USA Test Prep Cell Transfusion

The sodium-potassium pump is an example of

Active transport

In nerve cells the sodium-potassium pump is used to generate gradients of both sodium and potassium ions to propagate electrical signals that travel along nerves. This is a(n)

Active transport mechanism

Which of the letters above best models a molecule of water moving into the membrane via an aquaporin?

B

No matter what the cell type, prokaryotic or eukaryotic, plant or animal, the ____________ forms a protective barrier between the exterior environment and the interior of the cell.

Cell membrane

Which cellular organelle/part is present in all cells and helps to maintain homeostasis?

Cell membrane

Which type of membrane protein is correctly paired with its function?

Channel proteins; allows a specific molecule to pass

If the molecules are not in water, the randomly moving process shown in this diagram is known as

Diffusion

The movement of carbon dioxide out of cells and oxygen into cells can best be explained by which process?

Diffusion

The picture shows the active transport of ions by the sodium-potassium pump.How is diffusion different from this process?

Diffusion transfers particles from an area of high concentration to low concentration

Cell drinking; cell eating. Both are modeled here and are examples of

Endocytosis

Cells are able to remove large amounts of material using

Exocytosis

The cell is taking in substances through membrane proteins, without any energy expenditure of its own. The substances naturally follow their concentration gradient. However, they must go through the protein channels, because they are too large to squeeze through the cell membrane. This process is called

Facilitated Diffusion

This section of the cell membrane illustrates one method of cellular transport. Consider steps A, B, and C. What transport mechanism is represented by the model?

Facilitated Diffusion

When blood sugar (glucose) levels are elevated, insulin is released to trigger cells to take in glucose. Although insulin never enters the cell, it creates a signaling cascade that mobilizes Glut-4 transporters to the surface of the cell. What describes the movement of glucose into the cell using Glut-4 transporters?

Facilitated diffusion

Glucose is an important biomolecule. Which of these statements is true regarding the movement of glucose into and out of cells?

Glucose is an important biomolecule. Which of these statements is true regarding the movement of glucose into and out of cells?

Which one of these scenarios most likely uses facilitated transport to move molecules across the cell membrane?

Glucose moves with the concentration gradient from high to low concentration using a membrane protein.

The proteins in the cell membrane allow substances to come or go, based on their concentrations. This is an important part of _________________, which maintains the immediate conditions necessary for life.

Homeostasis

What term best describes region "b" of the phospholipid model above?

Hydrophobic

Which molecule would REQUIRE a channel or transport protein to cross the cell membrane

K+

It helps maintain homeostasis and is a boundary between the inside of the cell and the outside environment. It is the

Membrane

Substances that enter the cell without the expense of cellular ATP, but are too large to directly pass through the membrane, use ________________________ in order to gain access to the inside of the cell.

Membrane proteins

Which one of these molecules is LEAST likely to be represented by the yellow dots in the diagram?

O2

Which is NOT true regarding transport of molecules?

Osmosis is an active transport process that moves water against the concentration gradient

The model above shows the processes of phagocytosis, pinocytosis, and receptor-mediated endocytosis. What common feature is involved in each of these processes?

Particles moving into the cell involve enclosure in a membrane bound vesicle

Gases such as oxygen and carbon dioxide cross the plasma membrane by

Passive diffusion through the lipid bilayer

Substances like oxygen pass through the cell without the use of energy and move from an area of high concentration to an area of low concentration. This process is called

Passive transport

A labeled model of an amoeba is shown above. These are heterotrophic, single celled protists. They have unique cellular structures called pseudopodia that facilitate movement and food acquisition. What type of cell transport likely accounts for the formation of the food vacuole within the amoeba?

Phagocytosis

One way of balancing the concentration of ions and molecules within a cell is to use all but ______________ . ATP transfers one of its phosphate groups (becoming ADP) to a transfer protein. This protein changes its conformation so it can bring needed ions into the cell and get rid of unnecessary ions.

Phospholipid channels

A student notices that animal cells behave differently when exposed to solutions that are hypotonic compared to certain fungi, plant, and bacterial cell. The animal cell lyses while the other three do not. What structural difference accounts for the unique way animal cells react when exposed to water.

Rigid cell walls that prevent the expansion of the cells

Dialysis tubing is used as a model cell membrane, because is it semi-permeable, allowing small molecules to cross the membrane, but NOT larger molecules, like starch. A starch solution is placed in the dialysis tubing and then the dialysis tubing is placed in an iodine and water solution. Iodine is used as an indicator for the presence of starch. Normally, iodine is a yellow-brown color, but in the presence of starch, it turns a deep purple. After observing the experimental setup for 20 minutes, the iodine solution remains brown, but the starch solution inside the dialysis tubing is purple and swollen. Based on what you learned from the lab, starch is MOST likely to cross the cell membrane at which of the points indicated on the diagram?

