2.2 Water

Question 1

draw a water molecule

Answer 1

…

Question 2

water structure

Answer 2

water molecules are polar and H bonds form between them; water is made up from two H atoms covalently bonded to an O atom

Question 3

why are H atoms covalently bonded to an O atom

Answer 3

because of unequal sharing of electrons, because nucleus of O atom is more attractive to electrons than nuclei of the H atom, so electrons are orbiting closer to the O atom

Question 4

charge of atoms in a water molecule

Answer 4

H atoms have a partial positive charge and O has partial negative charge

Question 5

why is this an ionic bond

Answer 5

positive and negative ions attract each other to form ionic bond

Question 6

hydrogen bond

Answer 6

the force that forms when a H atom in 1 polar molecule is attracted to a slightly negative atom of another polar covalent molecule

Question 7

unequal electron distribution results in …

Answer 7

permanent dipole

Question 8

draw water polarity in water molecule

Answer 8

…

Question 9

properties of water

Answer 9

intermolecular bonding between H20 molecules give water distinctive properties; cohesive, adhesive, thermal and solvent properties, transport

Question 10

cohesion

Answer 10

the tendency of H20 molecules to stick to each other due to the hydrogen bonding between them

Question 11

why do we have high surface tension in H20

Answer 11

cohesive strenght because of large number of H bonds in H20 cause high surface tension of H20 (the stickiness, due to H bonding of H20 molecules makes h20 surface behave as strong elastic membrane, allowing small organisms or objects denser than H20 to float

Question 12

surface tension is also responsible for

Answer 12

also responsible for H2O droplets adopting spherical shape, minimizing SA:Vol ratio

Question 13

adhension

Answer 13

interaction that H2O molecules have with different molecules and explains why H2O molecules stick to other polar compounds by forming H bonds

Question 14

role of cohesion of water molecule

Answer 14

interaction between H2O molecules

Question 15

role of adhension of water molecule

Answer 15

interaction between H2O and surrounding material or surface

Question 16

thermal properties

Answer 16

the H bonds that hold H2O molecules
together are responsible for thermal properties of H2O including high specific heat capacity

Question 17

specific heat

Answer 17

the amount the amount of heat that must be absorbed or released for 1g of a substance to change T by 1C

Question 18

why is water a good coolant

Answer 18

because of the large amount of energy needed to turn liquid H2O into vapor H2O

Question 19

water has a high latent heath of vaporisation

Answer 19

the amount of heath 1g of liquid absorbs to change state to gaseous

Question 20

how does water cool down a body

Answer 20

when H2O in sweat evaporates on the surface of skin, it cools down its surface by taking away energy n the form of heat

Question 21

high boiling point

Answer 21

the highest T that water can reach in a liquid state 100C

Question 22

solvent properties

Answer 22

water is universal solvent - it can dissolve ionic compounds as well as polar compounds (glucose)

Question 23

water soluble materials

Answer 23

glucose, amino acids, NaCl

Question 24

not dissolved in H2O

Answer 24

fat soluble, water insoluble substances

Question 25

how do solvent properties work

Answer 25

occurs because the polar attraction of large quantities of water molecules can sufficiently weaken electrostatic forces and result in the dissociation of atoms

Question 26

all polar molecules and ions

Answer 26

freely associate and readily dissolve in H2O - hydrohilic

Question 27

non-polar molecules, fats and oils

Answer 27

don’t freely in H2O - hydrophobic

Question 28

transport

Answer 28

within blood, depends on solubility of materials

Question 29

water soluble substances

Answer 29

-NaCl (ions) and C6H12O6 (polar) - freely transported in the blood
-amino acids are transported in an ionized state (amine/carboxyl group charged)
-oxygen is soluble in low amounts - generally transported in eritrocites

Question 30

water insoluble substances

Answer 30

lipids (cholesterol, fat) are packed with proteins (lipoproteins) for transport

Question 31

other properties of water

Answer 31

transparency, less dense

Question 32

transparency

Answer 32

allowing light to pass through it (important for photosynthesis to occur in aquatic plants)

Question 33

less dense as a solid (ice) than as a liquid

Answer 33

adopts lattice formation (due to H bonds) so more space exists between H2O molecules so the ice is lighter than water (floats) and floating ice insulates bodies of H2O from freezing air when T is bigger than 0C

Question 34

benefits in living organisms of cohesive properties

Answer 34

1) allow water to be pulled up from the roots to the leaves of plants
2) permit insets, such as pond skaters, to walk/ float on the surface of water to catch their prey

Question 35

benefits in living organisms of adhesive properties

Answer 35

1) capillary action generated by adhesive forces assists the pumping action of the heart to help blood move though blood vessels
2) adhesion of water molecules to the cell wall of xylem vessels helps water move against gravity from the roots to the leaves

Question 36

benefits in living organisms of thermal properties

Answer 36

1) evaporation of sweat from body surfaces involves heat loss, which brings about a cooling effect
2) the high specific heat capacity of water makes aquatic ecosystems more stable than terrestrial

Question 37

benefits in living organisms of solvent properties

Answer 37

1) water dissolves mineral ions in the soil and transports it along xylem vessels from the roots to all parts of the plant
2) water in blood plasma dissolves a range of solutes and gases, which makes it possible for blood to transport nutrients and gases around the body
3) waters versatility makes it an universal solvent and medium for numerous biochemical reactions

Question 38

versatility

Answer 38

ability of water to exist as a liquid, solid and vapour

Question 39

transport of glucose

Answer 39

as a polar molecule, glucose is soluble in water so it can be transported in blood. Blood glucose concentration needs to be strictly maintained between certain levels because of its effect on osmotic potential (homeostasis)

Question 40

transport of amino acids

Answer 40

both - and + charged, soluble in water; solubility varies depending on their size and their R group.
With hydrophilic R group - easily dissolved in H2O and transported in blood
With hydrophobic R group - not easily dissolved in H2O and transported in lower concentration in blood

Question 41

transport of fats

Answer 41

nonpolar, generally insoluble in H2O, therefore transported in structures called lipoproteins

Question 42

lipoproteins

Answer 42

a single layer of phospholipids with proteins embedded among the molecules surrounding fat

Question 43

transport of cholesterol

Answer 43

required for synthesis of many biologically important molecules and is in membranes; requires help of transport lipoproteins to be transported in blood because its’ hydrophobic

Question 44

transport of oxygen

Answer 44

nonpolar, but so small that it’s soluble to a limited extent - tied to a protein hemoglobin to be transported in blood

Question 45

transport of sodium chloride

Answer 45

ionic compound, transported in the form of Na+ and Cl- ions - easily dissolved

Question 46

plasma contains

Answer 46

water, gases, vitamins and trace elements, organic molecules, ions

Question 47

gases contain

Answer 47

carbon dioxide and oxygen

Question 48

organic molecules contain

Answer 48

amino acids, nitrogenous waste, proteins, glucose, lipids

Question 49

proteins contain

Answer 49

fibrinogen, globulin, albumin