Azim Uddin 13M Unit 6A: Investigative project Submission date: 19/12/2019
Assignment Title: Project research
Introduction:
The project proposal will investigate photosynthesis. The process of photosynthesis is important for
all living things. We require plants to photosynthesise [6C0 2 + 6H2O –> C6H12O6 + 6O2] in order to
produce oxygen and remove carbon dioxide (CO 2) from the atmosphere as plants absorb CO 2. As we
face an ordeal with climate change; more CO 2 is being emitted through production of fossil fuels
which harms the environment. United Nation states that ‘global net human-caused emissions of
carbon dioxide (CO2) would need to fall by about 45 percent from 2010 levels by 2030, reaching ‘net
zero’ around 2050.’ (UN, 2019). This means that any remaining emissions would need to be balanced
by removing CO2 from the air. As plants absorb CO 2; helping the environment, the purpose of certain
light growing plants much faster will help improve climate change, enabling a better, sustained
future. This is because growing more plants will fix climate change as it will decrease CO 2 emissions.
In addition, plants provide us with fruits and a place for animals to live. Without plants our global
food chain system would break down and endanger the cycle.
In addition, this proposal will improve farming thus, benefitting farmers to take advantage of plant
growth. This will allow them to increase their yield crops and lead to more profit. The investigation
will provide information to greenhouses to improve their understanding of how different light
colours are effective in various ways leading to improvements in their greenhouse. Less economically
developed countries (LEDC’s) will benefit from this investigation to sustain and protect their
environment. Choi et al., 2015 stated plants under light emitting diode (LED) with colours such as
blue yielded much higher production of fruits then those with no light. (Choi et al, 2015). However,
LEDs have an initial price that is expensive and if they are overheated during winter as they depend
on the environments temperature it will lead to the device failing leading to repurchase and more
costs. (LEDs Magazine, 2019). Yet, the article by Choi et al., 2015 suggested that light does effect
plants and it encourages them to grow. Therefore, this will benefit those who are interested in plant
growth.
Lin et al., 2013 stated specifically that a combination of lights is the most effective for plant growth.
White light (sunlight) drives plant growth. Plants grown under red, blue and white LED were proven
to have better growth, nutrition, development, appearance and edible quality. (Lin et al., 2013). The
strength of his investigation was he compared plant growth; where red and blue light was combined
and red, blue and white light was mixed. This gives an insight on the effect of combined lights when
combined with white light, implying that white light has the most effect on plant growth. In
comparison, to Kim et al., 2006 investigation; he suggested that a higher amount of green photons
resulted in reduced plant growth. However, he also stated that when green light was combined with
red and blue light; they all enhanced plant growth. (Kim et al., 2006). This shows us that green light
is the least effective for plant growth and is important and relevant when preparing for the proposed
investigation as it provides information about the least effective colour for plant growth. However,
both scientists ascertained that when lights are combined together with their short and long
wavelengths, that they have the most effect on plant growth. This is because plants will absorb any
energy from light. This will be essential when partaking the planned investigation as it insights how
to prepare. Both studies showed us that plants react to the spectrum of lights, most specifically
when combined.
Background research:
There are two stages of photosynthesis: Light dependent and light independent reactions.
Stage 1 - Light dependent reaction:
1
, Azim Uddin 13M Unit 6A: Investigative project Submission date: 19/12/2019
Assignment Title: Project research
Firstly, the light dependent reaction occurs in the thylakoids of the grana in chloroplasts. Light
energy results in the excitation of electrons in the chlorophyll placed in the thylakoid membrane.
These electrons are then passed along a series of electron acceptors (photoionisation) in the
thylakoid membranes, collectively known as the electron carrier system. Energy from excited
electrons funds the production of ATP (adenosine triphosphate). 4 protons make one ATP molecule.
Electron loss from chlorophyll causes the splitting of water (photolysis). [H 2O –> 2H+ + 2e- + ½ O2].
Light splits water into protons (H+ ions), electrons and oxygen (waste). The protons are pumped
across the membrane using the ATP. The final electron acceptor forms NADP +. Oxygen is produced,
water to re-used, and electrons stream back to replace those lost in the chlorophyll. Hydrogen ions
(H+) from photolysis, together with NADP + forms NADPH2. (Hocking, Sochacki and Winterbottom,
2015). (A Level Biology, 2019).
Stage 2 - Light independent reaction:
There are two useful substances that are produced by the light-dependent stage, ATP and NADPH 2.
