AP Biology Unit 1 Practice Test & Exam | 26 Questions

Questions 1-3 refer to the following diagram of water molecules.

1. Which of the following best explains how the property illustrated in the diagram allows water to move from the roots to the leaves of a plant?

(A)Water's high specific heat allows it to absorb solar energy without a large temperature increase, powering transpiration.(B)Hydrogen bonds between water molecules create cohesion, which allows them to be pulled up in a continuous column.(C)The covalent bonds within water molecules are easily broken, allowing them to flow freely through vascular tissue.(D)Water's ability to act as a versatile solvent dissolves minerals in the soil, creating pressure that pushes water upwards.

2. Aquatic organisms are able to survive in temperate climates where lakes freeze in the winter. Which of the following properties of water is most directly responsible for this?

(A)Water is a powerful solvent, which allows it to dissolve gases like oxygen even under ice.(B)Water has a high heat of vaporization, preventing the entire lake from evaporating in the summer.(C)Solid water (ice) is less dense than liquid water, allowing it to float and insulate the water below.(D)Water exhibits strong surface tension, which prevents the ice from sinking into the liquid water.

3. Based on the diagram, which of the following correctly explains the relationship between the two types of bonds shown?

(A)The hydrogen bonds between molecules are stronger than the covalent bonds within molecules, giving water its stability.(B)The covalent bonds create a nonpolar molecule, which then allows for the formation of weak hydrogen bonds with other molecules.(C)The polar covalent bonds within a water molecule create partial positive and negative charges that allow for the formation of hydrogen bonds between molecules.(D)The hydrogen bonds and covalent bonds are equal in strength, allowing water to exist as a liquid at room temperature.

Question 4 refers to the image/diagram above.

4. A student creates the table above to summarize the elemental composition of macromolecules. Which of the following best describes the information presented?

(A)All major biological macromolecules are primarily composed of carbon, hydrogen, and oxygen.(B)The presence of nitrogen can be used to distinguish proteins and nucleic acids from carbohydrates and lipids.(C)Phosphorus is a key component of the cell membrane and is therefore found in lipids.(D)Sulfur is required for the synthesis of all 20 types of amino acids.

Questions 5-6 refer to the following chemical reaction.

5. Which of the following statements best explains the process shown in the diagram?

(A)Hydrolysis is occurring, where the addition of water breaks a covalent bond to form two monomers.(B)Dehydration synthesis is occurring, where water is removed to form a covalent bond between two monomers.(C)A catabolic reaction is occurring, releasing energy as a complex molecule is broken down into simpler ones.(D)A phospholipid is being formed from a glycerol molecule and two fatty acids.

6. The covalent bond formed between the two glucose monomers is called a glycosidic linkage. In a longer polymer, such as starch, hundreds of these linkages would form. If a cell needs to access the energy stored in a starch polymer, which process would it use?

(A)Dehydration synthesis, to add more glucose molecules and increase the energy content.(B)Hydrolysis, to break the glycosidic linkages by adding water, releasing glucose monomers.(C)Denaturation, to unfold the polymer by heating it, which breaks the bonds and releases energy.(D)Phosphorylation, to add phosphate groups to the starch, making it unstable and causing it to break apart.

7. A student observes that vegetable oil is a liquid at room temperature while animal fats (like butter) are solid. Both are composed of triglycerides. Which of the following is the most plausible scientific claim to explain this difference?

(A)The animal fats are denser because they contain more hydrogen atoms for every carbon atom.(B)The fatty acids in the vegetable oil are primarily unsaturated, and the resulting kinks in their structures prevent the molecules from packing closely together.(C)The vegetable oil is hydrophilic, allowing it to remain liquid in the presence of water vapor in the air, while the animal fat is hydrophobic.(D)The animal fats contain phosphorus, which increases the strength of intermolecular attractions and raises the melting point.

8. A scientist analyzes a sample of a nucleic acid and finds that it contains 22% adenine, 28% guanine, 28% cytosine, and 22% uracil. Which of the following claims is best supported by this evidence?

