PLANT PLANT PROCESSESPROCESSES

PhotosynthesisPhotosynthesis

ImportanceImportance

The “Reaction of Life”: The conversion of The “Reaction of Life”: The conversion of the sun’s energy into a form man and the sun’s energy into a form man and other living creatures can use.other living creatures can use.

““Photo” – lightPhoto” – light ““Synthesis” – to put togetherSynthesis” – to put together

3 Important Processes3 Important Processes

First, it transforms light energy from the First, it transforms light energy from the sun into chemical energy which is sun into chemical energy which is transported and stored in plants.transported and stored in plants.

Second, it “fixes” carbon dioxide into a Second, it “fixes” carbon dioxide into a solid form. solid form. (Component in all organic matter.)(Component in all organic matter.)

Third, produces oxygen as a by-product.Third, produces oxygen as a by-product.

Energy TransformationEnergy Transformation

The Earth receives vast quantities of energy from The Earth receives vast quantities of energy from the sun each day in the form of solar radiation the sun each day in the form of solar radiation (light).(light).

The useful form of radiation energy is called The useful form of radiation energy is called chemical energy.chemical energy.

One energy-yielding chemical which One energy-yielding chemical which photosynthesis produces is sugar (C6-H12-O6). photosynthesis produces is sugar (C6-H12-O6).

Carbon FixationCarbon Fixation

The process of photosynthesis where carbon The process of photosynthesis where carbon is fixed from atmospheric carbon dioxide and is fixed from atmospheric carbon dioxide and converted into carbohydrates by green converted into carbohydrates by green plants.plants.

It has been estimated that 620,000,000,000 tons It has been estimated that 620,000,000,000 tons of carbon is converted annually.of carbon is converted annually.

This is enough to This is enough to fill 97 railroad cars fill 97 railroad cars every every second of every second of every day all year long.day all year long.

Oxygen ProductionOxygen Production

Oxygen is considered a by-product Oxygen is considered a by-product of the photosynthetic process. of the photosynthetic process.

Plants produce enough of it to be Plants produce enough of it to be considered the primary source, considered the primary source, world wide.world wide.

What Is Unique?What Is Unique?

Because of their ability to produce Because of their ability to produce their own energy, plants are self-their own energy, plants are self-sufficient (autotrophic).sufficient (autotrophic).

All other forms of life need All other forms of life need sustenance from other living sustenance from other living creatures (heterotrophic).creatures (heterotrophic).

Examples: animals, fungi, bacteria, viruses, etc.Examples: animals, fungi, bacteria, viruses, etc.

(6)CO2 + (12)H2O (1)C6H12O6 + (6) H2O + (6)O2(6)CO2 + (12)H2O (1)C6H12O6 + (6) H2O + (6)O2

(Carbon Dioxide + Water Sugar + Water + Oxygen)(Carbon Dioxide + Water Sugar + Water + Oxygen)

Also written as:Also written as:

(6)CO2 + (6)H2O (1)C6H12O6 + (6) O2(6)CO2 + (6)H2O (1)C6H12O6 + (6) O2

Requirements of Requirements of PhotosynthesisPhotosynthesis

Living plantLiving plant

Supply of carbon dioxide from Supply of carbon dioxide from atmosphereatmosphere

Water from soil or atmosphereWater from soil or atmosphere

Light, usually from the sunLight, usually from the sun

Products of Products of PhotosynthesisPhotosynthesis

Carbohydrates such as sugars and Carbohydrates such as sugars and starchesstarches

WaterWater

OxygenOxygen

Factors Affecting Factors Affecting PhotosynthesisPhotosynthesis

Light Quality – chlorophyll reacts only to Light Quality – chlorophyll reacts only to certain wavelengths of light.certain wavelengths of light.

Light Intensity – some plants are sun Light Intensity – some plants are sun loving and others prefer shade. The loving and others prefer shade. The general rule, the brighter the light, the general rule, the brighter the light, the more efficient the process.more efficient the process.