These are needed to drive the light-independent stage. They react with glycerate 3-phosphate (GP)
to produce a triose sugar – triose phosphate. Triose phosphate is used either to produce a 6C sugar
or to form ribulose bisphosphate (RuBP). The conversion of triose phosphate (3C) to RuBP begins
Calvin’s cycle and utilises ATP, which supplies the energy required. A RuBP molecule (5C) together
with a carbon dioxide molecule (1C) forms two GP molecules (2 3C) to complete Calvin’s cycle. The
GP is then available to react with ATP and NADPH2 to synthesise more triose sugar or RuBP.
(Hocking, Sochacki and Winterbottom, 2015). (A Level Biology, 2019).
Furthermore, plants use photosynthesis to generate food and energy for growth and cellular
respiration. Photosynthesis uses sunlight to grow. Light is absorbed by a pigment called chlorophyll
embedded in the thylakoids membrane. This occurs during the light dependant stage. Whilst
photosynthesis occurs, chlorophyll absorbs blue and red light to grow and reflects green light. The
sun allows plants to produce its own organic molecules such as glucose. Plants absorb water,
sunlight and carbon dioxide to produce their own nutrients. Where the synthesis is occurring it is the
light independent stage. As plants absorb the food it leads to plant growth. (Hocking, Sochacki and
Winterbottom, 2015).
Figure 1:
Figure 1 shows
the stages of
photosynthesis.
(Hocking,
Sochacki and
Winterbottom,
2015).
2
, Azim Uddin 13M Unit 6A: Investigative project Submission date: 19/12/2019
Assignment Title: Project research
Factors that affect plant growth:
While investigating photosynthesis the investigation will measure specific factors that affect plant
growth such as the light spectrum, apical dominance and lateral bud growth.
The light spectrum: Figure 2:
The electromagnetic spectrum is the range of all possible
frequencies of electromagnetic radiation. The sun emits
maximum power in the visible region of the spectrum which is
white light at 400 – 700 nm (nanometre). Colours are of
different wavelengths of white light and range from red (700
nm) to violet (400 nm). The colours of the visible spectrum are
from longest to shortest wavelength: Red, orange, yellow,
green, blue, indigo, and purple. (Labman.phys.utk.edu, 2019).
Figure 2 shows visible light spectrum. (Maker Portal, 2019).
Apical dominance and Lateral bud growth:
Apical dominance controls the shoot tip over axillary buds. Growing shoot tips produce a hormone
called auxin which moves down the stem and inhibits the growth of axillary buds located below the
stem. Auxins cannot enter buds thus; they act as a secondary mechanism to promote bud growth
and grow into new branches. This is also known as lateral bud growth; as when the apical dominance
is lifted off the plant, elongation and lateral growth is promoted, and the buds grow into branches.
Auxins cause cells in the shoot of plant to grow faster. The shoot then grows towards light. Using the
spectrum light colours and placing them above the plants, it will trigger the hormone auxin and the
plant tip will grow much faster towards the light. (Barbier, 2017).
Seed germination:
Germination is the process of seeds developing into new plants. When the seed is moved around by
wind it sets at a new location and is covered with soil. It can then begin the process of germination.
Environmental factors can trigger the seed to grow and that is what we usually wait for. The seed
relies on water availability and temperature. Once the seed has been watered it begins a process
called imbibition. This is when enzymes within the seed start off the growth of the seed. As the seed
grows and reaches the surface it will start to take energy from the sun to continue to nourish and
grow. The seed will use natural light source from the sun which is also known as white light to grow.
The plant will grow towards the light; a process called photomorphogenesis. Seed germination links
to light as red light promotes seed germination whereas, blue light inhibits it. (Study.com, 2019).
Seed formation:
Plants reproduce the same way using their eggs and sperm. A male plant will release its pollen to
fertilize a female plants ovary. The ovary fertilizes and develops into seeds. As the seed is being
made carbohydrates and proteins are being stored inside of it. This will become food for plants to
develop into leaves. Light will increase plant growth as seeds require sunlight (white light) to grow.
This will allow the seed to increase carbohydrate and protein levels. The seed grows a protective
layer that is hard to protect them against the environment. The seed can then be used to grow more
plants in different areas that is moved by the wind. (Study.com, 2019).
