Photosynthesis Overview and Processes
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Questions and Answers

What is the primary purpose of chromatography in the context of photosynthesis?

  • To separate mixtures of pigments (correct)
  • To create energy from sunlight
  • To increase the rate of photosynthesis
  • To enhance the light absorption of chlorophyll

Which technique utilizes a thin layer of adsorbent for the separation of photosynthetic pigments?

  • Liquid chromatography
  • Gas chromatography
  • Thin-layer chromatography (TLC) (correct)
  • Paper chromatography

What is the retardation factor (Rf value) used for in chromatography?

  • To measure the total amount of pigment present
  • To characterize the nature of the stationary phase
  • To calculate the efficiency of photosynthesis
  • To determine the speed at which pigments travel (correct)

What advantage does thin-layer chromatography (TLC) have over paper chromatography?

<p>TLC separates mixtures more distinctly (D)</p> Signup and view all the answers

Which pigments are primarily involved in the light-dependent reactions of photosynthesis?

<p>Chlorophyll and carotenoids (B)</p> Signup and view all the answers

What should be labeled on the x-axis of the action spectrum for photosynthesis?

<p>Wavelengths in nanometers (D)</p> Signup and view all the answers

Where do the peaks of the photosynthesis rate occur on the spectrum?

<p>In the blue and red areas (D)</p> Signup and view all the answers

What characteristic should the curve of the action spectrum exhibit?

<p>A smooth curve (C)</p> Signup and view all the answers

At which part of the spectrum is the trough representing green light located?

<p>In the middle of the spectrum (D)</p> Signup and view all the answers

What type of scale should be utilized on the y-axis of the action spectrum graph?

<p>% scale (D)</p> Signup and view all the answers

What is the role of reduced NADP in photosynthesis?

<p>It is directly utilized in the Calvin cycle to produce carbohydrates. (B)</p> Signup and view all the answers

Which condition will most significantly limit the Calvin cycle's function?

<p>Low light intensity and insufficient reduced NADP. (B)</p> Signup and view all the answers

What happens to NADP after it is oxidized in the Calvin cycle?

<p>It is recycled back to the light dependent stage to accept electrons. (B)</p> Signup and view all the answers

How does a lack of carbon dioxide affect photosystem II?

<p>It prevents the acceptance of protons, thus inhibiting its function. (A)</p> Signup and view all the answers

What is a consequence of NADP not being returned quickly to the light dependent stage?

<p>Restriction of the Calvin cycle's performance. (B)</p> Signup and view all the answers

What is the primary research question being investigated?

<p>Does light intensity affect the rate of photosynthesis? (A)</p> Signup and view all the answers

Which method is suggested to improve the accuracy of measuring gas production?

<p>Using a gas syringe to collect and measure gas volume (A)</p> Signup and view all the answers

What variable must be controlled to prevent it from limiting the rate of photosynthesis?

<p>CO2 concentration (D)</p> Signup and view all the answers

How is temperature controlled in the photosynthesis experiment?

<p>By using a glass tank to absorb heat (D)</p> Signup and view all the answers

What is the purpose of boiling the water used in the experiment?

<p>To remove dissolved carbon dioxide (B)</p> Signup and view all the answers

What is the optimal concentration of sodium hydrogencarbonate to ensure adequate CO2 levels?

<p>0.1 mol dm-3 (B)</p> Signup and view all the answers

What trend is expected when plotting the number of bubbles produced per minute against lamp distance?

<p>Increased distance resulting in fewer bubbles (D)</p> Signup and view all the answers

Which of the following is a recommended practice for enhancing reliability in the photosynthesis experiment?

<p>Repeating the experiment at least twice for each distance (D)</p> Signup and view all the answers

What is the role of electrons produced during the photolysis of water in photosystem II?

<p>To replace lost electrons in the primary pigment molecule (C)</p> Signup and view all the answers

What is reduced during the process involving photosystem I?

<p>NADP+ (A)</p> Signup and view all the answers

In what part of the chloroplast do the light-independent reactions occur?

