Chapter 3 Advanced Bio Test

What is Cohesion, and how does it help plants?

Collectively, hydrogen bonds hold water molecules together Cohesion in water is a property of water that makes its molecules attracted to each other. A water molecule is made of one oxygen atom bonded to two hydrogen atoms. / Helps the transport of water against gravity in plant

The water molecule is a ______ molecule

Polar

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

--Cohesive behavior - Ability to moderate temperature - Expansion upon freezing - Versatility as a solvent

What is a calorie

A calorie (cal) is the amount of heat required to raise the temperature of 1 g of water by 1°C

What is Surface Tension?

A measure of how hard it is to break the surface of a liquid, and is related to Cohesion

What is heat

A measure of the total amount of kinetic energy due to molecular motion

Describe Water Polarity

A water molecule is polar because the oxygen atom at the top of the molecule has a more negative charge, while the hydrogen atoms have a more positive charge. Molecules of water are attracted to each other through these differences in polarity, forming the important hydrogen bonds that give water many of its unique properties. The polar nature of water makes it almost a universal solvent; the negative and positive poles of the molecule react with other molecules to break them apart.

What is Adhesion, and give an example

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

What is an Acid?

Any substance that increases the H+ concentration of a solution / Acidic solutions have pH values less than 7

What is a base?

Any substance that reduces the H+ concentration of a solution / Basic solutions have pH values greater than 7

What is evaporative cooling and how does it help organisms?

Heat of vaporization is the heat a liquid must absorb for 1 g to be converted to gas as a liquid evaporates, its remaining surface cools, a process called evaporative cooling • Evaporative cooling of water helps stabilize temperatures in organisms and bodies of water

Why does Ice float?

Ice floats in liquid water because hydrogen bonds in ice are more "ordered," making ice less dense • Water reaches its greatest density at 4°C • If ice sank, all bodies of water would eventually freeze solid, making life impossible on Earth Makes the hydrogen bonds stable

What is a buffer?

Substances that minimize changes in concentrations of H+ and OH- in a solution • Most buffers consist of an acid-base pair that reversibly combines with H+

What is temperature

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

What is specific Heat?

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

What is Kinetic Energy

The energy of motion

Discuss the dissociation of water molecules

The hydrogen atom leaves its electron behind and is transferred as a proton, or hydrogen ion (H+) - The molecule with the extra proton is now a hydronium ion (H3O+), though it is often represented as H+ Acid - The molecule that lost the proton is now a hydroxide ion (OH-) Base

How does water act as a heat bank?

Water absorbs heat from warmer air and releases stored heat to cooler air Water can absorb or release a large amount of heat with only a slight change in its own temperature Has a high specific heat

How is water the solvent of life?

Water is a versatile solvent due to its polarity, which allows it to form hydrogen bonds easily • When an ionic compound is dissolved in water, each ion is surrounded by a sphere of water molecules called a hydration shell Water can also dissolve compounds made of nonionic polar molecules • Even large polar molecules such as proteins can dissolve in water if they have ionic and polar regions Pushes non-polar and non charged substances (breaks into smaller pieces)

How can water's high specific heat be traced to hydrogen bonding?

Water's high specific heat can be traced to hydrogen bonding - Heat is absorbed when hydrogen bonds break - Heat is released when hydrogen bonds form • The high specific heat of water minimizes temperature fluctuations to within limits that permit life