Photosynthesis

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शिक्षकों के लिए: Photosynthesis (Biology, HL) के लिए इस्तेमाल के लिए तैयार लेसन स्लाइड्स, रिवीज़न नोट्स — इन्हें अपने लेसन में इस्तेमाल करें, या टॉपिक को एक इंटरैक्टिव क्लास एक्टिविटी की तरह चलाएं जिसे आपके शिक्षार्थी लाइव गेम की तरह खेलें।

लेसन नोट्स

The Process of Photosynthesis

Photosynthesis converts simple inorganic compounds into complex organic compounds using light energy.
It occurs in autotrophic organisms such as plants, algae and cyanobacteria.
It is an energy conversion: light energy is transformed into chemical energy stored in biomass.
The reactants are carbon dioxide and water; the products are glucose and oxygen.
Carbon dioxide is converted to glucose using hydrogen released when a water molecule is split.
Oxygen is released as a waste product.
The word equation for photosynthesis is: carbon dioxide + water → glucose + oxygen.
Energy is never created or destroyed, only converted from one form to another.

Balanced equation for photosynthesis

Separating Photosynthetic Pigments: Skills

Plants contain several photosynthetic pigments, which absorb different wavelengths of light.
There are two groups of pigments: chlorophylls (chlorophyll a and b) and carotenoids (β carotene and xanthophyll).
Chlorophylls absorb wavelengths in the blue-violet and red regions of the spectrum; they reflect green light, making plants appear green.
Carotenoids absorb wavelengths mainly in the blue-violet region of the spectrum.
Carotenoids surround the chlorophyll and absorb both similar and different wavelengths, expanding the range of wavelengths absorbed for photosynthesis.
Chromatography separates mixtures because different components travel through the material at different speeds.
The retardation factor (Rf value) is calculated as: distance moved by pigment ÷ distance moved by solvent.
In general, carotenoids have the highest Rf values (close to 1), chlorophyll b has a much lower Rf value, and chlorophyll a has an Rf value between those of carotenoids and chlorophyll b.
Paper chromatography is not as specific as other techniques; it does not give data on the amount of each pigment present or the wavelengths they absorb.

Chlorophyll within chloroplasts

Absorption Spectra

An absorption spectrum is a graph showing the absorbance of different wavelengths of light by a particular pigment.
Within chlorophyll, light energy excites electrons, triggering a transfer of electrons that leads to a series of reactions making up photosynthesis.
During photosynthesis, light energy is transformed to chemical energy when glucose is formed.
Chlorophylls absorb wavelengths in the blue-violet and red regions of the light spectrum.
Carotenoids absorb wavelengths of light mainly in the blue-violet region of the spectrum.
The chemical structure of pigment molecules determines the wavelengths of light that can be absorbed.
The green part of the spectrum is largely reflected from the leaf, which is why leaves usually appear green.

Absorption & Action Spectra: Skills

An action spectrum is a graph showing the rate of photosynthesis at different wavelengths of light.
The rate of photosynthesis is highest at the blue-violet and red regions of the light spectrum, as these are the wavelengths that chlorophylls and carotenoids can absorb.
There is a strong correlation between the cumulative absorption spectra of all pigments and the action spectrum.
Both graphs have two main peaks – at the blue-violet region and the red region – supporting the idea that the most light energy is absorbed at these wavelengths, leading to the fastest rate of photosynthesis.
Both graphs have a trough in the green-yellow region, supporting the idea that the least light energy is absorbed at these wavelengths, leading to the slowest rate of photosynthesis.
The rate of photosynthesis can be determined by measuring the volume of oxygen produced or the carbon dioxide consumption at different wavelengths of light.
When drawing an action spectrum, label the x-axis 'wavelength / nm' from 400 to 700 nm, and the y-axis 'Rate of photosynthesis / % of maximum rate' from 0 to 100.
The curve should have two peaks (blue and red) and a trough in the middle (green light).

