AP Biology Unit 1 practice questions
Try 10 multiple-choice questions from Unit 1 here. Pick an answer to see why it's right or wrong, then take the timed test above for a full AP-style set.
Question 1
A biologist observes water moving up a tall tree from the roots to the leaves. Which statement best describes the intermolecular forces that enable this movement against gravity?
Hydrogen bonds between water molecules create cohesion that pulls the column upward
Covalent bonds between water molecules create cohesion that pulls the column upward
Hydrogen bonds between water molecules create adhesion that pushes the column upward
Ionic bonds between water molecules create cohesion that pulls the column upward
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Answer: (A)
Describing the transpiration stream requires identifying the correct intermolecular forces. Hydrogen bonds form between water molecules (cohesion) to maintain the continuous column, while adhesion connects water to the xylem walls.
Question 2
Aquatic organisms often maintain stable internal temperatures even when air temperatures fluctuate wildly. Which property of water best explains this thermal stability?
Water's high specific heat absorbs significant thermal energy with minimal temperature rise
Water's high heat of vaporization prevents significant temperature change during evaporative cooling
Water's high density absorbs significant thermal energy with minimal temperature rise
Water's high polarity absorbs significant thermal energy with minimal temperature rise
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Answer: (A)
Connecting thermal stability to molecular properties reveals the role of specific heat. Water's high specific heat capacity allows it to absorb large amounts of energy to break hydrogen bonds before the kinetic energy (temperature) of the molecules increases significantly.
Question 3
During intense exercise, humans produce sweat that evaporates from the skin surface. Which statement describes the molecular mechanism of this cooling process?
Body heat is absorbed to break hydrogen bonds, converting liquid water to gas
Body heat is released to break hydrogen bonds, converting liquid water to gas
Body heat is absorbed to break ionic bonds, converting liquid water to gas
Body heat is absorbed to weaken hydrogen bonds, converting liquid water to gas
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Answer: (A)
Analyzing the thermodynamics of phase changes explains evaporative cooling. Heat energy from the body is absorbed to break the hydrogen bonds between liquid water molecules, allowing them to vaporize and carry the heat away.
Question 4
Sodium chloride (NaCl) dissolves readily in water. Which description explains how water molecules interact with the ions in solution?
Negative oxygen regions attract Na+, while positive hydrogen regions attract Cl-
Positive oxygen regions attract Na+, while negative hydrogen regions attract Cl-
Negative oxygen regions attract Cl-, while positive hydrogen regions attract Na+
Positive oxygen regions attract Cl-, while negative hydrogen regions attract Na+
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Answer: (A)
Applying knowledge of polarity to solvation explains how ionic compounds dissolve. Water's polar structure creates partial negative charges on oxygen that attract positive sodium ions, and partial positive charges on hydrogen that attract negative chloride ions.
Question 5
A water strider insect can walk across the surface of a pond without sinking. Which description explains the molecular basis of this phenomenon?
Hydrogen bonds between water molecules create high surface tension that resists the insect's weight
Covalent bonds between water molecules create high surface tension that resists the insect's weight
Hydrogen bonds between water molecules create low surface tension that supports the insect's weight
Ionic bonds between water molecules create high surface tension that resists the insect's weight
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Answer: (A)
Relating intermolecular forces to surface phenomena explains the water strider's ability. Hydrogen bonds between surface water molecules create a cohesive net (surface tension) strong enough to support the insect's weight.
Question 6
Water moves into the microscopic pores of a paper towel. Which statement describes the primary forces driving this movement?
Adhesion to polar cellulose surfaces pulls water against the force of gravity
Cohesion to polar cellulose surfaces pulls water against the force of gravity
Adhesion to nonpolar cellulose surfaces pulls water against the force of gravity
Cohesion to nonpolar cellulose surfaces pulls water against the force of gravity
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Answer: (A)
Distinguishing between adhesion and cohesion clarifies capillary action. Adhesion describes the attraction between water and the polar cellulose fibers of the paper, which draws the water into the pores against gravity.
