bio 1a chapter 5 hw

endocytosis

the cell membrane engulfs a particle in the cytoplasm and forms a vesicle around it. the cell expands energy to transport materials into the cytosol.

Exocytosis is the primary method of transporting large molecules out of the cell.

Exocytosis is the primary method of transporting large molecules out of the cell.

pinocytosis

cellular drinking. tiny vesicles are formed.

Select the statement that describes an electrochemical gradient.

combined chemical and electrical forces acting on ions across a membrane.

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

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.

uniporter

Uniporter carrier proteins work by binding to one molecule of substrate at a time and transporting it with its concentration gradient. Examples are the glucose receptors.

Which of the following describes the fluid mosaic model?

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

symporter

he symporter works in the plasma membrane and molecules are transported across the cell membrane at the same time.

Cell membranes are composed of phospholipids that have head and tail regions. The phospholipid 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

phagocytosis

large particles are engulfed. large vesicles are produced . pseudopodia are used.

antiporter

facilitated diffusion. An antiporter (also called exchanger or counter-transporter) is a cotransporter and integral membrane protein involved in secondary active transport of two or more different molecules or ions across a phospholipid membrane such as the plasma membrane in opposite directions.

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

The cell spends energy to move substances through a protein across the plasma membrane. Substances move from an area of lower concentration to an area of higher concentration.

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

1.) Proteins and other membrane components are embedded in the membrane. 2.)Individual phospholipids are not strongly attached to neighboring phospholipids.

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 sodium ions to enter the cell down their concentration gradient using a membrane channel. An inner ear hair cell allows chloride ions to flow down their concentration gradient after a molecule binds to a membrane receptor.

Exocytosis Exocytosis secretes materials from the cell through the fusion of a vesicle with the plasma membrane.

Exocytosis secretes materials from the cell through the fusion of a vesicle with the plasma membrane.

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 fatty acid tail regions of the phospholipids of the plasma membrane repel water.

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 membrane excluded the starch molecules, but the iodide ions diffused through.

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

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

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 molecules are the main structural components of the plasma membrane?

proteins and lipids

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

proteins used as hormones are moved out of the cell in which they were manufactured. A single-celled eukaryotic organism excretes digestive waste into the surrounding water. A nerve cell releases peptides used as messengers into the extracellular space.

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 regulates what enters and leaves the cell.

active transport

the movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy.