Chapter 2 Lab - Mastering

Which of the following helps most to explain why water has a high specific heat? (a) A water molecule can make 4 hydrogen bonds. (b) The water molecule has exceptionally strong covalent bonds. (c) Water temperature is exceptionally sensitive to heat. Both (a) and (b). Both (b) and (c).

(a) A water molecule can make 4 hydrogen bonds.

The open spaces in water's crystal structure make it possible for ... (a) aquatic life to exist at the North Pole. (b) water to have a low boiling point. (c) life to occur in hot springs. Both (b) and (c). (a), (b), and (c).

(a) aquatic life to exist at the North Pole.

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. Both (a) and (b). (a), (b), and (c).

(a), (b), and (c). (a) It results from hydrogen bonding. (b) It helps to pull water through plants. (c) It involves both cohesion

A buffer consists of undissociated acid (HA) and the ion made by dissociating the acid (A-). How does this system buffer a solution against decreases in pH? (a) HA dissociates and releases H+ and A- into solution. (b) A- reacts with H+ to become HA. (c) As the solution loses H+, HA replaces the lost H+. Both (a) and (c). None of the above.

(b) A- reacts with H+ to become HA.

Why doesn't oil mix with water? (a) Nonpolar molecules repel water molecules. (b) Polar molecules repel nonpolar molecules. (c) Polar molecules attract one another. (d) Nonpolar molecules attract one another. Both (a) and (d).

(c) Polar molecules attract one another.

Which statement is true of pH buffers? (a) They consist of strong acids and strong bases. (b) They keep the pH of the blood constant. (c) They consist of weak acids and weak bases. Both (a) and (b). Both (b) and (c).

(c) They consist of weak acids and weak bases.

To make a buffer, you need to ... (a) combine equal amounts of a strong acid and a strong base in water. (b) put either a strong acid or a strong base in water. (c) adjust the pH to 7.0. (d) have a weak acid or a weak base half ionized in water. Both (a) and (c).

(d) have a weak acid or a weak base half ionized in water.

Which pH value is the most acidic? *7 *5 *2 *12

2

Which pH value represents neutral? *3 *6 *7 *1 *3

7

Define denaturation. *A protein that has unfolded and broken down *A protein has linked with an enzyme and substrate *A protein that has been catalyzed *A protein that has linked together into a long polypeptide

A protein that has unfolded and broken down

Where does an enzyme bind to a substrate? *Active site *Distal edge *Receptor site *Acid monomer receptor

Active site

The pH scale ____________________. *is based on the hydrogen ion concertation of a solution *was devised in 1909 by a Danish biochemist *is a logarithmic scale *All of these statements are true. *ranges from 1 to 14

All of these statements are true.

Which answer helps to explain why all living cells need pH buffers? *Amino acid side chains have many carboxyl and amino groups. *ATP will not deliver energy if it is ionized. *Nucleic acids must have positive charges to form double helices. *Hydrogen bonds only form at medium pH values.

Amino acid side chains have many carboxyl and amino groups.

Which of these can release hydroxide ions? *Bases *Bases & Buffers *Acids *Buffers

Basses & Buffers

Water is a source of ______________ for chemical reactions in cells. (a) hydrogen atoms (b) oxygen atoms (c) energy Both (a) and (b) (a), (b), and (c)

Both (a) and (b) (a) hydrogen atoms (b) oxygen atoms

What factor is important in making it possible to cool yourself by sweating? Think carefully! (a) Molecules collide with varied angles and speeds. (b) Hydrogen bonds are relatively weak. (c) Water has more energy at the body surface. Both (a) and (b). (a), (b), and (c).

Both (a) and (b). (a) Molecules collide with varied angles and speeds. (b) Hydrogen bonds are relatively weak.

Which statement helps to explain why ice is less dense than liquid water? (a) Water molecules make hydrogen bonds at definite angles. (b) Cold molecules move less than warm molecules. (c) Hydrogen bonds lengthen in the cold. All of the above. Both (a) and (b).

Both (a) and (b). (a) Water molecules make hydrogen bonds at definite angles. (b) Cold molecules move less than warm molecules.

