biology EXAM #1 pt. 3 Flashcards by vjhvbh ghcghcv

Water is

the molecule that supports all life

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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:

water

Three-quarters

The abundance of water

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properties of water

Polarity of water and hydrogen bonding

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The polarity of water molecules results

The water molecule is a

in hydrogen bonding

polar molecule

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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),.

Allows them to form hydrogen bonds with each other

Contributes to the various properties water exhibits

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

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

-Solvent of life

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cohesion is:
due to :
helps:

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

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adhesion:
what is it:
in plants it is:

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

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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.

entender

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surface tension:
is related to
The result is

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

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moderation of temperature

Water moderates air temperature by:

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.

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Kinetic energy is:

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

Is the energy of motion

-thermal energy

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Heat:

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

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Temperature:
represents the:

Measures the intensity of heat

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

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The specific heat of a substance:

The specific heat of water is

Water resists changing its temperature because

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

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

-minimize temperature fluctuations to within limits that permit life

hydrogen bonds break
hydrogen bonds form

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Evaporation:

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

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Heat of vaporization:

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

-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

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

This helps:

this is due to-
it allows-

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

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:

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

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

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

-animals that depend on ice for their survival

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:

-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

A hydrophilic substance:

Has an affinity for water

A hydrophobic substance:

Does not have an affinity for water

Oil molecules are hydrophobic because : Hydrophobic molecules related to oils are:

they  have relatively nonpolar bonds the major ingredients of cell membranes

Since most ________________ occur in water: -It is important to learn to : -When carrying out experiments,

-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

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

-the sum of all masses of all atoms in a molecule -MOLES molecules of a substance in a given mass

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

6.02 x 10^23 6.02x1023 = 1g -Is the number of moles of solute per liter of solution

The dynamic equilibrium of water molecules: Dissociation of water molecules leads to

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

Water can dissociate into: Changes in the concentration of these ions: Changes in concentrations of ___and____ can drastically affect the :

Into hydronium ions and hydroxide ions -Can have a great affect on living organisms -changes in H+ and OH– chemistry of a cell

An acid A base

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

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

[H+][OH–] = 10^–14

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

pH = –log [H+]

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

pH = –(–7) = 7

Concentrations of H+ and OH– are Adding certain solutes, called ____________, modifies the : Biologists use the pH scale to describe whether:

equal in  pure water -acids and bases -concentrations of H+ and OH– -a solution is acidic or basic (the opposite of acidic)

Acidic solutions have pH values:

less than 7

Basic solutions have pH values :

greater than 7

Most biological fluids have pH values:

in the range of 6 to 8

The pH of a solution is determined by

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

The internal pH of most living cells Must remain close to

pH 7

Buffers Consist of an : example of a buffer:

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

Acid precipitation refers to : Is caused primarily by the Acid rain is thought to be responsible for Acid precipitation can damage:

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

Acidification Human activities such as______________ also threaten water quality main product of fossil fuel combustion

- burning fossil fuels -CO2

About ___% of human-generated CO2 is absorbed by CO2 dissolved in____________ forms ____________; this process is called:

-25% of human-generated CO2 is absorbed by the oceans - sea water; carbonic acid ocean acidification

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

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

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

-planets with water -Mars