Photosynthesis (A Level Only)

Belajar sambil bermain

Jawab soal-soal ini untuk dapat energi, lalu memancing dan menjelajah. Tanpa akun.

Untuk pendidik: slide pelajaran, catatan ulasan siap pakai untuk Photosynthesis (A Level Only) (Biology, AQA) — gunakan dalam pelajaranmu, atau jalankan topik sebagai aktivitas kelas interaktif yang dimainkan pembelajar sebagai permainan langsung.

Catatan pelajaran

Overview of Photosynthesis

Photosynthesis converts light energy into stored chemical energy within carbon compounds in plant tissues.
It consists of two stages: the light-dependent reaction and the light-independent reaction.
All reactions of photosynthesis take place within chloroplasts.
Chloroplasts are surrounded by a double membrane envelope filled with stroma.
The internal membranes consist of flattened, fluid-filled sacs called thylakoids, which can stack to form grana (singular granum).

The Light-Dependent Reaction

The light-dependent reactions occur on the thylakoid membranes within chloroplasts.
The membranes provide a large surface area to increase the number of light-dependent reactions.
Photosynthetic pigments (e.g., chlorophyll a and chlorophyll b) are arranged in photosystems within the thylakoid membranes.
Each pigment absorbs light at different wavelengths.
Light energy is converted into chemical energy stored in glucose molecules.

Photoionisation and Electron Transport

When light energy hits photosystems, electrons in chlorophyll are excited to a higher energy level and emitted; this is photoionisation.
The excited electrons are passed to a series of electron carrier proteins embedded in the thylakoid membrane, forming the electron transport chain.
Some energy from electrons is conserved in the production of ATP and reduced NADP (NADPH).
Photosystems are funnel-like structures that contain pigments absorbing light energy and transferring it to the primary pigment reaction centre.

ATP Production by Chemiosmosis

Excited electrons pass along the electron transport chain, releasing energy.
Electron carriers are alternately reduced (gain electron) and oxidised (lose electron).
Released energy pumps protons (H⁺ ions) from the stroma into the thylakoid lumen.
Protons return to the stroma down their concentration gradient via ATP synthase enzymes by facilitated diffusion; this is chemiosmosis.
ATP synthase catalyses the addition of inorganic phosphate (π) to ADP: ADP + π → ATP; this is photophosphorylation.
Reduced NADP (NADPH) is produced when hydrogen ions and electrons combine with NADP: 2H⁺ + 2e⁻ + NADP → NADPH.

Photolysis of Water

Light energy is used to break down water in photolysis, which occurs in the thylakoid lumen.
Equation: H₂O → 2H⁺ + 2e⁻ + ½O₂.
Protons are pumped across the thylakoid membrane during ATP production and join with NADP and electrons to form NADPH.
Electrons are passed to the photosystem to replace those lost during photoionisation.
Oxygen is a waste product that diffuses out of the cells into the leaf air spaces.

Required Practical: Investigating Photosynthetic Pigments with Chromatography

Chloroplasts contain several different photosynthetic pigments within the thylakoids.
Different pigments absorb different wavelengths of light, maximising light energy absorbed.
Chlorophylls absorb blue-violet and red regions; they reflect green light, making plants appear green.
Carotenoids absorb mainly blue-violet light.
Pigment groups include: chlorophyll a (blue-green), chlorophyll b (yellow-green), β-carotene (orange), xanthophyll (yellow).
Chromatography separates mixtures; paper chromatography uses paper, thin-layer chromatography (TLC) uses a thin layer of adsorbent like silica gel for faster and more distinct separation.
Method: draw a pencil line 1 cm above bottom of paper; grind leaf with acetone; spot pigment onto line; suspend paper in solvent below the line; remove before solvent reaches top; mark solvent front; calculate Rf value = distance moved by pigment ÷ distance moved by solvent.
Higher Rf indicates higher affinity with mobile phase (non-polar, soluble, small molecules); lower Rf indicates higher affinity with stationary phase (polar, less soluble, large molecules).