Starch crosses the cell membrane at E

Your lab group is experimenting with the diffusion of molecules across a membrane. Dialysis tubing is used as a model cell membrane because is it semi-permeable, allowing small molecules to cross the membrane, but NOT larger molecules, like starch. A starch solution is placed in the dialysis tubing and then the dialysis tubing is placed in an iodine and water solution. Iodine is used as an indicator for the presence of starch. Normally, iodine is a yellow-brown color (on the left), but in the presence of starch, it turns a deep purple (right). After observing the experimental setup for 20 minutes, the iodine solution remains brown, but the starch solution inside the dialysis tubing is purple and swollen. What CANNOT be concluded from the results?

Starch requires ATP energy fro transport and therefore cannot cross the dialysis tubing into the iodine solution

Living organisms use osmoregulation to balance solute and water concentrations in their cells, tissues and organs. Many marine organisms have internal solute concentrations that are similar to their environment. However, this is not typically true of freshwater and terrestrial organisms. Select what is likely to happen to the cells of a marine plant if placed in a freshwater environment?

The cells will swell and become turgid

The phospholipids of plasma membranes are amphipathic: they have both hydrophilic and hydrophobic regions. The hydrophobic core of the plasma membrane helps some materials move through the membrane, while it blocks the movement of others. How does the structure of the cell membrane help to enable its function?

The double layer of phospholipids positions the hydrophilic phosphate heads on the outer edge towards the external environment and on the inner side towards the watery cytoplasm.

The picture shows an Na+/K+ ATPase pump. What is a CORRECT interpretation of the picture?

The energy for the action of the pump is released by the utilization of ATP

The cell membrane is selectively permeable. O2 diffuses across the phospholipid bilayer. K+ must cross the cell membrane using a membrane protein. Which property of the cell membrane prevents the diffusion of K+?

The lipid tails are hydrophobic, repelling charged ions such as K+

Students performed a laboratory experiment to determine the molar concentration of red potatoes. They cut cubes from a whole red potato and massed them. They placed the cubes into various sucrose solutions, whose molar concentrations are shown above. The students then removed the potato cubes from the solutions twenty-four hours later and massed them again. They calculated the percent change for the potatoes in the various solutions. All of the data is displayed above. What is the approximate molar concentration of the red potatoes used in this experiment?

The red potatoes have approximately a 0.37 M solute concentration because this is where the potatoes would neither gain nor lose mass.

A student added a solution to the plant cell shown in image 1 which resulted in the plant cell undergoing changes, as shown in image 2. What best directly explains the observed changes?

The solution was hypertonic to the cell and caused water to leave the plant cells central vacuole and cytoplasm

Based on the requirements for channel and carrier proteins to move the molecules (shown in green) across the membrane, what can be concluded about the molecules?

They are too charged for polar to move through the phosholipids directly

Which statement explains the passage of a serine, an amino acid through the selectively permeable plasma membrane?

This molecule must utilize a transport protein to cross the cell membrane due to its large size and polar side chains

Which one of these is NOT an example using facilitated diffusion? A. Aquaporins facilitate the diffusion of water in the kidney tubules of many mammals. B. A carrier protein moves sucrose across the membrane with the concentration gradient. C. Using the sodium-potassium pump involves the hydrolysis of ATP and the release of Na+ to the outside of the cell D. Ca+2 moves from high cytoplasmic concentration to low concentration inside the cell using a membrane-spanning protein

Using the sodium-potassium pump involves the hydrolysis of ATP and the release of Na+ to the outside of the cell.

Cell membranes are selectively permeable, regulating which substances can pass through, as well as how much of each substance can enter or exit at a given time. In cells, some molecules can move down their concentration gradients by crossing the phospholipid portion of the membrane directly, while others must pass through membrane proteins. Which of these statements does NOT apply to facilitated diffusion?

V. used to move small and/or nonpolar molecules

The potato has a cavity on top, as shown in the picture. Some sugar solution is poured into the cavity and the potato is placed in a beaker of water. After some time, it is observed that there is a rise in the level of liquid in the cavity. This confirms that

Water from the beaker has moved into the cavity

An animal cell with a solute potential of -1.2 bars is placed into an open beaker containing a solution with a solute potential of -3.8 bars. What is the resulting movement of water in this example?

Water will move out of the cell because the beaker solution has a lower water potential than the cell.

The cell membrane is selectively permeable because of its molecular structure. Based on this, which one of these would NOT diffuse directly through the cell membrane?

macromolecules

The sodium-potassium pump functions to pump

sodium ions out of the cell and potassium ions into the cell.

Hydrolysis of ATP to ADP provides a mechanism for

sodium ions to move against their gradient

When B cells are activated by T-helper cells, they clone themselves and begin to secrete antibodies. Antibodies are large, Y-shaped proteins that recognize specific antigens that may be associated with pathogenic bacteria or other cell types. Based on the size and structure of antibodies, what best explains their export from activated B cells?

via exocytosis

Nutrients enter a cell ______ the concentration gradient by the process of _______.

with, diffusion