bio test water & water potential

water is found…

between cells of multicellular organism as interstitial fluid

water is crucial for organisms…

because it makes up the fluid (cytoplasm) in all cells and within organelles

where do chemical and metabolic reactions work best?

in an aqueous environment because water facilitates the necessary interactions for reactions.

what type of bond does water have?

polar covalent bonds, which allow it to form hydrogen bonds with other molecules

why do water molecules have polar covalent bonds?

because of unequal sharing of electrons between oxygen and hydrogen atoms

partial ___ charge over hydrogen

positive

partial ___ charge over oxygen

negative

cohesion

is the attraction between water molecules due to hydrogen bonding, which helps maintain water's surface tension and allows it to form droplets (water is attracted to water)

Cohesion allows…

the transport of water under tension in plants

pulling forces caused by the transpiration…

makes water move upwards against gravity as an intact water column

transpiration

evaporation of water from leaves

adhesion

attraction between the polar ends of water molecules and polar surfaces (water is attracted to other surfaces)

capillary action

helps water be drawn into a plant from an underground source in the soil

solvent properties of water

ability to dissolve a wide range of substances, particularly polar molecules and ions, due to its polar nature

Polar (partially charged molecules with a polar covalent bond) or charged molecules are…

hydrophilic and are therefore soluble – they dissolve well in polar liquids like water.​

Substances that are insoluble in water are…

molecules that don’t have a negative or positive charge or are non-polar (hydrophobic and repel water)

glucose

soluble

amino acids

mostly soluble

cholesterol

insoluble

fats & lipids

insoluble

oxygen

very weakly soluble in water

sodium chloride (salt)

soluble

buoyancy

vertical upwards force exerted by a liquid on an object which is placed on it

viscosity

resistance of a fluid to flow (usually the consequence of the type of bonding within the substance) eg. low viscosity=water

specific heat capacity

the amount of heat that must be added to one unit of mass of the substance in order to cause an increase of one unit in temperature

SHC for water?

specific heat capacity of water is very high because of hydrogen bonds which restrict molecular motion

thermal conductivity

the rate at which heat passes through materials (in water, conductivity is higher, as particles are closer together)

Solvation

The interaction of a solvent (often water) with the dissolved solute/works well with polar solutes

Solvent Polarity

The most important factor in determining how well a solvent solvates a particular solute.

Polar Molecule

Water is a good solvent because it is a polar molecule, and it will therefore dissolve polar solutes easily.

Osmotically Active

substances that are ___ dissolve in water and change the concentration of the solution.

Osmosis

The net movement of water from an area with a lower solute concentration to an area with a higher solute concentration across a semi-permeable membrane.

Isotonic Solution

There is no net movement of water between two isotonic solutions because there is no difference in concentration

Hypotonic Solution

A solution with a lower solute concentration compared to another solution.

Hypertonic Solution

A solution with a higher solute concentration compared to another solution.

Plasmolysis

When water leaves a plant cell in a hypertonic solution, the cell membrane pulls away from the cell wall, reduces the volume of the cytoplasm.

Turgor Pressure

The pressure exerted by the cell contents against the cell wall in a plant cell.

Crenation

Shrinkage of cells due to water loss in a hypertonic environment.

Lysed cell

A cell that has burst due to excessive water intake in a hypotonic solution, causing the cell membrane to rupture

solute

A substance dissolved in a solvent to form a solution, affecting osmotic balance

is water a good solvent and why?

Yes, because of its polarity, allowing it to dissolve many ionic and polar substances (eg. NaCl)

movement of water molecules due to osmosis depends on…

concentration of solute in the solution (form hypo to hyper)

what happens when an animal cell is put in a hypotonic solution?

water enters the cell by osmosis making it swell, and because it lacks the support of a cell wall the it eventually bursts

what happens when a plant cell is bathed in a hypertonic solution…

water exits the cell by osmosis, causing it to shrink and become plasmolyzed as the cell membrane pulls away from the cell wall (shriveled)

medical applications of isotonic solutions

intravenous drips, contact lens solutions, eye drops, rinsing wounds, frozen to slush for packing donor organs