Effect of pH on Sunflower Seeds Bio Lab Report PDF

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Effect of pH on Sunflower Seeds
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The Effect of pH on Germinating Sunflower Seeds

Abstract Germination is resumption of growth and development. Environmental factors such as temperature, light, pH, and soil moisture are all known to affect seed germination. In this lab, the

pH levels were tested on the effects of seed germination. In this experiment, replicates of three sunflower seeds were placed in petri dish which including soaked paper towels with the corresponding pH value tested: pH 3, pH 5.6 (control), pH 7, and pH 10. For this experiment, the question which was tested was: in which pH level will there be a more amount of seeds germinated? The null hypothesis stated the control, pH level of 5.6, will have all three seeds germinated. The research hypothesis one stated the pH level of 7 which is neutral will have all three seeds germinated. Research hypothesis #2 states the pH level of 3, acid rain, will have all three seeds germinated. Research hypothesis #3 states the pH level of 10, the most basic solution, will have all three seeds germinated. The probability of seeds which did not germinate for pH 5.6 and pH 10 is 0.917, or 91.7%. Based on the results, we reject the null hypothesis which states pH 5.6 (control) will germinate the seeds.

Introduction Seeds are a well-known source of protecting the young, embryonic sporophyte, consisting of food sources, and have a protective seed coat. (Freeman, Scott). In angiosperms, the first stage in the sporophyte life is seed development. (Freeman, Scott). Seeds develop in the parent plant. (Freeman, Scott). The embryo and endosperm develop inside the ovule and become

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surrounded by a covering called a seed coat. (Freeman, Scott). Due to seeds containing stored nutrients and the embryo used for growth and development once the seed germinates, they allow offspring to be much more successful in colonizing habitats. (Freeman, Scott). Many seeds germinate underground where light is not available and able to produce via photosynthesis. (Freeman, Scott). As the seeds mature, they are separated from the parent and dispersed. (Freeman, Scott). Once the seeds have dispersed from the parent plant, seeds may not germinate for a period of time. (Freeman, Scott). This is a condition known as dormancy. (Freeman, Scott). Dormancy is usually a feature of seeds from species that inhibit seasonal environments, which may be too cold or dry for the seedlings to thrive. (Freeman, Scott). Dormancy is an adaptation that allows the seed to be viable until conditions improve for it to thrive. (Freeman, Scott). Germination is resumption of growth and development. Environmental factors such as temperature, light, pH, and soil moisture are all known to affect seed germination. (“Article Access.”). Specifically in this lab, the pH levels were tested on the effects of seed germination. In this experiment, replicates of three sunflower seeds were placed in petri dish which including soaked paper towels with the corresponding pH value tested: pH 3, pH 5.6 (control), pH 7, and pH 10. The seeds studied in this experiment were sunflower seeds. Helianthus annuus L. is the scientific name for the sunflower seeds. (Canadian Food Inspection Agency). As most may know, the plant itself is tall ranging from 50 to 500 cm. (Canadian Food Inspection Agency). The stems are typically unbranched. (Canadian Food Inspection Agency). Sunflowers are usually large and yellow, but the color can range from lemon-yellow, orange, and reddish. (Canadian Food Inspection Agency). The sunflower seed may be linear, oval, or almost round. (Canadian Food Inspection Agency). Sunflowers are normally seeded in May, as it requires a long season to

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mature. (Canadian Food Inspection Agency). The sunflower is considered to be somewhat of a drought tolerant plant and will grow in a variety of soil types with soil pH’s of 5.7 to over 8. (Canadian Food Inspection Agency). pH is used to measure acidity or the amount of hydrogen ions in a solution. (Acids, Bases, & the PH Scale.”). pH is the negative logarithm of the hydrogen ion concentration. (Acids, Bases, & the PH Scale.”). Solutions with a high concentration of hydrogen ions have a low pH value making the solution overall acidic. Solutions with low concentrations of H+ ions have a high pH value making the solution basic. (Acids, Bases, & the PH Scale.”). The pH scale ranges from zero to fourteen. (What is PH). Pure water, or a neutral solution, has a pH value of 7. (What is PH). In this lab, a pH level of 5.6 is considered rain water. A pH value of 3 is considered acidic rain. Measuring pH is important to know which level will the seed germinate. For this experiment, the question which was tested was: in which pH level will there be a more amount of seeds germinated? The null hypothesis stated the control, pH level of 5.6, will have all three seeds germinated. The research hypothesis one stated the pH level of 7 which is neutral will have all three seeds germinated. Research hypothesis #2 states the pH level of 3, acid rain, will have all three seeds germinated. Research hypothesis #3 states the pH level of 10, the most basic solution, will have all three seeds germinated.

