Biology Chap 3 AP question
Which statement best describes the effect on water transport across the cell membrane if the aquaporin in the figure ceases to function?
Water molecules will still be able to move across the cell membrane but at a slower rate. Explanation : The aquaporin facilitates water passage, but water can still move across the membrane by osmosis.
Figure 1 shows a model of how a channel protein influences the movement of a particle across a cell's plasma membrane.Figure 1. A section of a cell's plasma membrane, showing a channel protein and a concentration gradient across the membrane. An investigator wants to understand whether a newly found membrane protein is involved in the membrane transport of a certain particle. Which investigation will help determine whether the new membrane protein is a channel protein involved in membrane transport?
Add more of the proteins to the plasma membrane and measure the rate of particle movement. Explanation: If the movement of particles is mediated by the channel protein, then an increase in proteins in the cell membrane should influence the rate of particle movement across the membrane.
Figure 1 shows a model of how a channel protein influences the movement of a particle across a cell's plasma membrane. Figure 1. A section of a cell's plasma membrane, showing a channel protein and a concentration gradient across the membrane. An investigator wants to understand whether a newly found membrane protein is involved in the membrane transport of a certain particle. Which investigation will help determine whether the new membrane protein is a channel protein involved in membrane transport?
Add more of the proteins to the plasma membrane and measure the rate of the particle movement. Explanation :If the movement of particles is mediated by the channel protein, then an increase in proteins in the cell membrane should influence the rate of particle movement across the membrane.
Which of the following best describes the numbered areas?
Areas 1 and 3 are polar, since the membrane molecules are aligned with water molecules. Explanation: As indicated in the diagram, the heads of the phospholipids in areas 1 and 3 are adjacent to water molecules, which shows that the phospholipid heads are hydrophilic.
A student formulated a hypothesis that water-soluble pollutants damage living organisms by increasing the permeability of cellular membranes. To test the hypothesis, the student investigated the effect of isopropanol and acetone on beet root cells. The vacuoles of beet root cells contain large amounts of betacyanin, a water-soluble pigment that is released into the extracellular environment as a result of increased membrane permeability. The student prepared identical samples of beetroot tissue and incubated each sample for 15 minutes in the specific solution for that group. At the end of the incubation period, the student measured the absorbance of 460 nm light for each sample. A greater concentration of betacyanin in the solution surrounding the beetroot cells results in a greater absorbance of 460 nm light. The results of the experiment are shown in the table above. The illustration above is a model of a typical beet root cell. Based on the experimental results, which of the following best represents the effect of acetone on the permeability of cellular membranes?
B (the one that starts with Betacyanin Molecule inside the Vacuole and ends with the 3 Betacyanin on each side of the cell wall)
Aquaporins are channel proteins that facilitate the transport of water across the cell membrane. One group of researchers hypothesizes that without functional aquaporins, no water will be able to enter the cell. A different group proposes an alternative hypothesis, stating that even with nonfunctional aquaporins, a small amount of water will still cross the cell membrane. An experiment is set up in which plant cells with mutated (nonfunctional) aquaporins and plant cells with normally functioning aquaporins are both placed in distilled water. Which of the following data would support the alternative hypothesis?
Cells with mutated aquaporins exhibit moderate turgor pressure and are hypertonic. Explanation : Even with mutated aquaporins, a small amount of water is able to enter and leave the cell. Thus, turgor pressure is not lost and the alternative hypothesis is supported.
Plant cell walls are composed of cellulose, while fungal cell walls are composed of chitin. A group of scientists hypothesize that this difference means the cell wall has largely different functions in plant cells and fungal cells. Alternatively, another group of scientists hypothesize 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?
In both plant cells and fungal cells, the cell wall surrounds the outside of the cell membrane. Explanation : 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.
Water is constantly diffusing into the cytosol of freshwater single-celled organisms. In order to maintain the proper solute concentrations in the cytosol, contractile vacuoles pump out the excess water. An experimenter placed single-celled organisms into various saline concentrations and recorded the ATP used by the contractile vacuole. The data are shown in the graph. Of the following, which additional investigation can be used to determine when the cells are in an isotonic solution?
Increasing the salinity of the environment a little at a time until the ATP usage reaches a minimum Explanation : If the environment is isotonic to the cell, the net flow of water due to diffusion is zero, and ATP is not used to pump water out of the cell.
A model of the plasma membrane showing several biological molecules, including a transmembrane protein, is shown in Figure 1. Which statement best explains why correct protein folding is critical in the transmembrane protein shown above?
Interactions of the hydrophobic and hydrophilic amino acids help to anchor the protein in the membrane. Explanation: Tertiary structure of the protein resulting from hydrophobic and hydrophilic interactions plays a key role in how the protein interacts with the hydrophobic tails and hydrophilic head of the membrane phospholipids.
Which of the following statements is true regarding the movement of substances across cell membranes?
Ions are unable to move through the phospholipid bilayer because the nonpolar tail regions of the phospholipids are hydrophobic.
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?
Na+ transport out of the cell requires ATP hydrolysis.