The Light-Independent Reaction (Calvin Cycle)

The products of the light-dependent reactions that pass to the light-independent reactions are ATP and reduced NADP (NADPH).
These are used to produce simple sugar molecules, which can be converted into complex organic molecules.
The light-independent reactions are not truly independent of light; they cannot continue indefinitely in darkness as ATP and NADPH will run out.
The Calvin cycle involves: carbon fixation (CO₂ combines with RuBP, catalysed by rubisco, forming unstable 6C compound that splits into two GP molecules); reduction of GP to triose phosphate (using ATP and reduced NADP); regeneration of RuBP (using ATP); and production of useful organic substances.
Triose phosphate can condense to form hexose phosphates, used to produce starch, sucrose, and cellulose.
Triose phosphate can be converted to glycerol and GP to fatty acids, which join to form lipids.
Triose phosphate is used in the production of amino acids for protein synthesis.

Limiting Factors of Photosynthesis

The main environmental factors that can limit the rate of photosynthesis are light intensity, carbon dioxide concentration, and temperature.
If any one factor is below optimum, the rate of photosynthesis is reduced even if others are at optimum.
Light intensity: as it increases, more electrons undergo photoionisation, more ATP and NADPH are produced, Calvin cycle progresses faster; eventually plateaus when another factor becomes limiting.
Carbon dioxide concentration: as it increases, more CO₂ combines with RuBP during carbon fixation, more GP is produced, converted to triose phosphate and organic compounds; trend continues until another factor limits.
Temperature: photosynthesis is enzyme-controlled; increase in kinetic energy increases reaction rate up to an optimum, beyond which enzymes denature and rate decreases.
Temperature has no significant effect on light-dependent reactions as they are driven by light energy, not kinetic energy; but temperature can affect stomatal closure and thylakoid membrane permeability.
Understanding limiting factors can be used to increase crop yields in glasshouses by monitoring and adjusting light, humidity, and CO₂.

Required Practical: Investigating the Rate of Photosynthesis

Aquatic plants (e.g., Elodea pondweed, algae, algal beads) can be used to investigate the effect of environmental factors on the rate of photosynthesis.
Method: aerate water, illuminate plant, set up in darkened room, add distilled water and sodium hydrogencarbonate (for CO₂ supply), cut stem at an angle, position lamp at set distance, measure volume of gas collected over set time, repeat at different distances.
Sodium hydrogencarbonate provides a controlled supply of dissolved carbon dioxide.
Cutting the stem at an angle increases surface area for bubble formation.
Alternative: immobilised algae beads (alginate gel with algae cells) have known surface area and volume, easier standardisation, but can be less reliable and harder to look after.
Other factors can be investigated: CO₂ concentration by adding different concentrations of NaHCO₃; temperature by placing plant in water baths at different temperatures.

Required Practical: Factors Affecting the Rate of Dehydrogenase Activity

During the light-dependent reactions, high-energy electrons are emitted from chlorophyll and eventually reduce NADP in a reaction catalysed by dehydrogenase enzymes.
Redox indicators (e.g., DCPIP, methylene blue) can accept these electrons instead of NADP; they become reduced and change colour: oxidised (blue) → reduced (colourless).
The rate at which a redox indicator changes colour can measure the rate of dehydrogenase activity, and therefore the rate of the light-dependent reaction.
Method: grind leaves with isolation medium, filter, centrifuge to obtain chloroplast pellet, re-suspend in isolation medium, keep on ice, add DCPIP, measure absorbance using a colorimeter over time at different light intensities.
As light intensity decreases, fewer electrons are released, so DCPIP accepts fewer electrons and takes longer to turn from blue to colourless.
A colorimeter gives an objective measure of the rate of colour change in DCPIP.

Slide

Step through every slide for this topic — plus flashcards and revision notes — with a free account.

