photosynthesis

Question 1

Equation for photosynthesis

Answer 1

Carbon dioxide + Water -> Oxygen and Glucose

Question 2

What is the structure of chloroplast?

Answer 2

• Double membrane encloses the stroma
• Stroma contains : starch grains, lipid stores, DNA, RNA and ribosomes
• Membrane - bound fluid filled flattened sacs called thylakoids
• A stack of this is called Grana
• These are linked by lamellae

Question 3

What is the equation for respiration?

Answer 3

Glucose + Oxygen -> Carbon Dioxide + Water

Question 4

What is the compensation point?

Answer 4

• The rate of photosynthesis is the same rate as is equal to the rate of respiration as the volume of carbon dioxide going in plant is same as going out

Question 5

Explain why measuring CO2 uptake may or may not give a better indication of photosynthetic activity than measuring oxygen production

Answer 5

• Oxygen produced might be used in respiration
• C02 produced during respiration might be used for photosynthesis

Question 6

What is the primary pigment?

Answer 6

Chlorophyll a - found at the reaction centre of each antenna complex

Question 7

Structure of Reaction centre, light harvesting system and photosystem

Answer 7

Chlorophyll a and its proteins are located in the reaction centre
The reaction centre is surrounded by accessory pigments and proteins = light harvesting system
Together known as Photosystem

Question 8

What are the accessories pigments

Answer 8

-Chlorophyll b and caretenoids (xanthophyll and beta carotene)
- Absorb different wavelengths of light compared to chlorophyll a this expands the wavelength range that can absorb light for use in photosynthesis

Question 9

What lights do caretenoids and chlorophyll reflect and absorb?

Answer 9

• Caretenoids absorb blue and reflect yellow and orange
  -Chlorophyll absorb red and orange and reflect green

Question 10

What is the importance of photosynthetic absorption in photosynthesis

Answer 10

Different pigments absorb different wavelengths of light
Accessory pigments transfer their energy to the primary pigments
The range of accessory pigments that are absorbed expands the wavelength range
Primary pigment excites and the electron moves down the Electron transport chain
This excites electrons to a higher energy level
used in light dependent reaction

Question 11

In TLC chromatography practical why do u need to crush the plants?

Answer 11

• To break down the cell wall and membrane to release the photosynthetic pigments

Question 12

In chromatography, why do you use a pencil

Answer 12

So it doe not dissolve within the solvent

Question 13

Calculate rF value

Answer 13

Distance moved by compound/distance moved by solvent front

Question 14

What happens in non-cyclic phosphorylation

Answer 14

• Produces NADPH, oxygen and ATP
• As light is absorbed by PSII this excites electrons = moves up energy level, each electron passed down a ETC to PS1
• Chlorophyll has been ionised
• Those electrons needs to be replaced by electrons in photolysis
• The energy lost is used to create a proton pump in the thylakoid
• Proton gradient formed and will diffuse through the ATP synthase down a conc gradient
• Electron passes through PSI = higher energy level
• NADP + e- + H+ = NADPH
• NADPH passes to light independent

Question 15

Differences in Cyclic Phosphorylation?

Answer 15

• PS1 only
• Only used if there is a limitation of water availability
• Electrons are not passed into NADP instead pack to PSI by ETC
• Only produces ATP

Question 16

Stages of light independent reaction

Answer 16

Fixation - RuBP reacts with CO2, the enzyme RuBisCO catalyses this reaction and forms 2 GP (each GP has three Carbons)
Reduction - 2x GP is reduced to 2 x TP, this is done by using reduced NADP (to form a H+ ion) and ATP (for energy) in this stage 1/6 TP molecules are used for hexose sugars like gluurse, lipids and amino acids
Regeneration = 5/6 molecules are used to regenerate RuBP using ATP

Question 17

How many turns of Calvin Cycle to form Glucose

Answer 17

3 turns = 1 TP
So 6 turns allows 2x TP to be formed and this can make a hexose sugar like glucose.

Question 18

What is a light harvesting system

Answer 18

The accessory pigments and the proteins together