Limiting Factors of Photosynthesis: Skills

An aquatic plant such as Elodea or Cabomba is a good choice for investigating photosynthesis because the rate can be measured by counting oxygen bubbles released from a cutting.
A hypothesis is a proposed explanation for an idea which may be true or false; it can be tested through observations or experiments.
The independent variable is the factor deliberately manipulated; the dependent variable is the factor measured; other variables must be controlled.
Light intensity, carbon dioxide concentration and temperature are all limiting factors that affect the rate of photosynthesis and can be altered experimentally.
As light intensity increases, the rate of photosynthesis increases (positive correlation) until light intensity is no longer limiting; then temperature or carbon dioxide concentration may become limiting.
An increase in temperature increases the rate of photosynthesis due to increased kinetic energy of enzyme and substrate molecules, resulting in more collisions and more enzyme-substrate complexes.
This increase continues until the optimum temperature; further increase causes enzymes to denature, so they cannot form enzyme-substrate complexes and the rate decreases.
In experiments, temperature can be controlled using a water bath or by placing a glass tank of water between the lamp and plant; carbon dioxide concentration can be controlled using sodium hydrogencarbonate solution.

Investigating light intensity

Carbon Dioxide Enrichment Experiments

Future rates of photosynthesis and plant growth can be predicted using enclosed greenhouse experiments and free air carbon dioxide enrichment (FACE) experiments.
Enclosed greenhouse experiments allow variables such as light, carbon dioxide, temperature and wavelengths of light to be manipulated or controlled.
Only small species that can be contained in a greenhouse can be studied using enclosed greenhouse experiments.
FACE experiments are carried out in natural ecosystems where carbon dioxide is pumped into the area to increase localised carbon dioxide concentrations.
FACE experiments allow larger plants and trees to be studied, but other variables cannot be controlled; they can be monitored to establish relationships.
In an experiment, the independent variable is the only variable that should be changed; controlled/confounding variables must be controlled or monitored; the dependent variable is measured.
It is essential that any variable that may affect the outcome is controlled for the results to be valid.

The fate of glucose in a plant

Photosystems

Chlorophyll and accessory pigments are grouped together as structures called photosystems, located in the thylakoid membranes.
Photosystems contain many chlorophyll molecules, accessory pigments (carotene and xanthophylls) and a reaction centre.
Photosystem I contains the reaction centre P700 (activated by light of 700 nm); Photosystem II contains the reaction centre P680 (activated by light of 680 nm).
Chlorophyll molecules and accessory pigments within Photosystem II absorb light energy (photons) and pass it to a chlorophyll molecule in reaction centre P680.
Electrons within the reaction centre of Photosystem II are excited to a higher energy level by photons of light; the chlorophylls are said to be photoactivated.
Excited electrons are donated to an electron acceptor in a reduction reaction.
The presence of many different types of pigment allows the photosystem to efficiently absorb light of different wavelengths.
The structured arrangement of pigments allows electrons to be excited in a controlled manner and directed along the electron transport chain.
All the pigments in photosystems I and II are required for photosynthesis to occur; a single pigment molecule would not be able to perform any part of photosynthesis.

Light Dependent Reactions

The light-dependent reaction relies on light directly and takes place in the thylakoid intermembrane space and across the thylakoid membrane.
Thylakoids are disc-like structures that make up the grana in stacks of up to 100; they contain chlorophyll and some have tubular extensions (intergranal lamellae) joining adjacent grana.
The thylakoid membrane contains a transfer chain where electrons are passed along a number of electron carriers in a series of oxidation-reduction reactions.
Three key processes occur during the light-dependent reaction: photolysis, chemiosmosis, and reduction of NADP.
Photolysis is the splitting of a water molecule using light energy; it occurs in Photosystem II.
Chemiosmosis is the synthesis of ATP using an electrochemical gradient produced by H+ protons; the proton gradient forms across the thylakoid membrane when protons are pumped from the stroma into the thylakoid space.
Reduction of NADP: NADP accepts electrons and H+ protons to become NADPH; this occurs in Photosystem I.
During the light-dependent reaction, light energy is converted into chemical energy in the form of ATP and reduced NADP; oxygen is given off as a waste product.
The useful products (ATP and reduced NADP) are transferred to the light-independent reaction within the chloroplast.