DAFTAR — GRATIS MASUK

Soal latihan

Pratinjau gratis — 8 dari 61 soal. Daftar untuk melihat semuanya.

1.Where in a chloroplast does the light-dependent reaction take place?
Easy
- AThylakoid membranes
- BStroma
- COuter chloroplast membrane
- DInner chloroplast membrane
2.What is the name of the process in which light energy excites electrons in chlorophyll, causing them to be emitted?
Easy
- APhotoionisation
- BPhotolysis
- CChemiosmosis
- DPhotophosphorylation
3.Which enzyme catalyses the fixation of carbon dioxide in the Calvin cycle?
Easy
- ARubisco
- BATP synthase
- CDehydrogenase
- DCarboxylase
4.The light-dependent reaction takes place in the stroma of the chloroplast.
Easy
True or false?
5.Chlorophyll absorbs green light most efficiently, which is why plants appear green.
Easy
True or false?
6.In the light-dependent reaction, what is the role of water?
Easy
- AIt provides electrons to replace those lost from chlorophyll and protons for NADPH production
- BIt provides carbon dioxide for the Calvin cycle
- CIt acts as the final electron acceptor in the electron transport chain
- DIt directly provides energy for ATP synthesis
7.Which of the following is produced during the light-dependent reaction and is required for the light-independent reaction?
Easy
- AATP and reduced NADP
- BGlucose and oxygen
- CCarbon dioxide and RuBP
- DGP and triose phosphate
8.What is the exact location of photolysis in a chloroplast?
Easy
- AThylakoid lumen
- BStroma
- CThylakoid membrane
- DIntermembrane space

