Arisha Zaman SLBio2 Mrs. Saima 13th March 2021
Photosynthesis Lab
(light exposure v/s plant growth)
Dactylis Glomerata, commonly known as cat-grass is a specific species of grass that naturally grows around Europe, Asia, and Northern Africa. (“Cocksfoot (Dactylis Glomerata) | Feedipedia”)It prefers cool temperatures and grows best in partial shade outdoors, or indirect sunlight if grown indoors. Cat grass grows upright for about 4 inches before they slowly start to wilt and die in a few weeks unless trimmed, the seeds also have the ability to regrow the grass multiple times.(“Growing Cat Grass for Your Feline - Is It Safe?”)Cat grass is found in many different varieties such as
wheatgrass, oat grass, barley grass, ryegrass, and flax; often, a mixture of these varieties is sold in the market.(“Growing Cat Grass for Your Feline - Is It Safe?”)Since this grass has the ability to stay fresh and regrow for a long time and is a long-rooted plant, they are often beneficial in terms of
rehabilitating lands with issues such as soil erosion.(“Cocksfoot (Dactylis Glomerata) | Feedipedia”)The reason why it is commonly referred to as cat grass is that it is highly beneficial for domestic cats. Cat parents grow this plant indoors from a windowsill for their cats to consume as it provides felines with essential nutrients, helps regulate furball digestion, and also distracts them from chewing on other houseplants.(“Growing Cat Grass for Your Feline - Is It Safe?”)
Generally, there are many natural factors that affect a plants’ growth. Every plant is different, cat grass specifically requires partial sun or only 8 hours of sun per day since excessive sunlight can burn the grass off and no sun at all will hinder the photosynthesis process, not allowing the grass to grow.(“The Top 18 Solutions to Stop Your Cat Grass from Dying - Archie Cat”)Light quality is also very important, the sun supplies wavelengths of red, orange, blue, indigo, green, violet, and yellow. Cat grass absorbs all these lights except for green, which is why they appear green to human eyes. It has been proven that blue light encourages leaf growth and red light encourages flowering. Red and blue combined, are essential for plant growth and specifically very useful for the germination process, the reason why the combination of these two lights is found on grow lights. Cat grass prefers 60-80 degrees F or a room temperature (25 degrees Celsius) since when the temperature is too low, the enzyme activity decreases and hinders nutrition distribution throughout the plant; and when the temperature is too high, it can result in depletion or extreme water loss. Since cat-grass is not subject to root-rot, they will not die off too much water, but they will die if there is not enough water. Even though humidity is a huge factor for most plants, cat grass seems to adapt to different sorts of
humidity levels perfectly but may droop slightly if it's extremely humid. The plant prefers any sort of
soil that holds moisture. Sufficient carbon dioxide is also essential for the grass to produce food, which is why it should be grown in a well-ventilated area.(Extension Web Support)
In order for any sort of plant to survive, it is essential that they create food for energy. Most plants go through a process called photosynthesis in order to convert light energy into chemical energy. The chlorophyll is a part of plants that is responsible for pigmentation. For grass, the
chlorophyll absorbs two different wavelengths of light which are red and blue, but we see the grass as green because that is the wavelength that the plant reflects, and doesn’t absorb.(“How Grass Grows | Why Is It Green? - Lawn Solutions Australia”)Plants absorb the energy from light and use that to go through a process called transpiration. During this, using the energy from the sun, the plant sucks up water from the soil through its roots, known as the capillary action.(“How Do Plants Suck up Water?”) Then, through the stomata present on the leaves/ blades of the plant, it takes in carbon dioxide. Then, inside the plant cells, the water loses electrons due to oxidation, and carbon dioxide gains electrons because of reduction.(National Geographic Society)At this stage, the water is transformed into the by-product: oxygen, which is then released into the atmosphere through the stomatal pores for living beings to breathe in, this process is known as photolysis. The carbon dioxide has been transformed into glucose, which is food for the plant.(“How Grass Grows | Why Is It Green? - Lawn Solutions Australia”)This entire process is essential to life on earth as without it, humans would not have oxygen to breathe, and plants would not have food to survive in order to produce the oxygen for living beings. However, it is essential for most plants to get about 12 hours of shade/ darkness every day, because plants respire at night, which is very important as during respiration, plants take in oxygen, and combine it with the glucose that it created throughout the day during photosynthesis, and then use it as an energy source, while releasing carbon dioxide to the atmosphere. (“Basics of Plant Respiration |
PRO-MIX”) (“Basics of Plant Respiration | PRO-MIX”)
Photosynthesis has two steps, The first step is known as the light-dependent reaction, it takes place in the thylakoid membrane of the chlorophyll, and it is responsible for storing energy from the heat of the sun/ light source and form chemical energies in the forms of ATP (adenosine triphosphate) and NADPH, which is needed for the second step of photosynthesis.(Bartee et al.)And the second step is known as the light-independent reaction or Calvin cycle, takes place in the chloroplast where the plants capture carbon and transform it into sugar.(Mary Ann Clark et al.)
