CH. 6-7 TEST

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 the distilled water in the beaker?

5

A net movement of water into the beaker occurs in which of the following dialysis tubes?

6

Site of conversion of chemical energy of glucose to ATP

A

Which of the following best describes the numbered areas?

Areas 1 and 3 are polar, since the membrane molecules are aligned with water molecules. 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.

Evolved from a photoautotrophic prokaryote

B

Site of glucose synthesis

B

Site of modification and packaging of proteins and lipids prior to export from the cell

C

Site of transport of materials into and out of the cell

D

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 adipose cells?

Golgi apparatus

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

Golgi complex

The illustration shows the active transport of hydrogen ions through a membrane protein. Which of the following best predicts the effect of not having ATP available to supply energy to this process?

H+ ions will stop moving through the protein. Metabolic energy such as ATP is required for active transport of ions against a concentration gradient.

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. 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. The figure shows a diagram of a phospholipid bilayer with an embedded transmembrane protein. The protein is coiled into a helical shape where it is buried between the membrane lipids. Polar areas of the protein are labeled on the portions of the protein that stick out from the two membrane surfaces. Nonpolar areas of the protein are labeled on the coiled portion that is buried between the membrane lipids. *Figure 1. Phospholipid bilayer with transmembrane protein* 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. 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.

The active transport pump used to move sodium ions across the membranes of gill cells in a freshwater fish has each of the following characteristics EXCEPT:

It uses osmosis to carry sodium ions into the cells.

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 statements best explains the processes 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. Passive transport is the net movement of substances down (with) a concentration gradient that does not require metabolic energy and active transport is the movement of substances up (against) a concentration gradient that requires energy.

A prokaryotic cell has which of the following?

Plasma membrane

This group of questions refers to the following groups of biological compounds. (A) Proteins (B) Carbohydrates (C) Nucleic acids (D) Lipids (E) Steroids Synthesized at the ribosome

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. The ribosomes associated with rough ER synthesize proteins that are then exported from the cell.

The salinity of a small inland lake has recently started to increase. Researchers are planning to study the lake over several decades to investigate how freshwater organisms survive significant changes in their natural habitat. Which of the following physiological mechanisms will the researchers most likely observe among the surviving organisms in the lake?

Single-celled organisms will use various mechanisms to counteract the increased flow of water from cells to the environment.

The figure above represents a rough endoplasmic reticulum. Which of the following best describes the role of the structure labeled Y?

Structure Y is the location where proteins are synthesized.

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

The Golgi apparatus

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 presents a diagram of a cell. The following parts are labeled: nucleus, endoplasmic reticulum, ribosomes, cytosol, and new protein in transport vesicle. The transport vesicle containing a new protein is shown in two positions: a start point and an end point. It starts out adjacent to the endoplasmic reticulum, and an arrow is drawn upward from the transport vesicle toward an unlabeled component. The unlabeled component appears to be a series of stacked flat sacs. A second arrow is drawn upward from this unlabeled component toward the plasma membrane, where the transport vesicle with new protein is shown at its end point just inside the plasma membrane. *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. 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.

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 solutions, 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.

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. *Figure 1. A model showing a cell engulfing a smaller cell* Which of the following provides evidence to best support the researchers' claim?

The organelle has a double membrane. 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.

The diagram above represents a typical rod-shaped bacterium. Which of the following best describes a feature shown in the diagram that is unique to archaea and bacteria?

The organism does not have a nuclear membrane surrounding its genetic material.

The figure below illustrates a eukaryotic cell. Which of the following best describes how the three structures indicated by the arrows work together?

To synthesize and isolate proteins for secretion or for use in the cell

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. The aquaporin facilitates water passage, but water can still move across the membrane by osmosis.

The figure above shows a series of microscope images taken over time of ovalbumin production in chick oviduct cells in response to stimulation with estrogen. The ovalbumin protein was detected using a fluorescent dye as shown by the white areas in the time-lapse sequence. The microscope images indicate that ovalbumin

crosses the endoplasmic reticulum membrane as it is translated, then moves to the Golgi apparatus, then to vesicles from which it is secreted