17.2 ATP synthesis

Question 1

Through what process is ATP produced in photosynthesis?

Answer 1

Chemiosmosis

Question 2

Define chemiosmosis.

Answer 2

Diffusion of proton from high concentration to low concentration through a selectively permeable membrane

Question 3

How does the movement of protons in chemiosmosis result in ATP synthesis?

Answer 3

Movement of protons down concentration gradient releases energy used in attachment of inorganic phosphate to ADP, forming ATP

Question 4

What has to be created for chemiosmosis to occur?

Answer 4

A proton gradient

Question 5

What are the 2 ways in which electrons are excited?

Answer 5

1. Electrons in pigments are excited by absorbing energy from sunlight
2. Excited electrons are released when chemical bonds are broken in respiratory substrate molecules

Question 6

After an electron has been excited, where does it go?

Answer 6

Enter the ETC and are used to generate a proton gradient

Question 7

What is an electron transport chain made up of?

Answer 7

A series of electron carriers, each with progressively lower energy levels

Question 8

In relation to proton gradients and electrons, how does an electron transport chain work?

Answer 8

• Excited electrons move from one carrier to another and release energy.
• The released energy is used to pump protons across a membrane, creating a concentration difference across the membrane - proton gradient
• Proton gradient is maintained due to membrane’s impermeability to H ions

Question 9

After protons have been pumped across a membrane, how do they move back down their concentration gradient? What does this movement cause?

Answer 9

Through hydrophilic membrane channels linked to ATP synthase

Flow of protons through these hydrophilic channels provides energy for synthesis of ATP