This is a ppt about the Photosynthesis in plants.

1. IGCSE BIOLOGY
SECTION 2 LESSON 4

2. Content
Section 2
Structures
and
functions
in living
organisms
a) Levels of organisation
b) Cell structure
c) Biological molecules
d) Movement of substances
into and out of cells
e) Nutrition
f) Respiration
g) Gas exchange
h) Transport
i) Excretion
j) Coordination and response

3. Content
Lesson 4
f) Respiration
g) Gas
exchange
f) Respiration
2.33 understand that the process of respiration
releases energy in living organisms
2.34 describe the differences between aerobic
and anaerobic respiration
2.35 write the word equation and the balanced
chemical symbol equation for aerobic
respiration in living organisms
2.36 write the word equation for anaerobic
respiration in plants and in animals
2.37 describe experiments to investigate the
evolution of carbon dioxide and heat from
respiring seeds or other suitable living
organisms.

4. Content
Lesson 4
f) Respiration
g) Gas
exchange
g) Gas exchange
2.38 understand the role of diffusion in gas exchange
Flowering plants
2.39 understand gas exchange (of carbon dioxide and oxygen) in relation
to respiration and photosynthesis
2.40 understand that respiration continues during the day and night, but
that the net exchange of carbon dioxide and oxygen depends on the
intensity of light
2.41 explain how the structure of the leaf is adapted for gas exchange
2.42 describe the role of stomata in gas exchange
2.43 describe experiments to investigate the effect of light on net gas
exchange from a leaf, using hydrogen-carbonate indicator
Humans
2.44 describe the structure of the thorax, including the ribs, intercostal
muscles, diaphragm, trachea, bronchi, bronchioles, alveoli and pleural
membranes
2.45 understand the role of the intercostal muscles and the diaphragm in
ventilation
2.46 explain how alveoli are adapted for gas exchange by diffusion
between air in the lungs and blood in capillaries
2.47 understand the biological consequences of smoking in relation to the
lungs and the circulatory system, including coronary heart disease
2.48 describe experiments to investigate the effect of exercise on
breathing in humans.

5. What is respiration?
What is gaseous exchange?

6. What is respiration?
What is gaseous exchange?
Respiration is the release of energy from
the breakdown of glucose, by combining it
with oxygen inside living cells.

7. What is respiration?
What is gaseous exchange?
Respiration is the release of energy from
the breakdown of glucose, by combining it
with oxygen inside living cells.
Gaseous exchange is the movement of
gases (oxygen and carbon dioxide) into
and out of an organism.

8. Respiration – two sorts
Aerobic respiration - in the
presence of oxygen.
Involves the complete
breakdown of glucose.
Provides more energy.
End products in animals and
plants: carbon dioxide and
water

9. Respiration – two sorts
Aerobic respiration - in the
presence of oxygen.
Involves the complete
breakdown of glucose.
Provides more energy.
End products in animals and
plants: carbon dioxide and
water
Anaerobic respiration - in the
absence of oxygen.
Involves the incomplete
breakdown of glucose.
Provides less energy.
End product in animals – lactic
acid. End product in plants -
ethanol

10. Aerobic respiration
Glucose + oxygen  carbon dioxide + water + energy

11. Aerobic respiration
Glucose + oxygen  carbon dioxide + water + energy
C6H12O6 + 6O2  6CO2 + 6H2O + energy

12. Aerobic respiration
Glucose + oxygen  carbon dioxide + water + energy
C6H12O6 + 6O2  6CO2 + 6H2O + energy
What do you
notice?

13. Photosynthesis
6CO2 + 6H2O C6H12O6 + 6O2
Light
Chlorophyll

14. Blood capillary
Glucose
Muscle cell

15. Blood capillary
Glucose
Muscle cell
Glucose + Oxygen
Glucose and oxygen
diffuse from the
blood into the muscle
cell

16. Blood capillary
Glucose
Muscle cell
Glucose + Oxygen  Carbon dioxide + Water
Glucose and oxygen
diffuse from the
blood into the muscle
cell
Carbon dioxide and
water diffuse from
the muscle cell into
the blood
Deoxygenated red
blood cells

