AP Biology Unit 2: Cells Practice Exam

Assessment for Unit 2: Cells

Estimated Time: 60 minutes

Exam Details

Questions: 35 total (33 multiple choice, 2 short answer)
Time: 60 minutes (recommended)
Topics Covered: Unit 2: Cells
Format: Multiple Choice, Short Answer questions matching real exam difficulty
Scoring: Instant results with detailed explanations

A. Multiple-Choice Questions (33 Questions)

Select the one best answer for each question.

Questions 1-3 refer to the following diagram of a eukaryotic cell.

1. Which numbered structure is the primary site of ATP synthesis through cellular respiration, featuring a highly folded inner membrane that increases surface area for metabolic reactions?

(A)1(B)2(C)3(D)4

2. A protein destined for secretion from the cell is synthesized and processed. Which of the following represents the most likely pathway for this protein?

(A)5 → 3 → 4 → Plasma Membrane(B)1 → 3 → 4 → Plasma Membrane(C)5 → 2 → 4 → Plasma Membrane(D)3 → 5 → 4 → Plasma Membrane

3. The structure labeled 2 contains its own circular DNA and ribosomes that are structurally similar to those of prokaryotes. Which of the following statements provides the best reasoning to explain this observation?

(A)The cell synthesized these components using genetic instructions from the nucleus to improve energy efficiency.(B)The structure evolved from an ancestral, free-living prokaryote that was engulfed by a larger host cell.(C)The structure is a temporary compartment that stores genetic material for the cell before it is needed by the nucleus.(D)The cell absorbed DNA and ribosomes from its environment and sequestered them within the organelle.

4. The fluid mosaic model of the plasma membrane is characterized by which of the following?

(A)A rigid, static structure of phospholipids and proteins.(B)A phospholipid bilayer with proteins and cholesterol that can move laterally.(C)A single layer of phospholipids with proteins embedded on the surface.(D)A membrane composed solely of proteins that regulate transport.

5. A scientist claims that compartmentalization within eukaryotic cells leads to increased metabolic efficiency. Which of the following observations best supports this claim?

(A)Prokaryotic cells are generally smaller than eukaryotic cells and have a higher surface area-to-volume ratio.(B)Some metabolic processes in eukaryotes, like glycolysis, occur in the cytosol, which is not a membrane-bound organelle.(C)Lysosomes maintain a highly acidic internal pH, which is optimal for the function of their digestive enzymes.(D)All living cells, both prokaryotic and eukaryotic, contain ribosomes for protein synthesis.

Questions 6-8 refer to the following experimental setup and data.

6. Based on the data, what is the surface area-to-volume ratio for the cube with a side length of 2 cm?

(A)2:1(B)3:1(C)4:1(D)6:1

7. Which of the following best describes a trend shown in the data?

(A)As the volume of the cube increases, the surface area-to-volume ratio increases.(B)As the side length of the cube decreases, the surface area-to-volume ratio increases.(C)The rate of diffusion is directly proportional to the volume of the cube.(D)The largest cube has the highest percentage of its volume penetrated by the acid.

8. The results of this experiment can be used to explain which of the following biological principles?

(A)Larger organisms require more complex circulatory systems to transport materials to all their cells.(B)Eukaryotic cells evolved membrane-bound organelles to increase their total volume.(C)The plasma membrane is selectively permeable to different types of molecules.(D)Active transport requires an input of metabolic energy to move substances against a gradient.

9. Which of the following molecules would be expected to cross the lipid bilayer of a plasma membrane most easily, without the help of a transport protein?

(A)Glucose ($C6H{12}O_6$)(B)A sodium ion ($Na^+$)(C)Oxygen ($O_2$)(D)A polypeptide

Refer to the figure below.

10. The diagram illustrates a process occurring in a eukaryotic cell. Which of the following best describes the function of the Golgi apparatus in this process?

(A)Synthesizing the initial polypeptide chain from an mRNA template.(B)Providing the metabolic energy (ATP) required for vesicle transport.(C)Modifying, sorting, and packaging proteins for their final destination.(D)Detoxifying harmful substances and synthesizing lipids.

11. A cell is placed in a solution containing a high concentration of a particular solute. The cell begins to actively transport the solute into its cytoplasm, where the concentration of the solute is already higher than in the surrounding solution. Which of the following is the most likely claim about this transport mechanism?

(A)It is a form of passive transport that utilizes a channel protein.(B)It is a form of facilitated diffusion driven by a concentration gradient.(C)It requires the expenditure of metabolic energy by the cell.(D)It involves the formation of a vesicle to engulf the solute.

