly used on nutrition labels to indicate food energy
The smallest measurable unit of heat energy in cells
The energy released when ATP is hydrolyzed
A nutrition label lists an item as 250 Calories (kcal). What does this value most directly represent?
250 individual calories used by the body to synthesize glucose
The energy needed to raise 250 kilograms of water by 1°C
The equivalent of 250,000 calories of energy, since each Calorie on labels equals one kilocalorie
The total energy stored as ATP after digestion
According to the concept of entropy presented, what happens during every energy transformation?
Entropy decreases as systems become more ordered
Entropy increases, reflecting greater disorganization or randomness
Energy is completely conserved with no loss
Heat is converted fully into work
What is the only way stated to maintain or bring about order in a system?
Decrease temperature
Remove heat
Add energy
Increase entropy
Which statement best describes heat in the context of the entropy discussion?
Heat is a highly organized form of energy
Heat is a highly disorganized form of energy
Heat has no relation to entropy
Heat always converts to chemical energy without loss
During photosynthesis as described, what form of energy is converted into what product?
Chemical energy to solar energy, producing oxygen
Solar energy to chemical energy (glucose)
Heat energy to mechanical energy (ATP)
Solar energy to kinetic energy (motion)
Which balanced summary equation corresponds to photosynthesis in the material?
C6H12O6 + 6O2 → 6CO2 + 6H2O
6CO2 + 6H2O → C6H12O6 + 6O2
6O2 + C6H12O6 → 6CO2 + 6H2O + energy
CO2 + H2O → CH4 + O2
Which outcome accompanies photosynthesis according to the entropy explanation?
No energy is lost; entropy remains constant
Some of the sun’s energy is lost as heat, increasing entropy
All light energy becomes glucose, decreasing entropy
Heat release lowers entropy
A tidy bedroom becomes messy over time without cleaning. Which law best explains this trend?
First Law of Thermodynamics only
Second Law of Thermodynamics (entropy tends to increase)
Law of Conservation of Matter
Hardy–Weinberg equilibrium
Which action aligns with the statement that order requires added energy?
Leaving a room untouched to keep it tidy
Opening a window to cool the room
Spending effort to organize and clean a messy room
Turning off the lights
Why can photosynthesis be used to illustrate both thermodynamic laws in biology?
It creates matter from nothing, violating conservation
It converts solar energy into chemical bonds (conservation of energy) while releasing some energy as heat (increasing entropy)
It decreases entropy without any energy input
It transforms heat entirely into work with perfect efficiency
Refer to the diagrams of hydrogen ion (H+) distribution across a membrane. Which condition corresponds to a lower entropy state?
Equal distribution of H+ on both sides of the membrane
Unequal distribution with H+ concentrated on one side
Random motion of H+ in a large volume with no membrane
No H+ present on either side
According to the ion distribution diagrams, what creates a potential for work across a membrane?
Equal distribution of ions (high entropy)
Difference in H+ concentration across the membrane
Absence of a membrane channel
Complete absence of ions
Which statement best explains why equal distribution of H+ has higher entropy?
Ions are confined to a smaller space and become ordered
Ions possess less freedom of movement
Ions are spread out evenly and can occupy a greater volume
Ions stop moving entirely
A cell establishes a high H+ concentration on one side of the membrane. Which outcome is most directly implied by the figure?
The system becomes more disordered and gains entropy
The system becomes more ordered and stores potential for work
No change in order or energy potential occurs
Entropy increases because ions are in a smaller space
From the ATP summary, which feature makes ATP an effective short-term energy carrier in cells?
It is a stable molecule that rarely changes
It easily loses a phosphate group to become ADP
It contains no phosphate groups
It does not participate in a cycle of breakdown and regeneration
Which set correctly lists the three structural components of an ATP molecule, as depicted in the model?
Adenine, ribose, and one phosphate group
Adenine, deoxyribose, and three phosphate groups
Adenine, ribose, and three phosphate groups
Guanine, ribose, and three phosphate groups
What does the abbreviation ATP stand for?
Adenosine triphosphate
Adenine triphosphate
Adenosine diphosphate
Adenine phosphate
During the ATP cycle, ATP breakdown typically yields which immediate products?
AMP only
ADP and phosphate
Ribose and adenine
Two phosphates and adenine
According to the ATP cycle figure, what process supplies the energy needed to regenerate ATP from ADP and P?
Protein synthesis
Cellular respiration
Photosynthesis only
Passive diffusion
Which statement best explains why ATP is suited as the cell’s energy currency?
It stores large, uncontrollable bursts of energy
Its breakdown releases energy slowly and cannot be coupled
It releases just enough energy quickly and can be easily coupled to required reactions
It cannot be regenerated once used
In the coupled reactions diagram, the energy-releasing reaction that commonly powers an energy-requiring reaction is identified as which process?
