BIO ch.5 (cont)

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

What is the basic difference between exergonic and endergonic reactions?

Exergonic reactions release energy; endergonic reactions absorb it.

The hydrolysis of DNA into nucleotides constitutes an exergonic reaction. Yet, DNA is quite stable. Why is this the case?

The activation energy required to initiate this reaction is seldom reached.

phagocytosis

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

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?

a hypertonic sucrose solution

During enzymatic reactions, substrates are converted to products. A property of enzymes that facilitates this reaction is that they are catalysts and therefore _____

change the rate of a reaction without being consumed by the reaction

In the process of osmosis, water displays a net movement from an area of __________ water concentration to an area of __________ water concentration.

higher.....lower

When an enzyme catalyzes a reaction,

it lowers the activation energy of the reaction

The mechanism of enzyme action is to

lower the energy of the activation of a reaction

an energy barrier

prevents the spontaneous breakdown of molecules in the cell.

Most of a cell's enzymes are

proteins

Anything that prevents ATP formation will most likely

results in cell death

Facilitated diffusion across a biological membrane requires ________ and moves a substance ________ its concentration gradient.

transport proteins....down