Water Test
Joe has 20 L of a 2 g/L solution. He diluted it, and created 3 L of a 1 g/L solution. How did he make such a solution?
(2)(V1)=(1g)(3L) 1.5 L
Joe has 20 L of a 2 g/L solution. To this solution he adds 30 L. What is the final concentration of the solution?
(2g/L)(20L)=(C2)(50L) .8 g
Joe has a 2g/L solution. He diluted it and creates 3 L of a 1 g/L solution. How much of the original solution did he dilute?
(2g/L)(V1)=1g(3L) L= 1.5 L
Cohesion/Adhesion
Cohesion is due to the weak hydrogen bonds that hold it together. Adhesion also helps connect one substance to another. These properties are important when transferring water. In a plant, the cohesiveness of the water pulls up water molecules farther down the plant,making sure that the plant is hyrdated against the force of gravity.
For each property, describe one example of how the property affects the functioning of living organisms.
Cohesion of water is essential to plants because it allows them to get water up their stems to the entire plant. High specific heat- Because most organisms are mostly water, this high specific heat allows them to adapt easier to changes in temperatures around them. Water's high surface tension is important for many animals, the water strider for example, is able to transport themselves across a body of water's surface without breaking it.
C2=
Final concentration of the solution, after dilution
V2=
Final volume after dilution
Describe the structural formula of water.
One molecule of water has one oxygen atom and two hydrogen atoms
C1=
Original concentration of the solution, before it gets watered down or diluted
Describe the types of bonds formed within a water molecule and between water molecules. How many other water molecules can bond with a water molecule.
Polar covalent bond between the water and oxygen: causes the hydrogen to become slightly positive and the oxygen to become slightly negative, polar because electronegativity is larger than .4 for each bond. Hydrogen bond: a weak bond between a molecule, each water can have 4 hydrogen bonds.
High Specific Heat
This can also be linked to hyrdrogen bonding. For a hydrogen bond to be broken, heat must be absorbed, and heat is released when it is formed.
High Surface Tension
This means that its surface is more difficult to stretch and break than the surfaces of other liquids. The reason for this is that the water molecules on the surface of the liquid are hydrogen-bonded to each other, but also to the molecules below them, creating a surface between the water and air.
V1=
Volume about to be diluted
How many molecules of water are needed to completely hydrolyze a polymer that is 11 monomers long? a. 10 b. 9 c. 12 d. 11 e. 8
a
In the double helix structure of nucleic acids, cytosine hydrogen bonds to a. guanine. b. ribose. c. adenine. d. deoxyribose. e. thymine.
a
The bonding of two amino acid molecules to form a larger molecule requires which of the following? a. removal of a water molecule b. addition of a water molecule c. formation of an ionic bond d. formation of a hydrogen bond e. both A and C
a
The enzyme amylase can break glycosidic linkages between glucose monomers only if the monomers are the á form. Which of the following could amylase break down? a. glycogen b. cellulose c. chitin d. A and B only e. A, B, and C
a
What is the pH of a solution with a hydroxyl ion(OH-) concentration of 10-12 M? a. pH 2 b. pH 12 c. pH 10 d. pH 14 e. pH 4
a
What is the term used for a protein molecule that assists in the proper folding of other proteins? a. chaperonin b. renaturing protein c. denaturing protein d. enzyme protein e. tertiary protein
a
Which bonds are created during the formation of the primary structure of a protein? a. peptide bonds b. hydrogen bonds c. disulfide bonds d. phosphodiester bonds e. A, B, and C
a
Which of the following ionizes completely in solution and is considered to be a strong base (alkali)? a. NaOH b. NH3 c. H2CO3 d. NaCl e. HCl
a
Why does ice float in liquid water? a. Hydrogen bonds stabilize and keep the molecules of ice farther apart than the water molecules of liquid water. b. Ice always has air bubbles that keep it afloat. c. The ionic bonds between the molecules in ice prevent the ice from sinking. d. The crystalline lattice of ice causes it to be denser than liquid water. e. The liquid water molecules have more kinetic energy and thus support the ice.
a
glucose and fructose. These two molecules are a. structural isomers. b. geometric isotopes. c. enantiomers. d. geometric isomers. e. nonisotopic isomers.