A substance that stabilizes pH is called a?

Buffer

Substances that stabilize the pH of a solution by either releasing H + when pH levels rise or binding H + when pH levels rise are called: *Bases *Acids *Neutral solutions *Buffers

Buffers

Which of the following structures represents the highest level of structural organization? *Atom *Cell *Organelle *Molecule

Cell

Which solution is the most likely to have a pH of 3 or 4? *Baking soda *Coffee *Water *Bleach

Coffee

To expand our lungs, pleural fluid is secreted into the pleural cavity and allows the lungs to "stick to" the inside of the cavity. When the muscles contract, the cavity expands, pulling our lungs open so that we can bring air into the lungs. Which property of water is used to expand our lungs? *Adhesion *Solubility *Cohesion *Reactivity

Cohesion

Which is an example of surface tension? *Hydrolysis reactions of water molecules and salts *Absorption of heat by the surface of a solution *Cohesion of water molecules at the air and water boundary of the alveolus *Tendency for evaporation on the surface of a solution

Cohesion of water molecules at the air and water boundary of the alveolus

What part of the atom is most critical for creating chemical bonds?

Electrons

In terms of chemical bonding, which part of the atom is the most important?

Electrons in outermost shell

What does enzyme specificity mean? *Enzymes require a specific temperature and pH for optimum activity *Enzymes can only bind to one type or shape of substrate. *Enzymes do not change or degrade after a reaction. *An enzyme is able to speed up several different chemical reactions

Enzymes can only bind to one type or shape of substrate.

As we exercise, our body produces heat through the process of cellular respiration. Although our body temperature does increase, the temperature change is slow and we are able to maintain a homeostatic temperature. Which property of water explains why our body temperature is slow to change? *Solubility *Adhesion of water *High heat capacity *High heat vaporization

High heat capacity

Two water molecules are weakly attracted to each other when a slightly positive hydrogen atom in the first molecule is attracted to the slightly negative oxygen atom on the second molecule. What type of bond is this? *Ionic *Hydrogen bond *Nonpolar covalent *Polar covalent

Hydrogen bond

Which of the following types of bonds occurs between water molecules?

Hydrogen bond (between water molecules but polar covalent bond within the water molecule)

Sodium chloride (NaCl) is an example of ___bond

Ionic bond

What happens to a protein that is exposed to acidic conditions? *It catalyzes. *It denatures. *It folds into a quarternary shape. *It reduces its pH.

It denatures.

In general, when comparing the effectiveness of over-the-counter antacids to sodium bicarbonate, how effective was sodium bicarbonate at neutralizing the acidity? *It had similar effectiveness *It had no effect *It was a lot more effective *It was a lot less effective

It had similar effectiveness

Why is Bromecresol purple used when demonstrating the role of buffers? *It makes a solution more acidic. *It stabilizes the pH of solution. *It reduces the acidity of a solution. *It indicates if a solution has changed from an alkaline to an acidic pH.

It indicates if a solution has changed from an alkaline to an acidic pH.

What happens to lactose when mixed with lactase? *It slowly breaks down into monosaccharides. *It more slowly bonds into disaccharides. *It folds more quickly into quarternary structures. *It more rapidly breaks down into monosaccharides.

It more rapidly breaks down into monosaccharides.

Much of the digestive system relies on the activity of enzymes. The stomach secretions include an enzyme (pepsin) along with HCl to reduce the pH in the stomach to a pH of 2. When the food moves into the small intestine, there are multiple secretions to raise the pH to 7. How would this pH change affect the activity of the stomach enzyme, pepsin? *It would denature pepsin. *It would increase the activity of pepsin. *There would be no change in the activity of pepsin. *The active site would be increased.

It would denature pepsin.

How does the way a buffer stabilizes pH during addition of acid differ from the way the same buffer stabilizes pH during addition of base? *The same buffer can't work for both acid and base. *In one case the buffer is strong; in the other case it's weak. *It's the same reaction running backward or forward. *In one case it adds H+; in the other case it adds OH-.

