2021 MCQ Practice Exam - AP Biology Well solved

The CFTR protein is made up of 1,480 amino acids linked together in a chain. Some humans produce a version of the CFTRprotein in which phenylalanine (an amino acid) has been deleted from position 508 of the amino acid chain. Which of the following best predicts how the amino acid deletion will affect the structure of the CFTR protein? D. It will affect the primary, secondary, and tertiary structures of the CFTR protein. Correct. A change in the primary structure of the CFTR protein will lead to changes in the secondary and tertiary structures. As a result, the protein will not fold properly and will not function normally. Bacteriophages are viruses that infect bacteria. In an experiment, bacteriophages were labeled with either radioactive phosphorus or radioactive sulfur. The labeled bacteriophages were incubated with bacteria for a brief amount of time and then removed. The infected bacteria cells were found to contain significant amounts of radioactive phosphorus but not radioactive sulfur. Based on the results of the experiment, which of the following types of molecules did the bacteriophages most likely inject into the bacteria cells? C. DNA Which of the following is responsible for the cohesive property of water? C. Hydrogen bonds between the oxygen atom of one water molecule and a hydrogen atom of another water molecule Which of the following best describes how amino acids affect the tertiary structure of a protein? B. The interactions of the different R-groups with other R-groups and with their environment determine the tertiary structure of the protein Correct. The tertiary structure is determined by the attractions, repulsions, and bonding between different amino acids. Changing the sequence of even two amino acids may affect the tertiary shape of the protein. Which of the following is most directly responsible for water's unique properties? D. It forms hydrogen bonds. The manner in which several different ions and molecules move through a cell membrane is shown in the diagram above. For each ion or molecule, the relative concentration on each side of the membrane is indicated. Which of the following accurately describes one of the movements taking place? D. Na+ transport out of the cell requires ATP hydrolysis. The rate of transpiration, the flow of water through the stem, and leaf water potential are measured in a tree during a 24-hour period under normal environmental conditions. The results from these measurements are shown in the graphs below. All of the following changes would be likely to decrease the rate of transpiration at 8 A.M. EXCEPT D. increasing the water potential of the soil If ATP breakdown (hydrolysis) is inhibited, which of the following types of movement across cell membranes is also inhibited? C. Passage of a solute against its concentration gradient The diagram above represents a typical rod-shaped bacterium. Which of the following best describes a feature shown in the diagram that is unique to archaea and bacteria? C. The organism does not have a nuclear membrane surrounding its genetic material. In an experiment, the efficiency of oxygen exchange across the plasma membrane is being assessed in four artificial red blood cells. The table above lists some properties of those artificial cells. Other conditions being equal, which artificial cell is predicted to be the most efficient in exchanging oxygen with the environment by diffusion? A. The cuboidal cell Which of the following scientific questions is most relevant to the model represented in the figure above? C. Which molecular substance is actively transported across the plasma membrane? The model below shows the structure of a portion of a plasma membrane in an animal cell. Which statement best explains the orientation of the phospholipid molecules in this model? B. The hydrophilic phosphate groups of the phospholipid molecules are attracted to the aqueous internal and external environments. Correct. The hydrophilic polar phosphate groups of the phospholipid molecules orient toward the polar internal and external aqueous environments, forming a bilayer that keeps the hydrophobic portions of the phospholipids away from the polar molecules.