Lecture 3 - Photosynthesis

Question 0

How is chlorophyll A easy to identify?

Answer 0

It fluoresces red under UV

Question 1

Where is chlorophyll located?

Answer 1

In the thylakoid membrane

Question 2

What happens in the grana?

Answer 2

Light energy is converted to chemical energy in the form of ATP to NADH

Question 3

What are the four main polypeptide complexes of the thylakoid membrane?

Answer 3

PSII
Cytochrome b6f
ATP synthase
PSI

Question 4

What happens in PSII?

Answer 4

Water is split then the electrons are passed on in the electron transport chain

Question 5

Where is PSI and ATP synthase located?

Answer 5

In non-appressed membranes

Question 6

Where are PSII are present?

Answer 6

In appressed membranes

Question 7

What happens in the calvin cycle?

Answer 7

Use ATP and NADPH to convert CO2 to sugar

Question 8

What are the three phases of the calvin cycle?

Answer 8

Carbon fisation
Reduction
Regeneration of carbon dioxide acceptor

Question 9

What offsets reduction of efficiency by oxygen binding to RuBisCO?

Answer 9

Photorespiration

Question 10

What are the key characteristics of C4 plants?

Answer 10

Has PEPC
Has bundle sheath cells
PEPC and RuBisCO are spatially separated
Kranz Anatomy
No PSII

Question 11

Why is no PSII required in C4 photosynthesis?

Answer 11

The reducing power is provided to bundle sheath cells through malage instead

Question 12

What indicates convergent evolution of C4 plants?

Answer 12

There are many C4 species spread across about 20 different damilies with no one family containing exclusively C4 plants

Question 13

What are the advantages of C4 photosynthesis?

Answer 13

Increases photosynthetic efficiency in hot bright environments
Increases water use efficiency

Question 14

How much is CO2 concentrated at point of fixation in C4 plants?

Answer 14

Ten fold due to PEPC’s high affinity for CO2

Question 15

Why is C4 photosynthesis no good in cold climates?

Answer 15

CO2 shuttling costs energy

Question 16

What evidence is there that C4 crops have a higher yield at subtropical temperatures?

Answer 16

Scientists have undertaken controlled experiments with C3 rice and C4 ‘rice’
The C4 outproduced the C3 by 50%

Question 17

What is the proposed process of creating C4 rice?

Answer 17

1. Gene discovery and molecular toolbox development and characterise regulatory controls
2. Transform rice to express Kranz anatomy and the C4 metabolic enzyme
3. Optimise C4 function in transgenic rice
4. Breed C4 from transgenics into local varieties