Soal lainnya

9.In the Calvin cycle, what is the immediate product of carbon dioxide fixation?
Medium
- ATwo molecules of glycerate 3-phosphate (GP)
- BOne molecule of triose phosphate
- COne molecule of ribulose bisphosphate (RuBP)
- DOne molecule of glucose
10.Which of the following statements about the Calvin cycle is correct?
Medium
- AIt uses ATP and reduced NADP to reduce GP to triose phosphate
- BIt produces ATP and reduced NADP for the light-dependent reaction
- CIt occurs on the thylakoid membranes
- DIt produces oxygen as a waste product
11.A student investigated the effect of light intensity on the rate of photosynthesis using pondweed. They measured the volume of gas collected in a syringe over 1 minute. Which gas was being collected?
Medium
- AOxygen
- BCarbon dioxide
- CHydrogen
- DNitrogen
12.In the light-dependent reaction, what is the role of ATP synthase?
Medium
- AIt allows protons to diffuse down their concentration gradient and catalyses ATP synthesis
- BIt pumps protons across the thylakoid membrane using ATP
- CIt transfers electrons to NADP
- DIt splits water into protons, electrons and oxygen
13.Which of the following is the correct equation for photolysis?
Medium
- AH2O → 2H+ + 2e- + ½O2
- B2H+ + 2e- + NADP → NADPH
- CADP + π → ATP
- DCO2 + RuBP → 2GP
14.In the Calvin cycle, what is the role of ATP?
Medium
- AIt provides energy to reduce GP to triose phosphate and to regenerate RuBP
- BIt provides phosphate groups to form GP
- CIt acts as an electron carrier
- DIt is used to split water
15.A plant is exposed to light of different wavelengths. Which wavelength would result in the lowest rate of photosynthesis?
Medium
- AGreen light (550 nm)
- BBlue light (450 nm)
- CRed light (650 nm)
- DViolet light (400 nm)
16.Which of the following are products of the light-dependent reaction? (select all that apply)
Medium
- AATP
- BReduced NADP
- COxygen
- DGlucose
- ECarbon dioxide
17.Which of the following statements about the Calvin cycle are correct? (select all that apply)
Medium
- AIt occurs in the stroma
- BIt uses ATP and reduced NADP
- CIt produces triose phosphate
- DIt requires light directly
- EIt produces oxygen
18.In the light-dependent reaction, protons are pumped across the thylakoid membrane by active transport.
Easy
True or false?
19.The light-independent reaction can continue indefinitely in darkness as long as ATP and reduced NADP are available.
Easy
True or false?
20.Match each pigment with its colour.
Medium
- Chlorophyll a
- Chlorophyll b
- β Carotene
- Xanthophyll
- Blue-green
- Yellow-green
- Orange
- Yellow
21.Place the following steps of the Calvin cycle in the correct order.
Medium
- Carbon dioxide fixation
- Reduction of GP to triose phosphate
- Regeneration of RuBP
- Production of useful organic substances
22.Match each photosynthetic pigment with its colour.
Medium
- Chlorophyll a
- Chlorophyll b
- β Carotene
- Xanthophyll
- Blue-green
- Yellow-green
- Orange
- Yellow
23.Place the steps of the Calvin cycle in the correct order, starting with carbon fixation.
Medium
- Carbon dioxide combines with RuBP, catalysed by rubisco
- The unstable 6C compound splits into two molecules of GP
- GP is reduced to triose phosphate using ATP and reduced NADP
- ATP is used to regenerate RuBP from triose phosphate
- Triose phosphate is used to produce organic molecules such as starch
24.Which of the following are products of photolysis of water? (select all that apply)
Medium
- AProtons (H+)
- BElectrons
- COxygen
- DNADPH
- EATP
25.Which of the following correctly describe the events of the light-dependent reaction? (select all that apply)
Hard
- AElectrons in chlorophyll are excited and emitted during photoionisation
- BExcited electrons pass along an electron transport chain in the thylakoid membrane
- CEnergy from electrons pumps protons from the stroma into the thylakoid lumen
- DProtons return to the stroma through ATP synthase by facilitated diffusion
- EReduced NADP is formed when NADP combines with oxygen and ATP