(A)The sample is DNA because the percentages of adenine and guanine are different.(B)The sample is a double-stranded DNA molecule because A pairs with T and G pairs with C.(C)The sample is an RNA molecule because it contains uracil instead of thymine.(D)The sample is a double-stranded RNA molecule because the percentage of A equals U and G equals C.

Question 9 refers to the image/diagram above.

9. Which level of protein structure is determined by the specific sequence of amino acids in the polypeptide chain?

(A)Primary(B)Secondary(C)Tertiary(D)Quaternary

10. The function of a protein is highly dependent on its specific three-dimensional shape. An enzyme, which is a type of protein, is exposed to an extreme pH. This causes the enzyme to lose its functionality. Which of the following best explains this observation?

(A)The extreme pH breaks the peptide bonds between amino acids, causing the primary structure to unravel.(B)The extreme pH disrupts the hydrogen bonds and ionic bonds that stabilize the tertiary structure, causing the protein to denature.(C)The extreme pH causes the cell to hydrolyze the protein, breaking it down into amino acids to be used for other purposes.(D)The extreme pH changes the sequence of amino acids in the protein, altering its primary structure and function.

11. Living organisms require nitrogen to build both proteins and nucleic acids. Which of the following describes how the nitrogen atom is incorporated into the monomer of each of these macromolecules?

(A)In amino acids, nitrogen is part of the carboxyl group; in nucleotides, it is part of the phosphate group.(B)In amino acids, nitrogen is part of the R-group; in nucleotides, it is part of the five-carbon sugar.(C)In amino acids, nitrogen is part of the amine group; in nucleotides, it is part of the nitrogenous base.(D)In amino acids, nitrogen is part of the central carbon; in nucleotides, it is part of the phosphodiester bond.

Questions 12-13 refer to the diagram below showing three different polysaccharides.

12. The structures shown are all polymers of glucose. Which of the following best explains the relationship between the structure and function of cellulose?

(A)The extensive branching allows for rapid release of glucose for energy in plant cells.(B)The linear chains pack closely together, forming strong hydrogen bonds that create a rigid structural material for plant cell walls.(C)The compact, helical shape allows for efficient storage of glucose in a small space within the plant's roots and seeds.(D)The alternating orientation of glucose molecules makes it easily digestible by most animals.

13. Glycogen (Diagram B) is the primary form of energy storage in animal muscle cells. Which feature of its structure is most directly related to its function of providing a rapid source of glucose when energy is needed?

(A)Its insolubility in water prevents it from disrupting the osmotic balance of the cell.(B)The large number of branches provides many ends from which glucose monomers can be rapidly hydrolyzed.(C)The strong covalent bonds make it a stable, long-term energy storage molecule.(D)The presence of nitrogen in its structure allows it to also be used for building proteins.

The diagram illustrates that the two strands of a DNA molecule are antiparallel.

14. The diagram illustrates that the two strands of a DNA molecule are antiparallel. Which of the following is a direct consequence of this structural feature?

(A)The genetic information is stored in the sequence of bases on both strands, providing a redundant copy.(B)The molecule twists into a double helix to protect the hydrophobic bases from the surrounding aqueous environment.(C)During replication, new nucleotides can be added to the 3' end of each growing strand.(D)The molecule is very stable due to the covalent bonds between the complementary base pairs.

15. Phospholipids are essential components of cell membranes. Based on their structure, which of the following is the most likely claim regarding their behavior in an aqueous (water-based) environment?

(A)They will dissolve completely, forming a homogenous solution with water.(B)They will spontaneously assemble into a bilayer, with the hydrophobic tails clustering together away from water and the hydrophilic heads facing the water.(C)They will form a solid, crystalline structure at the bottom of the container, as they are denser than water.(D)They will arrange themselves in a single layer on the surface of the water, with their hydrophobic tails pointing up into the air.

16. A water strider is an insect that can walk on the surface of a pond. This is possible due to a property of water. Which statement correctly links the property of water to the underlying chemical interactions?

