3.5.1.2 - Photosynthesis (Calvin Cycle) Flashcards Preview

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Flashcards in 3.5.1.2 - Photosynthesis (Calvin Cycle) Deck (17)
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1

The diagram shows Melvin Calvin's Lollipop experiment for identifying the products of the Calvin Cycle. Why was radioactive hydrogen carbonate supplied to the algae?

So that the substances into which the CO2 is incorporated can be identified.

2

Describe the Calvin Cycle

  1. CARBON FIXATION - Rubisco enzyme catalyses the reaction of RuBP with CO2 to produce 2x Glycerate-3-Phosphate (G-3-P).
  2. REDUCTION - NADPH reduces G-3-P into 2x Triose Phosphate (TP) with energy being provided by ATP.
  3. REGENERATION - 2 x TP are converted into orgnaic compounds e.g. glucose OR ATP is used to convert TP into RuBP for more turns of the Calvin cycle.

3

How many carbon aotms in Ribulose Bisphosphate (RuBP)?

5

4

Name the enzyme that catalyses the fixation of carbon dioxde into RuBP to produce glycerate-3-phosphate.

Rubisco

5

How many turns of the calvin cycle take place to produce 1 molecule of glucose?

6

6

How many carbon atoms in glycerate-3-phosphate?

3

7

What are the proudcts of every 6 turns of the carbon cycle?

1 x glucose molecule

5 x RuBP

8

What are the light independent reactions of photosynthesis sometimes referred to as?

The Calvin Cycle

9

What are the products of the Calvin cycle (LIR)?

Organic compounds e.g. glucose, amino acids, lipids

RuBP (Ribulose Bisphosphate)

10

How many carbon atoms in triose phosphate?

3

11

The diagram shows Melvin Calvin's Lollipop experiment for identifying the products of the Calvin Cycle. Why is a fast flow tap used in this experiment?

To terminate the reactions immediately.

12

The diagram shows Melvin Calvin's Lollipop experiment for identifying the products of the Calvin Cycle. Why is hot methanol supplied to the algae?

High temp will denature enzymes that catalyse reactions.

Methonal could denature the enzymes.

13

Does the Calvin Cycle require light to function?

No

BUT

The reactions will stop eventually in the absence of light because essential ATP and NADPH from light reactions will run out.

14

During the light-independent reaction of photosynthesis, carbon dioxide is converted into organic substances. Describe how. (6 marks)

  1. Carbon dioxide combines with ribulose bisphosphate / RuBP;
  2. Produces two glycerate-3-phosphate / GP;
  3. GP reduced to triose phosphate / TP;
  4. Using reduced NADP; and...
  5. ...Using energy from ATP;
  6. Triose phosphate converted to glucose / RuBP / ribulose bisphosphate 

15

Heat stress decreases the LDR - why does this lead to a decrease in the LIDR?

Less ATP

Less reduced NADP

16

A decrease in the activity of the enzyme rubisco would limit photosynthesis - why?

Less carbon dioxide reacts with RuBP

so

Less GP

17

where is rubisco found?

stroma (of chloroplast)