This is a very helpful power point on photosynthesis. Hope you enjoy it.......

2. Review Question
• Which mode of nutrition do the green plants
carry out?
A. Autotrophic nutrition
B. Heterotrophic nutrition

3. Sorry! You’re wrong!
• Heterotrophic nutrition is the mode of
nutrition in which organisms have to depend
on other organisms or dead organic matters as
their food sources. Green plants, however,
can make organic food by themselves using
simple inorganic substances.
Back

4. Very Good!
• Autotrophic nutrition is the mode of
nutrition in which organisms can make
organic food by themselves using simple
inorganic substances.
• The process by which the green plants
obtain nutrients is called :-
Photosynthesis

6. Overview of nutrition in green
plants
carbon dioxide and water
photosynthesis
carbohydrates (e.g. glucose) mineral salts
(e.g. NO3-, SO42-)
fatty acids glycerol amino acids water
nutrients for plants can be used to produce all
plant materials (e.g. enzymes, cell wall,
cytoplasm, cell membrane, chlorophyll)

7. Nature of photosynthesis
• Anabolic process
• Takes place in chloroplast
• Necessary factors :
•Carbon dioxide
•Water
•Sunlight
•Chlorophyll

8. Light

9. Light Absorption Spectrum
Why leave looked green?

10. Different pigments in absorption
spectrum

11. How light energy used?

12. Light reaction
• Light energy is trapped by chlorophyll in
chloroplast

13. Light reaction
Light energy absorbed by chlorophyll splits water molecules into
hydrogen and oxygen

14. Light reaction
Oxygen is released as a gas through stoma to outside

15. Light reaction
Hydrogen is fed into dark reaction

16. Dark reaction
• No light is required; can combines with CO2 to form
Hydrogen producedain light reactiontake place either in
Water is formed as by-product
carbohydrates
light or darkness

17. Chlorophyll Structure

18. Light Reaction
Photophosphorylation

19. Cyclic photophosphorylation

20. Dark Reaction
M. Calvin

21. Calvin Cycle

22. CHLOROPLAST

24. Fate of product of photosynthesis
Kreb
cycle

25. Factors affect rate of photosynthesis

26. Expt. Show effect of factors
Conc. Of Distance
NaHCO3
Heat

27. Fate of carbohydrate products in
the plant
carbon dioxide and water
photosynthesis
carbohydrates (e.g. glucose) mineral salts
(e.g. NO3-, SO42-)
fatty acids glycerol amino acids water

28. Fate of carbohydrate products in
the plant
carbon dioxide and water
photosynthesis
carbohydrates (e.g. glucose) mineral salts
(e.g. NO3-, SO42-)
fatty acids glycerol amino acids water
release energy by respiration

29. Fate of carbohydrate products in
the plant
carbon dioxide and water
photosynthesis
carbohydrates (e.g. glucose) mineral salts
(e.g. NO3-, SO42-)
fatty acids glycerol amino acids water
convert into starch for storage

30. Fate of carbohydrate products in
the plant
carbon dioxide and water
photosynthesis
carbohydrates (e.g. glucose) mineral salts
(e.g. NO3-, SO42-)
fatty acids glycerol amino acids water
change into sucrose and is transported
to other parts through phloem

31. Fate of carbohydrate products in
the plant
carbon dioxide and water
photosynthesis
carbohydrates (e.g. glucose) mineral salts
(e.g. NO3-, SO42-)
fatty acids glycerol amino acids water
combine to form fats and oils to form
cell membranes and as a food store

32. Fate of carbohydrate products in
the plant
carbon dioxide and water
photosynthesis
carbohydrates (e.g. glucose) mineral salts
(e.g. NO3-, SO42-)
fatty acids glycerol amino acids water
join together to become
protein molecules

33. Mineral requirements in plants
• In order to synthesize amino acids, nitrate
ions must be taken into the plant from the
soil through the root
• Other minerals are also necessary to
maintain the life of the plant

34. Expt. Show effect of minerals
Different
Nutrient
added

35. The importance of nitrogen
• For synthesis of proteins, chlorophyll, etc.
• Taken in the form of nitrate ions
• Deficiency symptoms:
– Little growth (no protein made)
– Yellowing of leaves (chlorophyll made)

36. The importance of magnesium
• Essential component of chlorophyll
• Deficiency symptoms:
– Yellowing of leaves (no chlorophyll made)
– Poor growth (no food manufactured because
of lack of chlorophyll)