Absorption of Light by Absorption of Light by ChlorophyllChlorophyll

wavelengthwavelength

Absorption

violet blue green yellow orange red

Chlorophyll absorbs blue-violet & red Chlorophyll absorbs blue-violet & red light bestlight best

Light Duration – the longer the day, the more Light Duration – the longer the day, the more photosynthesis takes place, and the more the photosynthesis takes place, and the more the plant grows.plant grows.

Carbon Dioxide Concentration – an increase Carbon Dioxide Concentration – an increase causes a greater rate of photosynthesis.causes a greater rate of photosynthesis.

Temperature – an increase in temperature Temperature – an increase in temperature normally increases photosynthesis. normally increases photosynthesis.

Water Availability – plants with water stress will Water Availability – plants with water stress will close their stomata and slow activity.close their stomata and slow activity.

ReviewReview Write the equation for photosynthesis.Write the equation for photosynthesis.

List 3 important processes in plants:List 3 important processes in plants:

What is light duration?What is light duration?

RespirationRespiration

StomStomaa

Guard CellGuard CellCarbon Dioxide (CO2)

Oxygen (O2)

The Respiration ProcessThe Respiration Process

Respiration is necessary in all living cells.Respiration is necessary in all living cells.

It is the controlled expenditure of an It is the controlled expenditure of an organism’s energy reserves to sustain its organism’s energy reserves to sustain its life processes.life processes.

Plants only have photosynthesis during Plants only have photosynthesis during daylight hours in cells with chlorophyll, daylight hours in cells with chlorophyll, but respire 24 hours a day in all cells.but respire 24 hours a day in all cells.

Respiration uses up stored energy and Respiration uses up stored energy and gives off heat.gives off heat.

Releases energy, evolves carbon dioxide, Releases energy, evolves carbon dioxide, and uses up oxygen.and uses up oxygen.

This has the opposite effect of This has the opposite effect of photosynthesis.photosynthesis.

Factors Affecting Factors Affecting RespirationRespiration

Temperature – as it increases, so does Temperature – as it increases, so does the rate of respiration.the rate of respiration.

Oxygen Concentration – lower oxygen Oxygen Concentration – lower oxygen concentrations in the environment will concentrations in the environment will result in a lower respiration rate. result in a lower respiration rate.

Soil Conditions – compacted or water-Soil Conditions – compacted or water-logged soils exclude air, and therefore logged soils exclude air, and therefore oxygen inhibiting respiration.oxygen inhibiting respiration.

Light – since plants grown in low light Light – since plants grown in low light photosynthesize at a reduced rate, the photosynthesize at a reduced rate, the level of available carbohydrates and rate level of available carbohydrates and rate of respiration is reduced.of respiration is reduced.

Respiration Affects AgRespiration Affects Ag

Since respiration is taking place 24 hours Since respiration is taking place 24 hours a day, it is important that the plant be a day, it is important that the plant be able to photosynthesize enough during able to photosynthesize enough during the day to provide for respiration during the day to provide for respiration during the day and night.the day and night.

If not accomplished, no energy will be If not accomplished, no energy will be available for growth and the plant will available for growth and the plant will stagnate or die.stagnate or die.

Most plants grow best when night Most plants grow best when night temperatures are about 9 degrees lower temperatures are about 9 degrees lower than daytime temperatures.than daytime temperatures.

Night temperatures in a greenhouse kept too Night temperatures in a greenhouse kept too warm will cause respiration rates to be high warm will cause respiration rates to be high and stall a crop’s growth.and stall a crop’s growth.

Respiration is closely tied to the degradation Respiration is closely tied to the degradation (the breakdown of the tissues) of harvested (the breakdown of the tissues) of harvested crops. crops.

