Regulation of systems Flashcards
Gas exchange in plants
Controlled by stomata
Open when turgid (filled with water)
Closes when flaccid (less water)
Allows CO2 and O2 in and out. H2O also goes out through stomata.
Movement of water and solutes
Plants absorb water for photosynthesis.
Absorb minerals like potassium, phosphorus and nitrogen.
Roots absorb water with their high SA:V ratio
There are two pathways taht eater can take: the cytoplasmic pathway and extracellular pathway
Cytoplasmic pathway (water and minerals)
Plasmodesmata (microscopic channels in cells) all water to be transported through the cell membranes of cells (through cytoplasm).
Active and/or osmosis
Plasmodesmata
microscopic channels in cells
Extracellular pathway (water and minerals)
water and minerals move between cells.
Transpiration
The loss of water throguh evaporation.
Creates negative pressure that pulls water up the plant.
Factors affecting transpiration
Increase:
heat
humidity decrease
light increase
more open stomata
Decrease:
cold
humid air
light decrease
more closed stomata
Adhesion
water is attracted to the xylem walls which creates upward force.
Cohesion
water sticks to itself which pulls other water up the plant.
Root pressure
Created when osmotic pressure pulls water into the roots pushing water up.
Homeostasis
The regulation of the human body’s internal environment.
Negative feedback loop
Ensure stability.
Can out any variations from optimal conditions
Positive feedback loop
Increases variation.
Maintains direction of stimulus.
E.g. uterine contractions during childbirth.
Receptors
Detects stimuli
Exoreceptors: external stimuli
Interoreceptors: internal stim
Types:
Photorecep.
Chemorecep.
Mechanorecep.
Thermorecep.
Effector
The cell/tissue/organ that carries out a response to a stimulus such as a hormone.
