Question
In an experiment, researchers provided a radiolabeled amino acid to living plant cells. After one hour, the researchers determined the amount of the radiolabeled amino acid that was in each of several subcellular compartments. The results of the experiment are represented in the table.
Which of the following conclusions about the radiolabeled amino acid is best supported by the results of the experiment?
A. It was mostly incorporated into nucleic acids that store the biological information.
B. It was mostly incorporated into proteins that regulate and manage metabolic reactions.
C. It was mostly incorporated into lipids that help separate cells from their surrounding environment.
D. It was mostly incorporated into carbohydrates that form protective structures outside the cells.
▶️Answer/Explanation
Ans: B
Amino acids are the building block of proteins, and the data indicate that most of the radiolabeled amino acid was in the mitochondria. Therefore, the data best support the conclusion that most of the amino acid molecules were incorporated into proteins that regulate and manage the metabolic reactions that occur in mitochondria.
Question
Researchers conducted an experiment to investigate the effects of a valinomycin treatment on skeletal muscle cells. Valinomycin is a naturally occurring substance that can be used as a drug. The results of the experiment are presented in the table.
Which of the following claims about the effects of the valinomycin treatment is best supported by the data presented in the table?
A. The valinomycin treatment caused an increase in the activity of the rough endoplasmic reticulum.
B. The valinomycin treatment caused an increase in the activity of the Golgi complex.
C. The valinomycin treatment caused a decrease in the activity of the lysosome.
D. The valinomycin treatment caused a decrease in the activity of the mitochondria.
▶️Answer/Explanation
Ans: D
The data indicate that the valinomycin treatment caused a decrease in the relative rate of ATP production, which likely resulted from impaired mitochondrial function.
Question
In an experiment, researchers compared the growth of two different plants, plant X and plant Y. The researchers maintained the plants under nearly identical conditions and observed that plant X grew faster than plant Y. The researchers also observed that the inner mitochondrial membranes of plant X had more folds than did those of plant Y.
Which of the following conclusions about increasing the number of folds in the inner mitochondrial membrane is best supported by the results of the experiment?
A. It increases the efficiency of photosynthesis, which results in faster cell growth.
B. It increases the surface area available for ATP production, which results in faster cell growth.
C. It increases the amount of space available for storing cellular wastes, which results in faster cell growth.
D. It increases the rate of protein transport to the plasma membrane, which results in faster cell growth.
▶️Answer/Explanation
Ans: B
The increased surface area of the folds will contain more ATP synthase, allowing for more efficient use of the chemiosmotic gradient and more efficient production of ATP. The observation that plant X grew faster than plant Y supports this conclusion.
Question
Which of the following claims is scientifically accurate and consistent with an observation that a decrease in lysosome production within a cell leads to a decline in mitochondrial activity?
A. A lack of lysosomes will cause a decrease in the synthesis of enzymes necessary for cellular respiration.
B. Fewer lysosomes will be available to break down macromolecules to provide the necessary nutrients for cellular respiration.
C. Fewer lysosomes will be available to store materials required for the functioning of the mitochondria.
D. Lysosomes will not be available to modify proteins so that they are targeted to the mitochondria.
▶️Answer/Explanation
Ans: B
A function of the lysosomes is the breakdown and recycling of macronutrients, such as carbohydrates. Products of carbohydrate breakdown such as glucose are utilized by the mitochondria in the process of cell respiration.
Question
Muscle cells have high ATP demands. Which of the following is a scientific claim about how the structure of the mitochondria in muscle cells should be different than it is in other cells because of the high energy demands of mitochondria?
A. The inner membrane of the mitochondria in muscle cells should have more folds to increase the surface area, allowing more ATP to be synthesized.
B. The inner membrane of the mitochondria in muscle cells should be more permeable to large enzymes, allowing the same reactions to occur in both compartments of the mitochondria.
C. The outer membrane of the mitochondria in muscle cells should be thicker, allowing more rapid diffusion of molecules into the mitochondria.
D. The outer membrane of the mitochondria of muscle cells should have more folds, increasing the surface area for faster diffusion of molecules from the cytoplasm.
▶️Answer/Explanation
Ans: A
The amount of ATP produced is related to the number of ATP synthase molecules located on the inner mitochondria membrane. Increasing the folds increases the number of ATP generation sites and results in more ATP production.