Transcript Plant Physiology

Plant Physiology
Chapter 16
Introduction to Environmental and
Agricultural Sciences
Introduction
As plants grow to maturity, the cells are
produced, divide, grow & become
specialized organs.
– Stems, leaves, roots, flowers, fruits, seeds.
– study of how these organs
function and the complex chemical
processes that permit the plant to live,
grow and reproduce.
 Physiology
Major Parts of a Plant
Photosynthesis
Most important life-sustaining process
Without photosynthesis, maintenance of
life on this planet would not exist
Plants need carbon dioxide to manufacture
food
Animals need oxygen to live
Photosynthesis permits animals and plants
to live and support each other
Photosynthesis
 Photosynthesis is
a series of processes in
which solar (light) energy is converted to
chemical energy in the form of a simple
sugar.
Chlorophyll and chloroplasts are essential
to this process.
Chlorophyll is the substance that gives
plant leaves their green color.
Photosynthesis
Chloroplasts are small membrane bound
bodies inside the cell that contain the green
chlorophyll pigment.
Chloroplasts are the actual site where solar
(light) energy is converted into stored
energy-simple sugars.
Photosynthesis
 Photosynthesis is
the conversion of carbon
dioxide and water in the presence of light
(energy) and chlorophyll into glucose,
oxygen and water.
Rate of Photosynthesis
 The rate of photosynthesis varies with the light
intensity, temperature and concentration of
carbon dioxide in the atmosphere.
 Light Intensity is the quality of light, or
brightness of light.
 Photosynthesis occurs best in a temperature range
of 65-85F.
– Extreme temperatures slow down or stop the
process completely.
 A lack of carbon dioxide can be a limiting factor
in the photosynthesis process.
Respiration
All living cells carry on the process of
respiration.
 Respiration is the process by which living
cells (plant or animal) take in oxygen and
give off carbon dioxide.
Respiration occurs both day and night.
Respiration
Respiration is a breaking down process
Uses sugars & starches produced by
photosynthesis and converts them into
energy.
Photosynthesis vs. Respiration
PHOTOSYNTHESIS
RESPIRATION
1. Food is produced
1. Food is used for plant energy
2. Energy is stored
2. Energy is released
3. Occurs in cells containing
chloroplasts
3. Occurs in all cells
4. Oxygen is released
4. Oxygen is used
5. Water is used
5. Water is produced
6. Carbon Dioxide is used
6. Carbon Dioxide is produced
7. It occurs in sunlight
7. It occurs in light and dark
Transpiration
 Transpiration is the process by which a plant
gives up water vapor to the atmosphere.
 Water loss takes place primarily through the leaf
stoma.
 A plant transpires 90% of the water that enters
through the roots.
 About 10% of the water that enters from the roots
is used in chemical processes and in the plant
tissues.
Transpiration
Functions of the water include transporting
minerals through the plant, cooling the plant,
moving sugars and plant chemicals and
maintaining turgor pressure.
Turgor means swollen or stiffened condition
as a result of being filled with liquid.
When plants do not have enough water,
turgor pressure is lost and the plant starts to
wilt.
Transpiration
How is transpiration affected?

Humidity
– Humidity

Wind & Other air movement
– Air Movement

Transpiration
Transpiration
Temperature
– Temperature
Transpiration
How is transpiration affected?
During dry weather, transpiration often
causes the plant to lose water faster than it
can be replace by the root system.
When this occurs, the guard cells will close
to slow down the rate of transpiration.
Enables the plant to preserve the water it
contains
How is transpiration affected?