Photophosphorylation

Photophosphorylation is the overall process of using light energy and the electron transport chain to generate ATP from ADP.
The photophosphorylation of ADP to ATP can be cyclic or non-cyclic, depending on the pattern of electron flow in photosystem I or photosystem II or both.
Cyclic photophosphorylation involves only photosystem I; an electron is excited and passed to an electron acceptor, transported via an electron transport chain, and passed back to the chlorophyll molecule in photosystem I.
As electrons pass through the electron transport chain, they provide energy to pump protons (H+) from the stroma to the thylakoid lumen via a proton pump.
A build-up of protons in the thylakoid lumen drives the synthesis of ATP from ADP and inorganic phosphate (π) by chemiosmosis.
Chemiosmosis is the movement of protons down their concentration gradient; the energy released is used by ATP synthase to synthesise ATP.
Non-cyclic photophosphorylation involves both photosystem I and photosystem II; excited electrons from Photosystem II are passed down a series of electron carriers forming the electron transport chain.
The electron carriers undergo a series of redox reactions; excited electrons gradually release energy used to generate a proton gradient.
The electrons are eventually picked up by the reaction centre in Photosystem I and used to reduce NADP (along with protons from the photolysis of water).
Cyclic photophosphorylation differs from non-cyclic in two key ways: it only involves photosystem I, and it does not produce reduced NADP.

Light Independent Reactions

The light-independent reactions take place in the stroma of the chloroplast, a thick protein-rich environment containing the necessary enzymes.
The light-independent reactions are also known as the Calvin cycle and have three main steps: carbon fixation, reduction, and regeneration.
Carbon fixation: the enzyme Rubisco catalyses the fixation of carbon dioxide by combination with ribulose bisphosphate (RuBP), a 5C compound, to yield two molecules of glycerate 3-phosphate (GP), a 3C compound.
Rubisco is the most abundant enzyme on Earth; it works relatively slowly, so high concentrations are needed in the stroma, and it is not effective at low carbon dioxide concentrations.
Reduction: GP is reduced to triose phosphate (TP) in a reaction involving reduced NADP and ATP.
Regeneration: RuBP is regenerated from TP in reactions that use ATP; five molecules of triose phosphate are converted to three molecules of RuBP.
One sixth of the triose phosphate is converted into usable products for the plant, such as hexose phosphates (for carbohydrates like starch, sucrose or cellulose), glycerol and fatty acids (for cell membranes), and amino acids (for protein synthesis).
The remaining five sixths of triose phosphate are used to regenerate RuBP; this is important because otherwise the supplies of RuBP would run out.
To produce one molecule of glucose, six turns of the Calvin cycle are needed.

Interdependence of Photosynthetic Reactions

The light-dependent and light-independent reactions are interdependent; one cannot occur without the other.
Products from the light-dependent reaction (reduced NADP and ATP) are directly used in the Calvin cycle to produce carbohydrates.
In low light intensity, these products are produced at a slower rate, limiting the conversion of GP to TP.
Once reduced NADP has been oxidised in the Calvin cycle, NADP is returned to the light-dependent stage to accept electrons at the end of the electron transport chain.
In high light intensity, the light-dependent reactions occur more quickly, providing more reduced NADP and ATP to drive the Calvin cycle.
If NADP is not returned to the light-dependent stage quickly enough, the process will be restricted.
Carbon dioxide, in the form of hydrogen carbonate ions (HCO3−), accepts protons from photosystem II when water is split during photolysis.
Hydrogen carbonate also plays an important role in the functioning of the electron transport chain.
A lack of carbon dioxide (and thus hydrogen carbonate) will not only prevent carbon fixation but also prevent photosystem II from functioning.

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साइन अप करें — फ्री लॉग इन

प्रैक्टिस सवाल

फ्री प्रीव्यू — 62 में से 8 सवाल। सभी देखने के लिए साइन अप करें।

1.Which of the following are the reactants of photosynthesis?
Easy
- ACarbon dioxide and water
- BGlucose and oxygen
- CCarbon dioxide and glucose
- DWater and oxygen
2.What is the primary role of a photosynthetic pigment?
Easy
- ATo absorb light energy
- BTo reflect all wavelengths of light
- CTo produce carbon dioxide
- DTo store glucose
3.Which region of the light spectrum is absorbed by chlorophyll a?
Easy
- ABlue-violet and red
- BGreen and yellow
- COrange and red
- DBlue-violet and green
4.Carotenoids absorb light mainly in the blue-violet region of the spectrum.
Easy
True or false?
5.In chromatography, which pigment would have the highest Rf value?
Medium
- ACarotene
- BChlorophyll b
- CChlorophyll a
- DXanthophyll
6.Where in the chloroplast do the light-dependent reactions take place?
Medium
- AThylakoid membrane
- BStroma
- COuter membrane
- DIntermembrane space
7.Where do the light-independent reactions (Calvin cycle) take place?
Medium
- AStroma
- BThylakoid membrane
- CThylakoid lumen
- DCytoplasm
8.Which of the following are products of the light-dependent reaction of photosynthesis? (select all that apply)
Medium
- AATP
- BReduced NADP
- COxygen
- DGlucose
- ECarbon dioxide

