How to Learn photosynthesis:

Photosynthesis is often seen as a difficult topic, but you can make perfect sense of it all if you approach it in the right way.

 

1. Know where Photosynthesis takes place. Learn the structure and function of the chloroplast  - the sites of photosynthesis and know that the light dependent reactions take place in the thylakoid membranes, and the Calvin cycle (the light independent reactions) take place in the stroma.

 

2. You need an overview of photosynthesis. A good overview  provides you with a framework onto which you can hang the details.

3. 'Actively' watch the video lessons on the Light dependent stages of photosynthesis in full as many times as needed and work through the knowledge check PDF that accompanies the lesson.

4. "Activly' watch the video lesson on the Calvin cycle - the light independent stages of photosynthesis in full as many times as needed and work through the knowledge check PDF that accompanies the lesson.

5. Repeat - Making your own diagrams, posters and revision notes. work through the knowledge check PDF's again making sure you can write well structured answers to the questions.

Photosynthesis can be divided into two easy steps.

The Light dependent reaction and the Light independent reactions (the Calvin Cycle).

What does it mean to "Actively" watch a lesson?

It simply means you need to watch the videos and take action! i.e. Don't be a 'passive' learner! just watching a lesson won't be much use. You need to download the PDFs that accompany the lessons,  make your own notes, create your own posters and diagrams... write your own answers to the questions... All the while, using the video and PDF to guide your learning, watching in full as many times as needed. Pause and rewind and actively engage. write down definitions and new terminology... use the learning outcomes to keep you on track. by spending some quality time, actively engaging in lessons you'll soon learn the concepts and be able to apply your knowledge - and if you need a recap, repeat the learning process to really embed the topics and biological concepts.

A Level Biology -

The Chloroplast - The site of Photosynthesis.

 

Check Where this Lesson fits into your Exam Specification!

Cell organelles the structure and function of chloroplasts the site of photosynthesis Notes with Knowledge Check Questions and Answers PDF for A- Level Biology
Cell organelles the structure and function of chloroplasts the site of photosynthesis A3 Poster PDF for A Level Biology

Chloroplasts are the organelles that house all the enzymes and other substances needed for photosynthesis.

A Level Biology -

An Overview of Photosynthesis.

 

Check Where this Lesson fits into your Exam Specification!

An Overview of Photosynthesis Notes with Knowledge Check Questions and Answers PDF for A- Level Biology
An Overview of Photosynthesis A3 Poster PDF for A Level Biology

The light-dependent reactions:

Light hits chlorophyll, which emits two high-energy electrons. These electrons are used, via a series of electron transfer reactions, to make ATP and NADPH. Replacement electrons for chlorophyll are provided when water is split, a process that also produces oxygen as a by-product.

The light-independent reactions (the Calvin Cycle)

ATP and NADPH are used, via a series of reactions known as the Calvin Cycle, to reduce carbon dioxide into glucose.

A Level Biology - Photosynthesis:

The Light Dependent Reactions of Photosynthesis

 

Check Where this Lesson fits into your Exam Specification!

Photosynthesis: the light dependent reactions of photosynthesis Revision Notes with Knowledge Check Questions and Answers PDF for A- Level Biology
Photosynthesis: the light dependent reactions of photosynthesis A3 Poster PDF for A Level Biology

The light-dependent reactions 

 

  • The light-dependent reactions take place on the thylakoids, where the chlorophyll molecules are housed

  • When a photon of light hits a molecule of chlorophyll, the pigment becomes excited and emits two high-energy electrons. 

  • These electrons pass down an electron transport system that synthesises ATP – this is called photophosphorylation

  • Energy from the excited electrons is also used to split water; this is photolysis and produces electrons to replace those lost by the chlorophyll, protons (H+ions) and oxygen as a by product

  • Electrons are used to make NADPH (reduced NADP).

  • ATP and NADPH are essential for the light independent reaction, and oxygen is released into the atmosphere.

A Level Biology - Photosynthesis: The Calvin Cycle -

The Light Independent Reactions of Photosynthesis

 

Check Where this Lesson fits into your Exam Specification!

Photosynthesis: the light independent reactions of photosynthesis  - The Calvin Cycle Revision Notes with Knowledge Check Questions and Answers PDF for A- Level Biology
Photosynthesis: the light independent reactions of photosynthesis - The Calvin Cycle A3 Poster PDF for A Level Biology

The light independent reactions (The Calvin Cycle)

 

  • The light independent reactions takes place in the stroma - the fluid part of the chloroplasts

  • The light independent reactions involves the reduction of carbon dioxide via a series of reactions known as the Calvin cycle.

  • ATP and NADPH are used to reduce the carbon dioxide. Supplies of these compounds depend on light, so the light independent reaction finishes soon after the light-dependent reaction.

  • The essential stages of the Calvin cycle are: -

  1. Carbon dioxide combines with the 5-carbon compound ribulose bisphosphate (RuBP). This reaction is catalysed by the enzyme Rubisco (ribulose bisphosphate carboxylase).

  2. This produces a highly unstable 6-carbon compound that immediately splits into two molecules of glycerate 3-phosphate (GP).

