Chapter 3: water Flashcards

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1
Q

The water molecule is a ___: The opposite ends have opposite charges.

A

polar molecule

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2
Q

Four of water’s properties that facilitate an environment for life are:​

A

Cohesive behavior​

Ability to moderate temperature​

Expansion upon freezing​

Versatility as a solvent
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3
Q

Collectively, hydrogen bonds hold water molecules together, a phenomenon called ___

A

cohesion​

Cohesion helps the transport of water against gravity in plants

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4
Q

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

A

Adhesion

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5
Q

___ is a measure of how hard it is to break the surface of a liquid

A

Surface tension

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6
Q

The ___ of a substance is the amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1ºC

A

specific heat

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7
Q

Water’s high specific heat can be traced to ___

A

hydrogen bonding

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8
Q

The ___ of water minimizes temperature fluctuations to within limits that permit life

A

high specific heat

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9
Q

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

A

evaporative cooling ​

Evaporative cooling of water helps stabilize temperatures in individual organisms

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10
Q

Ice floats in liquid water because, Solid water, or ice, is less ___ than liquid water. Ice is less dense than water because the orientation of hydrogen bonds causes molecules to push farther apart, which lowers the density.

A

dense

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11
Q

A ___ is a liquid that is a homogeneous mixture of substances

A

solution

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12
Q

A ___ is the dissolving agent of a solution​

A

solvent

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13
Q

The ___ is the substance that is dissolved​

A

solute

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14
Q

In an ___ water is the solvent

A

aqueous solution

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15
Q

A ___ substance is one that has an affinity for water (water-loving)

A

hydrophilic

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16
Q

A ___ substance is one that does not have an affinity for water (water-fearing)

A

hydrophobic

Oil molecules are hydrophobic

17
Q

A hydrogen atom in a hydrogen bond between two water molecules can shift from one to the other:
The hydrogen atom leaves its electron behind and is transferred as a proton, or hydrogen ion
(The molecule that lost the proton is now a ___

The molecule with the extra proton is now a ___, though it is often represented as H+

A

hydroxide ion (OH–)

hydronium ion (H3O+)

18
Q

Water is in a state of ___ in which water molecules dissociate at the same rate at which they are being reformed
In pure water, the concentration of the hydronium ion (H3O+ or H+) is equal to the concentration of the hydroxide ion (OH-)

A

dynamic equilibrium

19
Q

Changes in concentrations of H+ and OH– can drastically affect the ___ of a cell

A

chemistry

20
Q

Adding certain solutes, called ___ and ___, changes the concentrations of H+ and OH–

A

acids and bases

21
Q

Biologists use something called the ___ to describe whether a solution is acidic or basic

A

pH scale

22
Q

The pH scale ranges from ___.

A

0 to14

23
Q

An ___ is any substance that increases the H+ concentration of a solution

A

acid

Acidic solutions have pH values less than 7

24
Q

A ___ is any substance that reduces the H+ concentration (or increases the OH- concentration) of a solution

A

base (alkaline)

A basic solution has a pH value greater than 7

25
Q

Most biological fluids have pH values in the range of ___

A

6 to 8

26
Q

Each pH unit represents a ___ change in H+ ion concentration.

A

10 fold magnitude

10x10, 10x10x10, etc

27
Q

___ are substances that minimize changes in concentrations of H+ and OH– , and help maintain the pH of cells at a constant level

A

Buffers

The internal pH of most living cells must remain close to pH 7