Research Question:How does light exposure impact the growth (height-wise) of the plant (Dactylis Glomerata)?
Null Hypothesis:The difference in hours of light exposure that the plant receives does not affect the rate of photosynthesis or plant growth.
Hypothesis:It is predicted that as the hours of light exposure for the plant increase, the rate of plant growth will also increase.
Scientific Reasoning:This prediction has been made because it is impossible for plants to
photosynthesize without a light source. Even if the plant has a sufficient source of water and a lot of carbon dioxide in the atmosphere, without the energy from light, it can not put the water and carbon dioxide to any use. As the plant is exposed to more hours of light per day, it photosynthesizes more, which helps it create more food for itself and helps it grow faster.(“What Kind of Grass Will Grow without Sun?”)
Variables Table
Variables The likely impact upon the investigation How the variable will be changed/
measured/ controlled Independent
Grow Light Exposure (blue and red spectrum,
60 watts)
Light is a basic necessity for most plants because plants use light, carbon dioxide, and water to conduct a process called photosynthesis where the plants generate glucose for energy and release the oxygen from the water in the process. To convert the water into oxygen and carbon dioxide into glucose, the plants use light energy.
(Stauffer)
There will be 4 separate pots of plants, the first one will receive no light as it will be placed inside a closed, opaque cabinet the entire time, the second one will receive 3 hours of grow light per day, the third one will receive 6 hours of grow light per day, and the fourth one will receive 9 hours of grow light per day. Once the designated pots that are supposed to receive light have had the amount of light they need for the day, they will be placed inside the cabinet too, in order to prevent further exposure to any light.
Dependent Plant Growth (centimeters)
Depending on the amount of light that the plants get, the plant will be able to do photosynthesis. If a plant gets 9 hours of light a day, it will be able to produce more food for itself and grow faster. However, if a plant gets only 3 hours of light a day, it will photosynthesize and grow at a very slow rate.
The growth of the plants will be measured every day using a ruler, from the soil level to the tip, in centimeters.
Controlled
● Temperature (25 degrees C)
● Water (5 sprits)
● Soil (potting soil)
● It’s important to control the
temperature during the experiment, because due to different levels of light exposure the temperature of the plant may differ and cause an uneven rate of data; because when the temperature is too low, the plant grows slower, and when the
● The temperature of the plant pots will be kept constant, and also near room temperature at all times in a
well-ventilated room with an indirect window, and no fan/ air conditioning should be in use to maintain room temperature (25 degrees celsius)
● The water that’s given to each plant
● Seeds (tbsp)
● Recording data (10 pm)
temperature is too high, it can cause desiccation, leading to plant death.(“Effect of High Temperatures on Landscape Plants | Horticulture and Home Pest News”)
● The amount of water has to be controlled, plants need water for various reasons such as
photosynthesis, temperature cooling, and transportation of nutrients and minerals. However, if overwatered, the roots of the plant can rot and kill the plant.(“Water Is
Essential for Food Production”)
● There are many different types of soils, but the ones containing excessive sand (drains water very fast) or clay (cloggs the water drainage) are not good for the plants’ survival.(Raina)This is why, soil mixed with added fertilizers and nutrients such as moss, peat, pine bark, and perlite is needed.
