Topic 5 Flashcards
What are the 2 stages of photosynthesis?
Light-dependent stage (occurs in thylakoid membranes)
Light-independent (occurs in stroma)
What are grana joined together by?
Lamallae
What is chloroplasts made up of?
Grana (stack of thylakoids)
Starch grains
Stroma
Double membrane
Why do plants have different colours?
Photosynthetic pigments
Absorb certain wavelengths of light
What we see is what’s being reflected
What are the types of photosynthetic pigments?
Chlorophylls (a and b) (blue/green/yellow)
Carotenoids (xanthophyll and carotenes) (yellow/orange)
What is the structure of chlorophyll?
Magnesium in the middle
Hydrophilic porphyria ring group (lies flat on surface of thylakoids)(head)
Hydrophobic hydrocarbon chain (attaches to lipid membrane)(tail)
How is energy being absorbed by chlorophyll?
- excites pair of electrons with the Mg
- pass along electron transport chain
Why is the hydrophilic head lied flat on the thylakoids?
To maximise light absorption
How can you tell if a plant is magnesium deficient?
Yellow leaves - can’t make enough chlorophyll
Aka chlorosis
What are accessory pigments?
Carotenoids
They absorb wavelengths that aren’t well absorbed by chlorophylls and pass energy to chlorophyll a
Reflect yellow and orange light, absorb blue light
Why are there more colours in autumn months?
- cold nights: low temp destroy chlorophyll, enhancing red ccolour
- dry weather, sugars more concentrated in leaves , hence redder
- bright sunny days: more anthrocynin
= more colours like red and orange
What’s a photosystem?
Funnel shaped structures
Embedded in thylakoids membranes
Proteins holding them in place
What are the 2 types of photosystem?
PS1 AND PS2
wavelength of light they absorb out of visible spectrum of light
(Has a primary pigment reaction centre, at either P680 or P700)
What are PSI AND PSII
Photosystem I - absorbs light at 700 nm (found on inter-granal lamallae)
Photosystem II - at 680nm (found on grana)
What are the layers in plants? From top to bottom
Waxy cuticle
Upper epidermis
Palisade mesophyll
Spongy mesophyll
Lower epidermis
