17.2 ATP Synthesis

Question 1

In what 2 ways can electrons be excited to a higher energy level?

Answer 1

• Electrons in pigment molecules absorb photon
• Chemical bonds in respiratory substrate broken >> releases excited electrons

Question 2

What is the electron transport chain?

Answer 2

series of redox reactions & electron carriers

which allow excited electrons to release energy

Question 3

In the electron transport chain, each subsequent electron carrier has [lower/higher] energy level than the previous. This allows excited electrons to ____ energy as they pass from one carrier to the next.

Answer 3

lower

release

Question 4

What is the energy released by the excited electrons in the electron transport chain used for?

Answer 4

active transport of H⁺ ions across membrane

to create proton gradient

(thylakoid membrane in chloroplast, cristae in mitochondria)

Question 5

What is chemiosmosis?

Answer 5

Synthesis of ATP

driven by flow of protons

across membrane

Question 6

Outline the process of chemiosmosis:

Answer 6

1. Excited electrons pass through electron transport chain, releasing energy.
2. Energy used to actively transport H⁺ across membrane, creating proton gradient.
3. H⁺ move back via facilitated diffusion through ATP synthase membrane protein.
4. H⁺ diffusing down concentration gradient releases energy for phosphorylation of ADP to ATP.