ADP phosphorylation
ATP breakdown
Glycolysis
Electron transport chain
Which component differs between ATP and ADP?
The nitrogenous base
The sugar group
The number of phosphate groups
The presence of ribose
A cell needs energy for muscle contraction. Based on the ATP cycle, which immediate chemical change provides this energy?
ADP gains a phosphate to form ATP
ATP breaks down to ADP and phosphate
Adenine converts to ribose
Phosphate converts to ribose
Which statement aligns with the depiction of ATP structure in the figure?
The phosphate groups are directly attached to adenine
Ribose connects adenine to the chain of phosphate groups
ADP contains no phosphate groups
ATP contains deoxyribose sugar
In energy coupling as shown, what is the role of ATP in converting reactants C + D into products A + B?
ATP acts as a substrate incorporated into A + B
ATP provides energy upon hydrolysis to drive the reaction forward
ATP inhibits the energy-requiring reaction
ATP is regenerated from ADP during the reaction, releasing energy
Which statement best defines a coupled reaction in cellular processes?
Two reactions that occur independently without energy transfer
A reaction in which energy released by one process drives another process
Two reactions that both consume ATP at the same time
A reaction that can occur only in the presence of oxygen
During muscle contraction, which sequence occurs as ATP interacts with myosin?
Myosin releases ADP and Pi, then binds ATP, causing contraction to stop
Myosin binds ATP; ATP splits to ADP + Pi; release of ADP + Pi causes myosin to change shape and pull on actin
Myosin binds actin first; then ATP forms from ADP + Pi, powering the stroke
ATP binds actin directly, causing it to slide over myosin
What immediate role does ATP breakdown play in muscle movement?
It releases oxygen to the muscle fiber
It provides heat to warm the muscle
It provides energy that causes myosin to change shape and pull on actin
It stores glucose as glycogen
Which proteins directly interact to produce the sliding motion in muscle contraction?
Actin and tubulin
Myosin and actin
Keratin and myosin
Actin and collagen
Which organelle primarily produces ATP used for cellular work such as muscle contraction?
Chloroplast
Golgi apparatus
Mitochondrion
Ribosome
According to the flow-of-energy summary, which statement accurately links photosynthesis and cellular respiration?
Photosynthesis occurs in mitochondria and directly produces ATP for muscles
Cellular respiration in mitochondria breaks down carbohydrates to make ATP, while photosynthesis in chloroplasts uses light to synthesize carbohydrates
Both processes only occur in animals
Photosynthesis and cellular respiration both release oxygen as a final product
Which organelle captures solar energy to produce chemical energy in carbohydrates?
Mitochondrion
Chloroplast
Nucleus
Golgi apparatus
In the depicted energy flow, which molecules are inputs to the chloroplast during photosynthesis?
O2 and glucose
CO2 and H2O
ATP and heat
NADH and FADH2
According to the diagram, what leaves the mitochondrion as a byproduct of cellular respiration?
Solar energy
Heat
Glucose
CO2 only
What is the primary energy currency produced by mitochondria to power chemical, transport, and mechanical work?
NADPH
ATP
GTP
FADH2
Humans contribute to the cycling of molecules by performing which pair of actions?
Exhaling oxygen; eating only plants
Inhaling oxygen; eating plants and animals
Inhaling carbon dioxide; eating animals only
Exhaling carbon dioxide; producing glucose
Which statement best describes the relationship between photosynthesis and cellular respiration shown?
Both occur in chloroplasts and release O2
Photosynthesis uses CO2 and H2O to make carbohydrates and O2; respiration uses O2 to extract ATP from food
Respiration produces carbohydrates from heat; photosynthesis consumes ATP
Both processes convert heat into solar energy
By cellular respiration, humans use O2 and energy-rich food primarily to do what?
Store solar energy in chloroplasts
Make ATP to maintain the body and carry on activities
Convert heat directly into chemical energy
Produce only mechanical work without ATP
In the metabolic pathway figure, what do E1–E6 represent?
Substrates
Products
Enzymes
Coenzymes
Which statement about enzymes in metabolic pathways is supported by the material?
Enzymes make impossible reactions occur
Enzymes are protein catalysts that speed up reactions
Enzymes are consumed in the reactions they catalyze
Enzymes only function in mitochondria
Which scenario illustrates feedback inhibition as shown in the figure?
The first substrate binds E1, activating E2–E4 sequentially
The end product binds to E1 and reduces the pathway’s activity
Heat from mitochondria accelerates E1
ATP binding to chloroplast activates photosynthesis
What happens when the enzyme in the pathway is inactive, according to the figure?
The pathway accelerates to produce more product
The first substrate is converted directly to ATP
The metabolic pathway becomes inactive and no product forms
Photosynthesis compensates to maintain product level
Which statement best describes the role of enzymes in metabolism?