17. Blood capillary
Glucose
Muscle cell
Glucose + Oxygen  Carbon dioxide + Water
Glucose and oxygen
diffuse from the
blood into the muscle
cell
Carbon dioxide and
water diffuse from
the muscle cell into
the blood
Deoxygenated red
blood cells
Energy
Energy is used
for muscle
contraction

18. Levels of Organisation
A. Cells

19. Levels of Organisation
A. Cells
Mitochondria -
organelles inside the cell
where cellular
respiration takes place.
They absorb glucose and
oxygen, release the
energy and then convert
it into forms that are
usable by the cell.
Mitochondria are more
numerous in active cells
such as muscle cells.

20. Why anaerobic respiration?
If it is so inefficient compared with aerobic
respiration, why do cells bother?
Sometimes our muscles are
working so hard that the
lungs and bloodstream
cannot deliver oxygen fast
enough, so the muscles must
respire anaerobically.
This can lead to a build up of
lactic acid in the muscle.

21. Why anaerobic respiration?
If it is so inefficient compared with aerobic
respiration, why do cells bother?
A lactic acid build-up in
muscles can result in cramp,
an unpleasant and often
painful sensation caused by
muscle contraction or over-
shortening.

22. Why anaerobic respiration?
If it is so inefficient compared with aerobic
respiration, why do cells bother?
In order to break down
the lactic acid the body
needs more oxygen 
OXYGEN DEBT

23. Why anaerobic respiration?
If it is so inefficient compared with aerobic
respiration, why do cells bother?

24. Anaerobic respiration in
plants

25. Anaerobic respiration in
plants
Glucose  ethanol + carbon dioxide + energy

26. Anaerobic respiration in
plants
Glucose  ethanol + carbon dioxide + energy
C6H12O6  2C2H5OH + 2CO2

27. Anaerobic respiration in
plants
Glucose  ethanol + carbon dioxide + energy
C6H12O6  2C2H5OH + 2CO2
In plants, anaerobic respiration (respiration without
oxygen) is known as fermentation. This process is
commonly used to our advantage in the production of beer
and ales, and wine.

28. Aerobic v Anaerobic

29. Aerobic v Anaerobic
AEROBIC ANAEROBIC
A very efficient method of
producing energy.
Inefficient (incomplete
breakdown of glucose) –
releases 1/20th energy
compared to aerobic.

30. Aerobic v Anaerobic
AEROBIC ANAEROBIC
A very efficient method of
producing energy.
Inefficient (incomplete
breakdown of glucose) –
releases 1/20th energy
compared to aerobic.
Occurs during normal daily
activity.
Produces energy much
faster over a short time
period. Eg. sprinting

31. Aerobic v Anaerobic
AEROBIC ANAEROBIC
A very efficient method of
producing energy.
Inefficient (incomplete
breakdown of glucose) –
releases 1/20th energy
compared to aerobic.
Occurs during normal daily
activity.
Produces energy much
faster over a short time
period. Eg. sprinting
Produces energy more slowly
than anaerobic.
Build-up of waste products
eventually stops the muscle
from working

32. Content
Lesson 4
f) Respiration
g) Gas
exchange
g) Gas exchange
2.38 understand the role of diffusion in gas exchange
Flowering plants
2.39 understand gas exchange (of carbon dioxide and oxygen) in relation
to respiration and photosynthesis
2.40 understand that respiration continues during the day and night, but
that the net exchange of carbon dioxide and oxygen depends on the
intensity of light
2.41 explain how the structure of the leaf is adapted for gas exchange
2.42 describe the role of stomata in gas exchange
2.43 describe experiments to investigate the effect of light on net gas
exchange from a leaf, using hydrogen-carbonate indicator
Humans
2.44 describe the structure of the thorax, including the ribs, intercostal
muscles, diaphragm, trachea, bronchi, bronchioles, alveoli and pleural
membranes
2.45 understand the role of the intercostal muscles and the diaphragm in
ventilation
2.46 explain how alveoli are adapted for gas exchange by diffusion
between air in the lungs and blood in capillaries
2.47 understand the biological consequences of smoking in relation to the
lungs and the circulatory system, including coronary heart disease
2.48 describe experiments to investigate the effect of exercise on
breathing in humans.

