BIO 181 Exam 3

How many molecules of water are needed to completely hydrolyze a polymer that is 11 monomers long?

B) 10

Which of the following is not a polymer?

B) Glucose

The molecular formula for glucose is C6 H12 O6. What would be the milecular formula for a molecule made by linking three glucose together by dehydration reactions?

C) C18 H32 O16

An example of a hydrogen bond is the bond between?

A) The H of one water molecule and the O of another water molecule

Which of the following solutions has the greatest concentration of hydrogen ions [H+]

A) gastric juice at pH 2

Which of the following statements correctly defines a kilocalorie?

A) the amount of heat required to raise the temperature of 1kg of water by 1*C

Which of the following solutions has the greatest concentration of hydroxyl ions [OH-]

B) Seawater at pH 8

The slight negative charge at one end of one water molecule is attracted to the slight positive charge of another water molecule. What is this attraction called?

B) a hydrogen bond

A molecule with the chemical formula C6 H12 O6 is probably a?

C) Carbohydrate and monosaccharide only

What is the chemical mechanism by which cells make polymers from monomers?

C) Dehydration reactions

Why does ice float in liquid water?

C) Hydrogen bonds stabilize and keep the molecules of ice farther apart than the water molecules of liquid water

Lactose, a sugar in milk, is composed of one glucose joined by a glycosidic linkage to one galactose molecule. How is lactose classified?

C) as a disaccharide

If the pH of a solution is increased from pH 5 to pH7, it means that the?

C) concentration of OH- is 100 times greater than what it was at pH 5

In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by?

C) polar covalent bonds

Based on your knowlegde of the polarity of water molecules, the solute molecule is most likely

C) positively charged

Which of the following ionizes completely in solution and is considered to be a strong acid

D) HCI

Which of the following statements is true about buffer solutions?

D) They maintain a relatively constant pH when either acids or bases are added to them

Water's high specific heat is mainly a consequence of the?

D) absorption and release of heat when hydrogen bonds break and form

One liter of a solution of pH 2 has how many more hydrogen ions(H+) than 1 liter of a solution of pH 6?

E) 10,000 times more

Which of the following best summarizes the relationship between dehydration reactions and hydrolysis?

E) A and B are correct Dehydration reactions assembles polymers, and hydrolysis reactions break down polymers Macromolecular synthesis occurs through the removal of water and digestion occurs through the addition of water

If the pH of a solution is decreased from 9 to 8, it means that the?

E) Both B and D are correct Concentration of H+ has increased 10-fold(10X) compared to what it was at pH 9 Concentration of OH- has decreased to one-tenth (1/10) what it was at pH 9

Buffers are substances that help resist shifts in pH by?

E) Both B and D are correct Donating H+ to a solution when they have been depleted Accepting H+ when they are in excess

Which of the following ionizes completely in solution and is considered to be a strong base(alkali)?

E) NaOH

Pure, freshly-distilled water has a pH of 7. This means that?

E) The concentration of H+ ions in the water equals the concentration of OH- ions in the water