Studied by 0 people
Looks like no one added any tags here yet for you.
Membranes of chloroplast
Inner (smooth)
Outer (smooth)
Thylakoid
Site of light dependent photosynthesis
Grana
Stack of thylakoids
Lamellae
Unstacked thylakoids between grana
Stroma
Semi-liquid material inside the chloroplast
Lumen
water filled things inside the thylakoids
Where does photosynthesis take place
Inside the stroma and thylakoid membrane
Unique qualities of chloroplasts
Has own DNA and ribosomes
Replicate by binary fission
Overall equation for photosynthesis
6CO2 + 12H2O + light energy → C6H12O6 + 6O2 + 6H2O
Cuticle
Waxy outer layer of leaf
Protects from dessiccation, chemical and physical agents and uv radiation
Epidermis
Under cuticle, allows light to reach mesophyll
Spongy Mesophyll
Palisade Mesophyll
Parenchyma
Ground tissue (mesophyll layers in leaves)
Vascular tissue
Xylem (transport water and nutrients from root to leaf)
Phloem (transports photosynthate around plant)
3 types of plant tissue
dermal (lower and upper epidermis)
Ground tissue (parenchyma/mesophyll)
Vascular tissue (xylem and phloem)
Guard cells
Swell to create stomata to regulate the amount of CO2 entering and O2 leaving the leaf.
Guard cells are turgid
Stomata is open
Guard cells are flaccid
stomata is closed
Factors influencing stomata’s opening (generally)
Light -open
Dark - close
High CO2 inside leaf - close
Low CO2 inside leaf - open
Drought stress - close
Purpose of stomata
Regulate O2 and CO2 concentration in plant
Transpiration
Transpiration and purposes
Loss of water through stomata
creates a pull that helps move water and minerals up the plant
Creates a cooling effect by water evaporating off the plant
Which is more important to a plant: having CO2 or having H2O
H2O - hence why stomata will close during a drought
Abscisic acid
Phytohormone that overrides other signals and closes stomata during droughts
How do stomata open
Blue slight activates potassium pumps that move K+ into the cells
Creates a concentration gradient for water to enter cell by osmosis
Guard cells swell (become turgid). Thin outer wall and thick inner wall cause bean shape which opens stomata
Photoreceptor + example
where light reactions take place eg chlorophyll
Chlorophyll
Traps light energy and converts it into chemical energy
Absorbs blue-violet and red photons
Reflects green photons
Photosystems
Groups of chlorophyll found in thylakoid membrane
2 types of chlorophyll + structural differences
Chlorophyll a - CH3 in side chain
Chlorophyll b - CHO in side chain
Side chain (top right)
Chlorophyll a
Transfers energy of light to carbon fixation reactions of photosynthesis
Chlorophyll b
Accessory pigment,
Absorbs photons that chlorophyll a absorbs poorly, transfers energy to chlorophyll a
Carotenoid
Absorbs energy in blue-violet range
Reflects yellow-red range
Energy absorber more than photosynthetic
absorbs photons that could damage chlorophyll
Enzymes split molecule into 2 identical halves to produce vitamin A
Xanophylls
Accessory pigment that reflects yellow pigment
Anthocyanins
Reflect red, violet and blue photons
Found in cell vacuoles
What causes colon change in leaves during fall
Plants stop producing and disassemble chlorophyll
Anthocyanin is produced which causes the yellow, red and brown colours of the leaves
Where are accessory pigments found
Spread out in the thylakoid membrane
Placement of stomata in monocots vs dicots
Monocots would have stomata on either side of the leaf (grow straight up)
Dicots would have stomata on underside of leaf
They are avoiding direct sunlight
Spongy vs palisade mesophyll
Palisade - tall and stacked, does most photosynthesis, arranged to expose chloroplasts to maximum sun
Spongy - cubical, loosely packed, air pockets for rapid gas exchange
Photosynthesis in shady vs sunny areas
Shady - thinner, broad leaves. As many chloroplasts in spongy mesophyll as palisade mesophyll. Lower rates of respiration, photosynthesize more
Sunny - thicker leaves, more chloroplasts in palisade mesophyll than in spongy mesophyll, Higher rate of respiration