33. What is respiration?
What is gaseous exchange?
Respiration is the release of energy from
the breakdown of glucose, by combining it
with oxygen inside living cells.
Gaseous exchange is the movement of
gases (oxygen and carbon dioxide) into
and out of an organism.

34. What is gaseous exchange?
Gaseous exchange is the movement of
gases (oxygen and carbon dioxide) into
and out of an organism.
Gaseous exchange is brought about by the
actions of the breathing system (also
referred to in some textbooks as the
respiratory system)

35. The Breathing System

36. The Breathing System
Trachea –
surrounded by rings
of cartilage to stop it
collapsing

37. The Breathing System
Trachea –
surrounded by rings
of cartilage to stop it
collapsing
Ribs – these protect
the contents of the
thorax. There are 12
pairs of ribs in both
men and women.

38. The Breathing System
Trachea –
surrounded by rings
of cartilage to stop it
collapsing
Ribs – these protect
the contents of the
thorax. There are 12
pairs of ribs in both
men and women.
Rib muscles - the
intercostals. Raise
and lower the rib cage

39. The Breathing System
Trachea –
surrounded by rings
of cartilage to stop it
collapsing
Ribs – these protect
the contents of the
thorax. There are 12
pairs of ribs in both
men and women.
Rib muscles - the
intercostals. Raise
and lower the rib cage
Left lung

40. The Breathing System
Trachea –
surrounded by rings
of cartilage to stop it
collapsing
Ribs – these protect
the contents of the
thorax. There are 12
pairs of ribs in both
men and women.
Rib muscles - the
intercostals. Raise
and lower the rib cage
Left lung
Diaphragm – a sheet
of muscle used in the
mechanism of
breathing

41. The Breathing System
Trachea –
surrounded by rings
of cartilage to stop it
collapsing
Ribs – these protect
the contents of the
thorax. There are 12
pairs of ribs in both
men and women.
Rib muscles - the
intercostals. Raise
and lower the rib cage
Left lung
Diaphragm – a sheet
of muscle used in the
mechanism of
breathing
Right bronchus – a
branch of the trachea

42. The Breathing System
Trachea –
surrounded by rings
of cartilage to stop it
collapsing
Ribs – these protect
the contents of the
thorax. There are 12
pairs of ribs in both
men and women.
Rib muscles - the
intercostals. Raise
and lower the rib cage
Left lung
Diaphragm – a sheet
of muscle used in the
mechanism of
breathing
Right bronchus – a
branch of the trachea
Bronchiole - a
smaller branch of the
bronchus

43. The Breathing System
Trachea –
surrounded by rings
of cartilage to stop it
collapsing
Ribs – these protect
the contents of the
thorax. There are 12
pairs of ribs in both
men and women.
Rib muscles - the
intercostals. Raise
and lower the rib cage
Left lung
Diaphragm – a sheet
of muscle used in the
mechanism of
breathing
Right bronchus – a
branch of the trachea
Bronchiole - a
smaller branch of the
bronchus
Alveoli - clusters of
grape-like air sacs
where gas exchange
takes place

44. The Breathing System
Trachea –
surrounded by rings
of cartilage to stop it
collapsing
Ribs – these protect
the contents of the
thorax. There are 12
pairs of ribs in both
men and women.
Rib muscles - the
intercostals. Raise
and lower the rib cage
Left lung
Diaphragm – a sheet
of muscle used in the
mechanism of
breathing
Right bronchus – a
branch of the trachea
Bronchiole - a
smaller branch of the
bronchus
Alveoli - clusters of
grape-like air sacs
where gas exchange
takes place

45. Alveolus (plural alveoli)
Where oxygen and carbon dioxide move between
the lungs and the blood stream.

46. Bronchiole
Alveolus
There are millions of alveoli in each lung, very close to
blood capillaries

47. Bronchiole
Alveolus
1. Deoxygenated blood flow from the tissues, rich in
carbon dioxide
1

48. Bronchiole
Alveolus
2. Carbon dioxide diffuses out of the blood stream into
the alveoli, and then into the bronchiole
2

