Download Plant response to temperature change

Plant response to
temperature change
Hot environments
Plants need radiant energy from the sun
to photosynthesise, but needs to
remove most of this heat so as to
maintain an optimum temperature.
Removing heat
 Radiates heat into environment
Transpiration
 Evaporation of water from leaf
surface (transpiration)
 The air around plant is heated by
plant and rises, taking heat away
(convection)
 SA:V ratio of leaf increased. Also, Convection
Radiation
more “edges” means more cooling
 Heat shock proteins produced at
about 40 C to protect enzymes etc
Removing heat cont…
 Leaf orientation – turn side on to hot
sun
 Water storage in thick trunk
 Loss of leaves in summer/heat = no
stomata = no transpiration
Cold environments
 Ice forms around cells in freezing
temperatures
 Does not form inside cells, as there is a lot of
salt dissolved in there, which reduces freezing
point
 Water comes from cells doing metabolic
processes
 Ice shards pierce cell wall, but push cell
membrane inward, leaving cell intact
 If there is a MASSIVE drop in temperature, ice
will form inside cells and kill the cells
 Some plants (eg. Balsam Fir) can live in
temperatures down to -80 C
Activities
Glossary words: transpiration, heat
shock proteins
Quick Check questions pg 325