By slowing respiration rates after harvest, we By slowing respiration rates after harvest, we can improve the quality of goods reaching the can improve the quality of goods reaching the consumer.consumer.

Two Strategies:Two Strategies:RefrigerationRefrigeration

Increasing Atmospheric Increasing Atmospheric Concentration of NitrogenConcentration of Nitrogen

ComparisonComparison

PhotosynthesisPhotosynthesis RespirationRespirationRequires Carbon Dioxide and WaterRequires Carbon Dioxide and Water Requires Oxygen and Carbon Requires Oxygen and Carbon

CompoundsCompounds

Produces Oxygen and CarbohydratesProduces Oxygen and Carbohydrates Produces Carbon Dioxide and WaterProduces Carbon Dioxide and Water

Light Energy Trapped by ChlorophyllLight Energy Trapped by Chlorophyll Energy ReleasedEnergy Released

Takes Place in Light OnlyTakes Place in Light Only Takes Place in Both Light and in Takes Place in Both Light and in DarknessDarkness

Occurs Only in Cells With ChlorophyllOccurs Only in Cells With Chlorophyll All Living Cells RespireAll Living Cells Respire

ReviewReview

Does respiration occur in all living cells?Does respiration occur in all living cells?

Why is respiration inhibited in water-Why is respiration inhibited in water-logged soils?logged soils?

What does refrigeration do for agriculture What does refrigeration do for agriculture crops?crops?

TranspirationTranspiration

Stoma

TranspirationTranspiration

The process by which a plant cools itself The process by which a plant cools itself and releases water.and releases water.

About 90% of all water that enters the plants About 90% of all water that enters the plants from the roots is given off during from the roots is given off during transpiration. transpiration.

The other 10% becomes involved in The other 10% becomes involved in chemical processes or is tied up in the chemical processes or is tied up in the plants structure.plants structure.

The lower surface of the leaf is dotted The lower surface of the leaf is dotted with special pore-like structures called with special pore-like structures called stomatas.stomatas.

Openings occur in the stomata during the Openings occur in the stomata during the daylight hours to permit the exchange and daylight hours to permit the exchange and release of water vapor.release of water vapor.

Stomata close at night or when the plant is Stomata close at night or when the plant is water stressed.water stressed.

TranslocationTranslocation

TranslocationTranslocation

Water enters the plant through the root Water enters the plant through the root system and is transported throughout the system and is transported throughout the plant.plant.

The process is made possible by the The process is made possible by the “solvent of life”, plain water.“solvent of life”, plain water.

Example: Celery Stalk Lab

FunctionsFunctions

Transportation of NutrientsTransportation of Nutrients

Water is moved up through the sieve tubes from Water is moved up through the sieve tubes from the roots through the xylem to the rest of the the roots through the xylem to the rest of the plant.plant.

The water carries nutrients and important The water carries nutrients and important metabolites.metabolites.

Metabolites are the products of the chemical Metabolites are the products of the chemical reactions or “metabolism” of the plant.reactions or “metabolism” of the plant.

Transportation of Photosynthesis Transportation of Photosynthesis ProductsProducts

Water also moves through the phloem sieve Water also moves through the phloem sieve tubes to transport sugar produced by the leaves tubes to transport sugar produced by the leaves during photosynthesis to all parts of the plant.during photosynthesis to all parts of the plant.

Roots have no other means to nourish Roots have no other means to nourish themselves, and would die without translocated themselves, and would die without translocated sugars manufactured in the leaves.sugars manufactured in the leaves.

Physical SupportPhysical Support

Water being translocated adds turgor or stiffens Water being translocated adds turgor or stiffens the cells.the cells.

This pressure helps to provide support to leaves This pressure helps to provide support to leaves and new tissue.and new tissue.

ReviewReview

What does turgor pressure do for plants?What does turgor pressure do for plants?

Where does water enter a plant from?Where does water enter a plant from?

What is the “solvent of life”?What is the “solvent of life”?