Transcript Unit C 4-5 Determining the Importance of Photosynthesis and

LESSON 5
Determining the
Importance of
Photosynthesis and
Respiration
NEXT GENERATION SCIENCE/COMMON CORE STANDARDS ADDRESSED!
 MS‐LS1‐6. Construct a scientific explanation based on evidence for the role of
photosynthesis in the cycling of matter and flow of energy into and out of organisms.
[Clarification Statement: Emphasis is on tracing movement of matter and flow of energy.]
[Assessment Boundary: Assessment does not include the biochemical mechanisms of
photosynthesis.]
 MS‐LS1‐7. Develop a model to describe how food is rearranged through chemical reactions
forming new molecules that support growth and/or release energy as this matter moves
through an organism. [Clarification Statement: Emphasis is on describing that molecules are
broken apart and put back together and that in this process, energy is released.]
[Assessment Boundary: Assessment does not include details of the chemical reactions for
photosynthesis or respiration.]
 WHST.6‐8.2 Write informative/explanatory texts to examine a topic and convey ideas,
concepts, and information through the selection, organization, and analysis of relevant
content. (MS-LS1-6)
AGRICULTURE, FOOD AND NATURAL
RESOURCE STANDARDS ADDRESSED!
 PS.02.02. Apply knowledge of plant anatomy and the functions of plant
structures to activities associated with plant systems.
 Sample Measurement: The following sample measurement strands are
provided to guide the development of measurable activities (at different
levels of proficiency) to assess students’ attainment of knowledge and
skills related to the above performance indicator. The topics
represented by each strand are not all-encompassing.
 PS.02.02.01.a. Identify structures in a typical plant cell and summarize the function of
plant cell organelles.
STUDENT LEARNING OBJECTIVES
Explain photosynthesis and its importance.
Write the chemical equation for photosynthesis and
explain it.
Explain how light and dark reactions differ.
Define respiration and explain why it is important.
List four factors that affect the rate of respiration.
Explain the importance of transpiration to plants.
INTEREST APPROACH
(With the lights off in the classroom)
Could you survive and continue to make
energy if you were kept in the dark?
What effects would complete darkness have
on other mammals?
What effects would complete darkness have
on plants?
TERMS
Calvin cycle
Chlorophyll
Dark reactions
Glucose
Light reactions
Mitochondria
Photosynthesis
Respiration
Stomata
Transpiration
WHAT IS PHOTOSYNTHESIS?
WHAT IS PHOTOSYNTHESIS?
Photosynthesis is the manufacture of food
by plant cells.
Sugar is the major product of
photosynthesis and provides energy for
the plant.
Two phases of the photosynthesis process:
Energy gathering
Sugar making
2 PHASES OF PHOTOSYNTHESIS
Energy gathering: plant leaves soak up
sunlight.
Sugar making: Plants convert energy from
sunlight into stored chemical energy.
Chemical energy rearranges carbon dioxide
in the plant in the presence of chlorophyll
to form sugar.
Glucose, a simple sugar, is formed.
PHOTOSYNTHESIS
Photosynthesis is the most important
reaction on earth.
All life forms are dependent on the
reaction.
Occurs in the chloroplasts
CO2 + light + chlorophyll + H2O
C6H12O6 (glucose) + H2O + O2
NECESSARY FOR PHOTOSYNTHESIS TO
OCCUR
Chlorophyll - green colored substance in plants.
Light - leaves absorb necessary energy from the suns
rays or artificial light.
Carbon Dioxide - enters the plant through structures
called stomata in the leaves.
Carbon dioxide is split during photosynthesis.
Water - is also split during photosynthesis.
WHAT DOES THE CHEMICAL EQUATION
FOR PHOTOSYNTHESIS MEAN?
Photosynthesis is a series of chemical
reactions that yields the following
products:
Carbohydrates in the form of sugars and
starches.
Water.
Oxygen.
PHOTOSYNTHESIS EQUATION
Light + 6CO2 + 6H20
C6H12O6 + 6O2
LIGHT AND DARK REACTIONS
Photosynthesis is a series of
complex reactions that have been
divided into two major phases.