Methods For this experiment, one obtained the following materials. Four petri dish were obtained and labeled accordingly. The first petri dish was labeled pH 5.6 - control, the second pH 3, the third pH 7, and the fourth pH 10. After the petri dish were labeled, twelve sunflower seeds were obtained from the teacher assistant. The sunflower seeds were placed in a beaker with bleach

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solution to kill unneeded bacteria or other dirt on them. After letting the sunflower seeds soak for approximately 5-10 minutes, the seeds were placed on a paper towel to dry off. As the seeds were drying, the petri dish were prepared. White paper was cut into a circle approximately the size of the petri dish four times. The circles were placed on the bottom of the petri dish. Three sunflower seeds were placed in each petri dish. Filter papers which were soaked in the according pH solution were placed on top of the sunflower seeds in the appropriate petri dish labeled with the pH value. Lids were placed on the petri dish. The petri dish were placed in the according room. For the next seven days, each day the seeds were observed and the amount of seeds germinated were recorded. A table was created to specify the day number and the number of germinated seeds in each pH solution. After the collection of observation for seven days, an odds ratio test was performed. An odds ratio was performed to measure an association between an exposure and an outcome. After the odds ratio, graphs were established.

Results Table 1.1 Number of Germinated Seeds in 7-day Period pH Level

Day 1

Day 2

Day 3

Day 4

Day 5

Day 6

Day 7

Control (pH 5.6)

0

0

0

1

1

1

1

pH 3

0

1

2

3

3

3

3

pH 7

1

2

2

2

2

2

2

pH 10

0

0

0

0

0

1

1

Table 1.2 Odd Ratio Table for Day 3 DAY 3

p

q

pq

4

Treatment

Total Seeds Germinated

Total Seeds Germinated/Total Seed Number (3)

1-p

pxq

Control (pH 5.6)

3

0

1

0

pH 3

3

0.67

0.33

0.22

pH 7

3

0.67

0.33

0.22

pH 10

3

0

1

0

Graph 1.1 Probability of Germinated Seeds for Day 3

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Table 1.3 Odd Ratio Table for Day 4 DAY 4

p

q

pq

Treatment

Total Seeds Germinated

Total Seeds Germinated/Total Seed Number (3)

1-p

pxq

Control (pH 5.6)

3

0.33

0.67

0.22

pH 3

3

1

0

0

pH 7

3

0.67

0.33

0.22

pH 10

3

0

1

0

Graph 1.2 Probability of Germinated Seeds Day 4

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Table 1.4 Odd Ratio Table for Day 7 DAY 3

p

q

pq

Treatment

Total Seeds Germinated

Total Seeds Germinated/Total Seed Number (3)

1-p

pxq

Control (pH 5.6)

3

0.33

0.67

0.22

pH 3

3

1

0

0

pH 7

3

0.67

0.33

0.22

pH 10

3

0.33

0.67

0.22

Graph 1.2 Probability of Germinated Seeds for Day 7

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Legend for Graph 1.1 x-axis

Treatment

1

pH 5.6 (Control)

2

pH 3

3

pH 7

4

pH 10

In this experiment, the independent variable is the treatment which is the different pH values (5.6, 3, 7, and 10). The dependent variable is the amount of seeds germinated. The sample size is three, three seeds were placed in four petri dish. After the data collection, an odd ratio table was calculated. A graph based on the number of successes, or the probability of seeds germinated out of the sample size (12) was created. An odds ratio is a measure of association between an exposure and an outcome. The odd ratio (OR) is a relative measure of effect. In this

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experiment, the measure of effect is the measure of the pH used on the seeds. If an outcome of two groups is the same, the groups ratio will be one. The graph also shows standard error bars. Standard error bars indicate a general idea of how precise a measurement is and represent a 95% confidence interval. For pH 5.6 and pH 10, the number of seeds germinated is one out of three. pH 3 had three seeds germinated. pH 7 had two seeds germinated. The probability of seeds germinated for pH 5.6 and pH 10 is 0.33, or 33% according to Day 7 results. The probability of seeds germinated for pH 3 is 1, or 100% and pH 7 is 0.67, or 67%. Overall, pH 3 had the highest probability of seeds germinated according to Day 7 results. The probability of seeds which did not germinate for pH 5.6 and pH 10 is 0.67, or 67%. The probability for pH 3 is 0, or 0% and pH 7 0.33, or 33%. The highest probability for ungerminated seeds is pH 5.6 and pH 10 with 67%. For pH 5.6 and pH 10, the odds of success is 2 to 1. The odds of successes is 1 to 1 for pH 3 or we can say the odds of failures is 1 to 1. The odds of successes for pH 7 is 1 to 2. The odds of successes is calculated by p/q and the odds of failures is calculated by q/p. The standard error bars indicate a statistical significance. If error bars overlap, there is no statistical significance and if they do not overlap, there is a statistical significance. The error bars for pH 5.6 and pH 10 do not overlap with pH 3 indicating there is a statistical significance. The error bars for pH 5.6 and pH 10 overlap with pH 7 indicating there is no statistical significance. The error bars for pH 3 and pH 7 do not overlap as well.

