Chapter 3 Water: AP Biology

ocean acidification

-cause is the same as global warming (increase in CO2 in the atmosphere) -CO2 in water lowers the pH -carbonic acid dissociates into bicarbonate, which dissociates into carbonate (H+ is released, so the pH goes down) -because carbonate dominates at basic pH levels, and is used to make up shells and coral reefs, a higher pH level prevents calcium carbonate from forming

specific heat

-ex: at night, hydrogen bonds return, released in heat so that air temperature doesn't drop as much -ex: cacti stores water to stabilize temperature so it doesn't rise as far in the day or fall as far at night

Nonpolar molecules

-excluded by H2O -hydrophobic -can't make hydrogen bonds -interferes with H2O hydrogen bonding -forms clumps and migrates to surface of pushed into water

polar molecules

-mingle freely with H2O -hydrophilic -partial charges attract them to H2O -clumps are disbursed by H2O -dispersed molecules are available for chemical reactions

amphipathic molecules

-part of molecule is polar, part is nonpolar -polar part attracts H2O -water rejects nonpolar parts -results in organize groups of molecules -created biological structures, like membranes

10

1 pH change = _____ H+ concentration change

lattice

A regular arrangement of points in space (oxygen at points) -crystals

added heat

At boiling, all the __________ _______ is used to break hydrogen bonds. Free of the water mass, the departing stream carries away all the added energy, with none left over to raise the temperature.

B

In a water molecule, what type of bond is found between the oxygen and the hydrogens? A. hydrophobic B. polar covalent C. Nonpolar covalent D. Ionic E. Hydrophilic

a lot

It takes __ ___ of heat energy to change the temperature of water or make it vaporize.

more, less

More polar molecules dissolve _______ easily, but less polar molecules dissolve _______ easily.

small amount

Much of the heat absorbed by H2O is used to break H bonds. Only a _______ _________ of heat is left over to increase molecule motion, which increases temperature slightly.

electronegative

Oxygen is more _____________ than hydrogen, so it exerts a far stronger pull on electrons than hydrogen, so electron spend more time closer to oxygen.

B

Water has surface tension because... A. molecules at the surface make more hydrogen bonds B. hydrogen bonds between surface water molecules resist being stretched C. water tends to evaporate from the surface D. cohesion forces are weaker at the service E. there is positive pressure inside the water mass

D

Water is a source of ________ for chemical reactions in cells. A. hydrogen atoms B. oxygen atoms C. Energy D. A and B E. A, B, and C

provides

Water ________ hydrogen and oxygen atoms for making many biological molecules. -ex: photosynthesis (CO2 + H2O= O2+ C6H12O6) and protein/starch digestion

E

Which statement helps to explain why ice is less dense than liquid water? A. water molecules make hydrogen bonsai definite angles B. Cold molecules move less than warm molecules C. hydrogen bonds lengthen in the cold D. all of the above E. A and B

E

Which statement is true of water's tensile strength? A. it results from hydrogen bonding B. it helps to pull water through plants C. it involves both cohesion and adhesion D. A and B E. A, B, and C

C

Which statement must be mentioned in explaining why amphipathic molecules lineup at a water surface? A. non-polar groups repel water B. non-polar groups attract one another C. polar groups attract one another D. polar groups repel water E. all of the above

E

Why don't certain insects drown in water? A. The insect is flying just above the water surface B. The insect is very light C. The insect is swimming D. It is difficult to change the temperature of water E. The high surface tension of water allows the insect to remain on the surface

base

any substance that decreases the H+ concentration of a solution -pH > 7 -H+ < OH-

Acid

any substance that increases the H+ concentration of a solution -pH < 7 -H+ > OH-

Paper towels

are made up of molecules from plant cell walls, which form hydrogen bonds with H2O -cohesion pulls in more H2O molecules when soaking up water

Freezing

because there's two little energy to break bonds, each molecule forms for bonds that pull the molecules into a lattice arrangement

Adhesion

maintains the width of water mass by holding water to cell walls (or metal pipes) -Without it, the pulling force on H2O would make its mass thinner and thinner until it's so narrow that it breaks

Temperature

measures the heat energy of the average atom or molecule

leaf evaporation

moves water molecules up through the roots -exerts a pool relayed down word along a string of H2O molecules from leaf to root -as each water molecule evaporates, it pulls on the next water molecule (this relays the pull of evaporating H2O molecules all the way down to the roots)

boiling

occurs when all molecules have so much energy that their motions break most of the hydrogen bonds -liquid changes to gas bubbles (steam) -if heat is added, temperature stays the same because he is used to break hydrogen bonds -steam carries away energy

evaporation

process that exerts the pool on water molecules that is relayed from leaf to root via cohesion

surface tension

resists the entry of water repellent objects -to overcome it, a nonpolar object must push hard enough to break many hydrogen bonds -small object will sink if it concentrates enough weight on an area, which won't have enough hydrogen bonds to resist the force -ex: water strider

tensile strength

results from hydrogen bonds between water (cohesion) andand to cell walls (adhesion) -ex: water molecules in leaf evaporation resist breaking apart b/c of this

cooling by evaporation

sweating cools you off (pores open because of heated body, releasing sweat, and heat is transferred from skin to sweat, so then sweat evaporates)

coheres, adheres

Because of hydrogen bonding, water _________ it to itself and ________ to cell walls. That makes it possible to pull water through plants without breaking the water column.