3
, Azim Uddin 13M Unit 6A: Investigative project Submission date: 19/12/2019
Assignment Title: Project research
Method evaluations:
Firstly, Chen et al., 2004 cited by Bayat et al., 2018 stated light is the original energy source for plant
photosynthesis and growth. Many of plants physiological process is triggered by light. Spectral
composition (wavelengths), intensity and duration of light and the direction can influence the
development and growth of plants. This is relevant to the investigation project chosen where it
focuses on the growth of plants in relation to light. Rose plants were placed inside of 4 chambers
under the same climatic conditions; with temperature remaining constant and period of time – 12
hours light and 12 hours dark. The plants were under 4 light spectra, white, blue, red and 70% red
and 30% blue mixed for 3 weeks. Four fixed LED panels placed around the plant inside the chamber
and images were recorded to measure the height of plants. The results showed that plants grown
under monochromatic (containing one light) performed well, however were highly sensitive to high
light intensity than the white light or the combined light. Growing plants under monochromatic light
reduces the plants ability to cope with high light stress. (Bayat et al., 2018). This is relevant to the
investigation as white light is considered the most effective as well as, combining red and blue light
together. Whereas, Alam et al., 2007 investigated the effect of light qualities on dry matter
production, crop growth and chlorophyll content of onion. The method they used were red and blue
filter papers placed 30cm above the tip of the crops for 30 days. The experiment was conducted in
Bangladesh, geographically 18m above sea level. The results presented the opposite to the
investigation hypothesis. Red filter light had the most significant growth on these crops and followed
by blue light, they enhanced crop growth rate together. (Alam et al, 2007). There was a significant
pattern throughout researchers work where combined light has had the most effect on plant
growth. Moreover, it relates to the hypothesis within the investigation proposal as it will test for
similar trends and pattern in regard to plant growth.
Figure 3:
Figure 3 shows Bayat et al., 2018
investigation of plant growth
under different spectrum of light.
(Bayat et al, 2018).
One strength of using Bayet et al., 2018 method is that they tested one colour separately and
multiple colours together to measure the growth of the plant. They kept the conditions of the
environment the same including temperature and the time period. One variable that changed was
the plant under blue and red light only as it was then exposed to high light intensity. The test was
analysed over 3 weeks which meant that the results will more likely to be accurate and reliable to
use for an investigation. In relation to the proposed project, a similar time frame will be put in place
to analyse growth of plants to gain reliable and relevant results for third parties to use. Another
4
Assignment Title: Project research
Introduction:
The project proposal will investigate photosynthesis. The process of photosynthesis is important for
all living things. We require plants to photosynthesise [6C0 2 + 6H2O –> C6H12O6 + 6O2] in order to
produce oxygen and remove carbon dioxide (CO 2) from the atmosphere as plants absorb CO 2. As we
face an ordeal with climate change; more CO 2 is being emitted through production of fossil fuels
which harms the environment. United Nation states that ‘global net human-caused emissions of
carbon dioxide (CO2) would need to fall by about 45 percent from 2010 levels by 2030, reaching ‘net
zero’ around 2050.’ (UN, 2019). This means that any remaining emissions would need to be balanced
by removing CO2 from the air. As plants absorb CO 2; helping the environment, the purpose of certain
light growing plants much faster will help improve climate change, enabling a better, sustained
future. This is because growing more plants will fix climate change as it will decrease CO 2 emissions.
In addition, plants provide us with fruits and a place for animals to live. Without plants our global
food chain system would break down and endanger the cycle.
In addition, this proposal will improve farming thus, benefitting farmers to take advantage of plant
growth. This will allow them to increase their yield crops and lead to more profit. The investigation
will provide information to greenhouses to improve their understanding of how different light
colours are effective in various ways leading to improvements in their greenhouse. Less economically
developed countries (LEDC’s) will benefit from this investigation to sustain and protect their
environment. Choi et al., 2015 stated plants under light emitting diode (LED) with colours such as
blue yielded much higher production of fruits then those with no light. (Choi et al, 2015). However,
LEDs have an initial price that is expensive and if they are overheated during winter as they depend
on the environments temperature it will lead to the device failing leading to repurchase and more
costs. (LEDs Magazine, 2019). Yet, the article by Choi et al., 2015 suggested that light does effect
plants and it encourages them to grow. Therefore, this will benefit those who are interested in plant
growth.
Lin et al., 2013 stated specifically that a combination of lights is the most effective for plant growth.
