Bio Midterm

Which element would need to be removed from the molecule in Figure 6-2 to make it unsaturated?

• Carbon

• Hydrogen

• Oxygen

• Phosphorus

Consider the energy diagram for a chemical reaction in Figure 6-3. Overall, is energy released or absorbed?

• Absorbed, because the energy level increases during the reaction.

• Absorbed, because the energy level of the products is greater than that of the reactants.

• Released, because the reaction is initiated by the addition of heat.

• Released because the energy level of the reactants is greater than that of the products.

Which is the best description of activation energy?

• Heat added to initiate a reaction.

• Heat released as the reaction proceeds.

• Heat stored within the reactant molecules.

• Heat stored within the product molecules

A spontaneous chemical reaction occurs more rapidly when the reactants are held at 35 C rather than 25 C. Why would this be the case?

• The activation energy would be lower

• The activation energy would be higher

• The net energy release would be lower

• The net energy release would be greater

How does an enzyme influence a biological reaction?

• It increases the net energy difference between reactants and products

• It decreases the activation energy necessary to initiate the chemical change

• It increases the kinetic energy of reactants, thereby increasing their tendency to collide

• It decreases the kinetic energy of reactants, enabling them to undergo chemical change more easily

A student set up four test tubes containing starch solution in which to perform starch digestion. Supplies included amylase (enzyme that digests starch) and an incubator. In which tube listed would starch digestion proceed most quickly?

• Tube 1: No amylase, room temperature (25 C)

• Tube 2: No amylase, body temperature (37 C)

• Tube 3: Amylase present, room temperature (25 C)

• Tube 4: Amylase present, body temperature (37 C)

When added to water, how does an acid affect the pH and H+ concentration?

• Both pH and H+ decrease

• Both pH and H+ increase

• The pH decreases while the H+ increases

• The pH increases while the H+ decreases

Which element is found in proteins but not carbohydrates or lipids?

• C

• B

• N

• O

In humans and other multicellular organisms, which substance plays a central role as an energy source?

• Carbohydrate

• Fat

• Protein

• Water

Glycogen, used to store energy in the liver and muscle tissue, is an example of which type of molecule?

• Carbohydrate

• Protein

• Saturated fatty acid

• Steroid