Bio - Water And Life

Front 1

1st cells evolved in water...

Back 1

3 billion years ago before spreading onto land.

Front 2

Most cells are surrounded by water and cells are about...

Back 2

70-95% water.

Front 3

Water (H2O) is a polar molecule and hydrogen bonds form between...

Back 3

water molecules.

Front 4

What type of bonds form between the atoms within a water molecule?

Back 4

Covalent

Front 5

The oxygen end of the H2O molecule is more _______ than the 2 hydrogens -> meaning the electrons spend more time closer to the oxygen end than to the hydrogen ends of the H20 molecule -> oxygen end has a slight ___ charge & the hydrogen ends have a slight ___ charge -> the whole H2O molecule is "charged" -> results in _______ covalent bonds within each H20 molecule.

Back 5

Negative; - ; + ; polar

Front 6

Polar covalent bonds results in hydrogen bonding...

Back 6

...bonds that form between adjacent H20 molecules.

Front 7

What type of bonds form between adjacent water molecules?

Back 7

Hydrogen

Front 8

Hydrogen bond always involves a _________ atom [with a positive (+) charge] forming a bond with an adjacent atom [with a negative (-) charge] in a molecule (usually oxygen or nitrogen).

Back 8

Hydrogen

Front 9

Describe 4 properties of water that make the existence of life on Earth possible and give examples.

Back 9

Cohesion, Moderate, Expansion, and Solvent.

Front 10

Cohesion of H20 molecules:

Back 10

water molecules stay close to each other as a result of hydrogen. (Ex. water transportation in plants from the roots -> leaves)

Front 11

Difference between cohesion and adhesion?

Back 11

Cohesion is when hydrogen bonds hold H20 molecules together. Adhesion is clinging one substance to a different substance.

Front 12

Surface Tension:

Back 12

measure of how hard it is to break the surface of a liquid and related to cohesion. (Ex. water spiders, water striders, and belly flops)

Front 13

Moderation of Temperature by H20:

Back 13

water moderates air temperature by absorbing heat from the air.

Front 14

Water moderates air temp. by ________ heat from air that is warmer and ________ heat to air that is cooler -> very effective "heat bank" because it can absorb or release a large amount of heat with only a slight change in its own _____________.

Back 14

Absorbing; releasing; and temperature.

Front 15

Kinetic Energy:

Back 15

energy of motion; atoms and molecules are always moving.

Front 16

Heat:

Back 16

measure of total amount of kinetic energy due to molecular motion.

Front 17

Temperature:

Back 17

measures the intensity of heat due to the average kinetic energy of molecules.

Front 18

_________ scale is used to indicate temperature.

Back 18

Celsius

Front 19

Water freezes at ______˙C (that's a degree thing) and boils at _____˙C.

Back 19

0 (zero) & 100.

Front 20

Unit of heat is calorie. Calorie (defintion):

Back 20

is amount of heat required to raise the temperature of 1 g. of water by 1˙C.

Front 21

1,000 Calories=

Back 21

a kilocalorie.

Front 22

Water has a high specific heat (definition):

Back 22

is the amount of heat that must be absorbed or lost for 1 g. of that substance to change its temp. by 1˙C. (compared with most other substances)

Front 23

High specific heat of water due to its hydrogen bonds...

Back 23

Heat must be absorbed to break H-bonds.

Heat is released when H-bonds form.

Front 24

Costal areas have milder climates compared to inland regions -> because: large body of water (ocean) can absorb & store huge amount of solar heat during the day/summer while warming only a few degrees.

Back 24

During night/winter the gradually cooling water can warm the air.

Front 25

Big picture:

Back 25

Because of water's high specific heat, water that covers most of the Earth keeps temperature fluctuations on land & water (& in organisms) within limits of permit life.

Front 26

Transformation from a liquid to a gas is called?

Back 26

Vaporization or evaporation.

Front 27

H20 has a high "heat of vaporization"

Back 27

heat a liquid must absorb for 1 g. to be converted to gas.

Front 28

As liquid water evaporates, the surface of the liquid that remains behind "cools down" -> evaporative cooling: ______________; contributes to stability of temperature in lakes/ponds; prevent terrestrial organisms from overheating. (ex. evaporation of sweat from skin -> dissipates body heat/prevents overheating on hot day)

Back 28

surface of an object becomes cooler during evaporation.

Front 29

Expansion of H20 molecules upon freezing:

Back 29

H20 is one of a few substances that is less dense as a solid than as a liquid.

Front 30

Solid ice ______ on liquid H20 -> due to H-bonding -> at 0˙C, H20 molecules become "locked at arm length" into a crystal of ice -> ice crystal has fewer molecules of H20 compared to liquid H20 of the same volume (ice is ~ 10% less dense than liquid H20).

Back 30

Floats

Front 31

What is the significance that solid water is less dense then liquid water?

Back 31

Ice will float; so that animals can stay on top of or underneath.

Front 32

H20:

Back 32

The Solvent of Life

Front 33

Solute:

Back 33

Substance that is dissolved (sugar)

Front 34

Solvent:

Back 34

Dissolving agent of a solution (water)

Front 35

Aqueous Solution:

Back 35

Water is the solvent (sugar and water)

Front 36

Hydration Shell:

Back 36

Ionic compound is dissolved in water, each ion surrounded by a sphere of water molecules.

Front 37

Hydrophilic:

Back 37

Substance that has affinity for water (ions & polar molecules).

Front 38

Hydrophobic:

Back 38

Doesn't have affinity for water, repels, non ionic & form non polar covalent bonds.

Front 39

What happens to water when it ionizes (dissociates)?

Back 39

H+ (H positive) OH- (OH negative)

Front 40

What is an acidic solution?

Back 40

Any substance that increases the H+ (H positive) concentration of a solution.

Front 41

What is a basic solution?

Back 41

Any substance that reduces the H+ (H positive) concentration of a solution.

Front 42

Draw a pH scale on the line and indicate what numbers represent acid, base, or neutral solution:

Back 42

0-6 = acid or acidic; 7 = neutral; 8-14 base or basic

Front 43

Internal pH of most living cells is close to?

Back 43

7.0

Front 44

Remember that each pH value represents a ______________ in H+ (H positive) concentration.

Back 44

10 fold change

Front 45

How much more acidic is lemon juice (pH 2) compared to root beer (pH 6)?

Back 45

(10 x 10 x 10 x 10) more acidic = 10,000

Front 46

What are buffers and why are they important to life?

Back 46

Substance that minimizes changes in the concentration of H+ (H positive) and OH- (OH negative) in a solution, helps pH stability in human bond and many other biological solutions.