biology EXAM #1 pt. 3

Question 1

Water is

Answer 1

the molecule that supports all life

Question 2

All living organisms require _______ more than any other substance

_________________ of the Earth’s surface is submerged in water

the main reason the Earth is habitable:

Answer 2

water

Three-quarters

The abundance of water

Question 3

properties of water

Answer 3

Polarity of water and hydrogen bonding

Question 4

The polarity of water molecules results

The water molecule is a

Answer 4

in hydrogen bonding

polar molecule

Question 5

the polarity of water molecules allow for

About 15% of the molecules are bonded to four partners in short–lived clusters at any instant in liquid water at 37ºC (human body temperature),.

Answer 5

Allows them to form hydrogen bonds with each other

Contributes to the various properties water exhibits

Question 6

Four emergent properties of water contribute to Earth’s fitness for life:

Answer 6

-Cohesion
-Moderation of temperature
-Ice – less dense than liquid form of water, insulation of bodies of water by floating ice

-Solvent of life

Question 7

cohesion is:
due to :
helps:

Answer 7

Is the bonding of a high percentage of the molecules to neighboring molecules

Is due to hydrogen bonding

Helps pull water up through the microscopic vessels of plants

Question 8

adhesion:
what is it:
in plants it is:

Answer 8

Adhesion is an attraction between different substances, for example, between water and plant cell walls

the clinging of one substance to another, also plays a role. Adhesion of water to the walls of the cells helps counter the downward pull of gravity

water transport

Question 9

Evaporation from leaves pulls water upward from the roots through water–conducting cells, in this case located in the trunk of a tree. Cohesion due to hydrogen bonding helps hold together the column of water within the cells. Adhesion of the water to cell walls helps resist the downward pull of gravity. Because of these properties, the tallest trees can transport water more than 100 meters (m) upward—approximately one–quarter the height of the Empire State Building in New York City.

Answer 9

entender

Question 10

surface tension:
is related to
The result is

Answer 10

Is a measure of how hard it is to stretch or break the surface of a liquid

Is related to cohesion

collective strength of its hydrogen bonds

Question 11

moderation of temperature

Water moderates air temperature by:

Answer 11

Specific heat of water

-absorbing heat from air that is warmer and releasing the stored heat to air that is cooler

-Water is effective as a heat bank – it can absorb or release a relatively large amount of heat with only a slight change in its own temperature.

Question 12

Kinetic energy is:

The kinetic energy associated with random motion of atoms or molecules is called

Answer 12

Is the energy of motion

-thermal energy

Question 13

Heat:

Answer 13

Is a measure of the total amount of kinetic energy due to molecular motion. It is the thermal energy in transfer from one body of matter to another

Question 14

Temperature:
represents the:

Answer 14

Measures the intensity of heat

represents the average kinetic energy of the molecules in a body of matter

Question 15

The specific heat of a substance:

The specific heat of water is

Water resists changing its temperature because

Answer 15

Is the amount of heat that must be absorbed or lost for 1 gram of water to change its temperature by 1ºC. Much energy compared to alcohol and other compounds

1 cal/(g * ºC)

of its high specific heat

Question 16

Water has a high specific heat, which allows it to:
Heat is absorbed when
Heat is released when

Answer 16

-minimize temperature fluctuations to within limits that permit life

hydrogen bonds break
hydrogen bonds form

Question 17

Evaporation:

Answer 17

Is the transformation of a substance from a liquid to a gas

Question 18

Heat of vaporization:

It takes about ____ calories of heat to evaporate: (nearly double the amount needed to vaporize 1 gm of alcohol or ammonia)

Answer 18

-Is the quantity of heat a liquid must absorb for 1 gram of water to be converted from a liquid to a gas

-580; 1 gm of water at 25oC

Question 19

As a liquid evaporates, its remaining surface cools, a process called

This helps:

this is due to-
it allows-

Answer 19

evaporative cooling

• stabilize temperatures in organisms and bodies of water

-Is due to water’s high heat of vaporization
-Allows water to cool a surface

Question 20

Solid water, or ice is less:
and it:

why is it less ___?

In ice, each molecule is _________________________. Because __________________, ice has fewer molecules than an equal volume of liquid water.

in liquid water:

Answer 20

Is less dense than liquid water

Floats in liquid water

The hydrogen bonds in ice are more “ordered”and stable than in liquid water, making ice less dense

-hydrogen–bonded to four neighbors in a three–dimensional crystal

-the crystal is spacious

-Hydrogen bonds 
constantly break and re-form

Question 21

Since ice floats in water:

Many scientists are worried that global warming is having a profound effect on icy environments around the globe

The rate at which glaciers and Arctic sea ice are disappearing poses an extreme challenge to

Answer 21

Life can exist under the frozen surfaces of lakes and polar seas

-animals that depend on ice for their survival

Question 22

Water is a versatile solvent due to :

The solvent is the

The solute is the substance that

It can form:

The different regions of the polar water molecule can interact with

Water can also dissolve :

Even large polar molecules such as __________ can dissolve in _____ if they have :

Water can also interact with polar molecules such:

Answer 22

-its polarity

-dissolving agent of a solution

-that is dissolved

-aqueous solutions

-ionic compounds called solutes and dissolve them

-compounds made of nonionic polar molecules

-proteins
; water if they have ionic and polar regions.

