ch.2

Question 1

where does oxygen come from in the photosynthesis reaction

Answer 1

oxygen comes from water

Question 2

what is the overall equation for photosynthesis

Answer 2

6H2O + 6CO2 –> C6H12O6 + 6O2

Question 3

which organisms are capable of photosynthesis

Answer 3

cyanobacteria, algae, and plants

Question 4

why do all organisms need water

Answer 4

all organs and tissues in the body require water but to different extents

Question 5

which organs contain the highest proportion of water

Answer 5

the brain, eyes and blood

Question 6

how long can humans survive without water

Answer 6

72 hours no water

Question 7

what happens to most cells within the body in relation to water

Answer 7

most cells are surrounded by water and they themselves are 70-95% water

Question 8

what tole do hydrogen atoms of water play in organic molecules

Answer 8

the hydrogen atoms of water become incorporated into a large number of organic molecules

Question 9

what are dehydration reactions in relation to water

Answer 9

requires water for joining monomers

Question 10

what are hydrolysis reactions in relation to water

Answer 10

require water for separating polymers into monomers

Question 11

what is dehydration in biochemical terms

Answer 11

the joining of two monomers by the removal of a water molecule

Question 12

hydrolysis in biochemical terms

Answer 12

the separation of a polymer into monomers by the addition of a water molecule

Question 13

how is polarity formed in water molecules

Answer 13

electrons are more concentrated around oxygen, making hydrogen slightly positive and oxygen slightly negative

Question 14

what is a polar molecule

Answer 14

has regions of partial positive and negative charges due to unequal electron distribution

Question 15

hydrogen bonding in water

Answer 15

occurs between water molecules, holding liquid water together and making it vert cohesive

Question 16

what are the four properties of water

Answer 16

solvent: dissolves many substances
CAT (cohesion, adhesion, tension)
temperature
density

Question 17

what is the role of water as a solvent

Answer 17

is the dissolving agent and can dissolve mostly polar or ionic substances

Question 18

what happens when water is the solvent

Answer 18

when water is the solvent, it creates an aqueous solution

Question 19

why do nonpolar substances not dissolve well in water

Answer 19

nonpolar substances do not dissolve well in water because water is very polar and only attracted to charged particles

Question 20

what is the process of hydration in relation to ionic substances

Answer 20

the process of hydration involves the separation of individual cations and anions from each other when ionic substances dissolve in water

Question 21

how do water molecules interact with glucose

Answer 21

water molecules form hydrogen bonds with glucose, progressively removing individual monosaccharides from the solid

Question 22

what is required for large molecules like proteins to dissolve in water

Answer 22

large molecules like proteins can dissolve in water if they have ionic and/or polar regions on their surfaces

Question 23

what is the significance of cohesion in plants

Answer 23

helps plants get water from the roots to the leaves against the force of gravity

Question 24

what is adhesion in relation to water

Answer 24

the clinging of one substance to another, particularly if they have charged groups on their surface

Question 25

how do cohesion and adhesion contribute to capillary action

Answer 25

cohesion and adhesion together allow water to move in narrow tubes against or with the force of gravity

Question 26

what is the surface tension in water

Answer 26

how difficult it is to break or stretch the surface of a liquid due to cohesion among water molecules

Question 27

how does temperature affect the hydrogen bonding in water

Answer 27

when heat energy is added to water, it serves to break hydrogen bonds, reducing the degree of cohesion between the molecules

Question 28

what is specific heat in relation to water

Answer 28

the amount of heat that must be absorbed or lost for 1g of a substance to change in temperature by 1 degree Celsius

Question 29

how does water's high specific heat affect temperature changes

Answer 29

allows it to better resist temperature changes, acting as a temperature buffer

Question 30

how does water maintain stable aquatic life

Answer 30

waters ability to absorb and release energy with little temperature change helps maintain constant temperatures supporting

Question 31

what happens when water cools

Answer 31

when water cools, water molecules slow down, form hydrogen bonds and release heat energy to the surrounding environment

Question 32

what is evaporative cooling

Answer 32

water molecules with more energy escape the liquid phase, lowering the temperature of the remaining water

Question 33

how does the density of ice compare to liquid water

Answer 33

ice is less dense than liquid water, allowing it to float on the surface

Question 34

why is it important that ice floats on water

Answer 34

if ice sank oceans would freeze from the bottom up making life unstable

Question 34

what is the relationship between polar covalent bonds and solubility in water

Answer 34

polar covalent bonds are soluble in water because they are charged and attract water

Question 34

what does a low pH indicate

Answer 34

an acidic solution

Question 34

what does pH measure in an aqueous solution

Answer 34

pH measures the acidity or concentration of H+ ions in a solution

Question 35

neutral neurological pH range

Answer 35

7.35-7.45

Question 35

what effect does an acid have on the pH of a solution

Answer 35

increases the concentration of H+ ions in a solution, decreasing the pH

Question 36

what effect does a base have on the pH of a solution

Answer 36

increases the concentration of OH- ions in the solution, decreasing the concentration of H+ ions and countering acidic effects

Question 37

what is a pH buffer and what does it do

Answer 37

a substance that resists changes in pH - accepts H+ ions when they are in excess - donated H+ ions when they are depleted - occurs naturally from breaking down chemical compounds

Question 38

why is it important for pH in cells and other fluids to be highly regulated

Answer 38

changes in pH alter the shape of proteins and their effectiveness and function