They are substrates that are consumed during reactions.
They are organic catalysts that act on substrates to facilitate reactions.
They are products formed at the end of reactions.
They are inorganic cofactors that always increase reaction temperature.
According to the diagram of enzymatic action, what happens at the active site?
The enzyme is permanently altered and becomes a product.
The substrate binds and the reaction occurs, producing products.
Products bind to form substrate.
Energy is stored without chemical change.
Which statement about an enzyme's active site aligns with the induced fit model?
The active site is rigid and never changes shape.
The active site undergoes a slight shape change to accommodate the substrate.
The active site is identical for all enzymes.
The active site only binds products but not substrates.
What comparison is used to describe substrate specificity of an enzyme's active site?
Gears and belt
Lock and key
Plug and socket
Key and map
Which statement is TRUE regarding enzymes after they catalyze a reaction?
They are used up and must be replaced.
They are denatured by the products.
They return to their original shape after releasing product(s).
They become inactive permanently.
Which scenario best illustrates enzyme inhibition as described?
A substrate binds faster due to higher temperature.
An active enzyme is prevented from combining with its substrate.
Additional substrate increases reaction rate.
An enzyme increases activation energy.
Cyanide is described as a poison because it binds to and inhibits which enzyme?
ATP synthase
Rubisco
Cytochrome c oxidase
Amylase
Penicillin’s mode of action, as noted, is to:
Activate human enzymes in respiration.
Interfere with a bacterial enzyme that kills the bacteria.
Increase the affinity of bacterial substrates for human enzymes.
Bind to DNA to stop transcription.
Which statement best describes feedback inhibition in a metabolic pathway?
An initial substrate activates all downstream enzymes.
A product, when abundant, competes with the substrate for the active site to speed up the pathway.
An end product binds to a site other than the active site on the first enzyme, causing a shape change that shuts the pathway down.
Enzymes in a pathway are permanently inactivated by heat.
Which feature distinguishes competitive interaction at the active site from allosteric feedback inhibition as presented?
Competitive interaction involves product abundance at the active site, while allosteric feedback involves binding at a different site causing shape change.
Both involve binding at the same nonactive site.
Allosteric feedback increases substrate concentration at the active site.
Competitive interaction occurs only in nonbiological systems.
According to the diagram, what is the immediate consequence when the product P accumulates and binds to enzyme E1 at a site other than the active site?
Substrate S binds more quickly
E1 changes shape and loses function
E1 increases catalytic rate
P is converted back to S
In the active pathway illustration, which sequence correctly represents the ordered action of enzymes leading from the first substrate to the end product?
E4 → E3 → E2 → E1
E1 → E2 → E3 → E4
E2 → E1 → E3 → E4
E1 → E3 → E2 → E4
Which statement best defines feedback inhibition as depicted?
The first substrate blocks the active site of E1 to start the pathway
An end product binds allosterically to an early enzyme to downregulate the pathway
Each enzyme competes for the same active site on E1
Heat denatures all enzymes simultaneously to stop the pathway
What happens to substrate binding when E1 is inactivated by product binding in feedback inhibition?
Substrate S binds more tightly to the altered active site
Substrate S cannot bind, and the reaction stops
Substrate S is converted directly into P without E1
Substrate S binds to E4 instead
Which regulatory mechanism is illustrated by the product binding at the 'other site' on E1 rather than the active site?
Competitive inhibition
Substrate-level phosphorylation
Allosteric regulation
Coenzyme activation
When product levels drop after feedback inhibition has occurred, what is the next event in the pathway according to the figure?
E1 remains permanently inactive
E1 returns to its original shape and the pathway resumes
S is degraded to prevent waste
E4 converts P back to S to restart the pathway
Which statement best defines energy of activation (Ea) as presented?
The total energy released by a reaction
The energy needed to cause molecules to react with one another
The heat lost to the surroundings during a reaction
The energy stored in products compared to reactants
According to the material, how do enzymes affect the energy of activation for a reaction?
They increase Ea, slowing the reaction
They do not change Ea but increase temperature
They lower Ea, making reactions easier/faster
They convert substrates directly into products without affecting Ea
Which action is directly attributed to enzymes to facilitate reactions, besides lowering Ea?
They supply ATP for the reaction
They bring substrates into contact and may participate in the reaction
They convert endergonic reactions to exergonic reactions
They increase the potential energy of products
A reaction pathway shows a smaller activation energy barrier when an enzyme is present. What consequence does the material state follows from this change?
The reaction becomes slower due to reduced collisions
The reaction becomes easier/faster to occur
The overall energy of products increases
The reaction stops at the transition state
In the context of cellular processes that depend on enzymes, which transport process would most likely require additional energy input from the cell regardless of enzyme action?
