Ch 5 Bio

best describe phagocytosis

A cell engulfs a particle by wrapping pseudopodia around it and packaging it within a vacuole.

Most cellular work is accomplished by _____ energizing molecules by _____ them.

ATP ... phosphorylating

What is a difference between active transport and facilitated diffusion?

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

cell membrane transport true fact?

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.

Where does facilitated diffusion of solute occur?

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

Why doesn't the antibiotic penicillin harm humans?

Human cells do not have cell walls.

What type of process is diffusion?

It is a passive process.

passive transport?

Passive transport requires no expenditure of cellular energy.

an example of the second law of thermodynamics?

The aerobic respiration of glucose generates heat.

What does the second law of thermodynamics demand?

The second law of thermodynamics demands a total increase in entropy

Taq polymerase is an enzyme isolated from the organism Thermophilus aquaticus. This organism has been found living in the hot springs of Yellowstone National Park. This enzyme is used to copy human DNA from crime scenes. Most reactions are performed at ranges similar to those of the human body; however, what considerations should be made for optimum use of this enzyme?

The temperature should be raised.

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 what solution?

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

Cellular respiration is an example of _____.(reaction)

an exergonic reaction

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

the phosphorylation of ADP to form ATP is an _____ reaction that _____ energy.

endergonic ... requires an input of

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

If the entropy of a system is increasing, this means that _____.

energy input will be needed to maintain organization

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

What condition might result from an excess of aquaporins?

fluid retention in pregnant women

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, "fluid mosaic" _____

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

If the tertiary structure of an enzyme is changed, _____

its substrate may not fit properly in the active site

The mechanism of enzyme action is to _____.

lower the energy of the activation of a reaction

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

osmosis

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

phagocytosis

What term specifically refers to the intake of very large particles by cells?

phagocytosis

What best describes the general structure of a cell membrane?

proteins embedded in two layers of phospholipid

LDLs enter cells by means of _____.

receptor-mediated endocytosis

What enables a cell to pick up and concentrate a specific kind of molecule?

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 first law of thermodynamics _____

states that energy is neither created nor destroyed

Succinylcholine is structurally almost identical to acetylcholine, but if combined with the enzyme that normally hydrolyzes acetylcholine, the enzyme is no longer able to hydrolyze acetylcholine. This suggests that _____.

succinylcholine must be a competitive inhibitor of acetylcholine

enzyme inhibitors action of the competitive inhibitor?

the action of competitive inhibitors may be reversible or irreversible.

Energy is _____.

the capacity to perform work

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

A reaction is designated as exergonic rather than endergonic when _____.

the potential energy of the products is less than the potential energy of the reactants