BIO 112 Exam 2

Question 1

Describe the difference between potential and kinetic energy.

Answer 1

Potential: has the potential to move or do work
Kinetic: energy associated with movement

Question 2

Most organisms get energy from food. Where exactly is the energy located in food?

Answer 2

It is stored in chemical bonds holding glucose atoms together

Question 3

Describe the path of energy from the sun until it reaches a form of energy that we can use. Include autotrophs and heterotrophs in your answer.

Answer 3

Autotrophs capture solar energy during photosynthesis and transfer it to the chemical bonds that hold glucose together. Heterotrophs catabolize glucose and transfer the energy that is released when the chemical bonds are broken into ATP.

Question 4

Do these metabolic processes link or break chemical bonds, use hydrolysis or dehydration synthesis, and store or release energy?
- Anabolic
- Catabolic
- Exergonic
- Endergonic

Answer 4

• Anabolic: link, dehydration synthesis, store
• Catabolic: break, hydrolysis, release
• Exergonic: break, hydrolysis, release
• Endergonic: link, dehydration synthesis, store

Question 5

Draw an exergonic and endergonic energy diagram and know which one is anabolic and which is catabolic.

Answer 5

• Exergonic & catabolic, starts high and ends low
• Endergonic & anabolic, starts low and ends high

Question 6

All organisms use ATP as a source of energy to fuel metabolic reactions. How does ATP store and release energy?

Answer 6

ATP (with 3 phosphates) stores energy by adding a terminal phosphate group to ADP (two phosphates). ATP releases energy by removing the terminal phosphate from ATP to make ADP.

Question 7

What is energy coupling and how does it occur?

Answer 7

Energy coupling is when ATP hydrolysis (the removal of the terminal phosphate group) is linked to another process. This occurs when ATP transfers the phosphate group to another molecule.

Question 8

Explain how exergonic/catabolic and endergonic/anabolic reactions influence the ADP-ATP cycle.

Answer 8

ATP becomes ADP and provides energy for endergonic/anabolic reactions, the energy to transform ADP into ATP comes from catabolic/exergonic reactions.

Question 9

Enzymes are catalysts. What is the definition of a catalyst as it applies to metabolism?

Answer 9

A catalyst lowers the amount of energy that is needed for a metabolic reaction occur.

Question 10

In the lock and key theory of enzymes and substrates, what is the lock and what is the key?

Answer 10

Enzyme - lock
Substrate - key

Question 11

Identify substrate, active site, enzyme, and allosteric site on a diagram.

Question 12

Describe the function of an allosteric site on an enzyme.

Answer 12

It turns off (inhibits) or turns on (activates) an enzyme by changing the active site shape when something binds to the allosteric site.

Question 13

Describe the difference between competitive and allosteric inhibition.

Answer 13

• Competitive inhibition: a substrate binds to the active site and blocks the normal substrate from binding
• Allosteric inhibition: something binds to the allosteric site, which changes the active site shape so the normal substrate can’t bind to it

Question 14

What is the default and altered condition of allosteric inhibition? Allosteric activation?

Answer 14

• Allosteric inhibition: default on, altered off
• Allosteric activation: default off, altered on

Question 15

Write the chemical equation for aerobic cellular respiration and list which substrates are oxidized, which are reduced, and the products each substrate becomes.

Answer 15

Glucose + oxygen —> CO2 + H2O
Glucose is oxidized to become CO2
Oxygen is reduced to become H2O

Question 16

Define redox reaction.

Answer 16

Reaction that transfers an electron from one molecule to another

Question 17

Define oxidation.

Answer 17

Process where a molecule loses an electron

Question 18

Define reduction.

Answer 18

Process where a molecule gains an electron

Question 19

What is the role of NAD+ in glycolysis?

Answer 19

NAD+ gets reduced to NADH and carries electrons to the electron transport chain

Question 20

Where does glycolysis occur?

Answer 20

In the cytoplasm

Question 21

What process produces ATP during glycolysis?

Answer 21

Substrate-level phosphorylation

Question 22

List the 3 starting materials for glycolysis and the final products.

Answer 22

Starting substrates: glucose, ADP, NAD+
Ending products: pyruvate, ATP, NADH

Question 23

List the molecules that enter and leave pyruvate oxidation.

Answer 23

Enter: pyruvate, NAD+
Exit: acetyl-coA, CO2, NADH

Question 24

List the starting and ending molecules in the citric acid (Krebs) cycle.

Answer 24

Starting: acetylene-coA, NAD+, ADP, FAD
Ending: CO2, NADH, ATP, FADH2

Question 25

What process produces ATP during the citric acid cycle?

Answer 25

Substrate-level phosphorylation

Question 26

Label the mitochondria structures that are involved in aerobic cellular respiration and list what processes occur at or in these structures.

