Limiting Factors Affect The Rate Of Plants Photosynthesis (1)

Group 1

Limiting Factors
affect the Rate
of Plant’s
Photosynthesis


Outline of the Presentation
I.

II.

III.

• Introduce Photosynthesis process of
plants
• Light Intensity
• Temperature
• Concentration of Carbon Dioxide

• Conclusion


I. Introduction
1. Photosynthesis process of plants


Light

Advancing Chemical Sciences


2. Limiting Factors
*The law of limiting factors states that:
At any point in time, one of other factors will be in low
supply and limit the rate of photosynthesis. Thus, the
factor in lowest supply is called the limiting factor.

*Limiting factors that affects the rate of photosynthesis:
Light Intensity

Temperature

CO2 Concentration

*Rate of photosynthesis: describe how much sugar and oxygen a plant
can produce over time.


II. Limiting factors affecting the rate
of plant’s photosynthesis
1. Light Intensity

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*Stoma (khí khổng): is a pore, found in the epidermis (biểu bì) of
leaves that is used to control gas exchange.


Chlorophyll

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*Chlorophyll( chất diệp lục): a green pigment (sắc tố) found in
chloroplasts (lạp lục), present in all green plants.


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*Chloroplast ( lạp lục): tiny factories inside the cells of plants. It takes
the energy from the sunlight and use it to make plant food.


[rate of photosynthesis]
O

From O to A, as light
intensity increases, the
photosynthetic
rate also increase.
Light intensity is a
limiting
A
factor during this stage.

B
From A to B (saturated
point),
eventhough light intensity
increases, rate of

photosynthesis
remains constant. Light
intensity
is no longer a limiting
factor.


2. Temperature

.

250C

* Temperature speeds up all chemical reactions.
* The temperature increases => the enzymes get
more energy and the rate of photosynthesis increases.
* Enzyme: protein that act as catalysts (chất xúc tác) within cells.


.

250C

*250C is the optimal temperature.
*At that temperature, the enzyme is most efficient.


.

250C

*The temperature is higher than 250C => the rate
of photosynthesis falls rapidly.
*The enzymes are denatured.
*Denatured (biến dạng): change the shape


Why are the enzymes
denatured in high
temperature
(over 25 C) ?
0


*Enzymes and denatured process

.

*Substrate (chất nền): In this case, the two substrates for
photosynthesis are carbon dioxide (CO2) and water (H2O).


*Denaturing enzymes

.


.

The enzyme is denatured at 450C.

The rate of photosynthesis stops entirely.


3. Concentration of CO2
0.03-0.04%


0.03-0.04%

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*CO2 diffusion process

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*Diffusion (khuếch tán): the tendency of molecules to spread out in
available space.



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0.03-0.04%

CO2

PR

Certain C02
concentration
=> Photosynthesis stays
constant

PR: photosynthesis rate


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III. Conclusion
- Photosynthesis is the one of the most important
processes which supplies oxygen and gives off carbon
dioxide to our life.
- Photosynthesis process is directly dependent on the
supply

of

temperature,

light

intensity,

and

concentration of carbon dioxide. Limiting any one of
these factors can limit the rate of photosynthesis.

- With knowledge of limiting factors, it is possible to
control the growing conditions for crop plants. This
enables faster growing of plants and the increase of their
quality and yield.