Transpiration,
Respiration, and
Translocation
Topic 2016, 2017, and 2018
Matt Jakubik
Transpiration
 Transpiration- loss of water vapor from
the plant
 Water diffuses out of the plant from a
100% concentration in leaves to an area
of low concentration
Transpiration
 Water exits the
leaves through
openings in the
leaves through
stomata
Factors Affecting
Transpiration
 Temperature
 Humidity
 Air Currents
 CO2
 Soil Water Availability
Air Currents Affect
Transpiration
 Wind removes water vapor that is in the area
immediate to the plant.
 This removal of water vapor decreases the
water potential of the air in that area.
 Since water moves from higher to lower
potential areas, the decrease in potential
increases the rate of transpiration
Affects of CO2 on
Transpiration
 If carbon dioxide concentration in the air
increases, the plant will have its stomata
open less.
 With the stomata open less, the amount
of transpiration decreases.
Soil Water Availability
 As soil water availability increases, the
plant will have more excess water to
move through the plant.
 Therefore, increasing water availability in
the soil will increase the rate of
transpiration.
Transpiration
 95 % of water is lost through the stomata
 3-5% is lost through the leaf cuticle
 A corn plant will transpire up to 4 quarts
of water per day
Respiration




The plant breathing
When
At all times day and night
Done for energy purposes
Three Types of Respiration
 Aerobic Respiration- when oxygen is
adequate
 Anaerobic Respiration- when oxygen is
low
 Photorespiration- occurs only in
chloroplasts
 Plants get no usable energy from it
 C4 plants very little photorespiration so
plants can accumulate more dry matter
Photosynthesis
Respiration
Requires Carbon Dioxide and
Water
Requires Oxygen and
Carbohydrates (CHOs)
Produces Oxygen and
Carbohydrates (CHOs)
Produces Carbon Dioxide
and Water
Light Energy Trapped by
Chlorophyll
Energy Released
Takes Place in Light Only
Takes Place in Both Light
and in Darkness
Occurs Only in Cells With
Chlorophyll (the mesophyll cells
of the leaf)
All Living Cells Respire
(animals and plants)
Translocation
 Transports water in the xylem
 Transports food and minerals in the
phloem
http://www.botany.hawaii.edu/faculty/webb/BOT41
0/Xylem/Xylem-1.htm
Phloem Cells
Xylem Cells
http://www.botany.hawaii.edu/faculty/webb/BOT41
0/Xylem/Xylem-1.htm
http://www2.cdepot.net/~walser/worldofscience/Biology/Pictorial%20Help/Botany/diagram_layers_conif.htm
Translocation
 Source is the location where food is
produced (photosynthesizing leaves or
storage tissue)
 Sink is the location where all plant parts
are unable to meet their own nutritional
needs (roots and stems)
Source
Sink
http://www.bit.net.au/~peterrjo/plants.html
Water Potential and
Osmosis
 Osmosis is the diffusion of water across
membrane.
 Water potential is the potential energy of
water