02.11 - plants / photosynthesis - hard Flashcards
Meristem
Rapidly dividing undifferentiated cells found in the growing tips and roots.
Differentiate to form other types of cells
Xylem (brief)
Non-living transport tissue
which carries water + dissolved minerals from root to leaves
Phloem (brief)
Living transport tissue
Carries sugars + amino acids from leaves to rest of plant
What’s translocation
Movement of dissolved sugars from source to sink through the phloem to be stored or used immediately or stored
Phloem structure
Living cells in a tube shape
Contain little cellulose but no nucleus / organelles
Kept alive by companion cells
Sieve plates
End of each cell contains a sieve plate which has pores to allow dissolved sugars to pass from cell to cell
Transpiration
The evaporation of water when the stoma are open
Transpiration is the evaporation of water from the surface of a plant, such as from its leaves.
Xylem structure
hollow tubes strengthened by dead lignin
Adapted for water transport as the lignin dead so it won’t absorb the H2O
Why’s water important for the plant
Reactant photosynthesis
keeps cells turgid = without H2O plant droops
Why are minerals important for plants
Magnesium = chlorophyll production Nitrates = protein growth + amino acid production Potassium = general chemical reactions
Uses of glucose from photosynthesis (5)
- Respiration
- Convert into insoluble starch (storage)
- Convert to fat/oils (storage)
- Cellulose production (strengthens cell wall)
- Amino acid production
Effect of temperature on transpiration
As temp increases kinetic energy of water molecules increases - faster rate of diffusion and evaporation
Graph = increase then straight line
Effect of humidity on transpiration
Arid / dry = big difference in water concentration between leaf and environment so transpiration happens quickly
Moist = little difference in water concentration between leaf and environment so transpiration happens slowly
Graph = negative (goes down in straight line) staring at dry —> moist
Effect of air movement on transpiration
Wind reduces water vapour around the stone (diffusion occurs faster) maintains the concentration gradient.
Graph = goes up (starting at still —> windy)
Effect of light intensity on transpiration
Increases the number of open stoma so transpiration rate increases
Graph = goes up as light intensity increases
Limiting factor for photosynthesis (light intensity)
Increasing the light intensity increases the photosynthesis rates to a certain point until it’s no longer the limiting factor
Limiting factor for photosynthesis ( co2 concentration)
The atmosphere only contains 0.04% co2 so it’s often the limiting factor. As the co2 conc increases the rate of photosynthesis increases until its not the limiting factor anymore
Limiting factor for photosynthesis (temperature)
Temperature effects enzymes and photosynthesis is an enzyme controlled reaction.
As temperature increases the rate of photosynthesis increases up until a certain point, once it’s reached it’s optimum temperature that’s when photosynthesis rates are the highest. Anything after the optimum temp is when the enzymes begin to denature so the photosynthesis rates decrease rapidly
Epidermal tissue
Thin + transparent to allow more light to reach palisade cells
Waxy layer - water loss + infection prevention
Palisade mesophyll
Long + thin (rectangles) to fit more in a certain space
Contains lots of chloroplasts = more photosynthesis/ light absorption
Spongy mesophyll
Has air spaces so gases can diffuse rapidly
Has chloroplasts so that it can absorb any light that the palisade cells missed
Guard cells
Guard cells become turgid and swell when the water concentration in the leaf is high as the water moved into the guard cells via osmosis so the stoma open allowing H2O gas to diffuse out and CO2 to diffuse in . When the water concentration is low the water moves out of the guard cells causing them to become flaccid so the stoma shut so water vapour is unable to leave the leaf.
Flower
Reproductive organ
Leaf
Photosynthesis