  3. ATP and NADPH are used to reduce the GP into glyceraldehyde 3 phosphate (GALP)

  4. Some of the glyceraldehyde 3 phosphate is used to make carbohydrate such as glucose, but most of it is used to make more RuBP to continue the cycle. For every glucose molecule produced, five molecules are RuBP are re-synthesised.

Check Your Exam Specification
 

★ AQA A Level Biology Specification Reference: - 3.2.1 Cell structure: 3.2.1.1 Structure of eukaryotic cells. Chloroplasts (in plants and algae). 3.5.1 Photosynthesis (A-level only). 

 

★ CIE A Level Biology Specification Reference: - 13.1 Photosynthesis as an energy transfer process. Light energy absorbed by chloroplast pigments in the light dependent stage of photosynthesis is used to drive reactions of the light independent stage that produce complex organic compounds. b) state the sites of the light dependent and the light independent stages in the chloroplast.

 

★ Edexcel A Level Biology (Biology A – Salters-Nuffield) Specification Reference: - Topic 5: On the Wild Side: This topic builds an appreciation that photosynthesis is the primary process that underpins the majority of ecosystems. 5.9 Understand the structure of chloroplasts in relation to their role in photosynthesis.

★ Edexcel A Level Biology (Biology B) Specification Reference: - Topic 5: Energy for Biological Processes. 5.7 Photosynthesis: i Know the structure of chloroplasts, including: envelope, stroma, grana and lamellar structure.

★ OCR A Level Biology (Biology A) Specification Reference: - 5.2 Energy for biological processes. 5.2.1 Photosynthesis: (b) the structure of a chloroplast and the sites of the two main stages of photosynthesis. The components of a chloroplast including outer membrane, lamellae, grana, thylakoid, stroma and DNA. (c) (i) the importance of photosynthetic pigments in photosynthesis. To include reference to light harvesting systems and photosystems. (d) the light-dependent stage of photosynthesis.

★ OCR A Level Biology (Biology B) Specification Reference: - Module 4: Energy, reproduction and populations: 4.3 Photosynthesis, food production and populations - 4.3.1 Photosynthesis, food production and management of the environment : (a) (i) the ultrastructure of the chloroplast - To include the location of the components for the light-dependent reaction in the thylakoid membranes (light harvesting complexes, photosystems, electron transport chain and ATP synthase) and the location of the enzymes for the light-independent reactions in the stroma.

 

★ WJEC A Level Biology Specification Reference: - Energy for Life: 2. Photosynthesis uses light energy to synthesise organic molecules. Learners should be able to demonstrate and apply their knowledge and understanding of: (a) the distribution of chloroplasts in relation to light trapping (b) chloroplasts acting as transducers converting the energy of light photons into the chemical energy of ATP. (c) the process of light harvesting and the absorption of various wavelengths of light by chlorophyll and associated pigments and the energy transfer to reaction centres. (d) the basic features of Photosystems I and II.

★ AQA A Level Biology Specification Reference: - 3.5.1 Photosynthesis (A-level only)

 

★ CIE A Level Biology Specification Reference: - 13.1 Photosynthesis as an energy transfer process.

 

★ Edexcel A Level Biology (Biology A – Salters-Nuffield) Specification Reference: - Topic 5: On the Wild Side: This topic builds an appreciation that photosynthesis is the primary process that underpins the majority of ecosystems. 5.9 Understand the structure of chloroplasts in relation to their role in photosynthesis.

★ Edexcel A Level Biology (Biology B) Specification Reference: - Topic 5: Energy for Biological Processes. 5.7 Photosynthesis: i Know the structure of chloroplasts, including: envelope, stroma, grana and lamellar structure.

★ OCR A Level Biology (Biology A) Specification Reference: - 5.2 Energy for biological processes. 5.2.1 Photosynthesis: (b) the structure of a chloroplast and the sites of the two main stages of photosynthesis. The components of a chloroplast including outer membrane, lamellae, grana, thylakoid, stroma and DNA. (c) (i) the importance of photosynthetic pigments in photosynthesis. To include reference to light harvesting systems and photosystems. (d) the light-dependent stage of photosynthesis.

★ OCR A Level Biology (Biology B) Specification Reference: - Module 4: Energy, reproduction and populations: 4.3 Photosynthesis, food production and populations - 4.3.1 Photosynthesis, food production and management of the environment : (a) (i) the ultrastructure of the chloroplast - To include the location of the components for the light-dependent reaction in the thylakoid membranes (light harvesting complexes, photosystems, electron transport chain and ATP synthase) and the location of the enzymes for the light-independent reactions in the stroma. (b) the process of the light-dependent stage of photosynthesis. To include the transfer of light energy to chemical energy in the form of ATP and reduced NADP (details of cyclic and non-cyclic photophosphorylation are not required).

 

★ WJEC A Level Biology Specification Reference: - Energy for Life: 2. Photosynthesis uses light energy to synthesise organic molecules. Learners should be able to demonstrate and apply their knowledge and understanding of: (a) the distribution of chloroplasts in relation to light trapping (b) chloroplasts acting as transducers converting the energy of light photons into the chemical energy of ATP. (c) the process of light harvesting and the absorption of various wavelengths of light by chlorophyll and associated pigments and the energy transfer to reaction centres. (d) the basic features of Photosystems I and II.

