aerobic

process that requires air

Krebs cycle

The second stage of cellular respiration, in which pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions (p. 226)

electron

transport

chain

a series of proteins in which the high-energy electrons from the Krebs cycle are used to convert ADP into ATP (p 228)

What happens

during the Krebs cycle?

During the Krebs cycle, pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions.

How are high-energy electrons

used by the electron transport chain?

The electron transport chain uses high-energy electrons from the Krebs cycle to convert ADP into ATP.

Why is the Krebs cycle

 also known as

 the citric acid cycle?

Part A ends with citric acid,

 then in Part B the citric acid is broken down which ends up as ATP to be used for cellular activity (energy!).

See page 227 in text book

Why do runners

breathe heavily after a race?

You can think of a quick sprint building up an oxygen debt that a runner has to repay after the race with plenty of heavy breathing.

When the race is over, the only way to get rid of lactic acid is in a chemical pathway that requires extra oxygen.

Quick energy

lactic acid fermentation

(Can usually suppy enough ATP to last about 90 seconds for a quick sprint.)

Long-term energy

For exercise longer than about 90 seconds, cellular respiration is the only way to generate a continuing supply of ATP.

Comparing photosynthesis ad Cellular Respiration

They are almost opposite processes. 

Earlier in the chapter, the chemical energy in carbohydrates was compared to money in a savings account.  Photosynthesis is the process that "deposits"  energy.  Cellular respiration is the process that "withdraws" energy. The equations for photosynthesis and cellular respiration are the reverse of each other.

What happens to pyruvic acid during the Kreb cycle?