<p>Stroma (A)</p> Signup and view all the answers

Which of the following is involved in the reduction of NADP+ to NADPH?

<p>Protons and photoactivated electrons (D)</p> Signup and view all the answers

What is the correct formula representing the reduction of NADP+?

<p>NADP+ + 2H⁺ + 2e⁻ → NADPH + H+ (C)</p> Signup and view all the answers

What key process involves combining hydrogen ions with electrons in the light-dependent reactions?

<p>Reduction of NADP+ (C)</p> Signup and view all the answers

Which statement is true regarding the Calvin cycle?

<p>It involves the fixation of carbon. (B)</p> Signup and view all the answers

What is the primary function of the reduced ferredoxin in the light-dependent reactions?

<p>To assist in the reduction of NADP+ (B)</p> Signup and view all the answers

What is the relationship between light intensity and the rate of photosynthesis up to a certain point?

<p>Positive correlation (B)</p> Signup and view all the answers

What happens after light intensity reaches a certain level in photosynthesis?

<p>Temperature becomes a limiting factor (D)</p> Signup and view all the answers

When conducting an experiment to measure the effect of carbon dioxide concentration on photosynthesis, what must be done to keep temperature constant?

<p>Use a water bath at a set temperature (B)</p> Signup and view all the answers

To measure the rate of photosynthesis using sodium hydrogencarbonate, what should you do with the concentration?

<p>Increase it in increments (B)</p> Signup and view all the answers

What variable must be controlled when measuring the rate of photosynthesis in an aquatic plant with a lamp?

<p>Distance from the plant to the lamp (A)</p> Signup and view all the answers

In the photosynthesis experiment, increasing light intensity will eventually lead to what?

<p>No change in the rate of photosynthesis (A)</p> Signup and view all the answers

What would you expect to observe if both light intensity and carbon dioxide concentration are high?

<p>Photosynthesis will be at its maximum rate (B)</p> Signup and view all the answers

If a graph shows a positive correlation between light intensity and the rate of photosynthesis, what does this indicate?

<p>Higher light levels enhance photosynthesis to a certain extent (B)</p> Signup and view all the answers

Flashcards

Photosynthetic Pigments

Substances like Chlorophyll and Carotenoids that absorb light for photosynthesis.

Chromatography

A lab technique separating mixtures by different travel speeds of components.

Rf Value

A value representing a component's rate of movement during chromatography.

Paper Chromatography

A technique separating components by letting them pass through paper (cellulose).

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Thin-Layer Chromatography (TLC)

A technique for separating components through a thin layer of adsorbent.

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Action Spectrum for Photosynthesis

A graph showing the rate of photosynthesis at different wavelengths of light.

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X-axis of Action Spectrum

Shows the wavelengths of light (in nanometers, nm).

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Y-axis of Action Spectrum

Shows the rate of photosynthesis (percentage).

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Shape of Action Spectrum curve

A smooth curve, peaking in the blue and red areas, and having a trough in the green area.

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Importance of Action Spectrum

It demonstrates that different wavelengths of light affect photosynthesis differently.

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Investigating light intensity

A practical experiment to explore the relationship between light intensity and the rate of photosynthesis in a plant.

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Elodea

A common aquatic plant, like cabomba, used in experiments investigating photosynthesis because it produces visible oxygen bubbles.

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What is measured in the experiment?

The experiment measures the rate of photosynthesis by counting the number of oxygen bubbles released by the plant per minute.

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How is light intensity changed?

Light intensity is changed by varying the distance between the light source (lamp) and the plant. The closer the lamp, the more intense the light.

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Why control temperature?

Temperature influences the rate of enzyme reactions, including those involved in photosynthesis. Controlling it ensures temperature is not a confounding variable.

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Why control CO2 concentration?

Carbon dioxide is a reactant needed for photosynthesis. Controlling its concentration ensures it doesn't limit the rate of photosynthesis.

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What does the graph show?

