AQA Biology A-level RP08 - Dehydrogenase Activity in Chloroplasts Flashcards
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Questions and Answers

How is light intensity controlled? ______ of the lamp from the set up.

Adjust the distance

What is the function of the muslin cloth? To ______ out any debris in the ground leaf mixture but allowing chloroplasts to pass through.

filter

Why are the stalks of leaves removed before grinding? The stalks do not contain many ______.

chloroplasts

Outline the procedure of investigating the effect of light intensity, after chloroplast extract has been obtained. 1. 2. 3. 4. Set the ______ to the red filter. Zero using a cuvette containing chloroplast extract and distilled water. Place test tube in the rack 30cm from light source and add DCPIP.

<p>colorimeter</p> Signup and view all the answers

How is light intensity controlled? Perform the practical in a ______ so that the only light source is the lamp.

<p>dark room</p> Signup and view all the answers

Why are the stalks of leaves removed before grinding? The stalks do not contain many ______.

<p>chloroplasts</p> Signup and view all the answers

What is the function of dehydrogenase in chloroplasts? It catalyses the acceptance of electrons by NADP in the light dependent ______

<p>reactions</p> Signup and view all the answers

What is the function of DCPIP in the experimental setup?

<p>It acts as an alternate electron acceptor instead of NADP.</p> Signup and view all the answers

Why is the plant extract chilled in an ice-water bath before the experiment?

<p>To lower the activity of enzymes and prevent them from breaking down chloroplasts.</p> Signup and view all the answers

What is the role of dehydrogenase in chloroplasts during the light-dependent reactions?

<p>It catalyzes the acceptance of electrons by NADP.</p> Signup and view all the answers

How does DCPIP indicate the reduction of electrons in the experiment?

<p>It turns from blue to colorless when reduced.</p> Signup and view all the answers

Explain the setup of the control in the experiment.

<p>Fill a cuvette with chloroplast extract and distilled water.</p> Signup and view all the answers

What is the purpose of performing the practical in a dark room with the lamp as the only light source?

<p>To control and isolate the light source for the experiment.</p> Signup and view all the answers

Why is it important to adjust the distance of the lamp from the set up during the experiment?

<p>To regulate the light intensity reaching the chloroplast extract.</p> Signup and view all the answers

What role does the muslin cloth play in the experiment involving the ground leaf mixture?

<p>To filter out debris while allowing chloroplasts to pass through.</p> Signup and view all the answers

Why are the stalks of leaves removed before grinding?

<p>Due to the low chloroplast content in the stalks.</p> Signup and view all the answers

After obtaining the chloroplast extract, what steps are involved in investigating the effect of light intensity?

<p>Set the colorimeter to the red filter, zero using a cuvette with extract and water, place test tube 30cm from light source, add DCPIP.</p> Signup and view all the answers

Study Notes

Dehydrogenase Activity in Chloroplasts

  • Dehydrogenase catalyses the acceptance of electrons by NADP in the light dependent reactions.

DCPIP

  • DCPIP is a redox indicator dye that acts as an alternate electron acceptor instead of NADP.
  • It turns from blue to colourless when reduced.

Preparing Plant Extract

  • Remove stalks from leaves before grinding because they do not contain many chloroplasts.
  • Use muslin cloth to filter out debris from the ground leaf mixture, allowing chloroplasts to pass through.
  • Chill the plant extract in an ice-water bath to lower the activity of enzymes and prevent them from breaking down the chloroplasts.

Investigating Light Intensity

  • To control light intensity, adjust the distance of the lamp from the setup and perform the practical in a dark room.
  • Set up a control by filling a cuvette with chloroplast extract and distilled water.
  • Procedure to investigate the effect of light intensity:
    • Set the colorimeter to the red filter.
    • Zero using a cuvette containing chloroplast extract and distilled water.
    • Place the test tube in the rack 30cm from the light source and add DCPIP.

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Test your knowledge on the function of dehydrogenase in chloroplasts with this flashcard set from PMT Education. Learn about its role in catalyzing the acceptance of electrons by NADP in the light-dependent process.

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