(“The Dirt on Dirt - Potting Soil | Proven Winners”)
● The amount of seeds that are added to each pot needs to be controlled since the resources that a plant needs in order to grow such as light and water are being kept constant, the amount of seeds in each pot needs to be the same too, so that there is no fluctuation in the number of resources available compared to the number of seeds.
● The time at which the data for the plant growth will be recorded will be kept constant so that the plants have the same amount of time to grow, every day.
pot will be kept constant by allowing three sprays of water per pot, every day.
● The soil that will be used will be store-bought ready-mixed potting soil of the same brand so that all the plants get the same nutrients and fertilizers.
● The number of seeds added to each pot will be kept constant, as the seeds will be measured (in tablespoons) before it’s added in.
● The time at which the height of all the plants will be recorded every day will be 10 pm so that by then the plants have had their time to absorb the light, do photosynthesis, and grow for the day.
Uncontrolled
● Humidity
● Ventilation for 0-hour plants
● Since the windows will be left open for ventilation, the strong midday sun may cause humidity in the room. Even though it is not bad for the plan itself, it may cause bacteria/ molds to grow on the plants, causing them to die.
● To prevent bacterias and molds from growing on the plants while also allowing outside air for ventilation, a dehumidifier can be placed in the room, or leave some rock salts in the room which will also act as a natural dehumidifier.(ByeMould)
(“Reducing Humidity Indoors: What to Do When Humidity Is Too High”)
● Since the 0-hour plants will be kept inside a closed cupboard for 0 light exposure, they will also not receive any ventilation/ CO2.
● In order to prevent this, the plant can also be kept in an open spot such as a cornered desk of a room or a shaded spot outdoors with no light source at all, if such a spot is available.
Materials Table For Light Exposure vs Plant Growth Lab 12 plant pots (3-4 inch
wide) Ready-mixed potting
soil (2 kgs) 24 tablespoons of Cat grass/ Dactylis Glomerata seeds
Water spray bottle
Grow lights (2-3) 1 garden trowel Gloves Timer/ alarm
Paper Marker Scissors Clear Tape
Large Tray (s) Measuring spoon 12 zip lock bags Ruler
Procedure For Light Exposure vs Plant Growth Lab
1. First, using a marker and paper, create labels for all the pots. Leaving about an inch of space, write the labels “0hrs, 3hrs, 6hrs, 9hrs”, on the paper. Make sure to create two more copies of those labels to make a total of 12 labels since there will be a minimum of 3 trials.
2. Using clear tape, stick the 12 labels onto 12 different plant pots. To be more organized, take a large tray so that the water that is drained from the pot can be collected, and then organize the pots into 4 columns, each of the 4 different labels.
3. Wear hand gloves to prevent any mess; using the garden trowel, place the soil into all the plant pots, leaving a 2-inch room at the top of the pots (because the soil will inflate when the seeds start to germinate).
4. With the measuring spoon, measure out 2 tablespoons of the cat grass seeds and evenly sprinkle them on top of a pot, in order to keep the number of seeds constant for all the pots.
Repeat for all of the other pots.
5. Using the water spray bottle, spray the seeds once, just to hydrate the seeds before burying them in soil.
6. Take some more potting soil using the garden trowel, and sprinkle a thin layer of it on top of each pot, so that some parts of the seeds are still visible. Sprinkling a thin layer, about 1 cm, helps the seeds germinate easier as it doesn’t have to dig its way out of the soil which consumes more time.