The graph displays the relationship between light intensity (distance from lamp) and the rate of photosynthesis (number of bubbles).

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Improvements for the experiment

For a more reliable and accurate experiment, using a gas syringe to measure gas volume, repeating the experiment at least twice, and using a data logger for continuous measurements are recommended.

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Light intensity effect on photosynthesis

As light intensity increases, the rate of photosynthesis also increases until a point where it plateaus. This indicates that light intensity is the limiting factor.

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Limiting factor in photosynthesis

The factor that restricts the rate of photosynthesis even if other factors are present in optimal amounts.

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What happens when light is no longer limiting?

When light intensity reaches a point where it no longer limits the rate of photosynthesis, other factors like carbon dioxide concentration or temperature may become the limiting factors.

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Experiment setup for CO2 concentration effect

The experiment setup is similar to the light intensity experiment, but instead of varying light, you vary the concentration of carbon dioxide (CO2) using sodium hydrogencarbonate (NaHCO3).

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Effect of CO2 concentration on photosynthesis

As CO2 concentration increases, the rate of photosynthesis also increases until a point where it plateaus, indicating that CO2 levels are now limiting.

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Importance of keeping temperature constant

In the experiment measuring the effect of CO2 concentration, temperature is kept constant at 25°C using a water bath to isolate the effect of CO2.

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Constant light intensity during CO2 experiment

Keeping the lamp a fixed distance from the plant ensures a consistent light intensity throughout the experiment to observe the impact of varying CO2.

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Graph shape for CO2 and light intensity

The graph of the effect of both CO2 and light intensity on photosynthesis resembles a curve that increases to a plateau, indicating a limiting factor.

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What is the role of Photosystem I?

Photosystem I is involved in the reduction of NADP, a key component for the light-independent reactions.

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NADP Reduction Process

During NADP reduction, Photosystem I absorbs light energy, activates electrons to a higher energy level, and passes them to ferredoxin.

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Why is NADPH important for light-independent reactions?

Reduced NADP (NADPH) carries a pair of electrons, which are essential for the light-independent reactions, transferring energy to fuel carbon fixation.

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Where do light-independent reactions occur?

These reactions take place in the stroma of chloroplasts, a thick protein-rich environment containing the necessary enzymes.

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What are light-independent reactions called?

The light-independent reactions are also known as the Calvin cycle, a cyclic process involving carbon fixation.

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Main steps of the Calvin cycle

The Calvin cycle involves three main steps: carbon fixation, reduction, and regeneration of the initial carbon acceptor.

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Carbon Fixation

This step involves the incorporation of carbon dioxide into an organic molecule, using the enzyme RuBisCo.

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What is the importance of RuBisCo?

RuBisCo is a key enzyme in the Calvin cycle, responsible for catalyzing the initial carbon fixation step.

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Interdependent Reactions

The light-dependent and light-independent reactions of photosynthesis rely on each other. The products of one reaction are essential for the other to occur.

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Reduced NADP and ATP in Calvin Cycle

Reduced NADP and ATP, produced in the light-dependent reaction, are crucial for the Calvin cycle to convert carbon dioxide into glucose (sugar).

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NADP Recycling

The Calvin cycle uses up reduced NADP, which is then returned to the light-dependent reaction to be reused and continue the cycle.

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Carbon Dioxide and Photosystem II

Carbon dioxide, in the form of hydrogen carbonate ions (HCO3-), is needed for carbon fixation but also plays a role in the light-dependent reaction by accepting protons from water splitting in Photosystem II.

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Lack of Carbon Dioxide Impact

Limited carbon dioxide affects both photosynthesis stages: carbon fixation in the Calvin cycle stops and Photosystem II cannot function properly.

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Study Notes

Photosynthesis Overview

  • Photosynthesis is the process where simple inorganic compounds are converted into complex organic compounds.
  • This process occurs in autotrophic organisms such as plants, algae, and cyanobacteria.
  • Photosynthesis converts light energy into chemical energy, storing it in biomass.
  • The chemical energy stored in organic compounds provides most of the chemical energy needed for life processes in ecosystems.
  • Energy is only ever converted, not created or destroyed.