और सवाल

9.Which of the following statements about photosystems are correct? (select all that apply)
Medium
- APhotosystem I contains reaction centre P700
- BPhotosystem II contains reaction centre P680
- CPhotosystem I is involved in cyclic photophosphorylation
- DPhotosystem II is involved in cyclic photophosphorylation
- EPhotosystem I and II are involved in non-cyclic photophosphorylation
10.In cyclic photophosphorylation, both photosystem I and photosystem II are involved.
Easy
True or false?
11.Match each pigment with its colour.
Medium
- Chlorophyll a
- Chlorophyll b
- β carotene
- Xanthophyll
- Blue-green
- Yellow-green
- Orange
- Yellow
12.Place the steps of the Calvin cycle in the correct order.
Medium
- Carbon fixation
- Reduction
- Regeneration
13.Which of the following correctly describes photosynthesis as an energy conversion?
Easy
- ALight energy is converted into chemical energy stored in biomass
- BChemical energy is converted into light energy stored in biomass
- CLight energy is created from chemical energy in the leaf
- DChemical energy is destroyed and replaced by light energy
14.Which of the following are functions of the products of the light-dependent reaction in the light-independent reaction? (select all that apply)
Medium
- AATP provides energy to regenerate RuBP
- BReduced NADP provides hydrogen to reduce GP to TP
- CATP is used to reduce NADP to NADPH
- DOxygen is used to fix carbon dioxide
- EReduced NADP is used to split water
15.Match each pigment with its role in the light-dependent stage of photosynthesis.
Medium
- Chlorophyll a and b
- Carotenoid accessory pigments (xanthophyll, carotene)
- Light harvesting complex proteins: enzymes
- Light harvesting complex proteins: electron carriers
- Absorb wavelengths of light in the blue to violet and red regions of the spectrum
- Absorb wavelengths of light in the blue to violet region of the spectrum
- Catalyse the formation of ATP from ADP + π and the reduction of NADP to NADPH + H+
- Pass electrons down an electron transport chain
16.Place the steps of non-cyclic photophosphorylation in the correct order.
Medium
- Excited electrons from Photosystem II are passed to an electron acceptor
- Electrons pass down a chain of electron carriers via redox reactions
- Energy released pumps protons into the thylakoid lumen, creating a gradient
- Protons flow through ATP synthase, synthesising ATP by chemiosmosis
- Electrons are passed to Photosystem I and then used to reduce NADP
17.In chromatography, which pigment would be expected to have the highest Rf value?
Medium
- ACarotene
- BChlorophyll b
- CChlorophyll a
- DPheophytin a
18.A student set up an experiment to investigate the effect of light intensity on the rate of photosynthesis in pondweed. They placed a lamp at different distances from the plant and counted the number of oxygen bubbles produced per minute. Which of the following is the independent variable in this experiment?
Medium
- ADistance between the lamp and the plant
- BNumber of oxygen bubbles produced per minute
- CTemperature of the water
- DConcentration of sodium hydrogencarbonate
19.In cyclic photophosphorylation, only Photosystem I is involved and reduced NADP is not produced.
Easy
True or false?
20.Which of the following statements about the interdependence of the light-dependent and light-independent reactions are correct? (select all that apply)
Hard
- AReduced NADP and ATP from the light-dependent reaction are used in the Calvin cycle
- BIn low light intensity, the conversion of GP to TP is limited
- CNADP is returned to the light-dependent stage after being oxidised in the Calvin cycle
- DOxygen produced in the light-dependent reaction is used to fix carbon dioxide
- EThe light-independent reaction can occur without the light-dependent reaction
21.
A student investigated the effect of different colours of light on the growth of Arabidopsis thaliana seedlings. The results are shown in the table.
Colour of light Wavelength / nm Height of seedlings / cm Shoot length / cm Total biomass / g
Blue 450 2.3 2.0 2.4
Orange 600 3.5 2.8 2.8
Red 630 7.4 6.1 3.7
Which conclusion is best supported by these data?
Medium
- ARed light produces the greatest seedling height and biomass, while blue light produces the least.
- BBlue light produces the greatest biomass because it is absorbed most strongly by chlorophyll.
- COrange light produces the greatest height because it is in the green-yellow trough of the action spectrum.
