Photosynthesis

Question 1

Where do light reactions take place and what do they produce?

Answer 1

• they produce ATP and NADPH

- and it is in thylakoid membranes

Question 2

What is NAD used for?

Answer 2

It is used to accelerate oxidation of sugars, [NAD] is kept high

Question 3

What is NADHPH used for?

Answer 3

• it is used for reductions to make sugars

- [NADPH] is kept high

Question 4

How does energy absorption work?

Answer 4

• it is electron transition to a higher energy level, which can facilitate chemical reactions. Low energy, high wavelength. vice versa.

Question 5

What results in delocalized electrons?

Answer 5

• alternating/conjugated double bonds found in chlorophyll or beta carotene results in delocalized electrons - excited by certain wavelength of visible light

Question 6

What are 3 things that may happen with excited electrons?

Answer 6

1) might fall back to ground state releasing light of slightly longer wavelength and heats
2) resonance energy transfer - physical process, energy released when a chlorophyll electron falls back to ground state, it is used to exite neighbouring chlorophyl molecule of slightly longer wavelength
3) transfer electrons - redox

Question 7

In photosynthesis - which steps are redox and which are not?

Answer 7

• all initial steps from absorption of a photo until central chlorophyll is excited transfer of energy
• last step, electron transferred, redox reaction

Question 8

What is the strongest oxidizing agent in biology?

Answer 8

• chlorophyll lacking an electron

Question 9

What is the process of photosystem II and I?

Answer 9

• electrons released by photosystem II, move down electron transport chain and end up in photosystem I, where chlorophyll is excited and transferred to second electron transfer chain, which generates NADPH

Question 10

Cyclic electron transport

Answer 10

• no water split
• no oxygen released
• PS I on its own
• plants use this when they have made enough sugar

Question 11

Carbon fixation in stroma of chloroplasts

Answer 11

• describes conversion of C02 gas to sugar

- used up all of ATP and reducing power which is made in noncyclic electron transport

Question 12

What is the difference between NAD and NADP?

Answer 12

• same properties, occurs in plants and animals, made by separate pathways and independently regulated