Misc. Flashcards
Vertebrate immune responses involve communication over short and long distances. Which of the following statements best helps explain how cell surface proteins, such as MHC proteins and T cell receptors, mediate cell communication over short distances?
The proteins interact directly with proteins on the surfaces of other cells.
Notch is a receptor protein displayed on the surface of certain cells in developing fruit fly embryos. Notch’s ligand is a membrane-bound protein called Delta that is displayed on the surface of adjacent cells. When Notch is activated by its ligand, the intracellular tail of the Notch protein becomes separated from the rest of the protein. This allows the intracellular tail to move to the cell’s nucleus and alter the expression of specific genes.
Which of the following statements best explains Delta’s role in regulating cell communication through the Notch signaling pathway?
Delta restricts cell communication to short distances within a developing embryo.
In flowering plants, plasmodesmata are narrow channels through cell walls that connect the cytoplasms of adjacent cells. An explanation of how plant cells communicate across cell walls will most likely refer to the diffusion through plasmodesmata of which of the following?
Small, water-soluble molecules
Changing the shape or morphology of the mitochondrial inner membrane can change the efficiency of mitochondrial function.
Which of the following outcomes will most likely result from a change in the shape of the mitochondrial inner membrane from a highly folded surface to a smooth, flat surface?
Mitochondria will become less efficient because the surface area of the inner mitochondrial membranes will decrease.
The figure shows a process by which a cell might absorb food from its surrounding environment and break it down for use as a source of energy and matter. The process involves lysosomes, which are membrane-bound organelles that contain hydrolytic enzymes. Activation of the hydrolytic enzymes requires an acidic pH, and lysosomes maintain an internal acidic pH by using ion pumps.
Which of the following outcomes will most likely result from a loss of ion pump function in the cell’s lysosomes?
The internal pH of the lysosomes will increase, which will prevent the activation of hydrolytic enzymes and interfere with the intracellular digestion of food.
Which of the following statements best predicts the effect of increasing the permeability of the mitochondrial membranes to large molecules?
ATP production will decrease because of an increase in the occurrence of uncontrolled chemical reactions.
Researchers propose a model to explain variation in phytoplankton cell sizes in a marine environment. They base their model on the idea that smaller cells absorb nutrients more efficiently. The researchers predict that the mean diameter of phytoplankton cells will change by 50 micrometers for every 5-kilometer increase in distance from the shore because of a gradual decrease in nutrient availability. To test their model, the researchers determine that the phytoplankton cells found closest to shore have a mean diameter of 900 micrometers.
Based on the model, what will be the mean diameter of the phytoplankton cells that are found 25 kilometers from shore?
650 micrometers
A spherical bacterial cell has a radius of 3μm. The human egg cell has a radius of 100μm.
Which statement correctly indicates the cell that is able to more efficiently exchange materials with the external environment and provides a correct explanation?
The bacterial cell, because it has the largest surface-to-volume ratio.
Of the two cells represented in the figure, which would likely be more efficient at exchanging substances with the surrounding environment?
Cell A, because it has the larger surface-area-to-volume ratio.
Organelles such as mitochondria and the endoplasmic reticulum have membranes that compartmentalize reactions and other metabolic processes. To function properly, the organelles must move substances across their membranes.
Which of the following statements describes a feature shared by mitochondria and the endoplasmic reticulum that increases the efficiency of their basic functions?
They have highly folded membranes.
All eukaryotic cells contain at least one Golgi complex, typically located in the cytoplasm and near the endoplasmic reticulum.
Which of the following best describes a process that occurs within the Golgi complex?
Enzymatic modification of newly synthesized integral membrane proteins
Cells contain smaller components called organelles that are necessary for a cell’s survival. Organelle functions have often been compared to components of larger systems.
Which of the following functional differences between the rough and smooth endoplasmic reticulum (ER) is explained by the structural differences between them?
Rough ER can synthesize and package proteins for export, and smooth ER cannot.
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?
Fewer lysosomes will be available to break down macromolecules to provide the necessary nutrients for cellular respiration.
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?
The inner membrane of the mitochondria in muscle cells should have more folds to increase the surface area, allowing more ATP to be synthesized.
Researchers have proposed a model of the process by which a newly synthesized protein is transported to the plasma membrane and secreted into the extracellular space. The model is represented in Figure 1.Figure 1. A model of the intracellular transport of a newly synthesized secreted protein
Based on the model, the newly synthesized protein is transported directly from the endoplasmic reticulum to which of the following?
The Golgi complex