Answer 26

Inner membrane: electron transport chain Matrix: pyruvate oxidation and citric acid cycle Intermembrane space: H+ gradient

Question 27

Describe the process of chemiosmosis. - ___ carried by ___ are dumped into the ___. - As they move down the chain, their ___ is used to build a ___. - The ___ pass through ___ to produce ___. - ___ end up ___ oxygen to ___.

Answer 27

Electrons carried by NADH are dumped into the ETC. As they move down the chain, their energy is used to build a H+ gradient. The protons pass through ATP synthase to produce ATP. Electrons end up reducing oxygen to water.

Question 28

What is oxidative phosphorylation?

Answer 28

Chemiosmosis where oxygen is the terminal electron acceptor

Question 29

Explain the difference between substrate-level and oxidative phosphorylation. - Transfer of energy - S-L: ___ is synthesized with a ___ transferred from a ___ to ___. - O: ___ is synthesized when a ___ dissipates through ___.

Answer 29

Substrate-level phosphorylation: direct transfer of energy - ATP is synthesized with a phosphate group transferred from a molecule to ADP Oxidative phosphorylation: indirect transfer of energy - ATP is synthesized when a proton gradient dissipates through ATP synthase

Question 30

Fermentation does not produce ATP so why do cells conduct fermentation?

Answer 30

It oxidizes NADH to NAD+ and the NAD+ is needed in glycolysis to produce ATP

Question 31

Describe what happens during lactic acid fermentation and alcoholic fermentation.

Answer 31

Lactic acid fermentation: pyruvate is oxidized, producing NAD+ and lactic acid Alcoholic fermentation: pyruvate is oxidized, producing NAD+, CO2, and ethanol

Question 32

List 3 benefits associated with food fermentation.

Answer 32

- Adds nutrients, flavor, and vitamins - Makes food more digestible by breaking down fibers - Preserves food by creating an acidic environment that food spoilage bacteria can’t live in

Question 33

What is the terminal electron acceptor and the relative amount of ATP produced for the following: - Aerobic respiration - Anaerobic respiration - Fermentation

Answer 33

- Oxygen; high - Nitrate, sulfate, or CO2; medium - Organic molecules; none

Question 34

Write the chemical equation for photosynthesis and list which substrates are oxidized, which are reduced, and the products each substrate becomes.

Answer 34

CO2 + H2O —> glucose + oxygen CO2 is reduced to become glucose H2O is oxidized to become oxygen

Question 35

Identify the chloroplast structures that are involved in photosynthesis and list what process occurs at each of these structures.

Answer 35

Thylakoid membrane: light reactions Lumen: H+ gradient Stroma: carbon reactions

Question 36

Which colors of the spectrum does chlorophyll absorb, why are plants green?

Answer 36

Absorbs red and blue, reflects green

Question 37

List two differences between oxidative phosphorylation and photophosphorylation.

Answer 37

Oxidative: oxygen is the terminal electron acceptor and energy comes from breaking glucose chemical bonds Photo.: NADP+ is the terminal electron acceptor and energy comes from the sun

Question 38

Describe what happens in a photosystem. - ___ within the light-harvesting complexes ___ light and pass ___ to a special pair of ___ molecules in the ___. - The absorbed ___ causes an ___ from ___ to be transferred to the ___. - The ___ that are transferred are replaced with ___ from ___.

Answer 38

Pigments within the light-harvesting complexes absorb light and pass energy to a special pair of chlorophyll a molecules in the reaction center. The absorbed energy causes an electron from chlorophyll a to be transferred to the ETC. The electrons that are transferred from chlorophyll a are replaced with electrons from water.

Question 39

Describe chemiosmosis in photosynthesis including its important components. - ___ from ___ moving through the ___ is used to build a ___ in the ___. - The ___ pass through ___ to produce ___.

Answer 39

Energy from electrons moving through the ETC is used to build a H+ gradient in the thylakoid space. The protons pass through ATP synthase to produce ATP.

Question 40

Trace the path of electrons during the light phase of photosynthesis.

Answer 40

Water —> photosystem II —> electron transport chain —> photosystem I —> NADP+

Question 41

Describe how the atoms that make up water are used in the light reactions.

Answer 41

Oxygen: not used (given off as a waste product) Hydrogen: helps build the H+ gradient Electrons: replaces electrons that leave photosystems

Question 42

Be able to identify where the following are located on a diagram: a-k

Question 43

Briefly describe what happens during the three steps of the Calvin cycle. Make sure you know what order these processes occur in.

Answer 43

Carbon fixation (aka carboxylation): CO2 attached to RuBP by rubisco Reduction: ATP and NADPH supply energy to be locked into chemical bonds Regeneration: RuBP is regenerated