7. Until the seeds have germinated (until you can see white sprouts have come out of all the seeds in a pot), make sure to insert each of the pots in a zip lock bag, and seal it closed. Using a pin, poke a few holes in all the zip lock bags. This procedure will create a greenhouse effect, it will help hold in moisture so that the hard seed coat is softened, in order for the plant to sprout from within the seed. The holes will allow the seedlings to release the oxygen into the atmosphere and carbon dioxide too when it respires.
8. Take the water spray bottle, and give 5 spritzes of water to each of the plant pots, to keep the amount of water constant. Do this once daily for the duration of the experiment. (if the pot is still in a zip lock bag, take it out once every day to give water, and then seal it back in the zip lock bag).
9. Then, place the three pots with the label “0 hrs” inside a closed, opaque cabinet so that they do not receive any light.
10. Take the leftover pots to a room with no air conditioning or fans, to maintain room temperature.
11. Evenly distribute the pots around the tray.
12. Then attach grow lights to an even surface so that the lights are at an equal distance from the plants, and then place the tray with the pots under it.
13. Place two glasses filled with water on either side of the tray so that it can consume and evaporate excess energy to help maintain the room temperature.
14. Switch the lamp lights on, and then set an alarm for 3, 6, and 9 hours after the lamplight was turned on.
15. When 3 hours is over, take the three pots with the label of “3 hrs” and place them inside the cabinet to prevent further exposure to light. Do the same for the pots labeled “6 hrs” when 6 hours are over, and the ones labeled “9 hrs” when 9 hours are over.
16. Every day, repeat steps 8-14 and record the height of the plants inside all the pots using a ruler, in centimeters, at 10 pm (so that the measurements are taken at exactly 24 hours from the previous reading).
17. Once there are visible sprouts on the seeds, take the zip lock bag off for that pot and continue to follow steps 8-14 every day for 7 days. The cover has to be taken off so that the plant can have regular air circulation, not get trapped in excessive moisture, and so that the growth in height is not restricted by the cover.
Lab Setup Photos
Ethical, Environmental & Safety Concerns
During this lab, the seeds that have been used are a mixture of common seeds. Since grass is one of the most common plants that naturally grow and is also manually grown, grass seeds are widely available. However, specific grass seeds that are safe for human and feline consumption also consist of many sub-varieties, which can also be widely found since there are also many varieties of edible grass, which are commonly found, which is why using these seeds for this experiment will not be unethical. Also, after the experiment is conducted, to make sure that the grass is not wasted, it can be fed to felines at home, streets, or consumed by humans in the form of delicious food like
smoothies! It is also important to be aware of the environment since the plant is grown indoors if it is grown especially on the ground floor and with open windows, the moisture of the grass can invite pests, bugs, and mosquitos, which can be dangerous for humans living in that house. To prevent this, the windows of the room it is being grown in can be closed, or pesticides can be sprayed on the grass.
If the experiment is conducted outdoors, it should be conducted in a protected area so that stray cats do not eat the grass, because otherwise there will be invalid data at the end of the experiment. In case any leaf dies or dries out during this lab, it can be added to soils of other plants as it is enriched with carbon and can be used as compost.(“How to Prepare Dead Leaves for Compost”)It is important for the scientist to be careful with the pin while poking holes into the ziplock bag, as it can cause accidents and might transfer germs if it punctures through the skin. Other than that, this experiment does not require to use of any other harmful chemicals, ingredients, or sharp objects, which is why it is mostly a safe experiment to be conducted.
Results Qualitative Data
During this experiment, there were many qualitative factors that were observed as it was a week-long ongoing experiment. Firstly, when the seeds were initially potted, they had a fairly thick outer shell, the texture was similar to the outer shell of an onion. Since it was potted lightly in the soil, meaning it was not completely buried into the soil, some parts of the seeds were still peeking through.
This step was necessary because later during the experiment, it was observed that when the plant initially starts to germinate, the stem is very thin, weak, and fragile, because of which it would be hard for the plant to grow lengthwise and dig out of the soil if the seeds were buried too deep into the soil.
