COMP 1

Question 1

What term is used to refer to NADP in its reduced form?

Answer 1

Reduced NADP

The term ‘reduced NADP’ is used instead of NADPH + H+.

Question 2

What are the two types of photophosphorylation?

Answer 2

• Cyclic photophosphorylation
• Non-cyclic photophosphorylation

Question 3

What is the role of photolysis in the light-dependent stage?

Answer 3

It splits water into hydrogen, oxygen, and electrons.

Question 4

How is ATP produced during the light-dependent reaction?

Answer 4

Using ATP synthetase.

Question 5

Describe cyclic photophosphorylation.

Answer 5

PS1 absorbs light
This excites 2 electrons
Electron transport chain picks up electrons , generating ATP
Electron pairs exit and return back into PS1

Question 6

Describe non-cyclic photophosphorylation.

Answer 6

Electrons from PS11 have not returned
Replaced by photolysis - splitting of water molecule

Question 7

What happens to chlorophyll in PSII during non-cyclic photophosphorylation?

Answer 7

It is left with a positive charge, neutralized by electrons from the photolysis of water.

Question 8

What does the ‘Z scheme’ refer

Answer 8

The passage of electrons in non-cyclic photophosphorylation drawn like the letter Z.

Question 9

What is photolysis?

Answer 9

The splitting of water molecules by light, producing hydrogen ions, electrons, and oxygen.

Question 10

What is the consequence of the electrons not being returned to PSI in non-cyclic photophosphorylation?

Answer 10

The chlorophyll in PSI is left with a positive charge.

Question 11

What generates the electrochemical gradient in the thylakoid space?

Answer 11

Protons being pumped from the stroma into the thylakoid space.

Question 12

What does phosphorylation mean?

Answer 12

The addition of a phosphate group to a molecule.

Question 13

What is the primary source of energy for ATP production in the light-dependent reactions?

Answer 13

The energy released as electrons pass through the electron transport chain.

Question 14

Fill in the blank: The electrons produced in photolysis replace those lost from ______.

Answer 14

PSI.

Question 15

True or False: Cyclic photophosphorylation involves a linear pathway of electrons.

Answer 15

False.

Question 16

What byproducts are produced during the photolysis of water?

Answer 16

• Hydrogen
• Oxygen
• Electrons

Question 17

What is the function of an electron acceptor in cyclic photophosphorylation?

Answer 17

It picks up emitted electrons from PSI and passes them down the electron transport chain.

Question 18

What is the result of the proton gradient formed in the thylakoid space?

Answer 18

It generates potential energy for ATP synthesis.

Question 19

What does chemiosmosis generate?

Answer 19

ATP from the proton gradient.

Question 20

What is the role of nitritifying bacteria in the nitrogen cycle?

Answer 20

They convert ammonium ions to nitrites and nitrites to nitrates, releasing protons and electrons.

Question 21

What is the main process that involves the conversion of carbon dioxide and water into organic molecules?

Answer 21

Photosynthesis

Photosynthesis consists of light-dependent and light-independent stages.

Question 22

What are the two main types of reactions in photosynthesis?

Answer 22

Light-dependent reactions and light-independent reactions

Light-dependent reactions occur in the thylakoid membranes, while light-independent reactions occur in the stroma.

Question 23

Where do the light-dependent reactions of photosynthesis take place?

Answer 23

In the thylakoid membranes

The thylakoid membranes contain pigments that absorb light.

Question 24

What is the role of pigments in the light-dependent reactions?

Answer 24

To absorb photons of light and transfer energy to the reaction center

Pigments are crucial for capturing light energy.

Question 25

What enzyme is responsible for the oxidation of water in photosynthesis?

Answer 25

Photosystem II (PSII) ## Footnote PSII contains the only known enzyme that oxidizes water.

Question 26

What are the three factors that maintain the proton gradient between the thylakoid and the stroma?

Answer 26

* The proton pump associated with the electron transport chain * The photolysis of water in the thylakoid space * The removal of protons from the stroma reducing NADP ## Footnote These factors are essential for ATP production.

Question 27

What does the light-dependent stage of photosynthesis produce?

Answer 27

* NADPH * ATP * Oxygen ## Footnote These products are used in the light-independent reactions.

Question 28

Fill in the blank: The light-independent stage of photosynthesis occurs in the _______.

Answer 28

stroma ## Footnote The stroma is the fluid-filled space inside chloroplasts.

Question 29

What is the enzyme that catalyzes the reaction between ribulose bisphosphate and carbon dioxide?

Answer 29

Ribulose bisphosphate carboxylase (rubisco) ## Footnote Rubisco is the most abundant protein in the biosphere.

Question 30

What unstable compound is formed when ribulose bisphosphate combines with carbon dioxide?

Answer 30

A six-carbon compound ## Footnote This compound quickly splits into two molecules of glycerate-3-phosphate.

Question 31

What is the first carbohydrate made in photosynthesis?

Answer 31

Triose phosphate ## Footnote Triose phosphate is produced from the reduction of glycerate-3-phosphate.

Question 32

What molecule is reformed during the Calvin cycle to allow the cycle to continue?

Answer 32

Ribulose bisphosphate (RuBP) ## Footnote ATP provides the energy necessary for the regeneration of RuBP.

Question 33

True or False: The light-independent reactions require light to occur.

Answer 33

False ## Footnote Light-independent reactions do not directly require light but use the products from light-dependent reactions.

Question 34

What happens to most of the triose phosphate produced during photosynthesis?

Answer 34

It goes through a series of reactions to regenerate RuBP ## Footnote This regeneration is crucial for the continuation of the Calvin cycle.

Question 35

What is the role of reduced NADP in the light-independent reactions?

Answer 35

It serves as a source of reducing power to reduce carbon dioxide ## Footnote Reduced NADP is generated in the light-dependent stage.

Question 36

How is glucose phosphate formed in the Calvin cycle?

Answer 36

Some triose phosphate is converted to glucose phosphate and then into starch by condensation ## Footnote This process stores energy in the form of starch.

Question 37

What is light intensity in relation to photosynthesis?

Answer 37

A significant factor in controlling the rate of photosynthesis.

Question 38

How does light intensity affect the rate of photosynthesis?

Answer 38

As light intensity increases, the rate of photosynthesis increases until a certain point, after which it remains constant.

Question 39

What happens to photosynthetic pigments at high light intensity?

Answer 39

They can be damaged, leading to inefficient light absorption and failure of the light-dependent stage.

Question 40

Fill in the blank: Light intensity is a ______ factor in controlling the rate of photosynthesis.

Answer 40

limiting

Question 41

True or False: Light intensity is always a limiting factor for plant growth.

Answer 41

False.

Question 42

How does temperature affect the rate of photosynthesis?

Answer 42

Increased temperature increases the rate of photosynthesis until enzymes denature at high temperatures.

Question 43

Fill in the blank: Temperature is a ______ factor in controlling the rate of photosynthesis.

Answer 43

limiting

Question 44

What happens to enzymes at high temperatures?

Answer 44

They progressively denature, decreasing the rate of photosynthesis.