Please enable JavaScript.
Coggle requires JavaScript to display documents.
Unit 1.5 - Plants and Photosynthesis (The effect of wind on transpiration,…
Unit 1.5 - Plants and Photosynthesis
Equation for photosynthesis
6CO2 + 6H2O --->> C6H12O6 + 6O2
Glucose in plants
Used in respiration to provide energy for cellular energy
Transported as sucrose to growing points, stem and roots
Transformed into starch or oils for storage, cellulose for cell walls, protein for cell growth
Limiting factors
Light - limiting at night and at dawn and dusk. In the daytime, even on a very cloudy day, light is not likely to be limiting except in very shaded places
Temperature - can be a limiting factor on cold winter days
Carbon dioxide - will be limiting whenever the light and temperature are not. The level of carbon dioxide in the atmosphere is very low (0.04%)
Leaf structure and function
Cuticle - Waxy, waterproof layer that reduces water loss, it is transparent allowing light through to the lower layers of cells, which contain chloroplasts
Palisade layer - The cells are packed with chloroplasts for photosynthesis
Spongy layer - Contains large air spaces, allowing carbon dioxide to reach palisade cells for photosynthesis, the cells here also contain chloroplasts for photosynthesis
Guard cells - open and close the stomta, allowing carbon dioxide to enter of preventing water loss
How are roots adapted to their functions?
Roots don't have chlorophyll - they don't have sunlight
fine root hairs - increased surface area - more absorption
How does osmosis work?
Water moves from an area of higher concentration to lower concentration, down the water concentration gradient
Diffusion works when something needs to go down a concentration gradient
BUT - in plant rot cells, there are more minerals and salts inside the cell than outside, as the mineral salts are diluted in the soil water
Active transport moves minerals against their concentration gradient, from soil to roots
What else does a plant need?
Potassium - regulates the stomata - an absence makes yellow leaves
Nitrogen - needed to make protein - an absence means poor growth
Phosphorus - Involved in many processes - an absence means poor root growth
Transpiration works because water sticks to itself - it is cohesive and is transported up through the xylem vesselst
The cohesion theory is a theory of inter molecular attraction that explains the processes of water flow upwards (against the force of gravity) through the xylem of plants... water is constantly lost through transpiration from the leaf
The effect of wind on transpiration
Water diffuses into the plant at the roots by osmosis
Excess water evaporates from the stomata
As water is lost from the leaves, more water is pulled up from the roots...
...Because water sticks to itself (it is cohesive)
Wind moves more water particles from the surface of other leaves
This means there is more space for water in the stomata to evaporate out
More wind means water evaporates faster so transportation happens more quickly