(A)High specific heat, caused by strong covalent bonds, prevents the insect from sinking.(B)Adhesion, the attraction of water molecules to the insect's legs, holds the insect up.(C)Surface tension, created by the collective strength of hydrogen bonds between water molecules, supports the insect's weight.(D)The low density of water, resulting from its polarity, allows the lightweight insect to float.

Refer to the figure below.

17. Which component of the amino acid shown is responsible for the differences in properties among the 20 common amino acids?

(A)The amine group(B)The carboxyl group(C)The central carbon atom(D)The R-group

Refer to the figure below.

18. The diagram illustrates a biological process. Which statement correctly identifies and explains this process?

(A)It shows dehydration synthesis, as water is used to synthesize a polymer from monomers.(B)It shows hydrolysis, as water is used to break bonds within a polymer, releasing monomers.(C)It shows denaturation, as the enzyme is causing the protein to unfold into a linear chain.(D)It shows polymerization, as the enzyme is linking amino acids together to form a protein.

19. A student claims that the structure of RNA is less stable than the structure of DNA, making RNA more suitable for its role as a temporary messenger molecule. Which of the following pieces of evidence best supports this claim?

(A)RNA contains the sugar ribose, which has an extra hydroxyl group compared to deoxyribose, making it more reactive. RNA is also typically single-stranded, leaving its bases more exposed.(B)RNA contains uracil, which forms weaker bonds with adenine than thymine does, making the molecule less stable.(C)DNA is a much larger molecule than RNA, and its greater mass provides more structural stability.(D)RNA is synthesized in the nucleus but functions in the cytoplasm, and the journey between these locations inherently destabilizes the molecule.

20. Interactions between the R-groups of amino acids are responsible for forming the tertiary structure of a protein. A specific protein has a glutamic acid (acidic R-group) and a lysine (basic R-group) in close proximity. What type of interaction would be expected to form between these two R-groups?

(A)A covalent disulfide bridge(B)A hydrophobic interaction(C)An ionic bond(D)A hydrogen bond

21. Carbon is the fundamental element of life and forms the backbone of all major organic molecules. Which property of carbon is most responsible for its ability to form large, diverse molecules?

(A)Carbon has a high electronegativity, allowing it to form strong ionic bonds with other atoms.(B)Carbon can form four covalent bonds, allowing it to create long chains, branched structures, and rings.(C)Carbon is the most abundant element on Earth, making it readily available to all organisms.(D)Carbon atoms can readily form hydrogen bonds with each other, leading to stable, long polymers.

22. A scientist discovers a new polysaccharide in a species of fungus. It is found to be a structural component of the cell wall. Based on this function, which of the following is the most reasonable claim about the polysaccharide's structure?

(A)It is likely a highly branched polymer, similar to glycogen, for rapid energy release.(B)It is likely composed of linear chains that can form cross-links, creating a rigid and strong material.(C)It is likely a small, soluble molecule that can easily pass through the cell membrane.(D)It is likely composed of alternating types of monosaccharides to increase its complexity.

Refer to the figure below.

23. How does the molecular structure shown allow phospholipids to perform their primary function in a cell?

(A)The entirely nonpolar molecule can easily dissolve within the cytoplasm of the cell.(B)The molecule's amphipathic nature, having both a hydrophilic head and hydrophobic tails, allows it to form a stable barrier in an aqueous environment.(C)The charged phosphate group in the tail region attracts ions, helping to transport them across the membrane.(D)The long, saturated fatty acid tails allow the membrane to remain fluid at very low temperatures.

24. A segment of a DNA strand has the following sequence of bases:

(A)5' - TAC GGT CAG - 3'(B)3' - UAC GGU CAG - 5'(C)3' - TAC GGT CAG - 5'(D)5' - GAC TGG CAT - 3'

AP Biology Unit 1: Chemistry of Life Practice Exam

Exam Details

A. Multiple-Choice Questions (24 Questions)

B. Short Answer Questions (2 Questions)

AP Biology Unit 1: Chemistry of Life Practice Exam

Exam Details

A. Multiple-Choice Questions (24 Questions)

B. Short Answer Questions (2 Questions)