Photosynthesis and the Calvin Cycle Quiz

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Questions and Answers

What is the primary function of rubisco in the Calvin cycle?

To transport photosynthetic products

To produce energy in the form of ATP

To release oxygen as a byproduct

To fix carbon dioxide with ribulose bisphosphate (correct)

Which of the following compounds is produced during the reaction catalyzed by rubisco?

Glycerate 3-phosphate (correct)

Ribulose bisphosphate

ATP

Triose phosphate

How does temperature influence the rate of the light-independent stage of photosynthesis?

Temperature has no effect on the light-independent stage

Higher temperatures decrease the rate due to denaturation

Higher temperatures increase the rate due to increased kinetic energy (correct)

Lower temperatures enhance enzyme activity

What role does light intensity play in the process of photosynthesis?

It influences the rate of the light-dependent reactions Signup and view all the answers

What might occur if a plant is short of water?

Stomata will close to prevent water loss Signup and view all the answers

What is the reactant in the photosynthesis process, which is often present in low concentrations?

Carbon dioxide Signup and view all the answers

Which factor is NOT considered a direct limiting factor affecting photosynthesis?

Wind speed Signup and view all the answers

What is the main product generated from triose phosphate (TP) in the Calvin cycle?

Glucose Signup and view all the answers

What principle does chromatography rely on for separating chlorophyll pigments?

Differences in solubility in a solvent Signup and view all the answers

What is the purpose of calculating Rf values in chromatography?

To identify the pigments present in the extract Signup and view all the answers

Which variable affects how far up the TLC strip the pigment is carried?

The solubility of the pigments in the solvent Signup and view all the answers

What should be done immediately after applying the chlorophyll spot to the TLC strip?

Allow the spot to dry before applying more extract Signup and view all the answers

When preparing the TLC strip, what should you avoid doing with the powdery surface?

Touching it with your fingers Signup and view all the answers

What is the correct formula for calculating Rf values?

Rf = distance from start line to pigment spot / distance from start line to solvent front Signup and view all the answers

Why is it recommended to keep the pigment spot to a small diameter?

To prevent overlapping of the pigment spots Signup and view all the answers

What happens if you wait too long before adding the running solvent on the TLC strip?

The pigments may diffuse too far. Signup and view all the answers

What is the dependent variable in the investigation of photosynthesis?

The color change of the hydrogencarbonate indicator solution Signup and view all the answers

How can light intensity be calculated in this investigation?

light intensity = 1/distance² Signup and view all the answers

What role does sodium hydrogencarbonate play in the investigation?

It provides hydrogencarbonate ions for carbon dioxide Signup and view all the answers

What must be considered when varying the wavelength of light?

The effect of color filters on light intensity Signup and view all the answers

Which method can be used to analyze the results of the photosynthesis investigation?

Spearman's rank correlation Signup and view all the answers

Which of the following conditions is least likely to affect the rate of photosynthesis?

The type of plant used Signup and view all the answers

What must be observed when changing the light intensity during the experiment?

Temperature variations caused by the lamp's heat Signup and view all the answers

During photosynthesis, which coenzyme accepts hydrogen?

NADP Signup and view all the answers

What is the primary reason ATP synthesis is prevented by potassium cyanide?

It blocks the final electron carrier. Signup and view all the answers

What happens to the Krebs cycle when oxygen is absent?

It halts due to lack of NAD and FAD. Signup and view all the answers

How is pyruvate converted to lactate in mammals?

With the help of lactate dehydrogenase. Signup and view all the answers

What does oxygen debt refer to in the context of anaerobic respiration?

The amount of oxygen needed to metabolize lactic acid after exercise. Signup and view all the answers

What does the conversion of pyruvate to ethanol in yeast involve?

The enzyme alcoholic dehydrogenase. Signup and view all the answers

When oxygen becomes available after anaerobic conditions, what happens to lactate in the liver?

It is oxidized through the Krebs cycle. Signup and view all the answers

How does the absence of oxygen affect the function of the electron transport chain?

It terminates electron transfer entirely. Signup and view all the answers

Why is it necessary for pyruvate to be removed for glycolysis to continue under anaerobic conditions?

To avoid buildup of pyruvate. Signup and view all the answers

What is needed to compare the rates of respiration at different temperatures accurately?

A control respirometer with no organisms Signup and view all the answers

When plotting a graph of respiration rates, which axes should be used?

Distance moved on the y-axis and time on the x-axis Signup and view all the answers

What does the gradient of the graph represent in the context of respiration rates?

Rate of respiration Signup and view all the answers

In the context of measuring respiratory quotient (RQ), what is done with the second respirometer?

It should not contain soda lime but should have inert material Signup and view all the answers

How can the amount of carbon dioxide given out by organisms be determined?

By comparing manometer fluid movement in both tubes Signup and view all the answers

If the respiratory substrate is carbohydrate, what is the expected relationship between carbon dioxide given out and oxygen taken in?

The amounts will be approximately equal Signup and view all the answers

Which of the following is a step in the process of respiration discussed?

Removal of hydrogen from a substrate Signup and view all the answers

What role does carbon dioxide play in the rate of photosynthesis at high concentrations?

It acts as a limiting factor when in short supply. Signup and view all the answers

Which method can be used to measure the rate of photosynthesis in aquatic plants?

Measuring the rate at which oxygen bubbles are produced. Signup and view all the answers

What is the formula for calculating the respiratory quotient (RQ)?