A pathogenic bacterium has been engulfed by a phagocytic cell as part of the nonspecific (innate) immune response. Which of the following illustrations best represents the response?
Option C is correct
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
A student formulated a hypothesis that water-soluble pollutants damage living organisms by increasing the permeability of cellular membranes. To test the hypothesis, the student investigated the effect of isopropanol and acetone on beet root cells. The vacuoles of beet root cells contain large amounts of betacyanin, a water-soluble pigment that is released into the extracellular environment as a result of increased membrane permeability. The student prepared identical samples of beet root tissue and incubated each sample for 15 minutes in the specific solution for that group. At the end of the incubation period, the student measured the absorbance of 460 nm light for each sample. A greater concentration of betacyanin in the solution surrounding the beet root cells results in a greater absorbance of 460 nm light. The results of the experiment are shown in the table above. Which of the following is the dependent variable in the experiment?
The absorbance of 460 nm light by the treatment solutions
A student formulated a hypothesis that water-soluble pollutants damage living organisms by increasing the permeability of cellular membranes. To test the hypothesis, the student investigated the effect of isopropanol and acetone on beet root cells. The vacuoles of beet root cells contain large amounts of betacyanin, a water-soluble pigment that is released into the extracellular environment as a result of increased membrane permeability. The student prepared identical samples of beet root tissue and incubated each sample for 15 minutes in the specific solution for that group. At the end of the incubation period, the student measured the absorbance of 460 nm light for each sample. A greater concentration of betacyanin in the solution surrounding the beet root cells results in a greater absorbance of 460 nm light. The results of the experiment are shown in the table above. Which of the following graphs is the most appropriate representation of the experimental data?
The answer will be graph A, the graph that has separated bars and the weird measuring lines.
A pathogenic bacterium has been engulfed by a phagocytic cell as part of the nonspecific (innate) immune response. Which of the following illustrations best represents the response?
The answer will definitely be C Explanation: It demonstrates an understanding to interpret representations that describe a nonspecific immune response. In phagocytosis, a cell engulfs a bacterium by wrapping pseudopodia around it and packaging it within a membrane-enclosed vacuole. The bacterium is digested after the vacuole fuses with a lysosome containing hydrolytic enzymes. Digested particles can be exported out of the cell by exocytosis.
A team of biologists develop a new drug, and one team member hypothesizes that the drug is incapable of freely passing across the plasma membrane and requires the help of membrane proteins to enter cells. Alternatively, another biologist on the team hypothesizes that the drug can diffuse passively across the plasma membrane like O2 and CO2 can. Which of the following, if true about the drug, best supports the alternative hypothesis that the new drug will exhibit simple diffusion across plasma membranes?
The drug is a small nonpolar molecule. Explanation :Small nonpolar molecules freely pass across the plasma membrane. If the drug is a small nonpolar molecule, this supports the alternative hypothesis.
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?
The hydrophilic phosphate groups of the phospholipid molecules are attracted to the aqueous internal and external environments. Explanation : 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.
The following questions refer to the following diagram. For each phrase or sentence, select the labeled part to which it is most closely related. Each option may be used once, more than once, or not at all for each group. Site of transport of materials into and out of the cell
The plasma membrane which is part D
A student formulated a hypothesis that water-soluble pollutants damage living organisms by increasing the permeability of cellular membranes. To test the hypothesis, the student investigated the effect of isopropanol and acetone on beet root cells. The vacuoles of beet root cells contain large amounts of betacyanin, a water-soluble pigment that is released into the extracellular environment as a result of increased membrane permeability. The student prepared identical samples of beet root tissue and incubated each sample for 15 minutes in the specific solution for that group. At the end of the incubation period, the student measured the absorbance of 460 nm light for each sample. A greater concentration of betacyanin in the solution surrounding the beet root cells results in a greater absorbance of 460 nm light. The results of the experiment are shown in the table above. The student analyzed the data from the investigation and concluded that the estimate of the mean of one treatment group was unreliable. Which of the following identifies the treatment group most likely to have provided an unreliable estimate of the mean, and correctly explains why the estimate appears unreliable?
Treatment group II; it has a lower than expected mean absorbance and the largest standard error of the mean.
A student formulated a hypothesis that water-soluble pollutants damage living organisms by increasing the permeability of cellular membranes. To test the hypothesis, the student investigated the effect of isopropanol and acetone on beet root cells. The vacuoles of beet root cells contain large amounts of betacyanin, a water-soluble pigment that is released into the extracellular environment as a result of increased membrane permeability. The student prepared identical samples of beet root tissue and incubated each sample for 15 minutes in the specific solution for that group. At the end of the incubation period, the student measured the absorbance of 460 nm light for each sample. A greater concentration of betacyanin in the solution surrounding the beet root cells results in a greater absorbance of 460 nm light. The results of the experiment are shown in the table above. Based on the data from the investigation, which of the following is the best scientific question about organisms living in water that is polluted with organic solvents?
Will organisms living in polluted environments exhibit detrimental effects from an increased permeability of their cellular membranes?
Simple diffusion and facilitated diffusion are related in that both :
depend on a concentration gradient