49. Bronchiole
Alveolus
3. Oxygen diffuses from the bronchiole into the alveoli
and then into the red blood cells.
3

50. Bronchiole
Alveolus
4. Oxygenated blood now leaves the alveoli and carries
oxygen to the tissues.
4

51. Features of the alveoli:

52. Features of the alveoli:
1. A very large, moist
surface area.

53. Features of the alveoli:
1. A very large, moist
surface area.
2. An excellent capillary
blood supply

54. Features of the alveoli:
1. A very large, moist
surface area.
2. An excellent capillary
blood supply
3. Very thin cell
membrane separating
blood and lung

55. Ventilation
INHALATION = taking air into the lungs
EXHALATION = removing air from the
lungs

56. Ventilation
IN OUT
Nitrogen 79% Nitrogen 79%
Oxygen 21% Oxygen 16%
Carbon dioxide
0.04%
Carbon dioxide
4%

57. Ventilation
BREATHING IN
Rib cage moves
upwards and
outwards.
Diaphragm moves
downwards and
becomes flatter.
Overall effect:
volume of the thorax
increases, pressure
decreases, so air is
drawn IN

58. Ventilation
BREATHING OUT
Rib cage moves
downwards and
inwards.
Diaphragm moves
upwards and becomes
dome shaped.
Overall effect:
volume of the thorax
decreases, pressure
increases, so air is
pushed OUT

59. Content
Lesson 4
f) Respiration
g) Gas
exchange
g) Gas exchange
2.38 understand the role of diffusion in gas exchange
Flowering plants
2.39 understand gas exchange (of carbon dioxide and oxygen) in relation
to respiration and photosynthesis
2.40 understand that respiration continues during the day and night, but
that the net exchange of carbon dioxide and oxygen depends on the
intensity of light
2.41 explain how the structure of the leaf is adapted for gas exchange
2.42 describe the role of stomata in gas exchange
2.43 describe experiments to investigate the effect of light on net gas
exchange from a leaf, using hydrogen-carbonate indicator
Humans
2.44 describe the structure of the thorax, including the ribs, intercostal
muscles, diaphragm, trachea, bronchi, bronchioles, alveoli and pleural
membranes
2.45 understand the role of the intercostal muscles and the diaphragm in
ventilation
2.46 explain how alveoli are adapted for gas exchange by diffusion
between air in the lungs and blood in capillaries
2.47 understand the biological consequences of smoking in relation to the
lungs and the circulatory system, including coronary heart disease
2.48 describe experiments to investigate the effect of exercise on
breathing in humans.

60. Leaf adaptations
Cross section through a leaf
Lower epidermis – note the presence here
of stomata (tiny pores surrounded by
guard cells).
Inter-cellular air
spaces

61. Leaf adaptations
Cross section through a leaf
Lower epidermis – note the presence here
of stomata (tiny pores surrounded by
guard cells).

62. Leaf adaptations
Cross section through a leaf
Oxygen is absorbed and
carbon dioxide is
released direct from cells
to air spaces during
respiration.

63. Gaseous exchange in plants
6CO2 + 6H2O  C6H12O6 + 6O2
C6H12O6 + 6O2  6CO2 + 6H2O

64. Gaseous exchange in plants
6CO2 + 6H2O  C6H12O6 + 6O2
C6H12O6 + 6O2  6CO2 + 6H2O

65. Time of Day
12 mid-day
12 midnight 12 midnight
Oxygen
production
-
+

66. Time of Day
12 mid-day
12 midnight 12 midnight
Oxygen
production
-
+

67. Time of Day
12 mid-day
12 midnight 12 midnight
Oxygen
production
-
+

68. Time of Day
12 mid-day
12 midnight 12 midnight
Oxygen
production
-
+

69. Time of Day
12 mid-day
12 midnight 12 midnight
Oxygen
production
-
+

70. Time of Day
12 mid-day
12 midnight 12 midnight
Oxygen
production
-
+
respiration
photosynthesis

71. Time of Day
12 mid-day
12 midnight 12 midnight
Oxygen
production
-
+
Compensation
point
Compensation
point

72. End of Section 2 Lesson 4
In this lesson we have covered:
Respiration
Gaseous exchange