RQ = (x - y) / x Signup and view all the answers

What happens to the rate of photosynthesis when carbon dioxide concentration is increased?

The rate of photosynthesis increases. Signup and view all the answers

In the context of photosynthesis, what is meant by a 'limiting factor'?

A factor that restricts the speed or efficiency of a reaction. Signup and view all the answers

Why is it important to keep all other variables constant when studying the rate of photosynthesis?

To ensure that any changes can be attributed to the independent variable. Signup and view all the answers

What color change would indicate an increase in pH due to photosynthesis in calcium alginate balls containing algae?

Orange to red to magenta. Signup and view all the answers

What is the primary purpose of using the three-way tap in the apparatus for measuring photosynthesis?

To connect the oxygen collection system to the syringe. Signup and view all the answers

Which of the following is NOT a method mentioned for measuring the rate of photosynthesis?

Measuring the temperature above the plant. Signup and view all the answers

Study Notes

Respiration in Anaerobic Conditions

In anaerobic conditions, there is no oxygen.
Oxidative phosphorylation cannot occur because there's no electron acceptor.
Reduced NAD is not reoxidized, leading to a halt in the Krebs cycle and the link reaction.
Glycolysis can continue, providing a way to remove pyruvate and regenerate NAD.

Lactate Fermentation

In mammals, pyruvate is converted to lactate.
Lactate diffuses into the blood and is transported to the liver.
Liver cells convert lactate back to pyruvate, requiring oxygen.
This extra oxygen is called the oxygen debt or EPOC.

Ethanol Fermentation

In yeast and plants, pyruvate is converted to ethanol.
This process also regenerates NAD, allowing glycolysis to continue.

ATP Yield in Aerobic and Anaerobic Respiration

Anaerobic respiration produces a small amount of ATP compared to aerobic respiration.
Aerobic respiration produces typically 30-32 molecules of ATP per glucose molecule.
Only glycolysis occurs in anaerobic respiration, the Krebs cycle and oxidative phosphorylation do not.

Respiratory Substrates

Glucose is not the only respiratory substrate. Carbohydrates, lipids, and proteins can also be used.
Lipids release more energy per gram than carbohydrates or proteins.

Respiratory Quotient (RQ)

RQ is the ratio of carbon dioxide produced to oxygen consumed during respiration.
RQ values vary depending on the substrate used (carbohydrates = 1, lipids = 0.7, proteins = 0.8).
In anaerobic conditions, the RQ is infinity (∞) since no oxygen is used.

Using Respirometers

Respirometers measure the uptake of oxygen by respiring organisms.
Soda lime absorbs carbon dioxide produced during respiration.
Fluid movement in the respirometer tube reflects oxygen uptake.
The rate of respiration can be calculated from the distance the fluid moves.

Effect of Temperature on Respiration Rate

Higher temperatures increase the rate of respiration (within a certain range).
Temperature affects the rate of the light-independent stage of photosynthesis, not the light-dependent stage.
Temperature has a direct effect on reaction rates in enzymes.

Limiting Factors of Photosynthesis

Light intensity, temperature, and carbon dioxide concentration are limiting factors.
Light intensity is limiting at low light levels.
Increased light intensity beyond a certain point no longer limits the rate.
Carbon dioxide is limiting at low concentrations, rate increases with increasing concentration.
Temperature is limiting as it increases the rate of enzyme activity in a certain range.

Chloroplast Pigments

Chlorophyll a, chlorophyll b, carotene, and xanthophyll are examples of photosynthetic pigments.
Chlorophyll a is the most important pigment in photosynthesis; its absorption peaks are at 430nm (blue) and 662nm(red).
Carotenoids act as accessory pigments; they absorb light that chlorophyll cannot, converting energy from that light into a usable form.
Absorption spectra of these pigments define which wavelengths of light they absorb.
Action spectra show which wavelengths of light lead to the most oxygen production.

Separating Chlorophyll Pigments by Chromatography

Chromatography separates pigments based on their solubility in a solvent.
Rf values are used to identify pigments. Rf is the ratio of the distance a pigment travels to the distance the solvent travels, calculated as a percentage.

Light-Dependent Stage of Photosynthesis

The light-dependent stage involves splitting water molecules (photolysis).
Excited electrons move along an electron transport chain, generating ATP.
Electrons are eventually transferred to NADP+, reducing it to NADPH.
Oxygen is released as a byproduct of water splitting.
Two main pathways are cyclic and non-cyclic photophosphorylation.

Light-Independent Stage (Calvin Cycle)

The Calvin cycle utilizes ATP and NADPH to fix carbon dioxide into organic molecules.
RuBP (ribulose bisphosphate) is the initial carbon acceptor.
GP (glycerate-3-phosphate) is formed directly from the incorporation of carbon dioxide.
Triose phosphate (TP) is the first carbohydrate produced.
RuBP is regenerated to continue the cycle.

Factors Affecting Photosynthesis

Light intensity, CO2 concentration, and temperature are key factors.
Higher light intensity, CO2, and temperature increase the rate of photosynthesis.
Availability of water is a limiting factor because it is needed for the process.

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Description

Test your knowledge on photosynthesis, specifically the Calvin cycle and the role of rubisco. This quiz covers key concepts such as the effects of temperature and light intensity on the photosynthetic process. Challenge yourself with questions designed to deepen your understanding of plant biology.