Light reactions
Dark reactions.
LIGHT REACTIONS
LIGHT DEPENDENT REACTIONS
Light allows energy to be released in the
form of ATP which can be used by the plant
in the splitting of water and the release of
oxygen.
The pigments in chloroplasts absorb light
energy to form NADPH and ATP to be
used in the breakdown of CO2 in the dark
reactions.
DARK REACTION
LIGHT INDEPENDENT REACTIONS
A chemical known as RuBP (rubilose
biphosphate) absorbs carbon.
Carbon dioxide and RuBP join together
and go through a process called the Calvin
cycle.
WHAT IS THE CALVIN CYCLE?
CALVIN CYCLE
The Calvin cycle reduces carbon dioxide
to manufacture carbohydrates.
The NADPH and ATP synthesis from the
light reactions provide the energy needed
to power the Calvin cycle.
One molecule of glucose is formed as a
result of the Calvin cycle
RESPIRATION
The process by which an organism
provides its cells with oxygen so
energy can be released from digested
food.
RESPIRATION
Takes place in all living cells at all
times.
Takes place in the mitochondria of
all cells.
Mitochondria are energy
processing factories for plants.
“power plant of the cell”
PHOTOSYNTHESIS VS. RESPIRATION
Respiration yields the opposite results as
photosynthesis.
The process of photosynthesis absorbs
energy, consumes carbon dioxide and
releases oxygen.
Respiration uses energy, consumes oxygen
and releases carbon dioxide
FACTORS THAT AFFECT THE RATE OF
RESPIRATION
Temperature
Oxygen
Soil conditions
Light
TEMPERATURE
There is a direct relationship
between respiration and temperature
As the temperature increases so
does the rate of respiration.
OXYGEN
Oxygen is required for respiration to
take place.
As oxygen levels decrease so does
the rate of respiration.
SOIL CONDITIONS
Soil containing large quantities of
water cause the rate of respiration to
decrease because of the lack of
oxygen.
LIGHT
The amount of energy produced by
photosynthesis in low light conditions
is reduced.
Therefore, the amount of energy
available to conduct respiration is
lower.
TRANSPIRATION
Transpiration in plants is the loss of water
by evaporation through structures called
stomata.
Stomata are pores or openings in the plant
that allow for the exchange of water and
other substances.
Transpiration in plants is similar to
perspiration in humans.
WATER MOVEMENT IN PLANTS
Water molecules and transpiration
together form a force that is essential for
water movement through plants.
As water evaporates through the stomata
of plant, it creates a pull that aids in the
absorption of water by the roots.
(An analogy of using a straw to drink will help
students to visualize this process.)
HYDROLOGIC CYCLE
Transpiration is a vital link in the
hydrologic cycle.
Ninety-nine percent of all water taken
in by the plant is lost to transpiration.
Therefore, transpiration contributes
significantly to the generation of rainfall.
FACTORS THAT AFFECT THE RATE OF
TRANSPIRATION
Wind Speed
Temperature
Humidity
Drought
WIND SPEED
There is direct relationship between
wind speed and transpiration.
Higher wind speed creates higher
transpiration rates
TEMPERATURE
As temperature increases so does
the rate of transpiration because the
plant uses transpiration as a
mechanism to cool itself.
Once again there is a direct
relationship between temperature
and transpiration.
HUMIDITY
Humidity influences the rate of
transpiration because if the air is
already saturated with water vapor,
there will be a decrease in the rate of
evaporation.
DROUGHT
If the plant is experiencing drought
conditions it will close the stomata to
prevent needed water from escaping.
When the plants stomata are closed
transpiration does not take place.
REVIEW / SUMMARY
Why is photosynthesis important to
plant life?
What is the equation for
photosynthesis?
How do light and dark reactions
differ?
REVIEW / SUMMARY
What is respiration and why is it
important?
What factors affect respiration?
What is transpiration and why is it
important?
THE END