Module 5: ATP Synthesis

Question 1

The ATP produced in respiration and photosynthesis is synthesised primarily by what process?

Answer 1

chemiosmosis

Question 2

Chemiosmosis depends on the creation of what?

What provides the energy to do this?

Answer 2

a proton concentration gradient

the energy comes from excited electrons

Question 3

State and briefly describe the 2 ways in which electrons are excited

Answer 3

1)electrons present in pigment molecules are excited by absorbing light from the sun

2)excited electrons are released when chemical bonds in respiratory substrate molecules are broken (glucose)

Question 4

Where are excited electrons transported to and what does this generate?

Answer 4

they are transported to an electron transport chain and are used to generate a proton gradient

Question 5

An electron transport chain is made up of a series of what?

Answer 5

electron carriers , each with progressively lower energy levels

Question 6

Make 3 more points about how electron transport chains are used to create a proton gradient across a membrane

Answer 6

1)as high energy electrons pass from one electron carrier to another , energy is released
2)this energy is used to pump protons across the membrane
3)this creates a concentration difference across the membrane and therefore a proton gradient

Question 7

How is a proton gradient maintained across the membrane?

Answer 7

as a result of the impermeability of the membrane to hydrogen ions(protons)

Question 8

Describe the only way protons can move back through the membrane down their concentration gradient

Answer 8

by travelling through hydrophilic membrane channels linked to ATP synthase

Question 9

What does the enzyme ATP synthase do?

What does the flow of protons through these channels provide?

Answer 9

catalyse the formation of ATP

provides the energy used to synthesise ATP from ADP and Pi