IAL Biology Unit 4 Progress Quiz 2025 - 2026

Created by

Hosni chembio

teacher

Created by

Hosni chembio

teacher

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What is the process of adding phosphate to a molecule called?

Phosphorylation

What is photophosphorylation?

Adding phosphate to a molecule using energy from light

Define photolysis.

The splitting of a water molecule using light energy into an oxygen atom and two protons

What does hydrolysis refer to?

The splitting of a molecule using water

What are redox reactions?

Reactions that involve oxidation and reduction

What is ATP and its role in cells?

ATP (adenosine triphosphate) is the energy currency for cells in all organisms.

What are the three components of ATP?

Nitrogen base (adenosine), sugar (ribose), and three phosphate groups

What enzyme catalyzes the hydrolysis of ATP?

ATPase

What is the result of the hydrolysis of ATP?

ADP, inorganic phosphate group (Pi), and energy

How can ADP be converted back into ATP?

Through phosphorylation, which is a condensation reaction that requires a supply of energy.

What is photosynthesis?

The process where light energy is used to break the bonds in water molecules.

What do plants do with glucose produced during photosynthesis?

Glucose can be stored as starch or respired to release energy.

What is a coenzyme?

A molecule that aids the function of an enzyme.

What is NADP and its role in photosynthesis?

NADP is a coenzyme that transfers hydrogen atoms from one molecule to another.

Describe the structure of chloroplasts.

Chloroplasts have a double membrane called the chloroplast envelope and contain thylakoids arranged in stacks called grana.

What are thylakoids?

Fluid-filled sacs within chloroplasts that contain photosynthetic pigments.

What is the action spectrum?

The rate of photosynthesis at different wavelengths of light.

How is the Rf value calculated in chromatography?

Rf value = Distance travelled by the pigment / Distance travelled by the solvent.

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Boost your knowledge before diving into past papers. Use these questions to reinforce your understanding of the lessons and supercharge your revision. They'll help you recall key concepts and stay on top of your studies

Questions

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1. What is photophosphorylation?

A Adding phosphate to a molecule using energy from respiration B Adding phosphate to a molecule using water C Adding phosphate to a molecule using energy from ATP D Adding phosphate to a molecule using energy from light

2. What is the role of ATPase in the hydrolysis of ATP?

A It stores energy B It catalyzes the reaction C It inhibits the reaction D It transports ATP

3. What is the result of the hydrolysis of ATP?

A ATP, water, and energy B ADP, inorganic phosphate group, and energy C ADP, glucose, and energy D ADP, oxygen, and energy

4. What is photolysis?

A The splitting of a water molecule using enzymes B The splitting of a water molecule using light energy C The splitting of a water molecule using respiration D The splitting of a water molecule using ATP

5. What happens to glucose in plants?

A It can be converted into oxygen B It can be stored as starch or respired to release energy C It can be used to make ATP directly D It can be broken down into amino acids

6. What is the role of NADP in photosynthesis?

A Producing ATP B Splitting water molecules C Transferring hydrogen atoms from one molecule to another D Absorbing light energy

7. What is the function of the chloroplast envelope?

A Stores chlorophyll B Produces glucose C Keeps the reactants for photosynthesis close to their reaction sites D Transports water

8. Why do thylakoids have a large surface area?

A To separate different reactions B To allow as much light energy to be absorbed as possible C To store more enzymes D To produce more ATP

9. What is the role of the stroma in the chloroplast?

A Transports hydrogen atoms B Contains enzymes needed for making glucose C Produces oxygen D Stores light energy

10. How do coenzymes assist enzymes?

A By changing enzyme shape B By transferring a chemical group from one molecule to another C By providing energy D By absorbing light

11. What is the primary function of photosystems in the thylakoid membranes?

A To transport water within the plant B To store energy in the form of ATP C To absorb light energy for photosynthesis D To produce oxygen directly

12. Why do plants appear green?

A Because they do not contain any pigments B Because they absorb all wavelengths of light C Because they reflect red wavelengths of light D Because chlorophyll pigments reflect green wavelengths of light

13. What is the action spectrum?

A The range of wavelengths that plants can reflect B The rate of photosynthesis at different wavelengths of light C The different amounts of light absorbed by a pigment D The spectrum of colors visible to the human eye

