2.2 Water Flashcards Preview

IB Biology HL > 2.2 Water > Flashcards

Flashcards in 2.2 Water Deck (15)
Loading flashcards...

Outline the significance of the labeled parts of this diagram, showing the attraction between the three molecules (also explain delta negative). 

w. oxygen atom (higher electronegativity) x. hydrogen atom (lower electronegativity) y. intermolecular bond (hydrogen bond) z. polar covalent bond delta negative. slight negative charge as large oxygen atom attracts shared electron closer to itself than the hydrogen atom delta positive. slightly positive charge as large oxygen atom attracts shared electrons closer to itself than the hydrogen atom, creating a relatively positive charge in the hydrogen atom.


Explain the cohesive property of water. What is its significance in living things?

-Cohesive property of water refers to the binding together of two molecules of water, meaning the water molecules "stick" to their fellow water molecules. -It is useful for water transport in plants.


Explain the adhesive property of water.

Hydrogen bonds form between water molecules and other polar molecules, causing them to "stick" together.


Explain the high specific heat of water.

Hydrogen bonds restrict the motion of water molecules and increase in temperature require the breaking of hydrogen bonds. Energy is needed to do this. As a result, the amount of energy needed to be used or released in order to raise or lower the temperature of water is relatively large.


Explain the high latent heat of vaporization for water.

When a molecule ecaporates, it separates from other molecules in a liquid and becomes a vapour molecule. The heat needed to do this is called the latent heat of vaporization. Considerable amounts of heat are needed because hydrogen bonds need to be broken.


Explain the high boiling point of water.

The boiling point of substances is the highest temperature that it can reach in a liquid state. For the same reasons that water has a high latent heat of vaporization, its boiling point is high (100*C).


Explain waters solvent properties.

Polar nature of water means it forms a shell around charged and polar molecules, preventing them from clumping together and keeping them in solution. Water forms hydrogen bonds with polar molecules. Its partially negative oxygen pole is atracted to positively charged ions and its partially positive hydrogen pole is attracted to negatively charged ions, so both dissolve.


How are hydrophilic molecules different than hydrophobic ones?

Hydrophilic molecules are chemically attracted to water while hydrophobic molecules are insoluble in water but soluble in other solvents.


What types of molecules are hydrophilic? Hydrophobic?

-polar or ionic molecules are hydrophilic

-nonpolar non-ionic molecules are hydrophobic


How is water used as a coolant? What controls its release? What other forms of cooling via evaporation are found in other organisms?

-Water is secreted as swerat by sweat glands in skin. It's carried to the surface and spreads out. The head needed to evaporate water in the glands leaves the glands, cooling them. Blood passing underneath is therefore cooled.

-The hypothalamus controls the release of sweat. Its receptors monitor blood temperature and receive sensorty inputs from temperature receptors in skin. If the body is overheated, the hypothalamus stimulates the sweat glands to secrete sweat.

-Panting in dogs and birds. Transpiration in leaves.


The following are carried often in the blood, but which are insoluble or only slightly soluble: sodium chloride, amino acids, glucose, oxygen, fat molecules, cholesterol?

Amino acids, oxygen, fat molecules, cholesterol.


Describe the transport of amino acids in the blood.

Solublility depends on the R group. All amino acids are soluble enough to be dissolved in blood plasma though.


Describe the transport of oxygen in the blood.

-Only sparingly dissolved in water because water becomes saturated at low concentrations of O2 and because O2 solubility decreases as temperature increases.

-O2 carried by hemoglobin which has binding sites for O2 and increased capacity for O2 concentration.


Describe the transport of fat molecules in blood.

Cannot be dissolved in water as they are nonpolar and too large. Carried in lipoprotein complexes in blood, a single layer of phospholipids containing fats on the inside. Phosphate heads face outwards and tails face inwards, connecting with the fats. There are proteins in the phospholipid monolayer.


Describe the transport of cholesterol in the blood.

Mostly nonpolar so it isn't dissolvable in water. Positioned in the lipoprotein complex's monolayer.