- DAll three colours produce equal biomass, so wavelength has no effect on growth.
22.A researcher found that most of the light energy reaching the ground in a woodland area was in the 500-600 nm range, and few plant species grew below the tall trees. Which statement best explains this observation?
Hard
- ALight at 500-600 nm is poorly absorbed by chlorophyll, so little energy is available for photosynthesis below the canopy.
- BLight at 500-600 nm is strongly absorbed by chlorophyll, so it is used up before reaching the ground.
- CLight at 500-600 nm is in the blue-violet region, which is the main absorption peak of carotenoids.
- DLight at 500-600 nm is in the red region, which is the main absorption peak of chlorophyll a.
23.In an investigation into the effect of light intensity on the rate of photosynthesis in pondweed, the glass tank filled with water between the lamp and the plant is important because it:
Medium
- Aabsorbs heat emitted by the lamp, helping to keep temperature constant.
- Bremoves dissolved carbon dioxide from the water around the plant.
- Cincreases the concentration of carbon dioxide available to the plant.
- Dfilters out green light so that only red and blue light reach the plant.
24.A student set up pondweed in boiled and re-cooled water with a fixed mass of sodium hydrogencarbonate added. The lamp was kept at a fixed distance while the temperature was varied from 5°C to 50°C. The rate of photosynthesis increased up to about 30°C and then fell sharply. Which explanation is correct?
Hard
- AAbove the optimum temperature, enzymes such as Rubisco denature, so fewer enzyme-substrate complexes form.
- BAbove the optimum temperature, the light-dependent reactions stop because chlorophyll is destroyed.
- CAbove the optimum temperature, carbon dioxide becomes the limiting factor because it is less soluble.
- DAbove the optimum temperature, the rate of respiration increases and masks the rate of photosynthesis.
25.A student carried out thin-layer chromatography to separate photosynthetic pigments from a spinach leaf. The solvent front moved 8.0 cm from the origin. Pigment spot P moved 6.8 cm, pigment spot Q moved 4.8 cm, and pigment spot R moved 0.6 cm. Which of the following statements are correct? (select all that apply)
Hard
- AThe Rf value of pigment P is 0.85.
- BPigment Q is likely to be chlorophyll b.
- CPigment R is likely to be carotene.
- DThe Rf value of pigment R is 0.075.
- EPigment P is likely to be chlorophyll a.
26.An experiment was set up to investigate the effect of different wavelengths of light on the rate of photosynthesis in pondweed. Different colour filters were placed in front of the lamp, and the lamp was kept at the same distance from the plant throughout. Which of the following are correct statements about this investigation? (select all that apply)
Hard
- AThe independent variable is the wavelength of light.
- BThe dependent variable is the volume of oxygen produced per minute.
- CThe distance between the lamp and the plant should be varied for each filter.
- DAn experiment with no filter should be included to investigate white light.
- EThe number of bubbles released per minute can be used as a measure of the rate.
27.A plant is exposed to very high light intensity. The light-dependent reactions produce ATP and reduced NADP rapidly, but the rate of the Calvin cycle does not increase beyond a certain point. Which is the most likely explanation?
Hard
- ANADP is not returned to the light-dependent stage quickly enough, so the electron transport chain becomes restricted.
- BThe light-dependent reactions stop producing ATP because photosystem II becomes saturated with photons.
- CCarbon dioxide concentration increases, which inhibits Rubisco activity.
- DThe thylakoid membrane becomes impermeable to protons, preventing chemiosmosis.
28.In an investigation, the rate of photosynthesis in pondweed was measured at different carbon dioxide concentrations while temperature was kept constant at 25°C and light intensity was kept constant. The rate increased with carbon dioxide concentration up to 0.4 mol dm⁻³ and then levelled off. Which of the following is the best interpretation?
Medium
- ABetween 0 and 0.4 mol dm⁻³, carbon dioxide is the limiting factor; above 0.4 mol dm⁻³, another factor becomes limiting.
- BBetween 0 and 0.4 mol dm⁻³, light intensity is the limiting factor; above 0.4 mol dm⁻³, carbon dioxide becomes limiting.