14. How can the action spectrum of different pigments be determined?

A By calculating the energy levels of excited electrons B By exposing a water plant to different wavelengths of light and measuring oxygen production C By observing the color change in pigments under different lights D By measuring the absorption of light by pigments in a solution

15. What happens when chlorophyll a is exposed to ultraviolet light?

A The chlorophyll becomes inactive B Green fluorescence is observed due to energy absorption C Red fluorescence is observed due to excited electrons returning to lower energy levels D The chlorophyll molecules break down

16. What is the Rf value in chromatography?

A The distance travelled by the pigment B The ratio of the distance travelled by the pigment to the distance travelled by the solvent C The ratio of the distance travelled by the solvent to the distance travelled by the pigment D The distance travelled by the solvent

17. What is the final electron acceptor in the electron transport chain during photosynthesis?

A NADP B ATP C Oxygen D Water

18. What happens during photolysis in photosynthesis?

A Carbon dioxide is fixed into glucose B Water is split into protons, electrons, and oxygen C ATP is synthesized from ADP and inorganic phosphate D NADP is reduced to NADPH

19. Why is it important to compare Rf values using the same solvent?

A Different solvents have no effect on Rf values B Rf values differ in different solvents C Rf values are always the same regardless of the solvent D Solvents do not affect pigment solubility

20. What is cyclic phosphorylation?

A A process that produces ATP when there is plenty of NADPH and little ATP B A process that produces NADPH and ATP simultaneously C A process that splits water into protons, electrons, and oxygen D A process that reduces NADP to NADPH

21. What triggers the start of cyclic phosphorylation in plant cells?

A High levels of ATP and low levels of NADPH B Excess water and sunlight C High levels of oxygen and low levels of carbon dioxide D Plenty of NADPH and little ATP

22. Which photosystem is involved in cyclic phosphorylation?

A Both Photosystem I and II B Photosystem II C Photosystem I D Neither Photosystem I nor II

23. What is the main product of cyclic phosphorylation?

A Glucose B ATP C Oxygen D NADPH

24. During non-cyclic phosphorylation, what replaces the electrons that leave Photosystem II?

A Electrons from Photosystem I B Electrons from NADPH C Electrons from ATP D Electrons from photolysis of water

25. What is the role of ATPase in cyclic phosphorylation?

A Phosphorylates ADP into ATP B Absorbs light energy C Transfers electrons along the electron transport chain D Splits water molecules

Study Notes

Overview of Photosynthesis and Electron Transport

Photosynthesis is a vital process in plants that converts light energy into chemical energy, primarily through the light-dependent reactions occurring in the thylakoid membranes. This process involves key components such as chlorophyll, the electron transport chain, and the formation of ATP and NADPH, which are essential for the plant's energy needs.

Key Components of Photosynthesis

1. Photosystems and Pigments

Photosystems: Photosystem I (PSI) and Photosystem II (PSII) are crucial for capturing light energy. PSI re-excites electrons, while PSII initiates the electron transport chain.
Pigments: Key pigments include chlorophyll a, chlorophyll b, and carotenoids, which absorb light energy necessary for photosynthesis.

2. Electron Transport Chain

Function: A series of proteins in the thylakoid membrane facilitate the transfer of excited electrons, leading to energy loss that is harnessed for ATP production.
Proton Gradient: As electrons move through the chain, protons are pumped into the thylakoid space, creating a concentration gradient essential for ATP synthesis.

Energy Production Processes

1. ATP and NADPH Formation

ATP Production: Protons flow back into the stroma through ATPase, converting ADP and inorganic phosphate into ATP, which is crucial for cellular functions.
NADPH Formation: NADP acts as the final electron acceptor, forming NADPH during the light-dependent reactions, which is vital for subsequent stages of photosynthesis.

2. Types of Phosphorylation

Cyclic vs. Non-Cyclic: Non-cyclic phosphorylation produces both ATP and NADPH and releases oxygen as a byproduct, while cyclic phosphorylation generates ATP only, recycling electrons without producing NADPH.

Key Takeaways

Photosynthesis involves light-dependent reactions that convert light energy into chemical energy through the action of photosystems and the electron transport chain.
The formation of a proton gradient is essential for ATP production, which is facilitated by the movement of protons through ATPase.
NADP plays a critical role in accepting electrons to form NADPH, supporting the energy needs of the plant during the Calvin cycle.