a solution that contains LESS dissolved material than does anorganism living in

ID: 4834 • Letter: A

Question

a solution that contains LESS dissolved material than does anorganism living in it is _______ to thatorganism. A solution that containes MORE dissolved material than does anorganism living in it is _____ to that organism. What happens to the central vacoul of elodea cells when it isplaced in salt water? Will a sugar cube dissolve faster in iced tea or hottea? a solution that contains LESS dissolved material than does anorganism living in it is _______ to thatorganism. A solution that containes MORE dissolved material than does anorganism living in it is _____ to that organism. What happens to the central vacoul of elodea cells when it isplaced in salt water? Will a sugar cube dissolve faster in iced tea or hottea?

Explanation / Answer

(i) "The important thing for a (biologist) to know about osmosis and osmotic pressure is how particles dissolved in fluid environments affect (organisms) in those environments. For this purpose tonicity is a useful concept. Tonicity describes the behavior of cells in a fluid environment. The cells are the reference point, and the fluid environments are compared to the cells." (p. 99, Black, 1996)

(ii) Qualitatively different types of tonicity include:

(1) isotonic

(2) hypertonic (a.k.a., hyperosmotic)

(3) hypotonic (a.k.a., hypoosmotic)

(b) Highly osmotic:

(i) Because cells tend to concentrate the solutes found in their extracellular environment, they tend to have higher solute concentrations, intracellularly.

(ii) Therefore, water tends to flow into cells with what can be a considerable force.

(c) If the extracellular environment contains solute concentrations in excess of those displayed by the cell cytoplasm (e.g., in brine), then water will tend to flow out of a cell.

(7) Isotonic

(a) An extracellular solution that has effectively the same concentration of solutes as that found within a cell.

(b) This results in no net movement of water into or out of cells.

(c) For example, animal cells are bathed with isotonic solutions, and can be harmed by too dilute or too concentrated solutions.

(d) See movement of water in and out of cells illustration, below.