Secondly, there was not much of a difference on the first day. However, on the morning of the second day, the soil had visibly inflated in the 3, 6, and 9-hour pots, which meant that the seeds had already started to germinate and were pushing the soil upwards to grow out. There were also some tiny visiblewhite stems poking out of the soilfor those pots. At this stage, the seeds still had their zip lock bags on, and all the zip-lock bags got very foggy, except the 0-hour pots where there was a little bit of fog, but much less than all the other pots. By the night of the second day, the seeds had sprouted for the 6 and 9-hour pots for all the trials, and for 3-hour pots for one of the trials. On the third day, the seeds had sprouted for the 3-hour pots for the rest of the two trials, and the 6 and 9-hour pots continued to grow. However, even on the third day, there were no visible signs of germination/ sprouting on the 0-hour pots for any of the trials. By the fourth day, there was green grass growing from inside the white stem for 6 and 9-hour pots, and the same happened for the 3-hour pots on the fifth day. From then, the grass in the 3, 6, and 9-hour pots kept growing taller until day 7, whereas the 0-hour pots still looked almost exactly how they looked initially, except for the tiny amounts of fog.
Light Exposure (hours) vs Average Plant Growth (cm) Raw Data Tables- Trial Results
Trial 1:
Hours Of Light/ Day (+/- 5 mins)
Day 1 (height in
(+/-1cm)cm)
Day 2 (height in
(+/-1cm)cm)
Day 3 (height in
(+/-1cm)cm)
Day 4 (height in
(+/-1cm)cm)
Day 5 (height in
(+/-1cm)cm)
Day 6 (height in
(+/-1cm)cm)
Day 7 (height in
(+/-1cm)cm)
0 hrs 0 0 0 0 0 0 0
3 hrs 0 0 0.2 1.3 2.0 2.7 3.1
6 hrs 0 0.4 2.0 2.5 3.0 3.4 3.8
9 hrs 0 0.8 2.5 3.2 3.9 4.6 5.3
Trial 2:
Hours Of Light/ Day (+/- 5 mins)
Day 1 (height in
(+/-1cm)cm)
Day 2 (height in
(+/-1cm)cm)
Day 3 (height in
(+/-1cm)cm)
Day 4 (height in
(+/-1cm)cm)
Day 5 (height in
(+/-1cm)cm)
Day 6 (height in
(+/-1cm)cm)
Day 7 (height in
(+/-1cm)cm)
0 hrs 0 0 0 0 0 0 0
3 hrs 0 0.3 0.1 1.3 1.8 2.3 2.8
6 hrs 0 0.5 2.2 2.7 3.2 3.6 4.0
9 hrs 0 0.7 2.4 3.4 4.0 4.6 5.2
Trial 3:
Hours Of light/
(+/- 5 mins)Day
Day 1 (height in
(+/-1cm)cm)
Day 2 (height in
(+/-1cm)cm)
Day 3 (height in
(+/-1cm)cm)
Day 4 (height in
(+/-1cm)cm)
Day 5 (height in
(+/-1cm)cm)
Day 6 (height in
(+/-1cm)cm)
Day 7 (height in
(+/-1cm)cm)
0 hrs 0 0 0 0 0 0 0
3 hrs 0 0 0 0.5 1.2 1.7 2.3
6 hrs 0 0.4 2.0 2.7 3.2 3.6 4.1
9 hrs 0 0.8 2.7 3.5 4.2 4.8 5.5
Light Exposure (hours) vs Averaged Plant Growth (cm) Processed Data Table (AVE & STDEV)
Hours Of Light per Day
(+/- 5 mins) Trial
Height of Plant on Day 7(cm)
(+/-1cm) Average Height(cm) Standard Deviation
0 Hours
1 0
0 0
2 0
3 0
6 Hours
1 3.1
2.733333333 0.4041451884
2 2.8
3 2.3
6 Hours
1 3.8
3.966666667 0.1527525232
2 4
3 4.1
9 Hours
1 5.3
5.333333333 0.1527525232
2 5.2
3 5.5
Sample Calculations
❏ Average Height: The average height of the plants on day 7 was calculated using (=AVE (...)) formula on the excel sheet. It can be calculated manually using the following method.