-as proteins

Question 23

A hydrophilic substance:

Answer 23

Has an affinity for water

Question 24

A hydrophobic substance:

Answer 24

Does not have an affinity for water

Question 25

Oil molecules are hydrophobic because :

Hydrophobic molecules related to oils are:

Answer 25

they 
have relatively nonpolar bonds

the major ingredients of cell membranes

Question 26

Since most ________________ occur in water:

-It is important to learn to :

-When carrying out experiments,

Answer 26

-biochemical reactions

-calculate the concentration of solutes in an aqueous solution

-we use mass to calculate the number of solute molecules in an aqueous solution

Question 27

Molecular mass is

Number of molecules can be measured in _______. This represents an exact number of :

Answer 27

-the sum of all masses of all atoms in a molecule

-MOLES
molecules of a substance in a given mass

Question 28

1 mole (mole) = _________ molecules or daltons (Avogadro’s number and the unit “dalton” for ___________ = ______ )

Molarity:

Answer 28

6.02 x 10^23

6.02x1023 = 1g

-Is the number of moles of solute per liter of solution

Question 29

The dynamic equilibrium of water molecules:

Dissociation of water molecules leads to

Answer 29

the rate which water molecules dissociate is the same as the rate at which they are being formed.

acidic and basic conditions that affect living organisms

Question 30

Water can dissociate into:

Changes in the concentration of these ions:

Changes in concentrations of ___and____ can drastically affect the :

Answer 30

Into hydronium ions and hydroxide ions

-Can have a great affect on living organisms

-changes in H+ and OH–

chemistry of a cell

Question 31

An acid

A base

Answer 31

Is any substance that increases the hydrogen ion concentration of a solution

Is any substance that reduces the hydrogen ion concentration of a solution

Question 32

In any aqueous solution at 25°C the product of H+ and OH– is constant and can be written as

Answer 32

[H+][OH–] = 10^–14

Question 33

The pH of a solution is defined by the negative logarithm of H+ concentration, written as

Answer 33

pH = –log [H+]

Question 34

For a neutral aqueous solution, [H+] is 10^–7, so

Answer 34

pH = –(–7) = 7

Question 35

Concentrations of H+ and OH– are

Adding certain solutes, called ____________, modifies the :

Biologists use the pH scale to describe whether:

Answer 35

equal in
 pure water

-acids and bases

-concentrations of H+ and OH–

-a solution is acidic or basic (the opposite of acidic)

Question 36

Acidic solutions have pH values:

Answer 36

less than 7

Question 37

Basic solutions have pH values :

Answer 37

greater than 7

Question 38

Most biological fluids have pH values:

Answer 38

in the range of 6 to 8

Question 39

The pH of a solution is determined by

Answer 39

-the relative concentration of hydrogen ions
-Is low in an acid
-Is high in a base

Question 40

The internal pH of most living cells
Must remain close to

Answer 40

pH 7

Question 41

Buffers

Consist of an :

example of a buffer:

Answer 41

Are substances that minimize changes in the concentrations of hydrogen and hydroxide ions in a solution

acid-base pair that reversibly combines with hydrogen ions

Carbonic acid, an example of a buffer in human blood and other biological solutions

Question 42

Acid precipitation refers to :

Is caused primarily by the

Acid rain is thought to be responsible for

Acid precipitation can damage:

Answer 42

rain, snow, or fog with a pH lower than pH 5.6

• mixing of different pollutants with water in the air lowering pH below 5.2; example: H2SO4 and
  HNO3

-killing trees in many forests,

-life in Earth’s ecosystems

Question 43

Acidification
Human activities such as______________ also threaten water quality

main product of fossil fuel combustion

Answer 43

• burning fossil fuels

-CO2

Question 44

About ___% of human-generated CO2 is absorbed by

CO2 dissolved in____________ forms ____________; this process is called:

Answer 44

-25% of human-generated CO2 is absorbed by the oceans

• sea water; carbonic acid
  ocean acidification

Question 45

As seawater acidifies,

_______________ is required for calcification (production of calcium carbonate) by many marine organisms, including reef-building corals

Answer 45

H+ ions combine with carbonate ions to produce bicarbonate (HCO3)

Carbonate

Carbonic acid dissociates into hydrogen ions and bicarbonate

The added H+ combines with carbonate ions forming more bicarbonate ions

Question 46

The remarkable properties of water support life on Earth in many ways

Astrobiologists seeking life on other planets are concentrating their search on

To date, more than 800 planets have been found outside our solar system; one or two of them contain water

In our solar system, _______ has been found to have water

Answer 46

-planets with water

-Mars