White light (sunlight) drives plant growth. Plants grown under red, blue and white LED were proven
to have better growth, nutrition, development, appearance and edible quality. (Lin et al., 2013). The
strength of his investigation was he compared plant growth; where red and blue light was combined
and red, blue and white light was mixed. This gives an insight on the effect of combined lights when
combined with white light, implying that white light has the most effect on plant growth. In
comparison, to Kim et al., 2006 investigation; he suggested that a higher amount of green photons
resulted in reduced plant growth. However, he also stated that when green light was combined with
red and blue light; they all enhanced plant growth. (Kim et al., 2006). This shows us that green light
is the least effective for plant growth and is important and relevant when preparing for the proposed
investigation as it provides information about the least effective colour for plant growth. However,
both scientists ascertained that when lights are combined together with their short and long
wavelengths, that they have the most effect on plant growth. This is because plants will absorb any
energy from light. This will be essential when partaking the planned investigation as it insights how
to prepare. Both studies showed us that plants react to the spectrum of lights, most specifically
when combined.
Background research:
There are two stages of photosynthesis: Light dependent and light independent reactions.
Stage 1 - Light dependent reaction:
1
, Azim Uddin 13M Unit 6A: Investigative project Submission date: 19/12/2019
Assignment Title: Project research
Firstly, the light dependent reaction occurs in the thylakoids of the grana in chloroplasts. Light
energy results in the excitation of electrons in the chlorophyll placed in the thylakoid membrane.
These electrons are then passed along a series of electron acceptors (photoionisation) in the
thylakoid membranes, collectively known as the electron carrier system. Energy from excited
electrons funds the production of ATP (adenosine triphosphate). 4 protons make one ATP molecule.
Electron loss from chlorophyll causes the splitting of water (photolysis). [H 2O –> 2H+ + 2e- + ½ O2].
Light splits water into protons (H+ ions), electrons and oxygen (waste). The protons are pumped
across the membrane using the ATP. The final electron acceptor forms NADP +. Oxygen is produced,
water to re-used, and electrons stream back to replace those lost in the chlorophyll. Hydrogen ions
(H+) from photolysis, together with NADP + forms NADPH2. (Hocking, Sochacki and Winterbottom,
2015). (A Level Biology, 2019).
Stage 2 - Light independent reaction:
There are two useful substances that are produced by the light-dependent stage, ATP and NADPH 2.
These are needed to drive the light-independent stage. They react with glycerate 3-phosphate (GP)
to produce a triose sugar – triose phosphate. Triose phosphate is used either to produce a 6C sugar
or to form ribulose bisphosphate (RuBP). The conversion of triose phosphate (3C) to RuBP begins
Calvin’s cycle and utilises ATP, which supplies the energy required. A RuBP molecule (5C) together
with a carbon dioxide molecule (1C) forms two GP molecules (2 3C) to complete Calvin’s cycle. The
GP is then available to react with ATP and NADPH2 to synthesise more triose sugar or RuBP.
(Hocking, Sochacki and Winterbottom, 2015). (A Level Biology, 2019).
Furthermore, plants use photosynthesis to generate food and energy for growth and cellular
respiration. Photosynthesis uses sunlight to grow. Light is absorbed by a pigment called chlorophyll
embedded in the thylakoids membrane. This occurs during the light dependant stage. Whilst
photosynthesis occurs, chlorophyll absorbs blue and red light to grow and reflects green light. The
sun allows plants to produce its own organic molecules such as glucose. Plants absorb water,
sunlight and carbon dioxide to produce their own nutrients. Where the synthesis is occurring it is the
light independent stage. As plants absorb the food it leads to plant growth. (Hocking, Sochacki and
Winterbottom, 2015).
Figure 1:
Figure 1 shows
the stages of
photosynthesis.
(Hocking,
Sochacki and
Winterbottom,
2015).
2
, Azim Uddin 13M Unit 6A: Investigative project Submission date: 19/12/2019
Assignment Title: Project research
Factors that affect plant growth:
While investigating photosynthesis the investigation will measure specific factors that affect plant
growth such as the light spectrum, apical dominance and lateral bud growth.
The light spectrum: Figure 2:
The electromagnetic spectrum is the range of all possible
frequencies of electromagnetic radiation. The sun emits
maximum power in the visible region of the spectrum which is
white light at 400 – 700 nm (nanometre). Colours are of
different wavelengths of white light and range from red (700
nm) to violet (400 nm). The colours of the visible spectrum are
from longest to shortest wavelength: Red, orange, yellow,
green, blue, indigo, and purple. (Labman.phys.utk.edu, 2019).
