7.1

Question 1

Define autotrophs

Answer 1

Produced their own organic molecules through photosynthesis

Question 2

Define heterotrophs

Answer 2

Live on organic compounds produced by other organisms

Question 3

Explain oxidation reactions

Answer 3

loss of electrons

Question 4

Explain reduction reactions

Answer 4

gain of electrons

Question 5

Explain dehydrogenation reactions

Answer 5

lost electrons are accompanied by protons

Question 6

Define cellular respiration

Answer 6

• Includes both aerobic and anaerobic respiration but is often used to refer to aerobic respiration
• The fuel is oxidized and ultimately the final acceptor is reduced

Question 7

Explain the role of NAD+ in cellular respiration

Answer 7

• Electrons from organic compounds are usually first transferred to Nicotinamide adenosine dinucleotide (NAD+)
   NAD+ accepts 2 electrons and 1 proton to become NADH
• NADH passes the electrons to the electron transport chain
• The electron transport chain passes electrons in a series of steps instead of one explosive reaction
• Oxygen pulls electrons down the chain in an energy-yielding tumble
• The energy yielded is used to regenerate ATP

Question 8

Differentiate fermentation

Answer 8

 Absence of oxygen
 only uses glycolysis
 Final electron acceptor
* Organic molecule
 Pyruvate is reduced in order to oxidize NADH back to NAD+

Question 9

Differentiate aerobic respiration

Answer 9

 Presence of oxygen
 Final electron acceptor
* Oxygen
 Produces significant amount of ATP
 Pyruvate is oxidized to acetyl-Co A which enters the citric acid cycle

Question 10

Differentiate anerobic respiration

Answer 10

 Absence of oxygen
 Final electron acceptor is an inorganic molecule other than oxygen

Question 11

Identify the two mechanisms cells use to make ATP

Answer 11

• Substrate-level phosphorylation
• Oxidative phosphorylation

Question 12

what is substrate-level phosphorylation

Answer 12

 Transfer phosphate group directly to ADP
 Glycolysis

Question 13

what is oxidative phosphorylation

Answer 13

 ATP synthase uses energy from a proton gradient
 Electron transport chain and chemiosmosis

Question 14

Identify the four stages of cellular respiration

Answer 14

• Glycolysis
   Converts glucose to 2 pyruvate molecules
• Pyruvate oxidation
   Pyruvate is oxidized in the presence of oxygen
• Citric acid cycle
   oxidize acetyl coA to CO2
• Electron transport chain & chemiosmosis

Question 15

Identify where in the cell glycolysis occurs

Answer 15

cytoplasm

Question 16

List the three major phases of glycolysis

Answer 16

1. priming reaction
   - energy investment
2. cleavage
   - sugar splitting step
3. oxidation and ATP formation
   - energy payoff phase

Question 17

Describe the process of glycolysis

Answer 17

• “sugar splitting” converts glucose to two molecules of pyruvate
• 10-step biochemical pathway
• Takes place in cytoplasm and has 3 major phases
• Occurs whether or not oxygen is present
• Net production of 2 ATP and 2NADH molecules

Question 18

Calculate the energy yield from glycolysis

Answer 18

2 ATP
2 NADH

Question 19

Contrast how NADH is recycled in aerobic respiration

Answer 19

 NADH is oxidized by the electron transport chain using oxygen as final electron acceptor
* Electrons are transferred through a series of membrane carriers, ultimately reducing oxygen and forming water
* Occurs in mitochondria
 Produces significant amount of ATP

Question 20

Contrast how NADH is recycled fermentation

Answer 20

 Pyruvate is reduced, oxidizing NADH in the absence of oxygen
* Organic molecule is the final electron acceptor
* May be acetaldehyde in ethanolic fermentation (yeast) or when pyruvate itself is directly reduced producing lactate

Question 21

Explain the fate of pyruvate in aerobic respiration

Answer 21

when oxygen is available
o Starts with oxidation of pyruvate to produce acetyl-CoA which enters the citric acid cycle

Question 22

Explain the fate of pyruvate in fermentation

Answer 22

when oxygen is unavailable
o Reduces pyruvate to oxidize NADH back to NAD+

Question 23

Identify where in the cell pyruvate oxidation occurs

Answer 23

mitochondria

Question 24

Identify where in the cell citric acid cycle occurs

Answer 24

matrix of mitochondria

Question 25

Identify where in the cell electron transport chain occurs

Answer 25

inner mitochondrial membrane

Question 26

Describe how pyruvate oxidation links glycolysis with the citric acid cycle

Answer 26

Glycolysis creates pyruvate which creates acetyl-CoA (in the presence of oxygen) which the citric acid cycle can then use in the mitochondria to create energy

Question 27

Name the complex that catalyzes pyruvate oxidation

Answer 27

pyruvate dehydrogenase

Question 28

Identify the products of pyruvate oxidation

Answer 28

• 1 CO2
• 1 NADH
• 1 Acetyl-CoA
• multiply by 2 for per glucose molecule