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Plant Biology (Diseases (Communicable (Virus (TMV (Makes chloroplasts…
Plant Biology
Diseases
Defences
Chemical
Produce antibacterial chemicals
Stings
Physical
Bark
Protects against infection
Waxy cuticle
Protects against infection
Spikes
Prevent being eaten
Drooping leaves
Mimicry
Makes animals not want to eat it
Communicable
Virus
TMV
Makes chloroplasts yellow
Stops them photosynthesising as effectively
Bacteria
Fungi
Rose Black Spot
Treated by fungicides
Protists
Noncommunicable
Deficiencies
Nitrate
Chlorophyll decreases
Photosynthesis ability decreases
Magnesium ion
Chlorophyll decreases
Photosynthesis ability decreases
Insects
Aphids
Suck sap
Structure
Leaf
Features
Large surface area
Maximum absorption of light and carbon dioxide
Thin/Flat
Less distance to diffuse
Vascular tissue in the midrib
Transport water and minerals
Air spaces between cells
Diffusion of gases
Cells
Palisade mesophyll
Many chloroplasts
Arranged closely together
Next to the upper surface
Spongy mesophyll
Space inbetween
Gas exchange/Diffusion
Stomata
Roots
Stems
Xylem
Water and Minerals
Dead cells
Doesn't require energy
Phloem
Food substances
Living Cells
Sieve Tubes
No Nuclei
Cytoplasm connects to next cell
Companion Cells
Provides energy for transport
Supports sieve tubes
Cambium
Responses
Phototropism
Positive tropism in shoot
Negative tropism in root
Effect of light on growth of newly germinated seedlings
Put cotton wool into three petri dishes, and add the same volume of water to each dish.
Add ten seeds to each dish and place them in a warm place where they won’t be disturbed.
Once they have germinated one petri dish will sit in full light on a windowsill, the second will be in a dark cupboard, and the final dish will be placed in partial light.
Measure the height of the seedling after 10 days
Gravitopism
Negative tropism in shoot
Positive tropism
Hormones
Auxins
Diagram
Used in weed killer
Makes plant grow too fast for itself
Gibberellins
Initiate seed germination
Increase fruit size
Ethene
Ripen fruits faster
Transpiration etc
Transpiration
Water is constantly lost through diffusion into the air through the stoma
This must be taken back in through the roots
Factors
Temperature
Increases molecular movement - rate of diffusion increased
Humidity
Increases concentration of water outside the leaf - lowers concentration gradient
Air Movement
Removes water vapour from leaf surface
Light intensity
Increases photosynthesis rate - make stoma open
Measuring using Potometer
Diagram
The air bubble will move up the tube at the same rate water is taken up by the plant, and the bubbles movement can be measured
Photosynthesis
Limiting factors
Light intensity
Graph
Maximum limit reached
Carbon Dioxide concentration
Graph
Maximum limit reached
Temperature
Graph
Maximum limit reached and then the enzymes start to denature
Amount of chlorophyll
Uses of glucose produced
Respiration (Produce energy)
Starch (Stored for later)
Cellulose (Build cell walls)
Lipids (Storage in seeds)
Amino acids (Growth)
Takes place in chlorophyll
Carbon Dioxide + Water > Glucose + Oxygen