Questions 12-14 refer to the following diagram of a section of a plasma membrane and the graph of transport rates.

12. Which line in the graph corresponds to the mechanism of transport shown as Transport 2 in the diagram?

(A)Line 1, because the rate is directly proportional to concentration.(B)Line 1, because carrier proteins can transport solutes at an infinite rate.(C)Line 2, because the number of available carrier proteins becomes a limiting factor at high solute concentrations.(D)Line 2, because this type of transport does not depend on the concentration gradient.

13. The plateau observed for Line 2 is most likely due to which of the following?

(A)The depletion of ATP in the cell.(B)The saturation of all available transport proteins.(C)The establishment of equilibrium across the membrane.(D)The reversal of the concentration gradient.

14. The process depicted as Transport 2 is best described as an example of which of the following?

(A)Simple diffusion(B)Active transport(C)Endocytosis(D)Facilitated diffusion

15. Plant cells, fungal cells, and bacterial cells all possess a cell wall. In which of the following environmental conditions is the presence of a cell wall most advantageous?

(A)A hypertonic solution, where the cell tends to lose water.(B)An isotonic solution, where there is no net movement of water.(C)A hypotonic solution, where the cell tends to take up excess water.(D)An environment with a high concentration of nonpolar solutes.

16. A dialysis bag containing a 0.5 M sucrose solution is placed in a beaker containing a 0.2 M sucrose solution. The bag is permeable to water but not to sucrose. The solute potential ($Ψs$) of the 0.2 M solution is -0.49 MPa. What is the initial water potential ($Ψ$) of the solution in the beaker, and which way will net water movement occur? (Assume the pressure potential, $Ψp$, is 0 MPa).

(A)$Ψ = -0.49$ MPa; net water movement will be into the bag.(B)$Ψ = -0.49$ MPa; net water movement will be out of the bag.(C)$Ψ = +0.49$ MPa; net water movement will be into the bag.(D)$Ψ = +0.49$ MPa; net water movement will be out of the bag.

17. A student is asked to create a model of a portion of a plasma membrane that is specialized for active transport. Which of the following components is most important to include in the model to represent this function?

(A)A high density of cholesterol molecules to decrease fluidity.(B)A glycoprotein with a branched carbohydrate chain for cell-cell recognition.(C)A transmembrane protein that can bind to ATP.(D)An aquaporin channel for the rapid transport of water.

18. The endosymbiotic theory proposes that mitochondria and chloroplasts were once free-living prokaryotes. Which of the following pieces of evidence provides the strongest support for this theory?

(A)Both organelles are found within the cytoplasm of eukaryotic cells.(B)Both organelles can be destroyed by lysosomes if they become nonfunctional.(C)Both organelles have double membranes and reproduce by a process similar to binary fission.(D)Both organelles are involved in energy conversion processes for the cell.

19. The sodium-potassium ($Na^+/K^+$) pump is a transmembrane protein that is essential for nerve cell function. It moves three sodium ions out of the cell and two potassium ions into the cell for every molecule of ATP it hydrolyzes. This process is an example of:

(A)Cotransport, where both ions move down their concentration gradient.(B)Active transport, as it moves ions against their electrochemical gradients.(C)Facilitated diffusion, as it uses a protein to assist ion movement.(D)Osmosis, as it affects the water potential across the membrane.

Refer to the figure below.

20. Which of the following best explains the observation in Beaker 3?

(A)The concentration of solutes inside the cell is lower than in the surrounding solution, causing water to exit the cell.(B)The concentration of solutes inside the cell is higher than in the surrounding solution, causing a net influx of water.(C)The cell membrane actively pumped water out of the cell, causing it to shrink.(D)The surrounding solution has an equal solute concentration to the cell, resulting in no net water movement.

Refer to the table below.

21. A researcher is studying the transport of a substance into a cell. The initial rate of transport is measured at various external concentrations of the substance. The experiment is repeated in the presence of a metabolic poison that inhibits ATP synthesis. The results are shown in the table below.

(A)The substance moves into the cell via simple diffusion.(B)The transport of this substance requires metabolic energy.(C)The transport protein for this substance becomes saturated at 20 mM.(D)The metabolic poison enhances the rate of facilitated diffusion.

22. Ribosomes are found in all known forms of life. This universality suggests which of the following?

(A)Ribosomes are the most complex organelle in a cell.(B)All organisms must be able to perform photosynthesis.(C)Ribosomes and protein synthesis evolved early in the history of life.(D)All cells have a nucleus where ribosomes are produced.

23. A cell biologist treats a culture of animal cells with a drug that specifically disrupts the function of the smooth endoplasmic reticulum. Which of the following cellular processes would be most directly affected?

