76) Human babies and animals adapted to the cold are able to maintain their body temperatures because of the presence of brown fat. The mitochondria in brown fat have a protein in them called thermogenin, which allows the flow of hydrogen ions back through the inner mitochondrial membrane (bypassing the ATP synthase). Based on this and your understanding of cellular respiration, propose a mechanism by which brown fat helps keep babies and other animals warm.

77) Mitochondria can be isolated from cells and their production of ATP measured. You want to identify the mechanism of ATP production, so you isolate mitochondria, remove the outer membrane, and place them in a high pH solution. What will happen to the ATP production if you start to lower the pH by adding hydrogen ions to the solution?

Refer to the figure below, and then answer the question that follows.

78) Which stage or stages of aerobic respiration require both NAD+ and ADP as reactants?

A) glycolysis

B) the Krebs cycle

C) the electron transport chain

D) the Krebs cycle and the electron transport chain

E) glycolysis and the Krebs cycle

Refer to the figure below, and then answer the question that follows.

79) As electrons move through the electron transport chain, which of the following occurs?

A) Electrons are pumped from the inner compartment of the mitochondrion to the outer compartment of the mitochondrion.

B) Hydrogen ions move down their concentration gradient from the inner compartment of the mitochondrion to the outer compartment of the mitochondrion.

C) Energy from ATP is used to pump hydrogen ions across the inner membrane of the mitochondrion.

D) ATP is synthesized from ADP and P as hydrogen ions flow down the electron transport chain.

E) Hydrogen ions are pumped from the inner compartment of the mitochondrion to the outer compartment of the mitochondrion.