Figure 2 shows visible light spectrum. (Maker Portal, 2019).
Apical dominance and Lateral bud growth:
Apical dominance controls the shoot tip over axillary buds. Growing shoot tips produce a hormone
called auxin which moves down the stem and inhibits the growth of axillary buds located below the
stem. Auxins cannot enter buds thus; they act as a secondary mechanism to promote bud growth
and grow into new branches. This is also known as lateral bud growth; as when the apical dominance
is lifted off the plant, elongation and lateral growth is promoted, and the buds grow into branches.
Auxins cause cells in the shoot of plant to grow faster. The shoot then grows towards light. Using the
spectrum light colours and placing them above the plants, it will trigger the hormone auxin and the
plant tip will grow much faster towards the light. (Barbier, 2017).
Seed germination:
Germination is the process of seeds developing into new plants. When the seed is moved around by
wind it sets at a new location and is covered with soil. It can then begin the process of germination.
Environmental factors can trigger the seed to grow and that is what we usually wait for. The seed
relies on water availability and temperature. Once the seed has been watered it begins a process
called imbibition. This is when enzymes within the seed start off the growth of the seed. As the seed
grows and reaches the surface it will start to take energy from the sun to continue to nourish and
grow. The seed will use natural light source from the sun which is also known as white light to grow.
The plant will grow towards the light; a process called photomorphogenesis. Seed germination links
to light as red light promotes seed germination whereas, blue light inhibits it. (Study.com, 2019).
Seed formation:
Plants reproduce the same way using their eggs and sperm. A male plant will release its pollen to
fertilize a female plants ovary. The ovary fertilizes and develops into seeds. As the seed is being
made carbohydrates and proteins are being stored inside of it. This will become food for plants to
develop into leaves. Light will increase plant growth as seeds require sunlight (white light) to grow.
This will allow the seed to increase carbohydrate and protein levels. The seed grows a protective
layer that is hard to protect them against the environment. The seed can then be used to grow more
plants in different areas that is moved by the wind. (Study.com, 2019).
3
, Azim Uddin 13M Unit 6A: Investigative project Submission date: 19/12/2019
Assignment Title: Project research
Method evaluations:
Firstly, Chen et al., 2004 cited by Bayat et al., 2018 stated light is the original energy source for plant
photosynthesis and growth. Many of plants physiological process is triggered by light. Spectral
composition (wavelengths), intensity and duration of light and the direction can influence the
development and growth of plants. This is relevant to the investigation project chosen where it
focuses on the growth of plants in relation to light. Rose plants were placed inside of 4 chambers
under the same climatic conditions; with temperature remaining constant and period of time – 12
hours light and 12 hours dark. The plants were under 4 light spectra, white, blue, red and 70% red
and 30% blue mixed for 3 weeks. Four fixed LED panels placed around the plant inside the chamber
and images were recorded to measure the height of plants. The results showed that plants grown
under monochromatic (containing one light) performed well, however were highly sensitive to high
light intensity than the white light or the combined light. Growing plants under monochromatic light
reduces the plants ability to cope with high light stress. (Bayat et al., 2018). This is relevant to the
investigation as white light is considered the most effective as well as, combining red and blue light
together. Whereas, Alam et al., 2007 investigated the effect of light qualities on dry matter
production, crop growth and chlorophyll content of onion. The method they used were red and blue
filter papers placed 30cm above the tip of the crops for 30 days. The experiment was conducted in
Bangladesh, geographically 18m above sea level. The results presented the opposite to the
investigation hypothesis. Red filter light had the most significant growth on these crops and followed
by blue light, they enhanced crop growth rate together. (Alam et al, 2007). There was a significant
pattern throughout researchers work where combined light has had the most effect on plant
growth. Moreover, it relates to the hypothesis within the investigation proposal as it will test for
similar trends and pattern in regard to plant growth.
Figure 3:
Figure 3 shows Bayat et al., 2018
investigation of plant growth
under different spectrum of light.
(Bayat et al, 2018).
One strength of using Bayet et al., 2018 method is that they tested one colour separately and
multiple colours together to measure the growth of the plant. They kept the conditions of the
environment the same including temperature and the time period. One variable that changed was
the plant under blue and red light only as it was then exposed to high light intensity. The test was
analysed over 3 weeks which meant that the results will more likely to be accurate and reliable to
use for an investigation. In relation to the proposed project, a similar time frame will be put in place
to analyse growth of plants to gain reliable and relevant results for third parties to use. Another
4
