III. PHOTORESPIRATION

List environmental conditions that affect photosynthetic rate and how they affect it.

- Light Intensity: high increases rate and low decreases it

- Temperature: high increases rate and low decreases it. if too high, it can denature and decrease it though.

- CO2: increases rate if high and limits rate if low

- O2: high oxygen decreases photosynthetic rates.

** These are all true but have to double check on if this is the answer he wants

Reactions catalyzed by ribulose bisphosphate carboxylase (rubisco)

1. RUBP + CO2 → 2 phosphoglycerate

2. RUBP + O2 → 1 phosphoglycerate + 1 toxic glycolate // which is really RUBP + O2 ->

1 phosphoglycerate + 1 phosphoglycolate

what is glycolate converted to in the reaction that catalyzes ribulose bisphosphate carboxylase (rubisco) and why?

non-toxic compounds so it can be useful

^ to metabolic processes or possibly growth (this part is just an additional note)

Write out the actual name for Rubisco.

Ribulose Bisphosphate Carboxylase

how does Rubisco's characteristics contribute to causing photorespiration?

- very slow reaction rate (3-10 per second)
- does not bond tightly to substrates (weak)
- Can't distinguish O2 from Co2 so it will catalyze RUBP + O2 AND CO2

in photorespiration, glycolate modifies into ____?

glycerate

Photorespiration has how many compartments?

BONUS ? (not in notes): list those components.

3

chloroplasts, peroxisomes, and mitochondria

What molecules/substances does photorespiration use and release?

Uses O2
Releases CO2
Uses ATP that converts to ADP

How is photorespiration different than photosynthesis?

- photorespiration does the opposite to what photosynthesis wants

(it releases CO2 and uses ATP while photosynthesis consumes uses CO2 and makes ATP)

How does exposure to high light intensity or high temperature result in photorespiration?

- photosynthesis rate increases significantly

- results in high O2 concentration in leaf + low CO2 concentration in leaf

- RUBP + O2 happens instead of RUBP + CO2

draw a graph of photosynthetic rate and light intensity

!

The most important things that happen during the process of photorespiration:

1. what molecule it starts with
2. what the final product is
3. what substances are used and released in between

1. Ribulose Bisphosphate Carboxylase (Rubisco)

2. 1 phosphoglycerate and 1 phosphoglycolate

3. CO2, ATP -> ADP and O2

Since you have to write out the name of molecules on the test, write out RUBP, ADP, and ATP.

Ribulose Bisphosphate Carboxylase
Adenosine Triphosphate
Adenosine Diphosphate

Which reaction does photorespiration choose to use?

according to notes: RUBP + O2 ->

1 phosphoglycerate + 1 toxic glycolate

BUT that 1 toxic glycolate will convert so

it will be RUBP + O2 ->

1 phosphoglycerate + 1 phosphoglycolate