- CThe rate levels off because the plant has run out of water.
- DThe rate levels off because the temperature is too low for enzyme activity.
29.In an investigation into the effect of light intensity on photosynthesis, the water surrounding the pondweed is boiled and re-cooled to remove dissolved carbon dioxide before a set mass of sodium hydrogencarbonate is added.
Medium
True or false?
30.In free air carbon dioxide enrichment (FACE) experiments, all variables other than carbon dioxide concentration can be carefully controlled.
Medium
True or false?
31.Match each experimental observation with the correct interpretation.
Medium
- A pigment has an Rf value of 0.92
- A pigment has an Rf value of 0.58
- The rate of photosynthesis is highest at 450 nm and 650 nm
- The rate of photosynthesis is lowest at 550 nm
- The pigment is likely to be carotene
- The pigment is likely to be chlorophyll b
- These wavelengths correspond to the blue-violet and red absorption peaks
- This wavelength corresponds to the green-yellow trough in the action spectrum
32.Place the steps of an investigation into the effect of carbon dioxide concentration on the rate of photosynthesis in the correct order.
Hard
- Boil and re-cool water to remove dissolved carbon dioxide.
- Add a set mass of sodium hydrogencarbonate to the water.
- Place the aquatic plant in the water and position the lamp at a fixed distance.
- Keep the temperature constant at 25°C using a water bath.
- Record the number of bubbles released per minute.
- Increase the sodium hydrogencarbonate concentration in increments of 0.01 mol dm⁻³ and repeat.
33.Which of the following is the independent variable in this experiment?
Medium
- ADistance between the lamp and the plant
- BNumber of bubbles released per minute
- CTemperature of the water
- DConcentration of sodium hydrogencarbonate
34.As the lamp is moved further from the plant, the number of bubbles per minute decreases. Which is the best explanation?
Hard
- ALight intensity decreases with distance, so less light energy is absorbed for the light-dependent reaction.
- BThe temperature of the water decreases with distance, reducing enzyme activity.
- CCarbon dioxide concentration decreases with distance, limiting the Calvin cycle.
- DThe wavelength of light changes with distance, reducing absorption by chlorophyll.
35.In this experiment, the water surrounding the pondweed is boiled and re-cooled before a set mass of sodium hydrogencarbonate is added.
Medium
True or false?
36.A student sets up pondweed in a beaker and places a lamp at different distances from the plant. The number of oxygen bubbles is counted for three minutes at each distance. Which improvement would most increase the reliability of the results?
Medium
- ARepeat the experiment at least twice at each distance and calculate a mean
- BUse a brighter lamp at each distance
- CIncrease the number of bubbles counted by leaving the plant for longer
- DUse a different species of pondweed for each distance
37.In an investigation into the effect of light intensity on photosynthesis, the glass tank of water between the lamp and the pondweed has holes drilled in it so the water drains out. What is the most likely effect on the results?
Hard
- AThe temperature around the pondweed will rise, so the results will be affected by temperature as well as light intensity
- BThe light intensity reaching the pondweed will decrease, so fewer bubbles will be produced
- CThe carbon dioxide concentration will increase, so more bubbles will be produced
- DThe pondweed will receive more light, so the rate of photosynthesis will increase
38.A student investigates the effect of carbon dioxide concentration on the rate of photosynthesis in pondweed. They keep the lamp at a fixed distance and use a water bath at 25°C. Which of the following are controlled variables in this experiment? (select all that apply)
Hard
- ATemperature
- BLight intensity
- CCarbon dioxide concentration
- DNumber of bubbles produced per minute
- EVolume of water in the beaker
39.In an investigation into the effect of light intensity on photosynthesis, the water surrounding the pondweed is boiled and re-cooled before adding sodium hydrogencarbonate.
Medium
True or false?
40.Place the steps of the investigation into the effect of light intensity on the rate of photosynthesis in pondweed in the correct order.
Medium
