AP Biology: Unit 2 Topic Questions Formative Assessment Part 1

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?

B. Fewer lysosomes will be available to break down macromolecules to provide the necessary nutrients for cellular respiration. Answer B Correct. 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.

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. Answer A Correct. 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.

Plant cell walls are composed of cellulose, while fungal cell walls are composed of chitin. A group of scientists hypothesizes that this difference means the cell wall has largely different functions in plant cells and fungal cells. Alternatively, another group of scientists hypothesizes that despite their biochemical differences, plant and fungal cell walls serve similar functions. Which of the following observations would best support the alternative hypothesis described above?

B. In both plant cells and fungal cells, the cell wall surrounds the outside of the cell membrane. Answer B Correct. In both plants and fungi, a major function of the cell wall is to confer structural rigidity to the cell. Thus, in both cell types, the cell wall's location is similar. This is evidence supporting the alternative hypothesis proposed above.

The endosymbiont theory proposes a model for the evolution of mitochondria. According to the model, an ancestral eukaryote engulfed a small, free-living prokaryotic organism. The engulfed prokaryote then formed an endosymbiotic relationship with the eukaryotic host. Which of the following observations best supports the model?

C. Mitochondria and some prokaryotes share similar metabolic reactions that produce ATP. Answer C Correct. The observation that mitochondria and some prokaryotes share similar metabolic reactions that produce ATP supports the model that mitochondria are endosymbionts that originated from a free-living prokaryote.

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?

A. 650 micrometers Answer A Correct. The model predicts that phytoplankton cell size will decrease with increasing distance from the shore, resulting in increased efficiency of nutrient absorption. The correct value was arrived at by subtracting 250 from 900.

Two different models of a living cell are represented in the figure. Of the two cells represented in the figure, which would likely be more efficient at exchanging substances with the surrounding environment?

A. Cell A, because it has a larger surface-area-to-volume ratio. Answer A Correct. Of the two cells represented in the figure, Cell A has a larger surface-area-to-volume ratio of 0.91 compared to a surface-area-to-volume ratio of 0.75 for Cell B. Cell A would likely exchange substances with the surrounding environment at a greater rate.

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?

A. Enzymatic modification of newly synthesized integral membrane proteins Answer A Correct. The Golgi complex is a membrane-bound structure to which some proteins are moved from the rough endoplasmic reticulum, where they are enzymatically modified before being sent to a cellular membrane.

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?

B. The internal pH of the lysosomes will increase, which will prevent the activation of hydrolytic enzymes and interfere with the intracellular digestion of food. Answer B Correct. The lysosomes rely on the ion pumps to maintain an internal acidic pH. A loss of ion pump function will most likely result in an increase in the internal pH of lysosomes from acidic to neutral, which will prevent the activation of hydrolytic enzymes and interfere with the intracellular digestion of food.

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?

B. They have highly folded membranes. Answer B Correct. Compared with a smooth membrane, a highly folded membrane has a greater surface area that increases the rate of material transport across the membrane and provides more support for membrane-associated processes.

Which of the following statements best predicts the effect of increasing the permeability of the mitochondrial membranes to large molecules?

C. ATP production will decrease because of an increase in the occurrence of uncontrolled chemical reactions. Answer C Correct. ATP production will most likely decrease. Increasing the permeability of the mitochondrial membranes to large molecules will likely result in a variety of uncontrolled substrate-enzyme interactions that will disrupt normal mitochondrial function.

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. 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?

C. The Golgi complex Answer C Correct. Membrane proteins and secreted proteins are synthesized by ribosomes bound to the surface of the endoplasmic reticulum. As shown in the figure, a newly synthesized secreted protein is transported by vesicles from the endoplasmic reticulum directly to the Golgi complex.

Researchers claimed that a particular organelle originated from a free-living prokaryotic cell that was engulfed by a larger cell Which of the following provides evidence to best support the researchers' claim?

C. The organelle has a double membrane. Answer C Correct. The organelle's double membrane could have resulted from the process of endocytosis. Based on the claim, the organelle's inner membrane originated from the plasma membrane of the smaller cell and the organelle's outer membrane originated from the plasma membrane of the larger cell.

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?

D. Mitochondria will become less efficient because the surface area of the inner mitochondrial membranes will decrease. Answer D Correct. The change to the inner mitochondrial membrane will result in a decrease in the membrane's surface area, which will reduce the efficiency of mitochondrial function because there will be less surface area for reactions to occur.

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?

D. Rough ER can synthesize and package proteins for export, and smooth ER cannot. Answer D Correct. The ribosomes associated with rough ER synthesize proteins that are then exported from the cell.

Which of the following statements best supports the claim that certain organelles within eukaryotic cells evolved from free-living prokaryotic cells?

D. Some organelles contain their own DNA that is more similar to prokaryotic DNA in structure and function than to the eukaryotic DNA found in the cell's nucleus. Answer D Correct. The mitochondria and chloroplasts contain DNA more similar to prokaryote DNA in structure and function than to eukaryotic DNA. Eukaryotic DNA in the nucleus has additional structural proteins and a more complex process of protein synthesis. The most reasonable explanation involves the incorporation of one free-living prokaryote that eventually integrated with the structures and processes of their eukaryotic hosts.

An aspherical 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?

D. The bacterial cell, because it has the largest surface-to-volume ratio. Answer D Correct. The bacterial cell is more efficient in the exchange of materials with the external environment. While the egg cell is much larger than the bacterial cell, the egg cell has a surface-to-volume ratio that is 33 times smaller than the bacterial cell's surface-to-volume ratio.