37. Use of fertilizers in agriculture
• Continuous harvesting crops removes the
valuable mineral salts from soil
∴Fertilizers are added to replace such loss
• Two kinds of fertilizers:
– Natural fertilizers
– Chemical fertilizers

38. Natural fertilizers
• From manure
• Organic compounds in it are decomposed
by bacteria in soil to form mineral salts

39. Chemical fertilizers
• Mainly nitrogenous and phosphorous
compounds manufactured artificially

40. Comparison between natural and
chemical fertilizers
Natural fertilizers Chemical fertilizers
Very cheap More expensive
Contain humus which No humus so cannot
can improve soil improve soil texture
texture
Less soluble in water Very soluble in water
so less likely to be so more likely to be
washed away washed away

41. Comparison between natural and
chemical fertilizers
Natural fertilizers Chemical fertilizers
Less soluble in water Very soluble in water
so more difficult to be so easier to be
absorbed absorbed
Time is needed for the More readily to be
decomposition to used by the plants
complete before
nutrient is available to
plants

42. Importance of photosynthesis
• It is the only method to convert energy in
sunlight into chemical energy
– Animals have to depend on plants for food
supply
– Plants: producers; animals : consumers
• To maintain a constant oxygen level in the
atmosphere

43. Experiments to test for necessary factors
of photosynthesis
• Experimental set-up: To remove the factor
under study and to see if photosynthesis still
takes place
• Control set-up: Identical to experimental
set-up except that the missing factor is
present

44. A set-up to study whether light is
necessary for photosynthesis
Region B
Region A leafy shoot
water

45. Which is the control, the exposed region
A or the shaded region B?

46. What is the purpose of setting up
region A?
• As a control
Too simple and not explicit!
To show that photosynthesis cannot take place in the absence of
light

47. Destarching
• Reason:
– To avoid any existing starch in the leaves
interfering with the result, and to show that any
starch found after the experiment was produced
during the period of investigation
• Method:
– By placing the plant in dark for at least 24
hours

48. Parts of plant where
photosynthesis takes place
• Places where chloroplasts are found
• Mainly in the leaf because
– it contains a lot of chloroplasts
– it is well adapted for performing photosynthesis

49. Cross-section of a dicot leaf
upper
epidermis
protect
internal
tissues
from
mechanical
damage and
bacterial
and fungal
invasion

50. Cross-section of a dicot leaf
Cuticle
• a waxy
layer
• prevent
water loss
from the
leaf
surface

51. Cross-section of a dicot leaf
mesophyll

52. Cross-section of a dicot leaf
palisade
mesophyll
columnarmany
contains cells
closely packed
chloroplasts
together
∴absorb light
more
efficiently

53. Cross-section of a dicot leaf
irregular cells
loosely packed
together to leave
numerous large
air spaces
→allow rapid
diffusion of
less chloroplasts
gases
for
throughout the
photosynthesis
leaf
spongy
mesophyll

54. Cross-section of a dicot leaf
same as
upper
epidermis
except the
cuticle is
thinner
lower
epidermis

55. Cross-section of a dicot leaf
stoma
opening which
allows gases
to pass
through it to
go into or out
of the leaf

56. Cross-section of a dicot leaf
guard cells
control the
size of stoma

57. Cross-section of a dicot leaf
vascular
bundle
(vein)

58. Cross-section of a dicot leaf
xylem
•to transport
water and
mineral
salts
towards the
leaf

59. Cross-section of a dicot leaf
phloem
•to transport
organic
substances
away from
the leaf

60. Adaptation of leaf to
photosynthesis
Upper epidermis
and cuticle is
transparent
Allows most
light to pass to
photosynthetic
mesophyll
tissues

61. Adaptation of leaf to
photosynthesis
Palisade
mesophyll cells
are closely
packed and
contain many
chloroplasts
To carry out
photosynthesis
more efficiently

62. Adaptation of leaf to
photosynthesis
Spongy
mesophyll cells
are loosely
packed with
numerous large
air spaces
To allow rapid
diffusion of gases
throughout the
leaf

63. Adaptation of leaf to
photosynthesis
Numerous
stomata on
lower epidermis
To allow rapid
gaseous
exchange with
the atmosphere

64. Adaptation of leaf to
photosynthesis
Extensive vein
system
• Allow sufficient
water to reach
the cells in the
leaf
• To carry food
away from them
to other parts of
the plant

65. CHEMOSYNTHSIS
•Iron bacteria
•Colorless sulphur bacteria
•Nitrifying bacteria

66. Iron bacteria

67. Nitrifying bacteria