CH. 5 Sapling HW

Specialized cells can identify specific targets for ingestion and engulf proteins, debris, and other cells. What is the term for the cellular ingestion of large particles or cells?

phagocytosis

Which of the following is a function of cholesterol in a cell's plasma membrane?

regulating membrane fluidity

Plasma membranes are selectively permeable (semipermeable), meaning that...

the membrane permits the transport of only certain substances

Phospholipids are molecules that have two regions, the head and the tail, with distinct chemical properties. Classify the following descriptions as characteristics of the heads or or tails of phospholipids.

Heads: - hydrophilic - polar Tails: - does not mix with water - hydrocarbon-rich

Without resetting the lab, click on the "Antiporter" button on the left side of the lab. Add in at least three cyan square antiporters. Observe the results and complete the below sentences.

The concentration of squares inside the cell should not change The concentration of X-shaped molecules inside the cell should decrease

The sodium-potassium pump, also known as the Na+/K+ ATPase, is shown in this animation. The movement of ions through this membrane protein is an example of...

active transport

Select the statement that describes an electrochemical gradient?

combined chemical and electrical forces acting on ions across a membrane

Exocytosis is a type of cellular transport that allows materials to move across the plasma membrane of a cell. Which of the statements describe properties of exocytosis?

-exocytosis secretes materials from the cell through the fusion of a vesicle with the plasma membrane - exocytosis is the primary method of transporting large molecules out of the cell

Select the descriptions that apply to the sodium-potassium pump.

- Adenosine triphosphate (ATP) is necessary for the pump's function - The pump helps to maintain the concentration if sodium and potassium ions in living cells.

Which statements describe examples of facilitated diffusion?

- An erythrocyte low on glucose replenishes its supply using a membrane protein to transport glucose down its concentration gradient - A neuron allows potassium ions to leave the cell down their concentration gradient using a membrane channel - An inner ear hair cell allows potassium ions to flow down their concentration gradient using a membrane pump and cellular energy

Which of the following are properties of protein-facilitated active transport?

- Substances cross the plasma membrane by being pumped through a protein using ATP. - Substances move from an area of lower concentration to an area of higher concentration.

What does the fluid mosaic model describe about the structure of plasma membranes?

- a membrane has proteins and other components embedded among the phospholipids - individual phospholipids are not strongly attached to neighboring phospholipids

Exocytosis is one of the processes living organisms use to move molecules. Choose all the examples of exocytosis.

- pancreatic cells release digestive enzymes into the small intestine - a nerve cell releases peptides used as messengers into the extracellular space -a single-celled eukaryotic organism excretes digestive waste into the surrounding water

Which of the following molecules are the main structural components of the plasma membrane?

- proteins - lipids

Select the statements that accurately describe endocytosis.

- the cell expends energy to transport materials into the cytosol - the cell membrane pinches off to form an extracellular vesicle joined to the cell by filaments

Transport proteins allow the movement of ions and small molecules across plasma membranes. identify the type of transport protein from each example as uniporter, symporter, or antiporter.

A protein moves one Ca2+ out of the cell and three Na+ into the cell. - antiporter A protein allows glucose to flow into a cell down its concentration gradient. - uniporter A protein moves two Na+ ions into the cell with one glucose molecule. - symporter

Cholera causes diarrhea by impairing the absorption of salts and water in the small intestine. If left untreated, diarrhea sufferers can die of dehydration. A researcher is testing dehydration treatments in her lab. She infects cultures of intestinal cells with the cholera pathogen. She then applies treatments to the solution the cells are in before measuring the changes in cell volume and intracellular solute concentration. Select the best explanation for the results of the researcher\'s experiments, presented in the table below.

A symporter moves glucose and sodium into the cell, then water enters by osmosis.

Integral membrane proteins have different characteristics and functions than peripheral membrane proteins. Sort the statements into those that are properties of integral membrane proteins and those that are properties of peripheral membrane proteins.

Integral Membrane Proteins: - can be extended through the cell membrane - can move laterally (sideways) in the hydrophobic part of the membrane - act as tunnels through the cell membrane Peripheral Membrane Proteins: - found at the surface of the cell membrane

A and B are solutions of salt dissolved in water that are separated from each other by a semipermeable membrane in each scenario. Water can pass through this membrane, but the salt cannot. Match each pair of solutions to the net direction the water will flow between the two solutions.

Net flow toward solution A: solution A: 10% salt solution solution B: 5% salt solution Net flow toward solution B: solution A: 4% salt solution solution B: 14% salt solution No net flow: solution A: 2% salt solution solution B: 2% salt solution

Two forms of endocytosis are pinocytosis and phagocytosis. The following statements are characteristics of either pinocytosis or phagocytosis. Match each description to the appropriate category.

Pinocytosis: - extracellular fluid is engulfed - tiny vesicles are formed Phagocytosis: - large particles are engulfed - large vesicles are formed - pseudopodia are used

Now click on the "Passive" button on the left side of the lab. Add in at least three purple channels. Observe the results and complete the below sentences.

The concentration of circles inside the cell should decrease The concentration of squares inside the cell should not change The concentration of X-shaped molecules inside the cell should decrease

A selectively permeable membrane divides a container in half. One half of the container, Side A, is filled with a starch solution, while the other half, Side B, is filled with an iodine tincture. Starch is a large macromolecule that forms a milky white solution when dissolved. An iodine tincture contains very small iodide ions and is a brown solution. Iodide ions turn dark blue when they react with starch molecules. After several hours, Side A is dark blue, while Side B is brown. Which statement describes the diffusion of solutes through the membrane?

The iodide ions diffused through the membrane, but the starch molecules were excluded

Which choice describes diffusion?

The movement of a substance from a region where it is more concentrated to a region where it is less concentrated down its concentration gradient

The plasma membrane is an outer boundary that separates the interior of a cell from its external environment and is found in all cells. The molecules that make up the plasma membrane have a unique quality that helps to ensure the integrity of the cell. Considering the structure of the plasma membrane, which of the following choices best explains why human cells do not dissolve in water?

The plasma membrane is composed of phospholipids, which have hydrophobic regions

Which of the following describes the fluid mosaic model?

a phospholipid bilayer with various molecules embedded within and floating between the layers

Cell membranes are composed of phospholipids that have head and tail regions. The phospholoipid head is hydrophilic and spontaneously orients toward the environment. Which of the following phrases best describes the hydrophilic region of a phospholipid?

interacts with water

Facilitated diffusion is a protein-facilitated movement of solutes across a membrane from an area of higher concentration to an area of lower concentration. Which of the following best describes facilitated diffusion?

passive transport