Photosynthesis Diagram

  • The reactants of photosynthesis are carbon dioxide and water.
  • The products of photosynthesis are glucose and oxygen.
  • A leaf absorbs light energy to drive the process.

Photosynthesis Word Equation

  • Carbon dioxide + water + light energy → glucose + oxygen

Photosynthetic Pigments

  • Plants contain several different pigments, including chlorophylls and carotenoids, which absorb different wavelengths of light.
  • Chlorophyll absorbs light in the blue-violet and red regions of the visible light spectrum and reflects green light.
  • Carotenoids absorb light mainly in the blue-violet region of the spectrum.
  • This broader range of absorbed visible light increases the efficiency of photosynthesis.
  • Chromatography is used to separate different pigments based on their different properties, with varying affinities to a stationary and mobile phase.

Absorption Spectra

  • Absorption spectra are graphs showing how much light different wavelengths are absorbed by a pigment.
  • Pigments absorb certain wavelengths and reflect others, giving the plant its distinct color.
  • The shape and wavelength region of an absorption spectrum is directly linked to the light absorbed by a pigment, and thus its function in photosynthesis.

Action Spectra

  • Action spectra measure the rate of photosynthesis at different wavelengths of light.
  • The action spectrum shows the greatest rates of photosynthesis at blue-violet and red wavelengths.
  • This correlation demonstrates that these wavelengths are effectively used in the photosynthetic process.

Limiting Factors

  • Light intensity, carbon dioxide concentration, and temperature all affect the rate of photosynthesis.
  • At low light intensity, the rate of photosynthesis increases linearly as light intensity increases.
  • At higher light intensities, the rate levels off, as other factors become limiting.

Limiting Factors Experiments

  • Experiments can be set up to investigate the effects of varying light intensity, carbon dioxide concentration, and temperature on photosynthesis rates using aquatic plants like Elodea.
  • Measured variables like the rate of oxygen production can be used to demonstrate the effect of any particular factor.
  • Control variables such as temperature, carbon dioxide, and water quality must be monitored and kept constant.

Photosystems (HL)

  • Chloroplasts contain pigments like chlorophyll, along with accessory pigments like carotenoids and xanthophylls, organized into photosystems.
  • Photosystems are located in the thylakoid.
  • Photosystem I (PSI) and Photosystem II (PSII) are crucial for light-dependent reactions.
  • The pigment molecules (chlorophylls) within a photosystem absorb light and transfer the energy to a reaction center chlorophyll.

Light-Dependent Reactions (HL)

  • Take place within the thylakoid membranes of chloroplasts.
  • Involve the splitting of water molecules (photolysis).
  • Produce ATP (adenosine triphosphate) and reduced NADP (NADPH).
  • Oxygen is a byproduct.
  • Electrons flow from PSII to PSI through an electron transport chain.
  • The energy released during electron transfer pumps protons across the thylakoid membrane.
  • Chemosmosis drives the synthesis of ATP.

Light-Independent Reactions (HL)

  • The Calvin cycle, occurring in the stroma of chloroplasts.
  • Involves carbon fixation, reduction, and regeneration.
  • RuBisCo (an enzyme) fixes carbon dioxide to RuBP, creating a six-carbon molecule that splits into two three-carbon molecules.
  • These 3-carbon molecules are reduced to glyceraldehyde-3-phosphate (G3P, a type of sugar).
  • G3P can be used to produce glucose, starch, cellulose, or other organic compounds.
  • The cycle regenerates RuBP to allow the cycle to continue.

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HL IB Biology Photosynthesis PDF

Description

Explore the fascinating process of photosynthesis, where light energy is transformed into chemical energy by plants and other autotrophs. This quiz covers key concepts such as reactants, products, and the role of pigments in photosynthesis. Test your knowledge about how energy flows through ecosystems via this essential biological process.

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