a
A strong covalent bond between amino acids that functions in maintaining a polypeptide's specific three-dimensional shape is a (an) a. hydrophobic interaction. b. disulfide bond. c. hydrogen bond. d. ionic bond. e. van der Waals interaction.
b
For this pair of items, choose the option that best describes their relationship. (A) The number of alpha glucose 1-4 linkages in cellulose (B) The number of alpha glucose 1-4 linkages in starch a. Item (A) is greater than item (B). b. Item (A) is less than item (B). c. Item (A) is exactly or very approximately equal to item (B). d. Item (A) may stand in more than one of the above relations to item (B).
b
The difference between the sugar in DNA and the sugar in RNA is that the sugar in DNA a. can attach to a phosphate. b. contains one less oxygen atom. c. has a six-membered ring of carbon and nitrogen atoms. d. is a six-carbon sugar and the sugar in RNA is a five-carbon sugar. e. can form a double-stranded molecule.
b
The á helix and the â pleated sheet are both common polypeptide forms found in which level of protein structure? a. primary b. secondary c. tertiary d. quaternary e. all of the above
b
Upon chemical analysis, a particular polypeptide was found to contain 100 amino acids. How many peptide bonds are present in this protein? a. 100 b. 99 c. 98 d. 101 e. 97
b
Water is able to form hydrogen bonds because a. the oxygen atom in a water molecule has a weak positive charge. b. the bonds that hold together the atoms in a water molecule are polar covalent bonds. c. each of the hydrogen atoms in a water molecule is weakly negative in charge. d. oxygen has a valence of 2. e. the water molecule is shaped like a tetrahedron.
b
Which of the following hydrocarbons has a double bond in its carbon skeleton? a. CH4 b. C2H4 c. C3H8 d. C2H2 e. C2H6
b
Which of the following takes place as an ice cube cools a drink? a. A calorie of heat energy is transferred from the ice to the water of the drink. b. Kinetic energy in the drink decreases. c. Molecular collisions in the drink increase. d. The specific heat of the water in the drink decreases. e. Evaporation of the water in the drink increases.
b
Which type of interaction stabilizes the alpha (á) helix and the beta (â) pleated sheet structures of proteins? a. ionic bonds b. hydrogen bonds c. nonpolar covalent bonds d. hydrophobic interactions e. peptide bonds
b
Why are hydrocarbons insoluble in water? a. They are hydrophilic. b. The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages. c. They are lighter than water. d. The majority of their bonds are polar covalent carbon-to-hydrogen linkages. e. They exhibit considerable molecular complexity and diversity.
b
A molecule with the formula C18H36O2 is probably a a. protein. b. carbohydrate. c. fatty acid. d. nucleic acid. e. hydrocarbon.
c
At which level of protein structure are interactions between the side chains (R groups) most important? a. primary b. secondary c. tertiary d. quaternary e. all of the above
c
The structural level of a protein least affected by a disruption in hydrogen bonding is the a. secondary level. b. All structural levels are equally affected. c. primary level. d. tertiary level. e. quaternary level.
c
Which of the following contains nitrogen in addition to carbon, oxygen, and hydrogen? a. a monosaccharide such as glucose b. a steroid such as testosterone c. an amino acid such as glycine d. an alcohol such as ethanol e. a hydrocarbon such as benzene
c
Which of the following is not a polymer? a. cellulose b. starch c. glucose d. chitin e. DNA
c
A carbon skeleton is covalently bonded to both an amino group and a carboxyl group. When placed in water it a. is impossible to determine how it would function. b. would function only as an acid because of the carboxyl group. c. would function as neither an acid nor a base. d. would function as both an acid and a base. e. would function only as a base because of the amino group.
d
Research indicates that acid precipitation can damage living organisms by a. buffering aquatic systems such as lakes and streams. b. decreasing the Hmc013-1.jpg concentration of lakes and streams. c. increasing the OHmc013-2.jpg concentration of lakes and streams. d. washing away certain mineral ions that help buffer soil solution and are essential nutrients for plant growth. e. both B and C
d
Testosterone and estradiol are a. nucleic acids. b. phospholipids. c. carbohydrates. d. steroids. e. proteins.
