Lecture 2: Photosynthesis: Leaves, and light harvesting. Making ATP.

Question 1

ATP stands for

Answer 1

adenosine triphosphate

Question 2

Whats ATP used for

Answer 2

to drive various processes, such as transport, movement or chemical synthesis

Question 3

NADH and NADPH act as

Answer 3

universal reductants (electron carriers) in cells.

Question 4

NAD+ and NADP+ are

Answer 4

oxidants (oxidising agents)

Question 5

Photosynthesis what happens (redox potential)

Answer 5

Light energy is used to promote electrons from a low energy, high (positive) redox potential (water) to a high energy, low (negative) redox potential (NADPH). At the same time ATP is synthesised.

Question 6

Light absorption in leaves two types of cells used

Answer 6

• palisade cells

- mesophyll cells

Question 7

palisade cells in light absorption:

Answer 7

collimate light (act as light guides)

Question 8

mesophyll cells in light absorption:

Answer 8

mesophyll cells reflect light ( act like a ‘hall of mirrors’)

Question 9

chloroplasts avoidance of bright light

Answer 9

• to reduce photosynthesis rates when too much
• Chloroplasts are evenly distributed in low light but orientate to the side walls in high light.
• some arabidopsis mutants lack this response

Question 10

chloroplast structure:

Answer 10

• outer membrane
• intermembrane space
• inner membrane
• stroma (space inside)
• granum (stack of thylakoid)
• thylakoid
• thylakoid space (lumen)

Question 11

chlorophyll structureL

Answer 11

• in thylakoid membrane theres a cluster of pigment molecules embedded.
• porphyrin ring (light absorbing “head” of molecule)
• hydrocarbon tail

Question 12

difference between chlorophyll a & b in structure

Answer 12

b = CHO in certain position

a = CH3 in same position

Question 13

Chlorophyll a & b and carotenoids light absorbance

Answer 13

a = 420 + 680 
b = 480 + 650 
carotenoids = 450-500

Question 14

absorption of light by chlorophyll and electron movement description

Answer 14

• light hits electrons excited to highest electron state/lowest excited state from ground state
• drop from highest state due to heat loss to lowest excited state
• drop from lowest state to ground state due to
• fluorescence
• heat loss
• energy transfer

Question 15

efficient harvesting of light means

Answer 15

having a large chlorophyll antenna and transferring energy within it

Question 16

Light-harvesting chlorophyll-protein complex

Answer 16

(LHCP)
-photosystem embedded in thylakoid membrane
-