It's the same reaction running backward or forward.

What are the building blocks of carbohydrates? *Fatty acids *Glycerols *Amino acids *Monosaccharides

Monosaccharides

Two hydrogen atoms share electrons equally between each other, forming a molecule. What type of bond is this? *Polar covalent bond *Hydrogen bond *Ionic bond *Nonpolar covalent bond

Nonpolar covalent bond

Which statement must be mentioned in explaining why amphipathic molecules line up at a water surface? *Nonpolar groups attract one another. *Polar groups repel water. *Polar groups attract one another. *Nonpolar groups repel water. *All of the above.

Polar groups attract one another

Structure levels of protein: The amino acid sequence of the polypeptide.

Primary Structure

Rank the following levels of structural organization from smallest to largest unit: Cell, Molecule, Atom, Organelle, Proton

Proton, Atom, Molecule, Organelle, Cell

When added to an acidic solution, what color will Bromecresol purple buffer turn the solution? *Yellow *Purple *Green *Blue

Purple

Structure level of protein: The assembly of two or more polypeptide chains into the functional protein. Note that some proteins lack this structure.

Quarternary structure

As blood carbon dioxide levels rise, do blood hydrogen ion levels rise or fall? *Rise *Fall *There is no change.

Rise

Which level of organization is represented by an α-helix or β-pleated sheet? *Tertiary *Secondary *Primary *Quarternary

Secondary

Structure level of protein: Amino acids of the protein interact via H bonds to form an alpha helix or a beta-pleated sheet.

Secondary structure

Which solution would have the lowest concentration of hydrogen ions? *Solution with a pH of 3 *Solution with a pH of 10 *Solution with a pH of 5 *Solution with a pH of 8

Solution with a pH of 10

Structure level of protein: Interactions betwen R groups help to determine the shape the protein assumes after it is folded (Globular or fibrous protein).

Tertiary structure

A patient's blood pH has dropped from a normal of 7.4 to a low of 7.25. Describe the patient's blood pH. *The blood pH is now basic (alkaline) *The blood pH is now acidotic. *The blood has too little hydrogen ion. *The blood pH is too high.

The blood pH is now acidotic.

What happens when an acid and a base are mixed? *They buffer a solution. *They form salts and water. *They release electrons and protons. *They neutralize a solution.

They form salts and wate

What happens to blood hydrogen ion levels as carbon dioxide levels rise? *There is no change. *They go up. *They go down.

They go up

The action of many prescription drugs is to block the effects of enzymes by competitive inhibition. Explain what this means to your patient that is taking one of the drugs. *This drug helps by binding to the substrate instead of the enzyme. *This drug helps by breaking down the enzyme. *This drug helps by blocking the binding of the substrate to the active site. *This drug helps by blocking the binding of the substrate by binding to the enzyme.

This drug helps by blocking the binding of the substrate to the active site.

When is hydrolysis used? *To remove water molecules from macromolecules *To remove ethanol molecules from macromolecules *To break apart macromolecules *To merge smaller molecules into macromolecules

To break apart macromolecules (breaking them apart by adding the water back)

T/F pH imbalances are corrected by respiratory & urinary systems.

True

T/F Amino acids are monomeric unit of polypeptide chain.

True (Protein is made up of one or more linear chains of amino acids, each of which is called a polypeptide)

T/F- Nonpolar covalent bonds are hydrophobic.

True (they don't like to bond with water)

Why does an increase in carbon dioxide increase the quantity of hydrogen ions in blood? *When carbon dioxide is dissolved in water, it forms carbonic acid. *When carbon dioxides dissolves in water, it releases hydroxides. *When carbon dioxide mixes with water, it loses two electrons. *When carbon dioxide mixes with blood, it slows the transfers of hydrogen ions.

When carbon dioxide is dissolved in water, it forms carbonic acid.

Buffers work best when ... *about half of the buffer molecules are dissociated. *the pH is nearly neutral. *the ratio of H+ to OH- is close to 1.0. *nearly all of the buffer molecules are dissociated. *nearly all of the buffer molecules are undissociated.

about half of the buffer molecules are dissociated.

