1. PHOTOSYNTHESIS

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.
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4. Very Good! Photosynthesis
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
mineral salts
(e.g. NO3-, SO42-)
carbohydrates (e.g. glucose)
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
Water is formed as a by-product
No light is required; can take place either in light or darkness
Hydrogen produced in light reaction combines with CO2 to form carbohydrates

17. Chlorophyll Structure

18. Photophosphorylation
Light Reaction
Photophosphorylation

19. Cyclic photophosphorylation

20. Dark Reaction
M. Calvin

21. Calvin Cycle

22. CHLOROPLAST

24. Fate of product of photosynthesis
PGAL
Pyruvate +
coenzyme A
X 2
Glucose
&
Cellulose
Kreb
cycle
Fatty acid
Glycerol
Nitrate
Lipid
Protein

25. Factors affect rate of photosynthesis

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

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

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

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

30. Fate of carbohydrate products in the plant
carbon dioxide and water
photosynthesis
mineral salts
(e.g. NO3-, SO42-)
carbohydrates (e.g. glucose)
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
mineral salts
(e.g. NO3-, SO42-)
carbohydrates (e.g. glucose)
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
mineral salts
(e.g. NO3-, SO42-)
carbohydrates (e.g. glucose)
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 can improve soil texture
No humus so cannot improve soil texture
Less soluble in water so less likely to be washed away
Very soluble in water so more likely to be washed away

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

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: Method:
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
contains many chloroplasts
columnar cells closely packed 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 gases throughout the leaf
less chloroplasts for photosynthesis
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