Discussion

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The null hypothesis stated the control, pH level of 5.6, will have all three seeds germinated. The research hypothesis one stated the pH level of 7 which is neutral will have all three seeds germinated. Research hypothesis #2 states the pH level of 3, acid rain, will have all three seeds germinated. Research hypothesis #3 states the pH level of 10, the most basic solution, will have all three seeds germinated. Based on the results, we reject the null hypothesis which states pH 5.6 (control) will germinate the seeds. According to the observations, on Day 7, the number of seeds germinated is 1 out of 3. The probability of ungerminated seeds is 67%. The odds of successes is 11 to 1. The pH 10 value had the same results, but pH 10 was used as the research hypothesis #3. pH 7 was used as the second research hypothesis because the pH value was based on the neutrality of the solution. The value seven indicates the solution is neutral and is known as water. According to the error bars, there is only a statistical significance between pH values of 5.6 (control) and 10 with pH 3. The solution with pH 3 had three seeds germinated by Day 7. We fail to reject research #3 stating pH 3 will have three seeds germinated. Based on the data, unusual results were obtained. We used pH 5.6 based on the pH level of natural rain. According to the research as well, sunflower seeds germinate in pH values of 5.7 to 8. The pH value pH 3 is known as acid rain. (“What Is Acid Rain?). Acid rain is a broad term used to describe a form of precipitation with acidic components. (“What Is Acid Rain?). Acid rain is known to remove minerals and nutrients from the soil which help the plant or tree grow. (“What Is Acid Rain?). With all three seeds germinating in the petri dish with pH 3, the data raises concerns with possible errors in the experiment. During the experiment, many sources of errors may have caused inconsistent and unreliable data. One possible source is the possibility of the amount pH solution used. There may

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have been a possibility where a filter paper may have been soaked for too long or not soaked enough. Another possible source of error is the even distribution of resources such as exposure to sunlight. Some seeds may have had more exposure to sunlight and CO2 than other causing them to have more resources and nutrient which may help them germinate. To continue on with the source of error, the seeds prior to the experiment might have been exposed or treated differently. The seeds may have come from different sources which again may have had different exposures to amounts of resources and nutrients. The last source of error may have been the step where the seeds were soaked in bleach for 5-10 minutes prior to applying the pH solution. Bleach has a pH value of 12.6. (“PH Scale Comparison.”). . Since bleach is highly basic, there is a possibility where the pH value of bleach increased the other pH values. Since pH 3 is the lowest pH value, a pH value of 12.6 might have raised the pH value to the desirable pH for sunflower seeds to germinate. For future studies, I would use sunflower seeds from the same source to reduce inconsistencies. Instead of using bleach to sterilize or clean the seeds, I would soak the seeds in deionized water to reduce the chances of imbalancing pH values.

Works Cited “Acids, Bases, & the PH Scale.” Science Buddies, www.sciencebuddies.org/science-fair-projects/references/acids-bases-the-ph-scale. “Article Access.” BioOne, www.bioone.org/doi/pdf/10.1614/WS-03-139R2.

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Freeman, Scott. Biological Science. Pearson Education, 2017. Government of Canada,Canadian Food Inspection Agency, and Plant Health and Biosecurity Directorate. “The Biology of Helianthus Annuus L.” Canadian Food Inspection Agency, 4 Feb. 2015, www.inspection.gc.ca/plants/plants-with-novel-traits/applicants/directive-94-08/biologydocuments/helianthus-annuus-l-/eng/1330977236841/1330977318934. “PH Scale Comparisons .” PH Scale Comparisons, www.adbio.com/science/analysis/ph_scale.htm. What Is PH, academic.brooklyn.cuny.edu/biology/bio4fv/page/ph_def.htm. “What Is Acid Rain?” EPA, Environmental Protection Agency, 1 Mar. 2017, www.epa.gov/acidrain/what-acid-rain.

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