- Place a piece of pondweed into a beaker of water
- Place a lamp a set distance from the plant
- Record the number of bubbles observed in three minutes
- Repeat at different distances between the lamp and the plant
41.Name the process by which oxygen is produced during photosynthesis.
Easy
42.A pigment spot in a chromatography experiment moved 4.5 cm from the origin, while the solvent front moved 7.5 cm. Calculate the Rf value of the pigment.
Medium
43.Complete the sentence about the Calvin cycle.
Easy
The enzyme ____ catalyses the fixation of carbon dioxide by combining it with ____ to yield two molecules of glycerate-3-phosphate.
44.Name the enzyme that catalyses the fixation of carbon dioxide in the Calvin cycle.
Easy
45.In an experiment, a pigment spot moved 3.2 cm from the origin and the solvent front moved 8.0 cm. Calculate the Rf value of the pigment. Give your answer to 2 decimal places.
Medium
46.Complete the sentence about the Calvin cycle by filling in the missing terms.
Medium
In the Calvin cycle, carbon dioxide combines with the 5C compound ____ to form two molecules of the 3C compound ____, which is then reduced to triose phosphate.
47.In a thin-layer chromatography experiment, a pigment spot moved 5.4 cm from the origin and the solvent front moved 7.2 cm. Calculate the Rf value of the pigment. Give your answer to 2 decimal places.
Medium
48.A pigment has an Rf value of 0.65. If the solvent front moved 9.0 cm from the origin, calculate the distance moved by the pigment in cm.
Hard
49.Complete the passage about an investigation into limiting factors in photosynthesis.
Medium
In an investigation into the effect of light intensity on the rate of photosynthesis in pondweed, the independent variable is the ____ and the dependent variable is the ____. The glass tank of water between the lamp and the plant is used to control the ____. Sodium hydrogencarbonate is added to control the concentration of ____.
50.Name the process by which oxygen is produced during the light-dependent reaction of photosynthesis.
Medium
51.In chromatography, a pigment spot moved 6.0 cm and the solvent front moved 8.0 cm. State the Rf value of the pigment as a decimal.
Medium
52.In a thin-layer chromatography experiment, a pigment spot moved 4.8 cm from the origin and the solvent front moved 6.0 cm. Calculate the Rf value of the pigment.
Easy
53.Describe the process of photolysis of water and its importance in the light-dependent reaction.
Medium
54.Explain why the light-dependent and light-independent reactions of photosynthesis are described as interdependent.
Hard
55.Describe and explain how an increase in average summer temperature from 21°C to 24°C, combined with increased cloud cover, would impact the growth of Rhododendrons in an alpine habitat.
Hard
56.Explain why it is beneficial for plants to possess multiple photosynthetic pigments.
Hard
57.Describe the process of photolysis of water and explain its importance in the light-dependent reaction.
Hard
58.A pigment spot in a chromatography experiment moved 4.5 cm from the origin, while the solvent front moved 7.5 cm. Calculate the Rf value of the pigment.
Medium
- A0.6
- B-0.4
- C2.6
- D1.6
59.In an experiment, a pigment spot moved 3.2 cm from the origin and the solvent front moved 8.0 cm. Calculate the Rf value of the pigment. Give your answer to 2 decimal places.
Medium
- A-0.6
- B1.4
- C2.4
- D0.4
60.In a thin-layer chromatography experiment, a pigment spot moved 5.4 cm from the origin and the solvent front moved 7.2 cm. Calculate the Rf value of the pigment. Give your answer to 2 decimal places.
Medium
- A-0.25
- B2.75
- C0.75
- D1.75
61.A pigment has an Rf value of 0.65. If the solvent front moved 9.0 cm from the origin, calculate the distance moved by the pigment in cm.
Hard
- A5.85 cm
- B6.85 cm
- C4.85 cm
- D7.85 cm
62.In a thin-layer chromatography experiment, a pigment spot moved 4.8 cm from the origin and the solvent front moved 6.0 cm. Calculate the Rf value of the pigment.
Easy
- A1.8
- B-0.2
- C0.8
- D2.8

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इस टॉपिक के हर सवाल, स्लाइड्स, फ्लैशकार्ड और रिवीज़न नोट्स देखने के लिए फ्री अकाउंट बनाएं।

साइन अप करें — फ्री लॉग इन

पास्ट पेपर

इस टॉपिक के लिए पास्ट-पेपर प्रैक्टिस जल्द आ रही है।

जल्द आ रहा है

Colour of light	Wavelength / nm	Height of seedlings / cm	Shoot length / cm	Total biomass / g
Blue	450	2.3	2.0	2.4
Orange	600	3.5	2.8	2.8
Red	630	7.4	6.1	3.7