Bio Unit 2

Which of the following diagrams best represents hormone-activated gene expression.

Look for the diagram with a receptor molecule.

A student peeled the skins from grapes, exposing cells with membranes that are only permeable to water and small diffusible solutes. The student measured the mass of the peeled grapes. The students then placed each peeled grape into one of five solutions. After 24 hours, the students removed the grapes from the solutions, measured their final mass, and calculated the percent change in mass . Based on table 1, which of the folowing percentages is closest to the solute concentration of the grape?

1.3%

Dialysis tubing is permeable to water molecules but not to sucrose. Four dialysis tubes are half filled with 5 percent, 10 percent, 20 percent, and 40 percent sucrose solutions, respectively, and two dialysis tubes are half filled with distilled water. The dialysis tubes are all sealed at both ends, and the initial masses are determined. Five dialysis tubes are placed into beakers containing distilled water, and the sixth dialysis tube, containing distilled water, is placed into a 40 percent sucrose solution. The masses of the dialysis tubes are recorded at 30-minute intervals for 90 minutes, as shown in the table below. To model a plant cell, a permeable nonflexible case is placed around each piece of dialysis tubing. The greatest pressure potential will develop within number ____

4

Dialysis tubing is permeable to water molecules but not to sucrose. Four dialysis tubes are half filled with 5 percent, 10 percent, 20 percent, and 40 percent sucrose solutions, respectively, and two dialysis tubes are half filled with distilled water. The dialysis tubes are all sealed at both ends, and the initial masses are determined. Five dialysis tubes are placed into beakers containing distilled water, and the sixth dialysis tube, containing distilled water, is placed into a 40 percent sucrose solution. The masses of the dialysis tubes are recorded at 30-minute intervals for 90 minutes, as shown in the table below. The contents of which dialysis tube are initially isotonic to be distilled water in the beaker?

5

Dialysis tubing is permeable to water molecules but not to sucrose. Four dialysis tubes are half filled with 5 percent, 10 percent, 20 percent, and 40 percent sucrose solutions, respectively, and two dialysis tubes are half filled with distilled water. The dialysis tubes are all sealed at both ends, and the initial masses are determined. Five dialysis tubes are placed into beakers containing distilled water, and the sixth dialysis tube, containing distilled water, is placed into a 40 percent sucrose solution. The masses of the dialysis tubes are recorded at 30-minute intervals for 90 minutes, as shown in the table below. A net movement of water into the beaker occurs in which of the following dialysis tubes?

6 (maybe)

The figure above shows a model of a ligand precursor being cleaved to produce an active ligand that binds to a specific receptor. Which of the following is most likely to reduce the binding of the active ligand to its receptor?

A mutation in the receptor gene that causes a substitution of a charged amino acid for a nonpolar amino acid in the ligand binding site of the receptor.

Intact cells of two unknown cell types were placed into solutions with different concentrations of NaCl. Type I cells swelled and burst in the solution with the lowest concentration of NaCl. Type II cells swelled but did not burst in the solution with the lowest concentration of NaCl. Which of the following descriptions of cell type I and II are most consistent with the data?

Cell I: Animal cell surrounded by a plasma membrane only. Cell II: Plant cell surrounded by a plasma membrane and a cell wall.

Which of the following describes the most likely location of cholesterol in an animal cell.

Embedded in the plasma membrane

All eukaryotic cells contain at least on Golgi complex, typically located in the cytoplasm and near the endoplasmic reticulum. Which of the following best describes a process that occurs withing the Golgi complex?

Enzymatic modification of newly synthesized integral membrane proteins.

A model of epinephrine signalling. Two types of cells, alpha and beta cells, produce signaling molecules that affect blood sugar levels in opposite ways. Epinephrine is a chemical, often released during periods of exercise, that ultimately causes an increase in blood sugar levels in the body. Based on figure 1, which of the following best explains how exercise causes blood glucose levels to rise?

Epinephrine activates alpha cells, causing the release of glucagon, and inhibits beta cells, blocking the release of insulin.

Epinephrine is a protein hormone found in many animals. Epinephrine stimulates a signaling pathway that results in the breakdown of glycogen to glucose in the liver cells. Which of the following describes the initial steps in the process whereby epinephrine stimulates glycogen breakdown?

Epinephrine binds to a cell-surface receptor; the activated receptor stimulates production of the second messenger, cAMP.

Liver cells manufacture glycoproteins, while adipose cells store fat. Which of the following subcellular structures is likely to be more prominent in liver cells than in the adipose cells?

Golgi apparatus

A cell is treated with a drug that prevents the formation of new lysosomes. The cell continues to transcribe genes that code for hydrolytic enzymes that are normally found in the lysosomes and continues to translate mRNA for those proteins on membrane-bound ribosomes. The hydrolytic enzymes are most likely to accumulate in which of the following cellular structures.

Golgi complex

A student peeled the skins from grapes, exposing cells with membranes that are only permeable to water and small diffusible solutes. The student measured the mass of the peeled grapes. The students then placed each peeled grape into one of five solutions. After 24 hours, the students removed the grapes from the solutions, measured their final mass, and calculated the percent change in mass . Based on table 1 below, which of the following best explains the difference between certain solutions and the grapes?

Grape soda and NaCl have a lower water potential because these two solutions caused grape to lose water.

Which of the following best predicts the effect of not having ATP available to supply energy to this process.

