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Biology > C1.3 Photosynthesis > Flashcards

C1.3 Photosynthesis Flashcards

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1
Q

What is LDR

A

Light dependent reaction uses light energy to produce ATP and split up water molecules into h+ ions. Takes place in the thylakoid membrane

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2
Q

What is LIR?

A

(Light Independent Reaction/ Calvin cycle) uses ATP and H+ ions to ‘fix’ carbon dioxide and make glucose

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3
Q

What is Pigment?

A

Absorbs useful wavelengths of light that contain energy appropriate for photolysis in light dependent reactions

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4
Q

What is chlorophyll?

A

A chemical pigment that changes the color of reflected light stored in chloroplasts

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5
Q

What does the action spectrum indicate?

A

Which wavelengths of light can be used by a plant for light

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6
Q

What does the absorption spectrum measure?

A

Measures absorptions where various wavelengths of light represent different colours of light

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7
Q

What is photolysis?

A

The splitting or decomposition of a chemical compound by means of light energy or photons

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8
Q

What is chloroplast?

A

Plastid organelle containing chlorophyll and other pigments. 30-40 in a typical leaf cell.

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9
Q

What is the stroma?

A

A thick fluid between grana where various enzymes, molecules, and ions are found, and where the light independent reaction of photosynthesis occurs

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10
Q

What are thylakoids?

A
  • disk-like structures in chloroplast containing chlorophyll
  • Where LDR occurs
  • Stacked as grana
  • Generation of a proton gradient + chemiosmosis
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11
Q

What is Grana (granum)

A

A stack of thylakoids within the chloroplast of plant cells

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12
Q

What is non-cyclic photophosphorylation?

A

process where electrons move linearly from(PS-II) to (PS-I), producing ATP, NADPH, and oxygen through water photolysis.

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13
Q

What is cyclic photophosphorylation?

A

the synthesis of ATP coupled to electron transport activated by Photosystem I solely
(returns to initial state)

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14
Q

What happens at photosystem 1

A

Excited e- from PSII enters second electron chain (reduced NADP adds e-)

Redox reaction generates excited electrons

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15
Q

What happens at PSII?

A
  • Absorbs light for use to drive the oxidation of water.
  • Photolysis of H2O. O2 is released.
  • Builds concentration gradient inside thylakoid.
  • E- contribute to generate a proton gradient for H+.
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16
Q

What is photoactivation?

A

The initial stage of photosynthesis in chlorophyll molecules where the presence of light energy raises the total energy

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17
Q

What is chemiosmosis?

A
  • The movement of high energy e- through the electron transport chain.
  • Releases energy to run proton (H+) pump.
  • Pulls H+ from a high to low concentration gradient (ATP synthase enzyme).
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18
Q

What is RuBP (Ribulose Biphosphate)

A
  • 5 carbon sugar found in Calvin Cycle
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19
Q

What is NADP?

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A

Reduced to NADPH (Reduced NADPH) in LDR of photosythesis

20
Q

What is Rubisco?

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A
  • Enzyme used in LIR to fix carbon dioxide
  • High concentrations of Rubisco needed in stroma as it works rather slowly and is not effected in low CO2 concentrations
21
Q

What is thylakoid space?

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A
  • Very small volume
  • Steep proton gradient builds up after few photons of light has been absorbed
22
Q

Calvin cycle run down

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A
  • makes sugars from CO2 by using ATP and NADPH
  • Makes 3 Carbon sugars
  • 3 cycles are needed to make 1 G3P
  • 6 cycles are needed to make glucose
23
Q

What happens during Carbon fixation

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A
  1. CO2 attatches to RuBP
    - Unstable 6 carbon molecule splits in half
24
Q

What happens during reduction?

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A

_ Phosphorylation
- NADPH donates a e-

25
What happens during regeneration?
- ATP to ADP used - Accepts CO2 to start cycle once more
26
How many ATP and NADPH needed to make **1** glucose
18 ATP and 12 NADPH
27
How is oxygen created?
By the splitting of water molecule (happens in plants, algae, and cynobacteria)
28
How chromatography works:
1. Tear up leaf, grind with sand to extract leaf pigments 2. Draw a baseline on chromatography paper using a pencil 3. Pour solvent in beaker, ensure paper base just touches solvent and is not submerged 4. Allow solvent to slowly travel upwards through the paper 5. Remove paper from beaker, revealing the chromatogram 6. Analyse the chromatogram to identify different components of sample mixture 7. Mark distance travelled by solvent 8. Calculate Rf value
29
What are the pigments seperated by chromatography>
The pigments are separated by solubility
30
What is Rf Value and how is it calculated?
- Measures distance from **origin** to the **pigment** - Uses a ruler - Distance moved by **spot** /. distance moved by **solvent**
31
What is visible light composed of?
- Range of wavelengths - Violent, shortest wavelength (400nm) - Red, longest wavelength (700nm)
32
What wavelength of light are absorbed by photosynthetic pigments?
**chlorophyll** absorbs light, mainly blue and red light, **reflecting** green light
33
Similarities/ differences between action and absorption spectrum
**difference** - Absorption spectrum shows **wavelength** absorbed, action spectrum indicates the **effectiveness** **similarities** - Shows the impact of different wavelengths of light
34
What are the **limiting** factors of photosynthesis
- Temperature - Carbon dioxide - Light intensity
35
How does temperature impact photosynthesis
Photosynthesis increases with increase in temp. Due to more **kinetic energy** and more **successful collisions** occur, (to a maximum level, then denaturing of enzymes)
36
How does CO2 affect photosynthesis?
CO2 can increase photosynthetic rate, up to a maximum rate until it **levels off**
37
What is the Free Air Carbon-dioxide Experiment (FACE)?
- networks of pipes giving out **extra carbon dioxide** - Plants receive much higher levels of CO2 - Studied in controlled labs/ greenhouses - Researches can observe differences in rate of photosynthesis, plant growth patterns, yield quantity, quality... - Different types of plants responded more than others - Experiments takes years to complete, still a lot of data needed before predicting future - Increased CO2 will increase crop yield (hypthesis)
38
What are **photosystems**
- molecular arrays of pigment molecules - Located in **membranes** within chloroplast - Consist of chlorophyll + **accessory pigments** - When light is absorbed, reaction centre emits an **excited electron**
39
How + where is oxygen generated by photosynthesis?
- Photolysis of water - Oxygen is released as a waste product
40
How is reduced NADP formed
LDR, NADP is reduced by **PS1** in the **stroma** where it accepts **2 electrons** from PS1 and **hydrogen ion** from stroma
41
What is triose phosphate?
- In calvin cycle - Formed from CO2 fixation - leads to synthesis of glucose
42
How do the light-independent reactions depend on the light dependent?
- LD generates reduced NADP - PSII electrons reduce NADP - ATP is produced by proton gradient when protons are pumped into **thylakoid space** - LD produce **ATP** and ** reduced NADP**
43
Equation of photosynthesis (written)
Water + Carbon dioxide -> Glucose + water
44
Relationship between energy of photon and it's wavelength
The **higher** the energy of the photon, the **shorter** the wavelentgth.
45
What is the Antenna complex
- It consists of several light-harvesting protein complexes that contain accessory pigments - Acts as a funnel by harnessing + directing light energy to site where it can effectively be used
46
What are the advantages of the structured array of different types of pigment molecules in a photosystem
- Broadens range of wavelengths that can be absorbed - Some pigments can help protect against photodamage - Proximity of pigments to others in antenna facilitates efficient + effective transfer of energy
47

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