AP Biology Carbohydrates

Based on the reaction shown, which of the following statements is true?

• The reverse of this reaction requires the removal of water from the reaction in order to break down the dimer.

• If water is not added to the reaction, hydrolysis will not occur.

• The reverse of this reaction requires the addition of water in order to build the dimer.

• If water is not added to the reaction, dehydration synthesis will not occur.

The human body is capable of digesting the complex polymer starch into simpler subunits. This digestive process requires the presence of water and the enzyme amylase in order to break down starch into maltose. This is depicted below. Which of the following statements best describes the digestion of starch into maltose?

• This is a hydrolysis reaction that requires water to break down a complex polymer into simpler subunits.

• This is a dehydration synthesis reaction that produces water when forming a complex polymer from simpler subunits.

• This is a dehydration synthesis reaction that requires water to form a complex polymer from simpler subunits.

• This is a hydrolysis reaction that forms water by breaking down a complex polymer into simpler subunits.

In the reaction below, two glucose monomers combine to form the dimer maltose. Which of the following best explains the process of this reaction?

• To form a covalent bond, the monomers underwent a hydrolysis reaction.

• An ionic bond forms through dehydration synthesis, which combines the two glucose monomers and forms the maltose dimer.

• Water is added to the reaction to promote the formation of a covalent bond between the glucose monomers.

• A covalent bond forms through dehydration synthesis, which results in the formation of maltose and water.

Which of the following questions would a researcher most likely ask if they wanted to know whether a hydrolysis reaction or a dehydration synthesis reaction is occurring?

• Is an enzyme involved in the reaction?

• Are monomers identical to one another?

• Is water a reactant or product of the reaction?

• Which polymer is involved in the reaction?

Which of the following best describes the role that water plays in the reaction depicted below?

• In the reverse of this reaction, water is used to promote hydrolysis.

• Water is a product of this dehydration synthesis reaction.

• When water is added, the two monomers form a covalent bond that holds the dimer together.

• As a reactant, water cleaves the covalent bond that holds the dimer together.

If water was removed from the reaction depicted above, which of the following describes the most likely outcome of this removal?

• The reverse of the reaction would occur and the dimer would spontaneously form from the two monomers.

• The covalent bond that holds the dimer together would not be cleaved because hydrolysis would not occur.

• The covalent bond that holds the dimer together would not be cleaved because dehydration synthesis would not occur.

• The reverse of the reaction would occur and a covalent bond would spontaneously form between the two monomers.

Lactose is a dimer sugar composed of two monomeric subunits (galactose and glucose). In an investigation, researchers placed intestinal cells in a nutrient medium containing lactose. The researchers determined that the lactose had broken down to galactose and glucose in the manner depicted in the reaction below. The cells were then modified and re-exposed to the lactose medium. The researchers were no longer able to detect the presence of galactose and glucose. Which of the following conclusions best explains an outcome of this modification?

• The cells were able to undergo a reverse reaction and build lactose.

• The cells were unable to hydrolyze lactose, resulting in the formation of a covalent bond between galactose and glucose.

• The cells were able to perform dehydration synthesis reactions in order to break down lactose into its monomeric subunits.

• The cells were unable to hydrolyze the lactose dimer into its monomeric subunits.

Glycogen is a highly branched macromolecule usually stored in liver and muscle cells. If blood glucose levels decrease, glycogen breaks down to release glucose in a process called glycogenolysis. In this process, the glycogen polysaccharide goes through hydrolysis and breaks down into glucose monosaccharides. If a toxin were to inhibit glycogenolysis, which of the following statements best predicts a consequence of this inhibition?

• In response to the detection of low glucose levels, more glucose will be released from stored glycogen.

• The covalent bonds within an individual glucose monomer will not be cleaved.

• The covalent bonds between individual glucose monomers will not be cleaved.

• In response to the detection of low glucose levels, glycogen will continuously be broken down to release glucose.

In the reaction depicted below, maltose is broken down into two molecules of glucose. Which of the following best explains the process of this reaction?

• The addition of a water molecule cleaves the covalent bond holding maltose together.

• The reverse of this reaction would require the addition of water to build the maltose dimer from the glucose monomers

• This breakdown process requires the release of water as a product of the reaction.

• The ionic bond of maltose is broken down through the addition of water in this hydrolysis reaction.