Photosynthesis

Light Dependent Reaction

What pigments do they thylakoids contain in photosynthesis?

Chrolorplasts

What do different pigments absorb within thylakoids?

Different wavelengths of light

What do more pigments available in leaf mean?

More light absorbed available for photosynthesis

What is the name of the pigments that surround chloroplasts?

Accessory pigments

What is chlorophyll + acessory pigments called?

Light Harvesting clusters

What is the name given to the arrangement of acessory and primary pigments to gather and use light energy?

Photosystem

Why do leaves appear green?

Red and Blue light can be absorbed but Green light is relected

What is a limiting factor?

A factor that will limit the rate of a reaction when it is at a suboptimal level.

What 3 factors limit photosynthesis?

1. Light Intensity

2. Co2 concentration

3. Temperature

What do light intensity and co2 concentration graphs look like

Plateu is another factor becomes limiting

What does temperature graph look like?

How can limiting factors be overcome? X3

1. Artifical lighting

2. Co2 Waste

3. Greenhouses kept as specific temperatures

Why is temperature limiting?

Denatures the enzymes

What is the 1st stage of photosynthesis called?

Light dependent reaction

What does the light independent reaction (2nd) still rely on?

Products from light dependent reaction

Where does the light dependet reaction take place?

Thylakoid membrane

Where is the thylakoid membrane?

Between thylakoid space and stroma

What is the name of the enzyme needed to produce ATP?

ATP synthase

What is the reaction to form ATP?

ADP + Pi ——> ATP

Where does the energy come from to catalyse ADP?

Protons (H+ Ions)

Is there a higher concentration of H+ ions in the Stroma or Thylakoid Space? what does this mean

Thylakoid space making a conc gradient alllowing H+ ions to move acorss

What is the a higher concentration of H+ ions in the Thylakoid Space called?

Proton Gradient

Where does H+ move from thylakoid space the stoma by?

ATP Synthase

What is does H+ move from thylakoid space the stoma know as?

Chemiosmosis

What is H+ giving energy for ADP synthase to catalyse to ATP known as?

Photo phosphorylation

How is the Proton Gradient maintained?

Protons are actively transported from stroma to thylakoid space

How is energy provided to maintain proton gradient?

Redox reaction

How do you rememebr Redox reaction?

Oxidation

Is

Loss

Reduction

Is

Gain

Where are electrons provided by and how?

Chlorophyll absorbs light which exites 2 electrons

When electrons are excited from the chlorophyll where do they go?

Leave the chlorophll leaving it oxidised

What is the process of light oxidisng chlorophyll known as?

Photoionisation

What passes electrons along the membrane?

Electron transfer chain

How are electrons moved along the Electron transfer chain?

Oxidation Reduction Reactions

What would happen if protons werent actviely tansports back to thylakoid ,enbrane?

No gradient so no ATP Synthase so no ATP

What type of molecule is NADP?

Coenzyme

When electrons reach the final stage in the electron transfer chain what reacts with them to move them so more electrons can be passed?

NADP

What is NADP reduction reaction

NADP + H+ → Reduced NADP (NADPH)

What 2 molecules are made in light dependent reaction needed for light independenct reactio?

ATP
Reduced NADP

What do the electrons lost by photoionisation need to do?

Be replaced

How are electrons replaced in chlorophyll?

Photolysis

What is photolysis?

When electrons are lost during photoionisation they are replaced by water

What does light split the water into in photolysis?

• Protons

• Electrons

• Oxygen

What is oxygen used replaced in photolysis used for?

• Diffuse out of the plant

• Used in respiration

What are protons replaced in chlorophyll used for?

Maintain a high concentration in the thylakoid space

What are the electrons from photolysis used for

Replace those lost in chlorophyll

How many photosystems does the thylakoid membrane have?

2

What is excited electrons in PSI used for?

Transferred along electrons transfer chain and used for channel protein to actively transport a proton

Where does electrons from PSI go after providing energy for active transport?

Back to chlorophyll to be excited again and repeat the process

What is PSI an example of?

Cyclic photophosphorylation

Why does the plant have PSI if it doesnt create NADP or ATP?

• Absorbs different wavelengths of light

• Useful when there is enough ATP for light independent but not enough NADP as other reactions can occur

What is PSII an example of?

Non Cyclic photophosphorylation

How is the chloroplast well adapted for photosynthesis?

• Large SA

• Proteins in the grana hold the chlorophyll so the max amoutn of light can be absorbed at one time

• Thylakoid contrains ATP for productions and the membrane is selectively permeable

• Contain both DNA and Ribosomes

Why is a Large SA important for chloroplasts in photosynthesis?

Maximises the amount of ATP and NADPH that can be made at once

Why is a Proteins in the grana hold the chlorophyll important for chloroplasts in photosynthesis?

Maximum amount of light is able to be absorbed at one time

Why is Thylakoid membrane being selectively permeable improtnat?

Allows them to establish and maintain a proton gradient

Why is chloroplast contain both DNA and Ribosomes improtant?

Protins in light dependent reaction can be easily and quickly produces