(A)Synthesis of proteins destined for secretion.(B)Production of ATP through cellular respiration.(C)Synthesis of lipids and steroid hormones.(D)Digestion of engulfed bacteria.

24. Paramecium is a single-celled freshwater protist that contains a contractile vacuole, an organelle that actively pumps excess water out of the cell. The presence and activity of this organelle are a direct consequence of the Paramecium living in what type of environment?

(A)A hypertonic environment, causing water to constantly leave the cell.(B)An isotonic environment, where water balance is easily maintained.(C)A hypotonic environment, causing water to constantly enter the cell.(D)An environment with a high salt concentration.

Refer to the figure below.

25. The properties of the molecule shown are essential for the formation of the plasma membrane. Which of the following best describes how these molecules are arranged to form the barrier between the cell's interior and the external environment?

(A)They form a single layer with the hydrophilic heads facing the cytoplasm.(B)They form a bilayer with the hydrophobic tails facing the aqueous interior and exterior.(C)They form a bilayer with the hydrophilic heads facing the aqueous interior and exterior.(D)They are randomly scattered throughout the membrane with no specific orientation.

26. Aquaporins are channel proteins that facilitate the rapid movement of water across cell membranes. Some kidney cells have a high density of aquaporins in their plasma membranes. Which of the following is the most likely consequence of a genetic defect that reduces the number of functional aquaporins in these kidney cells?

(A)The cells would be unable to transport ions like $Na^+$ and $K^+$.(B)The rate of ATP synthesis in the cells would decrease significantly.(C)The cells would be less efficient at reabsorbing water, leading to dehydration.(D)The cells would be unable to synthesize proteins.

27. Lysosomes are membrane-bound organelles that contain hydrolytic enzymes. These enzymes are most active in the acidic environment inside the lysosome. What is the primary function of lysosomes?

(A)Synthesizing proteins for export from the cell.(B)Generating energy in the form of ATP.(C)Breaking down and recycling cellular waste, damaged organelles, and ingested materials.(D)Storing water, nutrients, and waste products in plant cells.

28. A student observes a plant cell under a microscope after it has been placed in a concentrated salt solution. The student sees that the plasma membrane has pulled away from the cell wall. Which of the following is the most valid scientific claim based on this observation?

(A)The salt solution was hypotonic to the cell, causing the cell to swell and push against the cell wall.(B)The cell wall lost its structural integrity due to the high salt concentration.(C)The salt solution was hypertonic to the cell, causing water to leave the cell and the vacuole to shrink.(D)The cell actively transported salt into the cytoplasm, causing the membrane to contract.

Refer to the figure below.

29. The process shown in the diagram results in the establishment of an electrochemical gradient. Which of the following best explains this outcome?

(A)The equal exchange of positive ions results in no net change in charge across the membrane.(B)The net export of one positive charge per cycle makes the inside of the cell more positive than the outside.(C)The net export of one positive charge per cycle contributes to a membrane potential where the inside is negative relative to the outside.(D)The process is electrically neutral but creates a strong concentration gradient for both ions.

30. Which of the following transport mechanisms requires energy to move large, bulk materials out of a cell via the fusion of a vesicle with the plasma membrane?

(A)Phagocytosis(B)Pinocytosis(C)Exocytosis(D)Facilitated Diffusion

31. Eukaryotic cells are compartmentalized, which allows for specialization. Which of the following is an example of how compartmentalization benefits a plant cell?

(A)The central vacuole stores water, maintaining turgor pressure that supports the cell.(B)The cell wall provides a rigid structure that prevents compartmentalization.(C)The cytosol provides a uniform environment for all metabolic reactions to occur simultaneously.(D)Ribosomes are freely distributed, allowing protein synthesis to occur anywhere in the cell.

32. A researcher claims that the cell wall of a bacterium provides a significant permeability barrier in addition to its structural role. Which of the following pieces of evidence would best support this claim?

(A)Bacterial cells have a plasma membrane located inside the cell wall.(B)The cell wall is primarily composed of peptidoglycan, a complex polymer.(C)Certain antibiotics that target cell wall synthesis cause the bacteria to lyse in hypotonic conditions.(D)The outer membrane of gram-negative bacteria contains porins that restrict the entry of large molecules like certain antibiotics.

Refer to the table below.

33. The table below shows the dimensions for four different spherical cells.

(A)Cell 1(B)Cell 2(C)Cell 3(D)Cell 4

B. Short Answer Questions (2 Questions)

Answer all parts of each question. Answers must be in essay form. Outlines or lists alone are not acceptable.

Question 34:

Question 35:

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