Photosynthesis

What Photosynthesis covers

Photosynthesis is the sixth section of Module 5. It covers the structure of the chloroplast and where each stage happens, the pigments and how chromatography separates them, the light-dependent reactions and photophosphorylation, the Calvin cycle, and the factors that limit the rate.

The 5 subtopics

Each one has its own page.

• Photosynthesis and chloroplast structureThe raw materials and products and how they mirror respiration, and the envelope, grana, thylakoids and stroma with the stage that happens in each.Open →
• Photosynthetic pigments and chromatographyWhat photosystems and light harvesting systems do, and how thin layer chromatography separates the pigments, with the Rf calculation.Open →
• The light-dependent stageWhat happens to an electron when a pigment absorbs light, non-cyclic and cyclic photophosphorylation, and the three things the photolysis of water provides.Open →
• The Calvin cycleCarbon dioxide fixation onto RuBP by rubisco, the conversion of glycerate 3-phosphate to triose phosphate, and what the triose phosphate goes on to build.Open →
• Limiting factorsLight intensity, carbon dioxide concentration, temperature and water stress, what each does to GP, RuBP and TP levels, and the inverse square law.Open →

What you need to know

Answer each one before you reveal it.

Take Photosynthesis further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

• Light-dependent stage vs Light-independent stage

  Light-dependent stage: the thylakoid reactions producing ATP and reduced NADP from light. Light-independent stage: the stroma reactions fixing carbon dioxide using those products.

• Photophosphorylation vs Photolysis

  Photophosphorylation: the making of ATP using light energy in the thylakoid membrane. Photolysis: the splitting of water by light to give electrons, protons and oxygen.

• Absorption spectrum vs Action spectrum

  Absorption spectrum: a graph of how much light of each wavelength a pigment absorbs. Action spectrum: a graph of the rate of photosynthesis at each wavelength.

Questions from this topic

Each one with the model answer underneath.

1. 1

   Define photosynthesis.

   Model answer

   Photosynthesis is the process by which light energy is captured and used to drive the synthesis of ATP and large organic molecules from inorganic molecules.

2. 2

   What are the raw materials of photosynthesis, and how do they relate to aerobic respiration?

   Model answer

   The raw materials of photosynthesis are carbon dioxide and water, which are the products of aerobic respiration.

3. 3

   What are the products of photosynthesis, and how do they relate to aerobic respiration?

   Model answer

   The products of photosynthesis are glucose and oxygen, which are the raw materials of aerobic respiration.

4. 4

   How is ATP produced in photosynthesis linked to cellular metabolism?

   Model answer

   ATP produced in photosynthesis is used in the light-independent stage to make sugars, and respiring those sugars produces the ATP that drives other metabolic processes in cells.

5. 5

   What structure surrounds the chloroplast?

   Model answer

   The chloroplast is surrounded by a double membrane (an outer and an inner membrane) called the envelope.

6. 6

   What are lamellae in a chloroplast?

   Model answer

   Lamellae are the internal membrane system of the chloroplast that connect grana.

What is inside Levo

Six ways to work the same material.

Photosynthesis revision questions

What does Photosynthesis cover in OCR A-Level Biology?

5 subtopics: photosynthesis and chloroplast structure, photosynthetic pigments and chromatography, the light-dependent stage, the calvin cycle and limiting factors. Each one has its own page with questions and model answers.

How is Photosynthesis organised?

By the OCR H420 specification, subtopic by subtopic, so it matches the order you are taught it in.