★ AQA A Level Biology Specification Reference: - The light-dependent reaction in such detail as to show that: chlorophyll absorbs light, leading to photoionisation of chlorophyll. Some of the energy from electrons released during photoionisation is conserved in the production of ATP and reduced NADP. The production of ATP involves electron transfer associated with the transfer of electrons down the electron transfer chain and passage of protons across chloroplast membranes and is catalysed by ATP synthase embedded in these membranes (chemiosomotic theory). Photolysis of water produces protons, electrons and oxygen.

 

★ CIE A Level Biology Specification Reference: - 13.1 Photosynthesis as an energy transfer process Light energy absorbed by chloroplast pigments in the light dependent stage of photosynthesis is used to drive reactions of the light independent stage that produce complex organic compounds. a) explain that energy transferred as ATP and reduced NADP from the light dependent stage is used during the light independent stage (Calvin cycle) of photosynthesis to produce complex organic molecules b) state the sites of the light dependent and the light independent stages in the chloroplast c) describe the role of chloroplast pigments (chlorophyll a, chlorophyll b, carotene and xanthophyll) in light absorption in the grana. f) describe the light dependent stage as the photoactivation of chlorophyll resulting in the photolysis of water and the transfer of energy to ATP and reduced NADP (cyclic and non-cyclic photophosphorylation should be described in outline only).

 

★ Edexcel A Level Biology (Biology A – Salters-Nuffield) Specification Reference: - Topic 5: On the Wild Side: This topic builds an appreciation that photosynthesis is the primary process that underpins the majority of ecosystems, and provides students with an understanding of how ecosystems work. 5.5 Understand the overall reaction of photosynthesis as requiring energy from light to split apart the strong bonds in water molecules, storing the hydrogen in a fuel (glucose) by combining it with carbon dioxide and releasing oxygen into the atmosphere. 5.6 Understand how phosphorylation of ADP requires energy and that hydrolysis of ATP provides an immediate supply of energy for biological processes. 5.7 Understand the light-dependent reactions of photosynthesis including how light energy is trapped by exciting electrons in chlorophyll and the role of these electrons in generating ATP, reducing NADP in photophosphorylation and producing oxygen through photolysis of water. 5.9 Understand the structure of chloroplasts in relation to their role in photosynthesis.

★ Edexcel A Level Biology (Biology B) Specification Reference: - Topic 5: Energy for Biological Processes. 5.7 Photosynthesis: i Know the structure of chloroplasts, including: envelope, stroma, grana and lamellar structure. Light-dependent stage: ii Understand the role of the thylakoid membranes in the light dependent stage of photosynthesis. iii Understand that the processes of cyclic and non-cyclic photophosphorylation result in the production of reduced NADP, ATP and oxygen.

★ OCR A Level Biology (Biology A) Specification Reference: - 5.2 Energy for biological processes. 5.2.1 Photosynthesis: (b) the structure of a chloroplast and the sites of the two main stages of photosynthesis. The components of a chloroplast including outer membrane, lamellae, grana, thylakoid, stroma and DNA. (c) (i) the importance of photosynthetic pigments in photosynthesis. To include reference to light harvesting systems and photosystems. (d) the light-dependent stage of photosynthesis. To include how energy from light is harvested and used to drive the production of chemicals which can be used as a source of energy for other metabolic processes (ATP and reduced NADP) with reference to electron carriers and cyclic and non-cyclic photophosphorylation AND the role of water.

★ OCR A Level Biology (Biology B) Specification Reference: - Module 4: Energy, reproduction and populations: 4.3 Photosynthesis, food production and populations - 4.3.1 Photosynthesis, food production and management of the environment : (a) (i) the ultrastructure of the chloroplast - To include the location of the components for the light-dependent reaction in the thylakoid membranes (light harvesting complexes, photosystems, electron transport chain and ATP synthase) and the location of the enzymes for the light-independent reactions in the stroma. (b) the process of the light-dependent stage of photosynthesis. To include the transfer of light energy to chemical energy in the form of ATP and reduced NADP (details of cyclic and non-cyclic photophosphorylation are not required).

 

★ WJEC A Level Biology Specification Reference: - Energy for Life: 2. Photosynthesis uses light energy to synthesise organic molecules. Learners should be able to demonstrate and apply their knowledge and understanding of: (a) the distribution of chloroplasts in relation to light trapping (b) chloroplasts acting as transducers converting the energy of light photons into the chemical energy of ATP. (c) the process of light harvesting and the absorption of various wavelengths of light by chlorophyll and associated pigments and the energy transfer to reaction centres. (d) the basic features of Photosystems I and II. (e) cyclic and non-cyclic photophosphorylation as sources of electrons for the electron transport chain. (f) photolysis as a source of electrons for Photosystem II. (g) the reduction of NADP by the addition of electrons and hydrogen ions in the stroma maintaining the proton gradient.

© 2020 Frankie Barnes - Learnbiology.net - All Rights Reserved.