Biology - Chapter 3 practice test

The effects would be drastically worse because the loss of the polar nature of water would greatly reduce its specific heat and its ability to moderate temperature. A loss of the polar nature of water would equate to a loss in the ability to form hydrogen bonds. Breaking hydrogen bonds absorbs energy, which accounts for water's high specific heat and its ability to influence and moderate climate.

If water were NOT a polar molecule, how would the effects of global warming differ from those currently observed or predicted to occur in the future?

Systems for temperature regulation would have to be much more efficient. In order for living things to inhabit a wide range of environments, temperature regulation would need to be more efficient for a fluid with a lower specific heat.

Imagine that organisms consisted of 70-95% alcohol instead of 70-95% water. Alcohol's specific heat is about half that of water. How would living things be different?

The oxygen atom in one water molecule and a hydrogen atom in another water molecule. The slightly negatively charged region of an oxygen atom of one water molecule is attracted to the slightly positively charged region of a hydrogen atom of another water molecule.

In a group of water molecules, hydrogen bonds form between which of the following?

Hydrophobic. For example, the hydrophobic behavior of oil molecules results from a prevalence of nonpolar covalent bonds. Nonpolar molecules do not have an affinity for water or other polar molecules.

A molecule that has all nonpolar covalent bonds would be __________.

The clinging of one substance to another substance. Adhesion is the attraction of one substance to another.

Adhesion is best described as which of the following?

The temperature of living things tends to change relatively slowly. A variety of nutrient molecules is readily available as dissolved solutes. Waste products produced by cell metabolism can be easily removed.

Cells are surrounded by water, and cells themselves consist of about 70-95% water. Which of the following occurs as a result?

Because it is polar, water's negatively charged oxygen atoms and positively charged hydrogen atoms are attracted to positively and negatively charged ions and molecules. Polar water molecules surround the individual ions or charged molecules, separating and shielding the ions or molecules from one another.

How does the polarity of water contribute to its ability to dissolve so many substances?

Heat of vaporization

Sweating has a cooling effect because of water's high __________.

Both caused by water's partial charges. Two molecules of water are held together by a hydrogen bond formed between the slight positive charge of the hydrogen and the slight negative charge of the oxygen. Water is a very versatile solvent, a quality traced to the polarity of the water molecule.

The ability of water molecules to form hydrogen bonds with other water molecules and water's ability to dissolve substances that have charges or partial charges are __________.

The specific heat of that substance. The specific heat of a substance is defined as the amount of heat that must be absorbed or lost to change the temperature of 1 g of that substance by 1°C.

The amount of heat required to change the temperature of 1 g of any substance by 1°C is defined as __________.

The heat of vaporization of that substance. Heat of vaporization is the quantity of heat a liquid must absorb for 1 g of it to be converted from the liquid to the gaseous state.

The amount of heat required to convert 1 g of any substance from the liquid to the gaseous state is defined as __________.

Polar. Because molecules of polar solvents have a positive and a negative pole, polar solvents are excellent solvents for ions and for other polar materials.

Water is a very versatile solvent because water molecules are __________.

The unequal sharing of electrons between the hydrogen and the oxygen atoms of a water molecule. Because oxygen is more electronegative than hydrogen, electrons of the polar bond spend more time closer to the oxygen atom, resulting in a slight negative charge on the oxygen atom and slight positive charges on the hydrogen atoms.

The partial charges on a water molecule occur because of __________.

Cohesion. Cohesion is a consequence of hydrogen bonding between water molecules.

The phenomenon responsible for maintaining the upward movement of water through vessels in a tree is __________.

Specific heat

The reason that coastal climates are more moderate than inland climates primarily water's high __________.

is called cohesion, acts to moderate temperature, provides the surface tension that allows small animals to move across a water surface, and helps to keep water moving through the vessels in a tree trunk

The tendency of water molecules to stay close to each other as a result of hydrogen bonding __________.

a higher boiling point. More heat is needed to vaporize 1 g of water than most other liquids.

Water has __________ than other liquids such as ethanol , reflecting its capacity to absorb large amounts of heat.

That atoms in the molecule have partial charges as a result of unequal sharing of electrons in a covalent bond. In the case of water, the oxygen is slightly negative and the hydrogen atoms are slightly positive.

Water is a polar molecule. What does this statement mean?

Hydrophobic. Substances that are nonionic and nonpolar repel water.

What are nonpolar molecules that cluster away from water molecules called?

All are properties related to hydrogen bonding. The extraordinary qualities of water are emergent properties resulting from hydrogen bonding.

What do cohesion, surface tension, and adhesion have in common with reference to water?

Ice floats because it is less dense than liquid water; floating ice insulates water below and provides a habitat for some species. The significant increase in Arctic air temperature over the past 50 years is causing a reduction in sea ice, compromising these beneficial effects of sea ice. The warming that has occurred in the Arctic has significantly affected the seasonal balance between ice and liquid water to the degree that sea ice communities are in danger.

Which of the following accurately relates the emergent properties of water to the effects of global warming in the Arctic?

Ice floats. Because water molecules in ice are farther apart than in liquid water, ice is less dense, and therefore, it floats.

Which of the following occurs because molecules of water are farther apart in ice than in liquid water?

In order to perform their function of separating the aqueous solutions outside of cells from the aqueous solutions inside of cells, cell membranes cannot be soluble in water. If cell membranes were hydrophilic, they would break down and dissolve in the presence of water, rendering them useless as a barrier.

Why are cell membranes composed primarily of hydrophobic molecules?

Surface tension. Water has a greater surface tension, a measure of how difficult it is to break the surface of a liquid, than most other liquids.

You can fill a glass of water to just slightly above the rim without the water spilling over the glass. What property of water best explains this phenomenon?