○ Sample calculation for ‘6 hours’ plant growth:
trial 1:3.1 cm,trial 2:2.8 cm,trial 3:2.3 cm 3.1 + 2.8 + 2.3 = 8.2
8.2 / 3 = 2.733333333 centimeters
○ Manual calculation formula:
trial 1 + trial 2 + trial 3 …..
--- number of trials
❏ Standard Deviation: The standard deviation for each set of trials was calculated using
(=STDEV (...)) formula on the excel sheet. It can be calculated manually using the following formula.
○ (“Standard Deviation: Calculating Step by Step (Article) | Khan Academy”)
(“Standard Deviation Calculator”)
Light Exposure vs Plant Growth Graph
Analysis Of Graph
This graph shows the relationship between the two variables, hours of light exposure and the average height of the plants after 7 days. Some plants got 0 hours of light exposure, but they were regularly watered at the same time as all the other plants. However, they still had no signs of germination or sprouting by the end of the experiment. The plants that were exposed to 3 hours of light source per day grew about 2.73 cm on average, the ones that got 6 hours grew about 3.97 cm on average, and the ones that got 9 hours per day grew the tallest, about 5.3 cm on average. It can be
stated that the variables have a positive correlation as it can be seen in the graph that when light exposure increases, plant growth also increases. As can be seen from the error bars on the graph, most of the data points have minimal variability in the data that was recorded, as almost all the data points don’t have differences in trial data that are larger than 1 cm, except for the plants under the 9 hour light exposure. The trial data for those plants vary by about 1 cm, however, that does not hinder the data points from following the trendline of the graph. The graph also has an r squared value of 0.961, which is very close to a perfectly fitted value of 1. This value suggests a positive linear relationship that is almost perfect. This shows that the data variance is not extremely high and the information provided on this graph is reliable. Lastly, the standard deviation value for all the sets of trials is very low, and all are less than 1. This indicated that the data that was collected in each of the trial sets are not too variant from the mean or expected value. This is another indicator of a successful experiment as all the data that was collected suggest the same results. A data point that could be
considered an outlier would be the height of the plant that got 3 hours of light exposure for trial 1. All the data points for each trial set varied by 0.3cm at the highest. However, the value for the 3-hour plant for trial 1 was 3.1, whereas the lowest value for that trial set is 2.3, which means that set had a variance of 0.8cm. Because of this reason, the data point for the 3-hour plants on the graph is
significantly higher than it should be according to the trendline, while all the others are fairly close to it. Therefore, this data is considered to be an outlier during this experiment, which could have occurred due to some other external factor or uncontrolled variable.
Discussion & Conclusion
The scientific reason behind why the hours of light exposure and the rate of plant growth have a positive correlation is simple. When there is more light, plants are able to take in more energy in order to create more chemical energy, in the form of ATP and NADPH. This means it has more chemical energy during the second phase of photosynthesis, during the Calvin cycle. That helps the plant create more food for itself, and that boosts the growth process of the plant, just like humans would grow healthy faster if the energy source in the form of food is increased. As observed during the experiment, the seeds for this grass usually germinate very quickly with some light source and more importantly, a humid environment since that is more important in order to help the grass emerge from the hard seed shells. However, once the seeds have sprouted, the growth starts to depend a lot on the hours of light that it receives since by then, the grass leaves have emerged and it starts to do the process of photosynthesis in order to grow. Reason being why the plants that got 9 hours of light per day grew the tallest, and so on.