H+ ions will move in the other direction through the protein.

A pathogenic bacterium had been engulfed by a phagocytic cell as part of the nonspecific (innate) immune response. Which of the following illustrations best represents the response?

Illustration with ribosomes. (Maybe)

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 min. (Maybe)

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 following questions refer to an experiment in which a dialysis-tubing bag is filled with a mixture of 3% starch and 3% glucose and placed in a beaker of distilled water, as shown below. After 3 hours, glucose can be detected in the water outside the dialysis-tubing bag, but starch cannot. If instead of the bag, a potato slice were placed in the beaker of distilled water, which of the following would be true of the potato slice?

It would gain mass

Which contains hydrolytic enzymes associated with the intracellular digestion of macromolecules.

Lysosome

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

Which of the following best describes the process of passive and active transport?

Passive transport is the net movement of substances down a concentration gradient that does not require metabolic energy. Active transport is the movement of substances up a concentration gradient that requires energy.

Which of the following components of the cell membrane is responsible for active transport.

Protein

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

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.

Cholesterol is an important component of animal cell membranes. Cholesterol molecules are often delivered to body cells by the blood, which transports the molecules in the form of cholesterol-protein complexes. The complexes must be moved into the body cells before the cholesterol molecules can be incorporated into the phospholipid bilayers of cell membranes. Based on the information presented, which of the following is the most likely explanation for a buildup of cholesterol molecules in the blood of an animal.

The animal's body cells are defective in endocytosis.

Intravenous (IV) solutions administered to patients are normally isotonic. Which of the following is most likely if an IV of distilled water is administered to a patient.

The cells that are exposed to hyptonic solutions will expand as water moves osmotically into cells from the blood.

Paramecia are unicellular protists that have contractile vacuoles to remove excess intracellular water. In an experimental investigation, paramecia were placed in salt solutions of increasing osmolarity. The rate at which the contractile vacuole contracted to pump out excess water was determined and plotted against osmolarity of the solution, as shown in the graph. Which of the following is the correct explanation for the data?

The contraction rate increases as the osmolarity decreases because the amount of water entering the paramecia by osmosis increases.

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

The cuboidal cell

A team of biologists devekio a new drug, and one team member hypothesizes that the drug is incapable of freely passing across the plasma membrane and requires the heko 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 the plasma membrane?

The drug is a SMALL NONPOLAR molecule.

Which of the following organelles modifies and packages for secretion the materials produced by the ribosomes?

The golgi apparatus

A student peeled the skins from grapes, exposing cells with membranes that are only permeable to water and small diffusible solutes. The student measured the mass of the peeled grapes. The students then placed each peeled grape into one of five solutions. After 24 hours, the students removed the grapes from the solutions, measured their final mass, and calculated the percent change in mass . Mercurial sulfhydryl is an inhibitor of aquaporins. Which of the following is the most likely effect of adding mercurial sulfhydryl to the distilled water solutions?

The grape cells will gain water more slowly because of a lack of facilitated diffusion.

A student peeled the skins from grapes, exposing cells with membranes that are only permeable to water and small diffusible solutes. The student measured the mass of the peeled grapes. The students then placed each peeled grape into one of five solutions. After 24 hours, the students removed the grapes from the solutions, measured their final mass, and calculated the percent change in mass . A student hypothsizes that the solute concentration of grape juice is higher than the solute concentration of the actual grape because the grape juice has added sugar. Based on the data in table 1 below, which of the following best evaluates the students hypothesis?

The hypothesis is not supported because the mass of the grape increased in the grape juice.

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 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.

Figure 1 shows a model of a signal transduction cascade, initiated by the binding of a ligand to the transmembrane receptor protein A. A DNA mutation changes the shape of the extracellular domain of transmembrane receptor protein A produced by the cell. Which of the following predictions is the most likely consequence of the mutation?

The molecule that normally binds to protein A will no longer attach, deactivating the cellular response.

Researchers claimed that a particular organelle originated from a free-living prokaryotic cell that was engulfed by a larger cell, as shown in figure 1. Which of the following provides evidence to best support the researchers' claim.

The organelle has a double membrane.

The following questions refer to an experiment in which a dialysis-tubing bag is filled with a mixture of 3% starch and 3% glucose and placed in a beaker of distilled water, as shown below. After 3 hours, glucose can be detected in the water outside the dialysis-tubing bag, but starch cannot. From the initial conditions and results described which of the following is a logical conclusion?

The pores of the bag are larger than the glucose molecules but smaller than the starch molecules.

In an experiment, cells were isolated from an aquatic plant and suspended in pond water, a sucrose sugar solution, or distilled water. All of the cells were then viewed under a microscope. Compared with the cell in the pond water, the cell in the sugar solution appeared shriveled, the cell in the distilled water appeared inflated. The results of the experiment are represented in figure 1. Which of the following statements best explains the observations represented in Figure 1?

There was a net movement of water out of the cell suspended in the sugar solution and a net movement of water into the cell suspended in the distilled water.

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 increase the efficiency of their basic function?

They have highly folded membranes.

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.

When a substance moves across the plasma membrane along a concentration gradient at a rate faster than would be expected by simple diffusion alone but without the expenditure of metabolic energy, the process is best described as...

facilitated diffusion

All of the following components are found in prokaryotic cells EXCEPT.

nuclear envelope