BIo

Which of the following is a difference between active transport and facilitated diffusion?

Active transport requires the expenditure of cellular energy, and facilitated diffusion does not.

Which of the following statements about cell membrane transport is true?

Active transport works with the assistance of proteins to move molecules from areas of low concentration to areas of high concentration.

Cells A and B are the same size and shape, but cell A is metabolically quiet and cell B is actively consuming oxygen. Oxygen will diffuse more quickly into cell _____ because _____.

B ... the diffusion gradient there is steeper

Green olives may be preserved in brine, which is a 20-30% salt solution. How does this method prevent contamination by microorganisms?

Bacteria can't survive in a hypertonic solution because they lose water.

Which of these statements describes what occurs in facilitated diffusion?

Facilitated diffusion of solutes occurs through protein pores in the membrane.

Which of the following statements is true about diffusion?

It is a passive process

Which of the following statements is true about passive transport?

Passive transport requires no expenditure of cellular energy.

Which of these situations accurately represents osmoregulation in organisms?

Plant cells need a hypotonic environment in order to stay turgid.

The membrane is referred to as a "fluid mosaic" structure. Which of the following statements is true?

The fluid is phospholipid, and the mosaic is protein.

The concentration of solutes in a red blood cell is about 2%. Sucrose cannot pass through the membrane, but water and urea can. Osmosis would cause red blood cells to shrink the most when immersed in which of the following solutions? (see book section: Module 5.5)

a hypertonic sucrose solution

When in solution, a molecule that moves slowly across an artificial membrane moves rapidly across a plasma membrane. This occurs regardless of whether the concentration of this molecule is higher inside or outside the cell. Using this information, which transport mechanism is most likely to be responsible for the movement of the molecule across a plasma membrane?

active transport

Stability of an animal cell plasma membrane is enhanced by _____.

cholesterol molecules

The movement of atoms, ions, or molecules from a region of higher concentration to regions of lower concentration is called __

diffusion

A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother's milk. These molecules probably enter the cells lining the baby's digestive tract via _____.

endocytosis

The secretion of neurotransmitters out of the nerve cell, from small vesicles at the end of the axon, can be considered an example of _____

exocytosis

Phospholipids are well suited to be the main structural components of membranes because they _____.

form a selectively permeable structure

When considering the formation of membranes, they _____.

form spontaneously in aqueous environments

If the volume of a cell increases when it is placed in an aqueous solution, that solution is said to be _____ to the cell.

hypotonic

The diffusion of water across a selectively permeable membrane is called _____.

osmosis

Some liver cells ingest bacteria, a function probably accomplished by _____.

phagocytosis

Which of the following terms specifically refers to the intake of very large particles by cells?

phagocytosis

Which of the following best describes the general structure of a cell membrane?

proteins embedded in two layers of phospholipid

How do LDL's enter the cell

receptor-mediated endocytosis

Seawater is dangerous to drink because _____.

seawater is hypertonic to your body tissues and drinking it will cause you to lose water by osmosis

The lipids in a cell membrane are arranged _____.

so that the nonpolar parts of two lipids point toward each other

The transport of molecules of a particular solute from inside an animal cell across the cell membrane to the extracellular fluid always requires energy when _____.

the concentration of the solute is lower inside the cell than outside it

Order of a phospholipid bilayer is ____.

water, hydrophilic head, hydrophobic tail, hydrophobic tail, hydrophilic head, water