Photosynthesis Flashcards
What is photosynthesis
- the process by which energy (in the form of light from the sun) is used to build complex organic molecules
Word equation for photosynthesis
carbon dioxide + water = glucose + oxygen
What are autotrophs
Organisms that can photosynthesis to produce their own complex molecules
What are heterotrophs
have to obtain complex organic molecules by eating other organisms
Key structural features of chloroplasts
- double membrane
- very flat- increases surface area to absorb light
- thylakoids
- grana/ granum
- lamellae
- stroma
What is a granum
A stack of thylakoids (fluid filled sacs formed by membranes)
What are lamellae
- join grana together
- bits of thylakoid membranes, membranous channels
What is the stroma
- the fluid enclosed in a chloroplast
- site of many chemical reactions
What is chlorophyll
- pigment molecule that absorb different wavelengths of light
- absorbs red and blue, reflects green
What are 4 main photosynthetic pigments
- chlorophyll A
- chlorophyll B
- carotenoids
- xanthophyll
Differences in roles of photosynthetic pigments
- chlorophyll A is in the reaction centre where photosynthesis occurs
- chlorophyll B, carotenoids, xanthophyll embedded in thylakoid membranes, joined to proteins, form light harvesting system
What is a photosystem
-the light harvesting system and reaction centre
- proteins and pigments collectively
Summary of the light dependent stage
- occurs in thylakoid membranes
- energy from sunlight is absorbed and used to form ATP
- hydrogen from water is used to reduce NADP
- Produces NADPH, ATP, oxygen
non-cyclic phosphorylation
- involves PSI + PSII
- electrons travel from PSII to PSI, losing electrons as they do so
- electrons lost from PSII are replaced by photolysis
- electrons from PSI pass down electron transport chain, form reduced NADP
- electrons lost from PSI replaced with electrons from PSII
What is photolysis, what is the equation
- light energy is used to split water
- water => hydrogen + electrons + oxygen