A solution with a pH of 3 is said to be __________, whereas a solution with a pH of 9.0 is said to be ____________. alkaline; neutral acidic; basic neutral; acidic alkaline; acidic

acidic; basic

The tendency for water molecules to stick or cling to another surface is called ________.

adhesion

A solution with a pH of 13 is called ______________. *neutral *acidic *alkaline *covalent

alkaline (basic)

This molecular compound is made from just three elements: carbon, hydrogen and oxygen and vary in number of carbons they have.

carbohydrates

Enzymes are biological ______, and they function to ________. *lipids; increase the rate of chemical reactions *proteins; break down carbohydrates *catalysts; increase the rate of chemical reactions *catalysts; decrease the rate of chemical reactions

catalysts; increase the rate of chemical reactions

The tendency of water molecules to cling to one another is called __________, and the tendency of water molecules to cling to another substance is called ______.

cohesion; adhesion

Dehydration synthesis is ___________. *breaking of a chemical bond by adding a water molecule *creation of a chemical bond by removing a water molecule *breaking of a chemical bond by removing a water molecule *creation of a chemical bond by adding a water molecule

creation of a chemical bond by removing a water molecule

How would an increase in hydrogen ions change the pH of blood?

decrease the pH

A mingling of molecules & ions describes what process?

dissolving

Bonds between neighboring water molecules is a ____ bond.

hydrogen bond

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

hydrogen bonds between surface water molecules resist being stretched.

The breaking of chemical bonds by the addition of water is a chemical reaction called

hydrolysis

Bond between metal and nonmetal

ionic bond

If a protein denature, then _________. *it is linked with an enzyme and substrate *it has unfolded and lost its three-dimensional structure *its primary structure is altered *it has catalyzed a chemical reaction

it has unfolded and lost its three-dimensional structure

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

it takes energy to break hydrogen bonds.

The pH scale ________________________. *measures the salt concentration of a solution *measures the hydrogen ion concentration of a solution *ranges from 1 to 7 *defines neutral as a pH of 5

measures the hydrogen ion concentration of a solution

Glucose is a _________. *polysaccharide *disaccharide *monosaccharide *polymer

monosaccharide (monosaccharides-deoxyribose, ribose, glucose, fructose, galactose / disaccharides-sucrose / polysaccharide-glycogen)

The basic building block(s) of carbohydrates is(are) *fatty acids. *monosaccharides. *glycerol. *starch. *amino acids.

monosaccharides

H2 is an example of a ___bond.

nonpolar covalent bond

What tool would help you determine the hydrogen ion concentration of urine? *Refractometer *Bromecresol purple *Deionized water *pH test strip

pH test strip

Water molecules rely on ________ to hold their hydrogen and oxygen atoms together.

polar covalent bonds

Glycogen is a _______. *simple sugar *monosaccharide *disaccharide *polysaccharide

polysaccharide

An enzyme is a ________. *monomer *carbohydrate *protein *lipid

protein

A buffer will ________. *bind hydroxide ions when the pH level drops *release hydrogen ions when the pH level rises *release hydrogen ions when the pH level drops *release hydroxide ions when the pH level rises

release hydrogen ions when the pH level rises

Enzyme specificity _____________________. *results because enzymes remain unchanged by the reactions in which they participate *results from the structure of the enzyme's active site *occurs because enzymes are proteins *explains why enzymes speed up chemical reactions

results from the structure of the enzyme's active site

When acids and bases are mixed, they react to form a __________and __________. *buffer; neutral solution *electron; proton *salt; water *neutral solution; water

salt; water

In a mixture of salt water, the salt is called the _____________. *solvent *substrate *solute *solution

solute

Because so many inorganic and organic molecules dissolve in water, water is known as the ____.

universal solvent

Water is called ________ because most molecules will dissolve in it.

universal solvent

Bromocresol purple is a pH indicator that turns in ______ in acidic environments and _____ in basic environments. *yellow; purple *green; yellow *blue; purple *purple; yellow

yellow; purple