Question 7
In freezing temperatures, a layer of ice forms on top of a lake, insulating the liquid water below. Which molecular property explains why the ice floats?
Stable hydrogen bonds lock molecules in a lattice that is less dense than liquid water
Stable covalent bonds lock molecules in a lattice that is less dense than liquid water
Stable hydrogen bonds lock molecules in a lattice that is more dense than liquid water
Stable covalent bonds lock molecules in a lattice that is more dense than liquid water
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Answer: (A)
Connecting molecular structure to density explains why ice floats. As water freezes, stable hydrogen bonds lock molecules into a fixed, expanded lattice structure that holds them further apart than in the chaotic liquid phase.
Question 8
A biologist observes that water moves from the roots to the leaves of a 100-meter tall redwood tree against the force of gravity. Which statement best explains how the molecular properties of water enable this continuous column of fluid to be maintained?
Hydrogen bonds between water molecules create cohesive forces that maintain the continuous column.
Covalent bonds between water molecules create cohesive forces that maintain the continuous column.
Hydrogen bonds between water molecules create adhesive forces that maintain the continuous column.
Ionic bonds between water molecules create cohesive forces that maintain the continuous column.
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Answer: (A)
Connecting hydrogen bonding to the physical property of cohesion explains how water molecules stick together. This intermolecular attraction allows the water column to withstand the tension created by transpiration without breaking.
Question 9
Ecologists note that air temperatures in coastal regions fluctuate less daily than in inland regions at the same latitude. Which explanation best connects this observation to the properties of water?
Water's high specific heat absorbs heat energy with minimal temperature change.
Water's high heat of vaporization prevents temperature change in coastal regions.
Water's polarity allows hydrogen bonding that absorbs heat energy with minimal temperature change.
Water's high density absorbs heat energy with minimal temperature change.
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Answer: (A)
Linking specific heat to temperature stability explains the environmental observation. Water can absorb or release large amounts of thermal energy with only a small change in its own temperature, buffering the surrounding air temperature.
Question 10
During intense exercise, the human body produces sweat which cools the skin surface as it dries. Which statement best explains the molecular mechanism responsible for this cooling effect?
Breaking hydrogen bonds to vaporize water absorbs significant heat energy from the skin.
Forming hydrogen bonds to vaporize water absorbs significant heat energy from the skin.
Breaking covalent bonds to vaporize water absorbs significant heat energy from the skin.
Breaking hydrogen bonds to condense water releases significant heat energy to the skin.
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Answer: (A)
Connecting the phase change to energy transfer explains evaporative cooling. Energy (heat) from the body is consumed to break the hydrogen bonds between water molecules, allowing them to escape as gas and lowering the temperature of the remaining surface.
What's on the AP Biology Unit 1 practice test
The standard version takes about 60 minutes and follows the timing and directions of the AP exam, sized to one unit:
- 20 Multiple Choice Questions (30 minutes)
- 1 FRQ – FRQ 1 – Interpreting and Evaluating Experimental Results (Long) (15 minutes)
- 1 FRQ – FRQ 3 – Scientific Investigation (Short) (15 minutes)
Questions are drawn from 1507 multiple-choice questions and 62 FRQs written for Unit 1, Chemistry of Life.
Practice AP Biology Unit 1 FRQs
Answer the unit's free-response questions one at a time and get a score on every part.
- FRQ 1 – Interpreting and Evaluating Experimental Results (Long) (7 questions)
- FRQ 2 – Interpreting and Evaluating Experimental Results with Graphing (Long) (3 questions)
- FRQ 3 – Scientific Investigation (Short) (12 questions)
- FRQ 4 – Conceptual Analysis (Short) (16 questions)
- FRQ 5 – Analyze Model or Visual Representation (Short) (12 questions)
- FRQ 6 – Analyze Data (Short) (12 questions)
Review Unit 1 before you start
- 1.1 Structure of Water and Hydrogen Bonding
- 1.2 Elements of Life
- 1.3 Introduction to Biological Macromolecules
- 1.4 Properties of Biological Macromolecules
- 1.5 Lipids
- 1.6 Nucleic Acids
- 1.7 Proteins