D.2.3: Water Potential

Animal cells vs. plant cells behaviour in hypo/hypertonic solutions

Animal cells become crenated (shriveled) or lysed (burst) due to the lack of cell wall, but plant cells become plasmolysed (shrunken, most of water gone, organelles centralised, cell can no longer perform its function) or turgid (saturated with water, ideal condition) 

Crenation

(extreme shrinkage until a cell becomes crinkled, typically from water loss)

Red blood cells behaviour in hypertonic medium

They have no cell wall, so the cell immediately loses water until crenation

Red blood cells in hypotonic solution

Water will enter the red blood cell, possibly to the point of bursting

Adaptations to prevent harmful swelling and shrinkage of cells

Contractile vacuole in single-celled aquatic animals: collects excess water in the cell and routinely empties it into the surrounding environment by fusing with the cell membrane (prevents swelling)

Effects of dehydration in humans

• Light-headedness and fainting

• Build-up of waste products in kidney tubules

• Blood flow diminished by muscle cramping and

Hydrostatic pressure

The pressure that a fluid exerts within a confined space against the boundary of the space.

Turgor pressure

Hydrostatic pressure specifically within plant cells