Bios 351: Water Activity And Osmotic Pressure?

Front 1

What is the equation for determining water activity?

Back 1

vapor pressure of solution / vapor pressure of pure water

Front 2

Why does water activity decrease with the addition of salts or solutes?

Back 2

Water becomes involved in breaking ionic bonds and forming solvation shells around charged species to maintain them in solution.

Front 3

What is osmosis?

Back 3

movement of water from a higher concentration (of water) to a lower concentration (of water)

Front 4

A medium where solute concentrations on the outside of the cell are lower than in the cytoplasm is designated as ____________________.

Back 4

hypotonic

Front 5

Environments where the solute concentration is the same inside and outside the cell are termed ____________________.

Back 5

isotonic

Front 6

What type of cells (bacterial or animal) require isotonic environments?

Back 6

animal

Front 7

Why are bacteria able to survive hypotonic environments?

Back 7

The cell wall protects bacteria from bursting when water enters the cell.

Front 8

____________________ environments exist when the solute concentration is greater on the outside of the cell relative to the cytoplasm.

Back 8

hypertonic

Front 9

What happens to a bacterial cell in a hypotonic environment?

Back 9

Not much - water may enter the cell but the cell wall prevents the cell from bursting.

Front 10

What happens to a bacterial cell when it is in a hypertonic environment?

Back 10

Water leaves the cell, possibly resulting in plasmolysis.

Front 11

What are halophiles?

Back 11

Organisms that require high concentrations of salt.

Front 12

What are halotolerant bacteria?

Back 12

Organisms that can tolerate moderate amounts of salt.

Front 13

What are osmophiles?

Back 13

Organisms that can grow in high concentrations of sugars.