PHOTOSYNTHESIS

The process of manufacturing food
in plants, mainly sugar, from carbon
dioxide and water in the presence
of chlorophyll, utilizing light energy
and releasing oxygen gas

Raw materials for photosynthesis

from the atmosphere
which diffuses into the intercellular spaces
of the leaf through the stoma

absorbed from the environment by
the cells; in vascular plants, this absorption
is by the roots and water is transported to
the leaves through the xylem

Source of energy

Most effective light energy

Mainly reflected from and transmitted through thr leaves

Only those wavelengths that can be
absorbed by the chloroplast pigments
are useful in photosynthesis

Therefore, the proces s may be
considered as one in which the solar
energy is converted to chemical energy
and stored in the form of

enables the plant to
absorb light energy and to use the
absorbed energy in the production
of sugars

yellow pigments

yellow orange
pigments

range of
t e m p e r a t u r e f o r
photosynthesis is from 5
to 40°C

range of t e m p e r a t u r e f o r
photosynthesis is from

important intransferring hydrogen atoms, electrons and energy

speed up the
chemical reaction
- also present in chloroplasts

the principal
end product in the majority of plants

a 3-carbon
compound which is the first product formed

2 molecules of PGA is readily converted
to

a 4-carbon compound
which is the f irst product formed in some
plants termed the C4 plants as differentiated
from the C3 plants

light to
chemical energy; release of O2; product
ATP and NADH; thylakoid membrane

chlorophyll
becomes active

chlorophyll
expels highly energized electron ;
becomes positively charged

process
in which ATP is formed from ADP

uses ATP

Involves the absorption of light
energy and the production of an
energy-rich compound, ATP, a
p r o c e s s c a l l e d
photophosphorylation
Es sential l y a water-spl itting
operation by means of which
hydrogen is made available for the
next step

involves the incorporation of
CO2 into the final production
- CO2 brought into the system
through reactions called Calvin
cycle

Xylem

Phloem