26.A pigment spot travels 6.4 cm from the origin while the solvent front travels 10.0 cm. What is the Rf value of this pigment?
Medium
- A0.64
- B1.56
- C0.36
- D6.4
27.In thin layer chromatography of leaf pigments, which pigment would be expected to have the highest Rf value?
Medium
- ACarotene
- BChlorophyll b
- CChlorophyll a
- DXanthophyll
28.A student's chromatogram shows a pigment with an Rf value of 0.66. Using the reference ranges (carotene 0.89–0.95; neoxanthin 0.05–0.11; chlorophyll a 0.64–0.69; chlorophyll b 0.53–0.62; pheophytin a 0.78–0.86), which pigment is it?
Hard
- AChlorophyll a
- BChlorophyll b
- CCarotene
- DPheophytin a
29.Match each term with its correct description.
Medium
- Photoionisation
- Photolysis
- Chemiosmosis
- Rf value
- An electron is emitted from chlorophyll after absorbing light
- The splitting of water using light energy
- Protons returning through ATP synthase down their gradient
- Distance moved by pigment ÷ distance moved by solvent
30.Which of the following are valid reasons why a plant benefits from having several different photosynthetic pigments? (select all that apply)
Hard
- ADifferent pigments absorb different wavelengths of light
- BMore of the light spectrum can be absorbed, maximising light energy captured
- CCarotenoids absorb wavelengths mainly in the blue-violet region
- DPigments reflect the wavelengths they absorb most efficiently
- EEach pigment is restricted to absorbing only green light
31.Why does the rate of photosynthesis plateau at high light intensity?
Medium
- ALight intensity is no longer the limiting factor and another factor, such as temperature or carbon dioxide concentration, is now limiting
- BChlorophyll is destroyed by the high light intensity
- CThe plant stops respiring
- DPhotolysis stops occurring in the thylakoid lumen
32.Which of the following are environmental variables, other than light intensity and temperature, that can affect the rate of photosynthesis? (select all that apply)
Medium
- ACarbon dioxide concentration
- BHumidity
- COxygen concentration
- DWater availability
- ESodium hydrogencarbonate concentration in a pondweed investigation
33.In the DCPIP practical investigating dehydrogenase activity, which of the following are correct? (select all that apply)
Hard
- ADCPIP accepts electrons that would otherwise reduce NADP
- BA colorimeter can give an objective measure of the rate of colour change
- CDecreasing light intensity increases the time taken for the tube to turn green
- DThe chloroplast extract is kept in an ice-cold water bath to slow chloroplast activity
- EDCPIP changes from colourless to blue as it becomes reduced
34.In the Calvin cycle, ATP is used both to reduce GP to triose phosphate and to regenerate RuBP.
Medium
True or false?
35.A plant is placed in darkness after being in bright light. Which of the following best explains the resulting change in Calvin cycle intermediates?
Hard
- AGP cannot be converted to triose phosphate, so GP builds up and RuBP falls
- BRuBP builds up because it cannot combine with carbon dioxide
- CTriose phosphate builds up because ATP is still plentiful
- DGP falls because carbon dioxide fixation increases
36.Describe the relationship between carbon dioxide concentration and the rate of photosynthesis shown on the graph.
Medium
- AThe rate increases as CO2 concentration increases until it reaches a plateau
- BThe rate decreases steadily as CO2 concentration increases
- CThe rate stays constant at all CO2 concentrations
- DThe rate increases indefinitely with CO2 concentration
37.Identify a possible limiting factor at point X on the plateau.
Medium
- ALight intensity
- BCarbon dioxide concentration
- COxygen concentration
- DChlorophyll concentration
38.Name the variable measured here to assess the rate of photosynthesis.
Medium
- AVolume of oxygen produced per minute
- BDistance from the lamp
- CTemperature of the water
- DMass of pondweed
