The document discusses photosynthesis and the food web. It explains that photosynthesis traps sunlight and converts it into chemical energy that powers life on Earth. Photosynthesis has three main events - light capturing, light-dependent reactions, and light-independent reactions. It also describes that chloroplasts contain pigments like chlorophyll a and b and carotenoids that absorb sunlight for photosynthesis. Chlorophyll transforms light energy into ATP and NADPH through two photosystems during the light-dependent reactions. The oxygen produced by photosynthesis comes from splitting water molecules during this process.

1. UNIVERSITY OF FOOD INDUSTRY- HOCHIMINH CITY
BIOLOGY
1

2. THE FOOD WEB

3. 7.1 Photosynthesis and Life
• trap radiant energy from sunlight and convert it
into the energy of chemical bonds in large
molecules, such as carbohydrates,
• estimated 99.9% of life on Earth relies on
photosynthesis for its energy needs

4. 7.2 An Overview of Photosynthesis

5. Sunlight minus absorbed
wavelengths or colors equals
the apparent color of an
object.
The feathers of male cardinals are
loaded with carotenoid pigments.
These pigments absorb some
wavelengths of light and reflect
others.

6. Why are plants green?
Transmitted light

7. WHY ARE PLANTS GREEN?
Plant Cells
have Green
Chloroplasts
The thylakoid
membrane of the
chloroplast is
impregnated with
photosynthetic
pigments (i.e.,
chlorophylls,
carotenoids).

8. 7.2 An Overview of Photosynthesis
• Chlorophyll: An important molecule in the process of harvesting
sunlight,
• light energy is transformed to chemical-bond energy in the form of
ATP,

9. 3 distinct events in the photosynthesis
• Light-capturing events,
• Light-dependent reactions,
• Light-independent reactions

10. Light-Capturing Events:
• Chlorophyll consists of
chlorophyll a and
chlorophyll b,
• Chlorophyll capture light
energy and become
excited,

11. Chloroplast Pigments
• Chloroplasts contain several pigments
– Chlorophyll a
– Chlorophyll b
– Carotenoids
Figure 7.7

12. Chlorophyll a & b
•Chl a has a methyl
group
•Chl b has a carbonyl
group
Porphyrin ring
delocalized e-
Phytol tail

13. Light-Dependent Reactions:

14. Water-splitting
photosystem
NADPH-producing
photosystem
ATP
mill
• Two types of photosystems
cooperate in the light reactions

15. Plants produce O2 gas by splitting H2O
• The O2 liberated by photosynthesis is made from the oxygen in water (H+
and e-)

16. Light-Independent Reactions

18. C3-C4 and CAM photosynthesis

19. 7.4 Other Aspects of Plant Metabolism

20. 7.5 Interrelationships Between
Autotrophs and Heterotrophs

21. Be ready for next lesson!