Passive transport down a concentration gradient
Active transport against a concentration gradient
Simple diffusion across the membrane
Facilitated diffusion through channels
Which statement best defines passive transport across a cell membrane?
Movement of molecules using ATP against their concentration gradient
Movement of molecules down their concentration gradient without additional energy input
Endocytosis of large particles into vesicles
Pumping ions through proteins using energy from respiration
According to the notes on passive transport, which type of molecule most easily crosses the phospholipid bilayer by simple diffusion?
Large polar molecules
Ions with charge
Non-polar, hydrophobic molecules
Small peptides
Which transport process specifically requires membrane proteins such as channels or carriers but does not require cellular energy?
Osmosis
Active transport
Facilitated diffusion
Exocytosis
Water is polar. Which protein type explained in the notes accounts for its faster-than-expected movement across membranes?
Sodium-potassium pumps
Aquaporins
Clathrin-coated pits
Dynein motors
In the three-panel fishbowl diagram showing dye dispersal over time, what outcome does the final panel illustrate?
Active transport of dye into fish
Equal distribution of dye and water molecules (equilibrium)
Aggregation of dye at the bottom due to gravity
Pumping of dye through a membrane
Based on the dye crystal demonstration, which factor primarily drives the movement observed?
ATP hydrolysis by membrane pumps
A concentration gradient causing diffusion
Bulk flow created by cilia
Chemical reactions converting dye to water
In the facilitated diffusion figure, what role does the orange structure spanning the membrane play?
It acts as a carrier protein that changes shape to move solute down its gradient
It is a proton pump that expends ATP
It is a cellulose wall limiting transport
It is a vesicle that engulfs extracellular fluid
Which statement best contrasts simple diffusion and facilitated diffusion across the plasma membrane?
Both require ATP but use different proteins
Simple diffusion needs carrier proteins; facilitated diffusion does not
Simple diffusion moves non-polar molecules directly through the bilayer; facilitated diffusion uses specific transport proteins
Facilitated diffusion moves molecules against their gradient; simple diffusion moves down the gradient
A polar molecule needs to cross the plasma membrane without energy expenditure. Which mechanism is most appropriate according to the notes and figure?
Simple diffusion through phospholipids
Facilitated diffusion via a specific channel or carrier
Endocytosis
Active transport using ATP
At equilibrium in diffusion, which description is accurate based on the dye demonstration?
Net movement of molecules continues from low to high concentration
Net movement of molecules stops; distribution is uniform though individual molecules still move randomly
All molecular motion ceases
Molecules become larger and sink
Which statement best defines facilitated diffusion in cellular membranes?
Passive transport using carrier proteins without ATP
Active transport using ATP to move solutes up their gradient
Bulk transport via vesicles across membranes
Random movement of any molecules without membrane involvement
In osmosis, which component must be selectively permeable to allow the process shown to occur?
Solute only
Water only
Both solute and water equally
Neither solute nor water
According to the demonstration, water moves in response to which gradient?
Solute concentration gradient directly
Water concentration gradient, inversely related to solute concentration
Electrical gradient only
Hydrostatic pressure gradient only
What is the expected direction of net water movement when solute cannot cross the membrane and one side has higher solute concentration?
From the higher solute side to the lower solute side
From the lower solute side to the higher solute side
No net movement will occur
It oscillates randomly with no trend
Which statement correctly distinguishes osmosis from simple diffusion?
Osmosis requires ATP while simple diffusion does not
Osmosis involves movement of water across a semipermeable membrane
Osmosis moves solutes across membranes only
Osmosis can occur only in gases
A cell places a membrane that is permeable to water but not solute between two solutions. Which outcome matches the model?
Water moves until the water concentration gradient reaches zero
Solute diffuses until its gradient reaches zero
Water moves up its own concentration gradient
No gradients change because the membrane blocks all movement
Carrier proteins in facilitated diffusion primarily function to
Hydrolyze ATP to power transport
Bind specific solutes and move them down their concentration gradient
Create pores that allow any molecule to pass
Pump solutes against their gradient
Which condition would increase the rate of osmosis across a semipermeable membrane as depicted?
Increasing the solute size so it can cross the membrane
Increasing the difference in solute concentration across the membrane
Decreasing the water permeability of the membrane to zero
Equalizing solute concentrations on both sides
In the diagram, why does the final water level differ between the two compartments after osmosis proceeds?
Water accumulates on the side with higher solute concentration due to lower free water concentration
Solute particles physically push water molecules across the membrane
Water is actively pumped by carrier proteins
Hydrostatic pressure instantly equalizes levels on both sides
Which description best captures the relationship between solute concentration and free water concentration in osmosis?
They are directly proportional
They are inversely proportional
They are unrelated
Both remain constant during osmosis
