PHOTOSYNTHESIS Practical: Investigating Light & Photosynthesis
an endothermic reaction in which carbon dioxide and and water combine to rate of photosynthesis can be measured using volume / time.
form glucose. requires energy transferred by light from the sun The effect of these limiting factors on the rate of photosynthesis can be investigated in the following ways:
Plants are Light intensity – change the distance of a light source from the plant (light intensity is proportional to
Autotrophs – they can make complex molecules from simple molecules. 1/d2)
Producers - can make their own food, so are the first at the start of all food Carbon dioxide concentration – add different quantities of sodium hydrogen carbonate to the water
chains surrounding the plant, this dissolves to produce CO2.
This equation can also be shown as a balanced chemical equation Temperature (of the solution surrounding the plant) – place the boiling tube containing the submerged
6 CO2 + 6 H20 ---> C6 H12 O6 + 6 O2 products of photosynthesis plant in water baths of different temperatures
Plants use the glucose Results and analysis
they make as a source of Initially, as the distance from the light source decreases, the volume of oxygen produced increases
energy in respiration This is because as the light intensity increases, the rate of photosynthesis increases
They can also use it to At a certain point, light is no longer the limiting factor and so an increase in light intensity (decrease in the
Produce starch for distance) will not result in an increase in photosynthesis
storage In this experiment, care needs to be taken to ensure that the temperature is not affected as the light
To form cellulose to make source moves closer
cell walls evaluation
Produce amino acids C - We are changing the distance of the light source from the pondweed
(used to make proteins) O - The same plant or same species, age/size of plant is used
three main factors that limit the rate of photosynthesis: R - We will repeat the investigation several times to ensure our results are reliable
Temperature Light Intensity and Carbon Dioxide concentration M1 - We will observe the volume of oxygen produced
The number of chloroplasts or the amount of chlorophyll in the chloroplasts M2 - ...after a given time
can also affect the rate of photosynthesis S - We will control the temperature of the room and carbon dioxide concentration
COMMERCAIL USE OF PLANT HORMONES
Temperature B6 - PLANT STRUCUTES AND THIER FUNCTIONS Plant hormones can be extracted / artificially made & used by gardeners
The temperature of the and farmers in agriculture to usefully control plant growth to get larger yields.
environment affects how Auxins : selective weed killers. done by farmers who don’t want smaller yields as a
much kinetic energy all result of competition. cause weed to grow uncontrollably and die without affecting
particles have – so plant. they can take cuttings of the plant and dip the tips in ‘rooting powders’ as
temperature affects the speed they encourage the rapid development of roots
at which carbon dioxide and Ethene : used to control ripening of fruit during storage and transport. delay
water move through a plant ripening of fruits in storage by adding chemicals to stop ethene from being
Light intensity produced.
The more light a plant Positive phototropism Gibberellins used to promote flowering , End seed dormancy - aid seed germination
receives, the faster the rate If light shines on a growing shoot from Increase fruit size (promotes development) and Produce seedless fruit - If
of photosynthesis all directions, auxin is distributed gibberellins are applied to the unpollinated flowers of some plants, the fruit grows
Trend will continue until evenly throughout the shoot and the but no seeds develop within it
light intensity is no longer cells in the shoot grow at the same PLANT HORMONES AND GROWTH
plants grow in response to
the limiting factor as light rate - this is what normally happens Plants need to be able to grow in response to
1. light: leaves can absorb it for
has no affect. with plants growing outside certain stimuli and the directional growth
photosynthesis
∝
light intensity 1 ÷ distance² When light shines on the shoot responses made by plants are known as tropisms
2. gravity: shoots grow upwards
measured using light meter. predominantly from one side, the
Carbon dioxide concentration and roots grow downwards
auxin produced in the shoot tip
more carbon dioxide present, the faster the reaction can occur A response to light is a
concentrates on the shaded side of
trend will continue until CO2 is no longer the limiting factor. phototropism, gravity is a
Chlorophyll (contain chlorophyll which absorbs light energy) the shoot, making the cells on that
geotropism and water is
The more chloroplasts a plant has, the faster the rate of side elongate and grow faster than the
Hydrotropism
photosynthesis. It can be affected by: cells on the sunny side
growth towards the stimulus =
1. Diseases (such as tobacco mosaic virus) This unequal growth on either side of
positive tropism.