These results are helpful towards answering the research question and verifying the
hypothesis since through this lab, it was possible to thoroughly observe, understand, and analyze the relation between hours of light exposure and how it impacts the rate of plant growth with multiple
trials for more accurate answers. In response to the research question “how does light exposure impact the growth (height-wise) of the plant (Dactylis Glomerata)?” that had been set to answer through this lab, as the light exposure is increased, the rate of plant growth also increases as it is an essential part of photosynthesis, the process that helps a plant grow. Thus, the hypothesis “it is predicted that as the hours of light exposure for the plant increase, the rate of plant growth will also increase” is accepted due to verification from this lab's results. As the research question has been thoroughly answered, and the hypothesis has been verified with scientific reasoning and lab results, it can be concluded that this lab is a success.
Evaluation & Extension
During this experiment, there were several things that were successful. Firstly, the amount of water that was provided for all the plants and the time of data collection were successfully kept constant every day, which contributes towards the meaningful results that were derived from the lab.
It is also a great idea to use red and blue spectrum lights instead of sunlight for this lab. The reason why is first, sunlight is inconsistent, it does not provide the same amount of light, with the same amounts of wavelengths, from the same distance/ angle at all times. This could have been an uncontrolled variable that might have affected the experiment. Therefore, the grow lights that were used for this experiment were a much better alternative as they have a constant wattage, produce the same wavelengths of light, and also contains the two spectrums of light that are absolutely essential for the growth of the grass, the red lights helped the seeds germinate and increase biomass, whereas the blue lights increased the turf density and encouraged root growth.(“Recreational Systems
International”)Secondly, the zip lock bags were very helpful in terms of creating a greenhouse effect, it is important to trap moisture and create a humid environment for the seeds in order for the outer shells of the seeds to soften so that the roots and stems can come out of the seed. The zip-lock bags did exactly that as they trapped all the water that was evaporating in order to create a humid
environment. Some improvements that could have been made to the experiment would give more accurate results. Such as, when all the plant pots were done having their designated time of light exposure, they were kept inside a closed cupboard to prevent any sort of light exposure. However, because of that, a variable that should have been kept constant at all times is the ventilation so that the plants have access to carbon dioxide at all times, was not kept constant since inside the cupboard, there is only a limited amount of air available for the plants. Next time, the plants can be simply kept in an open cupboard that is in complete shade and is away from the window, additionally, the room’s lights should also be turned off. This way, the plants are not limited to only some air and it also will not affect the hours of light exposure it is supposed to get. An article by Clearway Community Solar shows the results of a very similar lab that had been conducted. Over there, they planted basil seeds in three different cups, one of which was allowed full sun exposure, another was allowed partial
sun exposure, and the last one was allowed limited sun exposure. All of them were kept in an open room for sufficient ventilation and carbon dioxide, and they were all watered at the same time in the same amounts too. By the end of the 2-week long experiment, the seeds that received full sun had the largest leaves, the one in the partial sun had thin sprouts that were leaning towards the direction of the sun, and the one with limited sun had a few thin sprouts that had turned yellow. This shows that with more light exposure, the plant was able to bloom and grow the most, whereas in the partial sun it was still growing, but slowly. Lastly, the one with the limited sun was also growing very slowly, but it started to become yellow which meant it was about to die. This happened because the plant did not receive a sufficient amount of sun, because of which it was not able to create food for itself or function any chlorophylls, which caused the loss of pigment and is considered as one of the signs of plant death.(“How Light Affects Plant Growth | Clearway Community Solar”)The results in the lab are very similar to this lab, as both of the labs conclude in one finding, which is that more sun exposure encourages faster growth in plants and makes them healthier, whereas less sun causes the growth rate to slow down.
During this experiment, one of the important variables that are needed during photosynthesis was the independent variable (light source), to further analyze how plants photosynthesize, for an extension lab another variable such as water can be controlled. In that lab, the procedure would be the same, but instead, the light source would be a controlled variable that would be kept constant for all the plants, and there will be different amounts of water that the plants will receive each day. This will enable the scientist to thoroughly study how water deprivation, underwatering, sufficient watering, and overwatering can affect the growth of a certain plant.(“How Does Water Affect Plant Growth?”)
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