3.1b Photosynthesis Flashcards
1
Q
Why is light energy absorbed by photosynthetic pigments?
A
to generate ATP for photolysis
2
Q
What are the fates of light when it hits the leaf?
A
- absorbed
- transmitted
- reflected
3
Q
What do carotenoids do?
A
they extend the range of wavelengths absorbed and pass the energy to chlorophyll for photosynthesis.
4
Q
What is the process of the light reactions stage
A
- Absorbed light energy excites electrons in the pigment molecule.
- Transfer of these electrons through the electron transport chain releases energy
- to generate ATP by ATP synthase.
- Energy is also used for photolysis, in which water is split into oxygen, which is evolved,
- and hydrogen ions, which are transferred to the coenzyme NADP to form NADPH
5
Q
What is the process of carbon fixation?
A
- The enzyme RuBisCO fixes carbon dioxide by attaching it to ribulose bisphosphate
- The 3-phosphoglycerate produced is phosphorylated by ATP
- and combined with hydrogen ions from NADPH to form glyceraldehyde-3-phosphate
- Glyceraldehyde-3-phosphate is used to regenerate RuBP and for the synthesis of glucose
6
Q
What are the uses of glucose?
A
- respiratory substrate
- synthesised into starch
- synthesised into cellulose
- passed onto other biosynthetic pathways
- > DNA, protein, fat
7
Q
What is different about each pigment?
A
they absorb a different range of wavelengths of light