2. Lack of nutrients (such as magnesium) the shoot causes the shoot to bend
growth away from the stimulus =
3. Loss of leaves (fewer leaves means fewer chloroplasts) and grow in the direction of the light.
negative tropism
an endothermic reaction in which carbon dioxide and and water combine to rate of photosynthesis can be measured using volume / time.
form glucose. requires energy transferred by light from the sun The effect of these limiting factors on the rate of photosynthesis can be investigated in the following ways:
Plants are Light intensity – change the distance of a light source from the plant (light intensity is proportional to
Autotrophs – they can make complex molecules from simple molecules. 1/d2)
Producers - can make their own food, so are the first at the start of all food Carbon dioxide concentration – add different quantities of sodium hydrogen carbonate to the water
chains surrounding the plant, this dissolves to produce CO2.
This equation can also be shown as a balanced chemical equation Temperature (of the solution surrounding the plant) – place the boiling tube containing the submerged
6 CO2 + 6 H20 ---> C6 H12 O6 + 6 O2 products of photosynthesis plant in water baths of different temperatures
Plants use the glucose Results and analysis
they make as a source of Initially, as the distance from the light source decreases, the volume of oxygen produced increases
energy in respiration This is because as the light intensity increases, the rate of photosynthesis increases
They can also use it to At a certain point, light is no longer the limiting factor and so an increase in light intensity (decrease in the
Produce starch for distance) will not result in an increase in photosynthesis
storage In this experiment, care needs to be taken to ensure that the temperature is not affected as the light
To form cellulose to make source moves closer
cell walls evaluation
Produce amino acids C - We are changing the distance of the light source from the pondweed
(used to make proteins) O - The same plant or same species, age/size of plant is used
three main factors that limit the rate of photosynthesis: R - We will repeat the investigation several times to ensure our results are reliable
Temperature Light Intensity and Carbon Dioxide concentration M1 - We will observe the volume of oxygen produced
The number of chloroplasts or the amount of chlorophyll in the chloroplasts M2 - ...after a given time
can also affect the rate of photosynthesis S - We will control the temperature of the room and carbon dioxide concentration
COMMERCAIL USE OF PLANT HORMONES
Temperature B6 - PLANT STRUCUTES AND THIER FUNCTIONS Plant hormones can be extracted / artificially made & used by gardeners
The temperature of the and farmers in agriculture to usefully control plant growth to get larger yields.
environment affects how Auxins : selective weed killers. done by farmers who don’t want smaller yields as a
much kinetic energy all result of competition. cause weed to grow uncontrollably and die without affecting
particles have – so plant. they can take cuttings of the plant and dip the tips in ‘rooting powders’ as
temperature affects the speed they encourage the rapid development of roots
at which carbon dioxide and Ethene : used to control ripening of fruit during storage and transport. delay
water move through a plant ripening of fruits in storage by adding chemicals to stop ethene from being
Light intensity produced.
The more light a plant Positive phototropism Gibberellins used to promote flowering , End seed dormancy - aid seed germination
receives, the faster the rate If light shines on a growing shoot from Increase fruit size (promotes development) and Produce seedless fruit - If
of photosynthesis all directions, auxin is distributed gibberellins are applied to the unpollinated flowers of some plants, the fruit grows
Trend will continue until evenly throughout the shoot and the but no seeds develop within it
light intensity is no longer cells in the shoot grow at the same PLANT HORMONES AND GROWTH
plants grow in response to
the limiting factor as light rate - this is what normally happens Plants need to be able to grow in response to
1. light: leaves can absorb it for
has no affect. with plants growing outside certain stimuli and the directional growth
photosynthesis
∝
light intensity 1 ÷ distance² When light shines on the shoot responses made by plants are known as tropisms
2. gravity: shoots grow upwards
measured using light meter. predominantly from one side, the
Carbon dioxide concentration and roots grow downwards
auxin produced in the shoot tip
more carbon dioxide present, the faster the reaction can occur A response to light is a
concentrates on the shaded side of
trend will continue until CO2 is no longer the limiting factor. phototropism, gravity is a
Chlorophyll (contain chlorophyll which absorbs light energy) the shoot, making the cells on that
geotropism and water is
The more chloroplasts a plant has, the faster the rate of side elongate and grow faster than the
Hydrotropism
photosynthesis. It can be affected by: cells on the sunny side
growth towards the stimulus =
1. Diseases (such as tobacco mosaic virus) This unequal growth on either side of
positive tropism.
2. Lack of nutrients (such as magnesium) the shoot causes the shoot to bend
growth away from the stimulus =
3. Loss of leaves (fewer leaves means fewer chloroplasts) and grow in the direction of the light.
negative tropism
