✅11 - Photosynthesis Flashcards Preview

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Flashcards in ✅11 - Photosynthesis Deck (34)
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1
Q

Where is the site of photosynthesis?

A

The chloroplasts, within the leaf

2
Q

How are the leaves adapted for photosynthesis?

A

Large surface area to absorb light
Little overlapping of leaves
Thin, most light is absorbed in top few micrometers
Transparent cuticle/epidermis that let light through to mesophyll cells
Long, narrow upper mesophyll cells with many chloroplasts
Numerous stomata for gas exchange
Air spaces between mesophyll to allow raid diffusion

3
Q

What is the equation for photosynthesis?

A

6CO2 + 6H20 ———> C6H12O6 + 6O2

4
Q

What are the stages of photosynthesis?

A

Capturing light energy
Light dependent reaction
Light independent reaction

5
Q

What is the stroma?

A

A fluid filled matrix where the light independent reaction takes place.

6
Q

What is photoionisation?

A

When chlorophyll is struck by light and an electron is removed.

7
Q

Where do the electrons from photoionisation go?

A

They are taken up by an electron carriers

8
Q

Describe chemiosmotic theory:

A

Proton pumps pump H+ ions into the thylakoids through the cell membrane
Energy used for this process comes from electrons released by the photolysis of water
Photolysis also produces protons which increase concentration in thylakoids space
-Creates and maintains a concentration gradient across thylakoids membrane
Protons cross membrane through ATP synthase channels
As the protons pass through the cause a change of structure of enzyme which catalysts synthesis of ATP

9
Q

What is photolysis?

A

The splitting of water using light

10
Q

What is the equation for photolysis?

A

2H2O ———> 4H+ + 4e- +O2

11
Q

What happens to the protons produced by photolysis?

A

The pass out of the thylakoids through ATP synthase and are taken up by NADP,which goes to the light independent reaction

12
Q

What are the products of the light dependent reaction?

A

ATP, NADPH and Oxygen (byproduct)

13
Q

How are chloroplasts adapted to carry out the light dependent reaction?

A
  • Thylakoids membranes provide large surface area for attachment of chlorophyll, electron carriers and enzymes
  • A network of proteins in the Grana hold the chlorophyll in a very precise manner that allows maximum light absorption
  • The Granal membranes have ATP synthase channels within them which catalyse ATP production, also selectively permeable which allows a proton gradient to form
  • Chloroplasts have DNA and ribosomes so they can quickly and easily manufacture some of the proteins involved in LDR
14
Q

What are the products of the LDR use for?

A

To reduce glycerate-3-phosphate in the LIR

15
Q

Why does the LIR cease to occur without light?

A

It requires the ATP and NADH from the light dependent reaction to function

16
Q

Where does the light independent reaction take place?

A

In the stroma

17
Q

Describe the Calvin cycle:

A
  • CO2 from atmosphere diffuses into leaf and dissolves in water around mesophyll cell walls, then into stroma
  • CO2 reads with Ribulose Bisphosphate, catalysed by Rubisco
  • This produces 2x glycerate-3-phosphate
  • NADPH from LDR used to reduced it to 2x triose phosphate using ATP
  • NADP reformed and goes back to LDR to be used again
  • Some TP converted into organic substances
  • Most used to regenerate RuBp using ATP from LDR
18
Q

How is the chloroplast adapted to the Light Independent Reaction?

A
  • The stroma contains all enzymes needed
  • Stroma is membrane bound which means chemical environment has high concentration of enzymes and substances
  • Stoma fluid surrounds the Grana so products of LDR can readily diffuse into the stroma
  • Contains DNA and Ribosomes so can quickly and easily manufacture some of proteins needed
19
Q

Where in the cell is rubisco found?

A

In the stroma of the chlorplast

20
Q

Where does the light depenedent reaction take place?

A

In the thylakoid membrane

21
Q

What absorbs light?

A

Chlorophyll

22
Q

What process is ATP made by in the light dependent reaction?

A

Photophosphorylation

23
Q

Why does the LIR occur less if the LDR occurs less?

A

Because there are less products (ATP and NADPH) of the light dependent reaction, so the LIR occurs less

24
Q

What is chemiosmosis?

A

The process of electrons flowing down the electron transport chain and creating a proton gradient across the membrane to drive ATP synthesis

25
Q

How does CO2 enter the leaf?

A

Through the stomata, and diffuses into the stroma of the chlorplast

26
Q

What is CO2 combined with?

A

Ribulose Bisphosphate, RuBP

27
Q

How many many of the Carbons in TP are used to regenerate RuBP?

A

5

28
Q

What is the leftover carbon from TP used to make?

A

Useful organic substances

29
Q

How many molecules of TP does 3 turns of the cycle create?

A

6

30
Q

How many times would the Calvin cycle have to turn to create a hexose sugar?

A

6

31
Q

What does 6 turns of the Calvin cycle require?

A

18 ATP and 12 NADPH

32
Q

At what wavelength does photosystem 1 absorb light?

A

700nm

33
Q

What is non-cyclic phosphorylation?

A

The light independent reaction

34
Q

What is cyclic phosphorylation?

A

The calvin cycle/light dependent reaction