Light Dependent

Question 1

What is photosynthesis?

Answer 1

The process of converting light energy to chemical energy to make carbohydrates.

Question 2

What happens to atoms during photosynthesis?

Answer 2

Excitation of atoms by light energy, particularly the electrons.

Question 3

Define chemical reaction.

Answer 3

A process in which one or more substances (reactants) form new substances (products), involving changes in structure and state of matter.

Question 4

What are oxidation-reduction reactions (redox reactions)?

Answer 4

Chemical reactions that involve the transfer of electrons between two chemical compounds.

Question 5

What is oxidation?

Answer 5

The loss of electrons.

Question 6

What is reduction?

Answer 6

The gain of electrons.

Question 7

What is a reducing agent?

Answer 7

A reactant that causes the reduction of another reactant by donating electrons.

Question 8

What is an oxidizing agent?

Answer 8

A reactant that causes the oxidation of another reactant by accepting electrons.

Question 9

Fill in the blank: Phosphorylation means to _______.

Answer 9

[add a phosphate group]

Question 10

Fill in the blank: Dephosphorylation means to _______.

Answer 10

[remove a phosphate group]

Question 11

What are enzymes?

Answer 11

Catalysts in biochemical reactions that speed up chemical reactions.

Question 12

What suffix do enzyme names typically end with?

Answer 12

-ase.

Question 13

What is the function of lipase?

Answer 13

Helps in breaking down lipids into glycerol and fatty acid chains.

Question 14

What is the role of electron carriers?

Answer 14

Binds and carries high energy electrons between compounds in pathways.

Question 15

What is the oxidized form of NADP+?

Answer 15

NADP+.

Question 16

What is the reduced form of NADP+?

Answer 16

NADPH.

Question 17

Where does photosynthesis take place?

Answer 17

Inside the chloroplast.

Question 18

What is mesophyll?

Answer 18

Tissue in the leaf’s interior where chloroplasts are found.

Question 19

What are thylakoids?

Answer 19

Flattened sacs in chloroplasts, site of light-dependent reactions.

Question 20

What occurs during light-dependent reactions?

Answer 20

Solar energy is absorbed, driving the transfer of electrons and hydrogen ions to produce ATP and NADPH.

Question 21

What are the two major events of photosynthesis?

Answer 21

• Light-dependent reactions * Light-independent reactions (Calvin Cycle)

Question 22

What is the primary function of photosystems?

Answer 22

To absorb sunlight and use it to energize electrons.

Question 23

What are the two types of photosystems?

Answer 23

• Photosystem II * Photosystem I

Question 24

What is the reaction center of Photosystem II?

Answer 24

P680.

Question 25

What is the reaction center of Photosystem I?

Answer 25

P700.

Question 26

What happens when a photon strikes a pigment molecule in photosystem II?

Answer 26

It boosts an electron to a higher energy level.

Question 27

What happens to excited electrons in the reaction center?

Answer 27

They escape to the primary electron acceptor.

Question 28

True or False: The chemical equation in a chemical reaction must always be balanced.

Answer 28

True.

Question 29

What happens when an electron switches from the Excited State to the Ground State?

Answer 29

An electron goes back to a lower energy orbital, and energy is released.

Question 30

What is the role of a photon in the excitation of pigment electrons?

Answer 30

A photon strikes a pigment molecule, boosting one of its electrons to a higher energy level.

Question 31

What is P680 in the context of Photosystem II?

Answer 31

P680 is a pair of chlorophyll a molecules in the PS II reaction-center complex that gets excited by energy.

Question 32

What occurs after electrons escape from P680?

Answer 32

P680 becomes P680+ (missing an electron), and the electrons must be replaced.

Question 33

What is the source of replacement electrons for P680?

Answer 33

Water is the source of replacement electrons for P680.

Question 34

What products are generated from the splitting of a water molecule?

Answer 34

Two electrons, two hydrogen ions (H+), and one oxygen atom.

Question 35

What is an Electron Transport Chain (ETC)?

Answer 35

A series of membrane-bound carriers that pass electrons from one carrier to another.

Question 36

Which components make up the electron transport chain between PS II and PS I?

Answer 36

Plastoquinone (Pq), a cytochrome complex, and plastocyanin (Pc).

Question 37

What does the buildup of H+ ions in the thylakoid space create?

Answer 37

An electrochemical gradient between the thylakoid space and stroma.

Question 38

What is chemiosmosis?

Answer 38

The process where H+ ions flow through ATP synthase, releasing energy to convert ADP into ATP.

Question 39

What happens when photons strike the pigments of PS I?

Answer 39

Energy is relayed to the reaction center chlorophyll a (P700), exciting its electrons.

Question 40

What is the role of NADP+ reductase in the light-dependent reactions?

Answer 40

It helps transfer electrons to NADP+, reducing it to NADPH.

Question 41

What are the two types of electron flow in light reactions?

Answer 41

* Non-Cyclic Electron Flow (Linear Electron Flow) * Cyclic Electron Flow

Question 42

What is produced during Cyclic Electron Flow?

Answer 42

Only ATP is produced, with no NADPH generated.

Question 43

What happens when the ATP supply drops in the chloroplast?

Answer 43

The chloroplast shifts to cyclic photophosphorylation to replenish ATP.

Question 44

In cyclic electron flow, where do photoexcited electrons from PS I get shunted?

Answer 44

They are shunted back from ferredoxin (Fd) to chlorophyll via the cytochrome complex and plastocyanin (Pc).

Question 45

What is the final product of the reduction of NADP+?

Answer 45

NADPH.

Question 46

Fill in the blank: The process of ATP production through the flow of H+ ions is called _______.

Answer 46

[chemiosmosis]

Question 47

True or False: The second electron transport chain creates a proton gradient.

Answer 47

False.