d
The function of each protein is a consequence of its specific shape. What is the term used for a change in a protein's three-dimensional shape or conformation due to disruption of hydrogen bonds, disulfide bridges, or ionic bonds? a. stabilization b. renaturation c. destabilization d. denaturation e. hydrolysis
d
The tertiary structure of a protein is the a. organization of a polypeptide chain into an á helix or â pleated sheet. b. bonding together of several polypeptide chains by weak bonds. c. overall protein structure resulting from the aggregation of two or more polypeptide subunits. d. unique three-dimensional shape of the fully folded polypeptide. e. order in which amino acids are joined in a polypeptide chain.
d
What gives rise to the cohesiveness of water molecules? a. hydrophobic interactions b. nonpolar covalent bonds c. ionic bonds d. hydrogen bonds e. both A and C
d
Which of the following polymers contain nitrogen? a. starch b. glycogen c. cellulose d. chitin e. amylopectin
d
Which of the following statements correctly describes geometric isomers? a. They have different molecular formulas. b. They have the same chemical properties. c. Their atoms and bonds are arranged in different sequences. d. They have variations in arrangement around a double bond. e. They have an asymmetric carbon that makes them mirror images.
d
A molecule with the chemical formula C6H12O6 is probably a a. carbohydrate. b. lipid. c. monosaccharide d. A and B only. e. A and C only.
e
All of the following statements concerning saturated fats are true except a. They are one of several factors that contribute to atherosclerosis. b. They are more common in animals than in plants. c. They contain more hydrogen than saturated fats having the same number of carbon atoms. d. They generally solidify at room temperature. e. They have multiple double bonds in the carbon chains of their fatty acids.
e
Altering which of the following levels of structural organization could change the function of a protein? a. primary b. secondary c. tertiary d. quaternary e. all of the above
e
Consider two solutions: solution X has a pH of 4; solution Y has a pH of 7. From this information, we can reasonably conclude that a. solution Y has no free hydrogen ions (Hmc014-1.jpg). b. the concentration of hydrogen ions in solution X is 30 times as great as the concentration of hydrogen ions in solution Y. c. the concentration of hydrogen ions in solution Y is 1,000 times as great as the concentration of hydrogen ions in solution X. d. the concentration of hydrogen ions in solution X is 3 times as great as the concentration of hydrogen ions in solution Y. e. None of the other answer choices correctly describes these solutions.
e
If 2 molecules of the general type shown in Figure 5.1 were linked together, carbon 1 of one molecule to carbon 4 of the other, the single molecule that would result would be a. sucrose. b. glucose. c. galactose. d. fructose. e. maltose.
e
Large organic molecules are usually assembled by polymerization of a few kinds of simple subunits. Which of the following is an exception to this statement? a. cellulose b. an enzyme c. a contractile protein d. DNA e. a steroid
e
Temperature usually increases when water condenses. Which behavior of water is most directly responsible for this phenomenon? a. the change in density when it condenses to form a liquid or solid b. reactions with other atmospheric compounds c. the high surface tension of water d. the release of heat by the breaking of hydrogen bonds e. the release of heat by the formation of hydrogen bonds
e
Which action could produce a carbonyl group? a. the replacement of the nitrogen of an amine with oxygen b. the addition of a thiol to a hydroxyl c. the addition of a hydroxyl to a phosphate d. the addition of a sulfhydryl to a carboxyl e. the replacement of the -OH of a carboxyl group with hydrogen
e
Which chemical group is most likely to be responsible for an organic molecule behaving as a base? a. carbonyl b. hydroxyl c. phosphate d. carboxyl e. amino
e
Which of the following is a false statement concerning amino groups? a. They are basic in pH. b. They contain nitrogen. c. They are found in amino acids. d. They are components of urea. e. They are nonpolar.
e
Which of the following statements best describes the carbon atoms present in all organic molecules? a. They were incorporated into organic molecules by plants. b. They were processed into sugars through photosynthesis. c. They are ultimately derived from carbon dioxide. d. Only A and C are correct. e. A, B, and C are correct.
e
You have a freshly-prepared 1M solution of glucose in water. You carefully pour out a 100 mL sample of that solution. How many glucose molecules are included in that 100 mL sample? a. 12.04 ´ 10-23 b. 6.02 ´ 10-24 c. 3.01 ´ 10-23 d. 6.02 ´ 10-23 e. 6.02 ´ 10-22
e