2.13 MC Answers and Review

⛔STOP!⛔ Before you look at the answers make sure you gave this practice quiz a try so you can assess your understanding of the concepts covered in unit 1. Click here for the practice questions: AP Biology Unit 2 Multiple Choice Questions

Facts about the test: The AP Biology exam has 60 multiple choice questions and you will be given 1 hour 30 minutes to complete the section. That means it should take you around 22 minutes to complete 15 questions.

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1.  Prokaryotic cells and eukaryotic cells have unifying characteristics that provide evidence for a common ancestor. What are three of these?

B. Cell membranes, nucleic acids, mitochondria

C. Cell membranes, DNA, chloroplasts

D. DNA, cell walls, ribosomes

Answer: Prokayra does not have mitochondria or chloroplasts. All living things contain at the very least a cell membrane, ribosomes for protein synthesis, and nucleic acids to carry genetic information.

📄 Study AP Biology, Unit 2.0: Cell Structure and Function

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2.  Single-celled protists with this organelle benefit from the ability to live in a hypotonic environment without bursting from the influx of water.

A. Lysosome

B. Vacuole

D. Secretory Vesicle

Answer: In a hypotonic environment single-celled protists take in water through the process of osmosis. Instead of bursting from the increase of water inside the cell, the contractile vacuole takes in water and expands. The vacuole can then contract and release the water back into the environment.

📄 Study AP Biology, Unit 2.1: Cell Structure: Subcellular Components

3. These membrane-bound organelles display unique folds and curves that help to increase surface area for enhanced efficiency:

A.  rough endoplasmic reticulum, nucleus, lysosome

B. vacuole, vesicles, nucleus

C. Golgi complex, rough endoplasmic reticulum, ribosomes

Answer: The Golgi complex, mitochondria, chloroplast, endoplasmic reticulum display folded structures which allows them to function more efficiently. Golgi can process and package more proteins, mitochondria generate more ATP, chloroplast harness for energy from the sun

📄 Study AP Biology, Unit 2.1: Cell Structure: Subcellular Components

4. The inside channel of a transport protein is likely to be:

A. acidic

B. basic

D. hydrophobic

Answer: Protein channels allow small, charged molecules or polar molecules to cross the plasma membrane. Hydrophilic amino acids will line the inner portion of the channel to allow this movement.

📄 Study AP Biology, Unit 2.4: Plasma Membranes

5. Which substance would most easily pass through a semi-permeable cell membrane?

A.  magnesium ions

C. glucose

D. proteins

Answer: Carbon dioxide is small, uncharged, and nonpolar. Charged molecules like magnesium cannot pass through. Glucose is a larger molecule requiring GLUT transporters.

📄 Study AP Biology, Unit 2.5: Membrane Permeability

6. A small amount of water ______ pass through the plasma membrane without assistance

A.  CAN

B. Needs receptor proteins to

C. Needs ATP to

D. CANNOT

Answer: Individual water molecules are small enough to pass through the cell membrane unassisted. Although water is polar, it is small to pass through. During osmosis when there is a net flow of water moving in bulk, aquaporins are required.

📄 Study AP Biology, Unit 2.5: Membrane Permeability

7.  Aquaporins allow water to move through plasma membranes regardless of water's polarity. Water moving through aquaporins is an example of this:

A.  Protein pump

B. Receptor-mediated transport

D. Active transport

Answer: Facilitated diffusion is an example of passive transport. The movement of water across a cell membrane does not require energy but it is facilitated or helped through aquaporin membrane proteins.

📄 Study AP Biology, Unit 2.7: Facilitated Diffusion

8.  Choose the correct pairing:

A.  Pinocytosis: cellular eating

B. Phagocytosis: cellular drinking

C. Pinocytosis: macrophage engulfing

D.Phagocytosis: cellular eating

Answer: In Latin, phago- means to eat or ingest. Phagocytosis is the process of a cell eating or engulfing a large particle.

📄 Study AP Biology, Unit 2.6: Membrane Transport

9. A mutation causes the membrane of a lysosome to become leaky. Describe a result of this:

A.  Water will rush into the lysosome causing it to burst.

C. The pH of the cell will denature the hydrolytic enzymes.

D. The lysosome will repair the membrane and not die.

Answer: The lysosomal membrane separates hydrolytic enzymes from the cytosol. Without this membrane, hydrolytic enzymes are capable of destroying essential components in the cytosol.

📄 Study AP Biology, Unit 2.2: Cell Structure and Function

10. This organelle contains a double membrane which provides compartmentalization to separate different metabolic reactions

B. endoplasmic reticulum

C. gogli complex

D. vacuole

Answer: The key word here: metabolic reactions. During aerobic cellular respiration, the Kreb's cycle occurs in the mitochondrial matrix, and the inner mitochondrial membrane hosts the electron transport chain.

📄 Study AP Biology, Unit 2.2: Cell Structure and Function

11. Students place an animal cell in a hypertonic environment. What happens?

A.  water enters the cell causing it to sink

B. Water enters the cell causing it to swell

C. Water leaves the cell causing the solution to become more hypertonic

Answer: In a hypertonic environment, the concentration of solutes is higher outside of the cell. To reach equilibrium, a net flow of water will exit the cell, causing the cell to lose water and become smaller in volume.

12. A plant cell and animal cell enter a hypotonic environment. Which cell type prefers this environment?

A.  Plant cell because it will become flaccid

C. Animal cell because it will become turgid

D. Animal cell because it will swell

Answer: In a hypotonic environment the concentration of solutes outside of the cell is less than inside of the cell. The concentration of solutes inside of the cell is higher, so water will move into the cell, causing cell volume to increase. In a plant cell the pressure inside the cell increases causing the cell to become turgid (swollen). Plants like this!

13. The water potential of pure water is:

A.  10

B. -1

C. 1

Answer: Pure water does not contain any solutes. As solutes are added to a solution, water potential becomes more negative.

 14. What would cause the leaves of a plant to wilt?

A.  If the pressure potential of the leaves increased to 1 Mpa

B. If water potential outside of the plant cell is higher than the water potential of the plant cells

D. If the pressure potential

Answer: Water moves from high to low potential. If the water potential outside of the cell is lower, water will exit the plant cells, causing wilt.

15. Osmoregulation in plants occurs by

A.  changing the permeability of the cell membrane

B. the opening and closing of the chloroplast

C. changing the permeability of the cell wall

Answer: A pair of guard cells surround each stoma-the pore-like opening where gas exchange occurs. Guard cells experience movement of ions to alter water potential and experience a net flow of water (either in or out depending on whether or not ions enter or exit respectively)

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