B

Because of ocean acidification, the price of which of the following foods is most likely to increase? A. squid B. shellfish C. tuna D. swordfish

polar covalent bonds

Bonds between oxygen and hydrogen (because oxygen has a negative charge and hydrogen has a positive charge)

A

Dissolving is best described as... A. A mingling of molecules and/or ions B. Breaking covalent bonds C. A separation of molecules into neutral atoms D. molecules breaking into ions E. A change from a solid to a liquid

4, hydrogen

Each water molecule is joined to _____ other water molecules by ___________ bonds.

organizes

H2O _________ other kinds of molecules into structures that make up cells based on polarity (nonpolar, polar, amphipathic).

heat

H2O can gain and lose _______ with little change in temperature because much of it is used to break hydrogen bonds.

dissociate

H2O molecules break apart into hydrogen ions and hydroxide ions or ___________ into ions (rarely).

C

How are oyster larvae affected by ocean acidification? A. oyster larvae are killed by carbon dioxide in acidified ocean waters B. acidified ocean waters are too cloudy for photosynthesis to occur underwater C. oyster larvae cannot grow shells in acidified ocean waters D. acidified ocean waters favorite fish that eat oyster larvae

break

Some molecules _______ into ions, but most won't. -ex: sugar molecules stay intact and trade their original H bonds with water -ex: Salt doesn't consist of molecules, so it's just ions that separate in water

higher, lower

The _________ the pH, the _______ the H+ concentration.

neutral solution

The concentration of hydrogen ions is equal to the concentration of hydroxide ions

time

The electrons spend more _______ with the oxygen of the water molecule then with a hydrogens of water. -Thus, the oxygen has a net negative charge and the hydrogens have a net positive charge.

stretched

The hydrogen bonds between surface water molecules are normally slightly __________. Like a _________ sheet of rubber, the service tends to contract and resists being penetrated.

open

The ice lattice has _________ spaces because of the angles at which hydrogen bonds form. Heat energy can break water molecules free of the lattice so they move into the openings.

aquatic life

The open spaces in water's crystal structure make it possible for ___________ ______ to exist at the North Pole.

less dense

The openings in the lattice make ice _______ _________ than liquid water, so it floats. That causes water to freeze from the top down, so there's always liquid in which organisms can live.

freezing point

The temperature at which a liquid changes into a solid (< 0°)

electronegativity

The tendency of an atom to pull electrons towards itself is referred to as its _________.

D

The unequal sharing of electrons within a water molecule makes the water molecule... A. have a low surface tension B. ionic C. hydrophobic D. polar E. change easily from a liquid to gaseous form

repulsion

There is no _________ between nonpolar molecules and water; they don't mix because water molecules attract one another and won't make room for molecules that lack attractive charged regions. -water molecules pull one another together behind the departing nonpolar molecule

D

Though you add heat, the temperature of boiling water remains constant because..... A. it takes energy to break covalent bonds B. water has a constant boiling temperature C. it takes energy to circulate water D. it takes energy to break hydrogen bonds E. None of the above. The temperature rises during boiling.

C

What is the chemical reaction responsible for the oceans becoming more acidic? A. carbon dioxide reacts with sea water, forming sulfuric acid B. methane reacts with sea water, forming carbon dioxide C. carbon dioxide reacts with sea water, forming carbonic acid D. carbon dioxide reacts with sea water, forming nitric acid

B

What is the main reason that oceans are becoming more acidic? A. The dumping of garbage and sewage into the oceans B. absorption by the oceans of carbon dioxide generated by burning fossil fuels C. large crude oil spills in the ocean D. fertilizer runoff in major rivers flowing into the oceans

sugar, salt

When _________ dissolves in water, the molecules remain intact but mingle with water molecules. When _______ dissolves, its Na+ and Cl- ions separately mingle with water.

energy

When molecules collide and rebound, one may give ________ to the other. The average molecule gains ________ as much as it loses _________.

molecular motion

When you heat water, much of the heat is used to break hydrogen bonds. Only the remaining heat can increase _____________ ____________, raising the temperature.

D

Which factor is important in making it possible to cool yourself by sweating? A. molecules collide with varied angles and speed B. hydrogen bonds are relatively weak C. water has more energy at the body surface D. A and B E. A, B, and C

A, B

Which of the following are consequences of ocean acidification? Select all that apply. A. corals and coral reefs are not able to form their hard skeletons B. clams, muscles, lobsters, and shrimp are not able to form strong enough shells C. animals and oceans cannot get enough oxygen D. Ocean temperatures are dropping

A

Which of the following helps most to explain why water has a high specific heat? A. A water molecule can make four hydrogen bonds B. The water molecule has exceptionally strong covalent bonds C. water temperature is exceptionally sensitive to heat D. A and B E. B and C

pure water

concentration of H+ and OH- are equal (has a pH of 7, which is neutral)

polar

________ water molecules pull together, holding the _________ parts of the amphipathic molecules and squeezing out the nonpolar parts. That leaves the nonpolar parts waving in the air.

random collisions

__________ ____________ allows some molecules to accumulate more energy than other molecules. The weakness of hydrogen bonds lets those molecules escape, leaving the cooler molecules behind.

objects

____________ will sink if it can make hydrogen bonds and soak up H2O.

Cohesion

hydrogen bonds cause H2O molecules to stick together -helps to keep gravity from pulling the H2O molecules back down in leaf evaporation -creates a force called surface tension

floating ice

insulates the water below, keeping it liquid

Ice density

is less than liquid water's density because hydrogen bonds pull molecules into a lattice -if temperature increases, heat breaks down the crystals and water molecules fill the spaces, forming a denser liquid -allows aquatic life to persist in areas with cold winters

oil

is nonpolar and can't form H bonds, so it can't mix with water

heat

is the total kinetic energy stored in a random motion of atoms or molecules

pH scale

used to express the concentration of hydrogen ions in a solution

hydrogen bonds

very week bonds that hold water molecules together

Sublimation

when solid ice turns into a gaseous vapor -even in the cold, molecules can gain enough energy in collisions to break away