photosynthesis, botany

1. Photosynthesis
Dr. Hasbi Ara Mostofa
Assistant Professor
Department of Microbiology
Shaheed Suhrawardy Medical College

3. • Photosynthesis is the process by which plants use sunlight, water, and
carbon dioxide to create oxygen and energy in the form of sugar.

4. Requirement
• Chlorophyll- the pigment in plants that makes them green, is essential
to the photosynthetic process.
• Sunlight.
• Water.
• Carbon Dioxide

5. Process
• The three events that occur during the process of photosynthesis are:
(i) Absorption of light energy by chlorophyll.
• (ii) Conversion of light energy to chemical energy and splitting of
water molecules into hydrogen and oxygen.
• (iii) Reduction of carbon dioxide to carbohydrates.

8. • Photosynthesis takes place in two stages:
• light-dependent reactions and the Calvin cycle (light-independent
reactions).
• Light-dependent reactions, which take place in the thylakoid
membrane, use light energy to make ATP and NADPH.

9. • the light independent process (also called dark reactions or the
Calvin-Benson cycle) takes place in the stroma of the chloroplast.
• Carbon dioxide is modified by series of chemical reactions to form
carbohydrates.
• The energy for these reactions comes from ATP and NADPH
generated during the light dependent process.

10. • Light-dependent reactions
Goal
Convert light energy
into chemical energy
Location
Chloroplasts—
thylakoids
Input
Sunlight, H2O,
NADP+
, ADP
Output NADPH, ATP, O2

11. • Light-independent reactions
Goal
Use stored chemical
energy to “fix”
CO2 and create a
product that can be
converted into
glucose
Location
Chloroplasts—
stroma
Input CO2, NADPH, ATP
Output
NADP+
, ADP, G3P
(Two G3P can be
made into C6H12O6)

13. Food production
• Plants use a process called photosynthesis to make food.
• During photosynthesis, plants trap light energy with their leaves.
• Plants use the energy of the sun to change water and carbon dioxide
into a sugar called glucose.
• Glucose is used by plants for energy and to make other substances
like cellulose and starch.

14. Thank you