39.Which of the following variables need to be controlled in this investigation? (select all that apply)
Medium
- ATemperature of the water
- BCarbon dioxide concentration in the water
- CDistance from the lamp
- DVolume of oxygen produced
- EDuration of each measurement
40.Which statement correctly describes the role of the products of photolysis?
Hard
- AProtons are pumped across the thylakoid membrane and combine with NADP and electrons to form NADPH, while electrons replace those lost from the photosystem
- BProtons combine with oxygen to form water, while electrons form ATP
- CProtons are used to reduce GP to triose phosphate, while electrons form NADPH
- DProtons diffuse out of the leaf as a waste product, while electrons are used to fix carbon dioxide
41.Complete the sentence about the light-dependent reaction.
Medium
The process by which water is split using light energy is called ____, and it occurs in the ____.
42.Complete the sentence about the Calvin cycle.
Medium
In the Calvin cycle, carbon dioxide combines with ____ to form an unstable 6C compound, which splits into two molecules of ____.
43.Name the enzyme that catalyses the fixation of carbon dioxide in the Calvin cycle.
Easy
44.Name the process by which ATP is produced during the light-dependent reaction.
Easy
45.In an investigation, a student measured the volume of oxygen produced by pondweed over 5 minutes. The volume collected was 15 cm³. Calculate the rate of oxygen production in cm³ per minute.
Medium
46.At 90 cm from the lamp the rate of photosynthesis is 12 bubbles per minute. At 10 cm the rate is 18 bubbles per minute. Calculate the percentage increase in the rate of photosynthesis when the distance is reduced from 90 cm to 10 cm.
Medium
47.A pondweed releases 15 cm³ of oxygen in 5 minutes. Calculate the rate of oxygen production in cm³ per minute.
Medium
48.Name the process by which ATP is produced on the thylakoid membranes during the light-dependent reaction.
Medium
49.Name the redox indicator that changes from blue to colourless when it accepts electrons in the dehydrogenase activity practical.
Medium
50.A chloroplast extract reduces DCPIP so that absorbance falls from 0.80 to 0.20 over 4 minutes. Calculate the rate of decrease in absorbance per minute.
Hard
51.Complete the sentence about the products of the light-dependent reaction.
Medium
The two products of the light-dependent reaction that pass to the Calvin cycle are ____ and ____.
52.Name the carbohydrate that triose phosphate can condense to form, which is then used to make sucrose.
Medium
53.Describe how light energy is used during the light-dependent reaction of photosynthesis.
Hard
54.Explain why the rate of photosynthesis decreases when carbon dioxide concentration is reduced.
Hard
55.Explain why it is beneficial for plants to possess multiple photosynthetic pigments.
Hard
56.Describe how you would use thin layer chromatography to separate photosynthetic pigments from a leaf sample.
Medium
57.Explain why the rate of photosynthesis decreases at high temperatures.
Medium
58.In an investigation, a student measured the volume of oxygen produced by pondweed over 5 minutes. The volume collected was 15 cm³. Calculate the rate of oxygen production in cm³ per minute.
Medium
- A3 cm³/min
- B2 cm³/min
- C4 cm³/min
- D5 cm³/min
59.At 90 cm from the lamp the rate of photosynthesis is 12 bubbles per minute. At 10 cm the rate is 18 bubbles per minute. Calculate the percentage increase in the rate of photosynthesis when the distance is reduced from 90 cm to 10 cm.
Medium
- A50 %
- B45 %
- C55 %
- D60 %
60.A pondweed releases 15 cm³ of oxygen in 5 minutes. Calculate the rate of oxygen production in cm³ per minute.
Medium
- A4 cm³/min
- B2 cm³/min
- C3 cm³/min
- D5 cm³/min
61.A chloroplast extract reduces DCPIP so that absorbance falls from 0.80 to 0.20 over 4 minutes. Calculate the rate of decrease in absorbance per minute.
Hard
- A-0.85 absorbance units/min
- B1.15 absorbance units/min
- C2.15 absorbance units/min
- D0.15 absorbance units/min

Catatan ulasan

## Photosynthesis (A Level) **Overall equation:** light energy is converted into chemical energy stored in glucose. Two stages: **light-dependent** (thylakoid membranes) and **light-independent** (stroma). ### Chloroplast structure - Double membrane envelope, filled with **stroma**. - Internal membranes form flattened, fluid-filled sacs = **thylakoids**; stacks = **grana** (singular granum). - Thylakoid membranes contain photosynthetic pigments arranged in **photosystems**; large surface area increases number of light-dependent reactions. ### Light-dependent reaction - **Photoionisation:** light energy excites electrons in chlorophyll to a higher energy level; electrons are emitted from the chlorophyll molecule. - Electrons pass along the **electron transport chain** (carrier proteins in thylakoid membrane), alternately reduced and oxidised. - **Chemiosmosis:** energy released pumps protons (H⁺) from stroma to thylakoid lumen; protons return by facilitated diffusion through **ATP synthase**. - **Photophosphorylation:** ATP synthase catalyses ADP + Pi → ATP. - **Reduced NADP:** 2H⁺ + 2e⁻ + NADP → NADPH. - **Photolysis** (in thylakoid lumen): H₂O → 2H⁺ + 2e⁻ + ½O₂. Protons used in ATP production/NADPH; electrons replace those lost in photoionisation; oxygen is waste. - Do not call proton pumping active transport (no ATP used). ### Required practical: pigments & chromatography - Pigments: chlorophyll a (blue-green), chlorophyll b (yellow-green), β-carotene (orange), xanthophyll (yellow). - Chlorophylls absorb blue-violet and red; reflect green. Carotenoids absorb mainly blue-violet. - TLC uses thin adsorbent layer (e.g. silica gel); separates faster and more distinctly than paper. - Method: pencil origin line ~1 cm from bottom; grind leaf with acetone (dissolves membranes); spot pigment; suspend paper with solvent below pencil line; remove before solvent reaches top; mark solvent front. - **Rf = distance travelled by pigment ÷ distance travelled by solvent** (measure to centre of spot). - Higher Rf = higher affinity for mobile phase (non-polar, soluble, small). Lower Rf = higher affinity for stationary phase (polar, less soluble, large). Carotenoids highest Rf (~1), chlorophyll b lowest, chlorophyll a in between. ### Light-independent reaction (Calvin cycle) Uses ATP and reduced NADP from light-dependent stage. 1. **Carbon fixation:** CO₂ + RuBP (5C) → unstable 6C → two GP (3C), catalysed by **rubisco**. 2. **Reduction:** ATP and reduced NADP reduce GP to **triose phosphate**. 3. **Regeneration:** ATP converts five of six carbons in two triose phosphate molecules back to RuBP. 4. **Products:** triose phosphate → hexose phosphates → starch, sucrose, cellulose; glycerol + fatty acids → lipids; amino acids → proteins. ### Limiting factors - **Light intensity:** more photoionisation → more ATP/NADPH → faster Calvin cycle. Plateaus when another factor limits. - **CO₂ concentration:** more CO₂ combines with RuBP → more GP → more triose phosphate/organic compounds. - **Temperature:** enzyme-controlled; kinetic energy increases rate until enzymes denature. Little effect on light-dependent reactions (light-driven). - Glasshouses manage light, humidity, CO₂ to maximise yield; balance yield vs cost. ### Required practical: rate of photosynthesis - Aquatic plant (Elodea) or algal beads; aerate water; add NaHCO₃ for CO₂; lamp at set distances; measure volume of O₂ per minute. - Algal beads: known surface area/volume (standardisation) but less reliable. - **Dehydrogenase/DCPIP:** excited electrons reduce DCPIP instead of NADP; blue → colourless (green with chloroplasts). Colorimeter measures absorbance decrease; lower light intensity = slower colour change.

Photoionisation: Light energy excites electrons in chlorophyll to a higher energy level and they are emitted from the chlorophyll molecule.
Photolysis: Light energy breaks down water in the thylakoid lumen: H₂O → 2H⁺ + 2e⁻ + ½O₂.
Chemiosmosis: Protons are pumped across the thylakoid membrane from stroma to lumen, then return down the concentration gradient by facilitated diffusion through ATP synthase.
Photophosphorylation: The addition of inorganic phosphate to ADP to form ATP, using light as the energy source.
Reduced NADP (NADPH): Formed when hydrogen ions in the stroma and electrons from the electron transport chain combine with NADP: 2H⁺ + 2e⁻ + NADP → NADPH.
Rubisco: Enzyme (ribulose bisphosphate carboxylase) that catalyses the fixation of carbon dioxide to RuBP in the Calvin cycle.
RuBP: Ribulose bisphosphate, a five-carbon sugar that combines with CO₂ during carbon fixation.
GP: Glycerate 3-phosphate, a three-carbon compound produced when the unstable six-carbon compound splits; reduced to triose phosphate.
Triose phosphate: Three-carbon compound produced by reduction of GP using ATP and reduced NADP; used to regenerate RuBP or make organic substances.
Rf value: Distance travelled by pigment ÷ distance travelled by solvent; used to identify pigments.
Limiting factor: A factor (light intensity, CO₂ concentration, temperature) that, if below optimum, reduces the rate of photosynthesis even if others are at optimum.
DCPIP: Redox indicator that accepts electrons instead of NADP, changing from blue (oxidised) to colourless (reduced); used to measure dehydrogenase activity.

Unlock all 61 questions & more

Buat akun gratis untuk melihat setiap soal, slide, kartu flash, dan catatan ulasan topik ini.

DAFTAR — GRATIS MASUK

Soal ujian lampau

Latihan soal ujian lampau untuk topik ini segera hadir.

Segera hadir