ELEMENTARY SCIENCE FAIR

Project Abstract / Bibliography

Student’s Name: Michelle Charvet Proenca

Project Title: Grow, Grow, Grow!

Abstract

The purpose of this experiment is to determine if the plant receiving most light will grow the tallest. I hypothesized that the result would be that if I placed a plant close to the window, it would grow taller than a plant in the dark, based on the fact that plants grow best in the light, and use sunlight to make photosynthesis.

I started the project by collecting the necessary materials. First I placed cotton balls inside 3 foam cups. Inside each foam cup I placed 4 beans and watered them. One cup was placed close to a window, another cup was placed away from the window but receiving light and the last cup was placed inside a dark closet. The results were that the plants in the dark grew the tallest, but had the smallest and most light colored leaves. The plants close to the window grew smallest, but had the biggest and greenest leaves. Also, the plants placed close to the window bent towards the light.

In conclusion, my hypothesis was wrong. The plants without light grew the tallest since they were looking for light to survive. The application that my experiment has in our daily lives is that if you want to plant a plant to have seeds and fruit it is best to plant it close to sunlight, because plants that are close to sunlight grow stronger and healthier.

Bibliography

NEWTON, Division of Education Programs (DEP) of Argonne National Laboratory, Ask a Scientist, http://www.newton.dep.anl.gov

Plants Know the Way to Grow, http://www.fastplants.org/pdf/activities/know_the_way.pdf, 09/24/2011

Science with me, Learn about Photosynthesis, http://www.sciencewithme.com/learn-about-photosynthesis/, 09/24/2011

Space Garden, How Do Plants Know Which Way to Grow? “Tropisms” http://www.spacegarden.net/downloads/Gravitropism.pdf, 09/24/2011

Sumangal, B, Pitara Kids Network, Why do Plants Lean Toward Sunlight? http://www.pitara.com/discover/5wh/online.asp?story=56, 09/24/2011

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Acknowledgements

I thank my teacher, Ms. Abijalil, for guiding me through this project, my mom for helping me to set up the experiments and type the texts, and my father for helping me find the references for the background research.

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Problem Statement

Will the plant receiving most light grow the tallest?

Background

Plants grow best in the light. The sunlight is an important source of energy which plants use in a process called photosynthesis. In photosynthesis, plants combine carbon dioxide found in the air and water from the soil and change them into glucose and oxygen. Photosynthesis means “putting together with light”. Plants figured out how to use solar energy to make their food millions of years ago. They use the light energy from the sun and convert it into chemical energy that is stored as sugar in the plant.

Charles Darwin proved and explained that a growing grass always bends towards sunlight. This is due to a phenomenon called phototropism. Leaves lean towards sunlight for photosynthesis, without sunlight plants can’t survive. Plant cells have a substance called auxin, that lets the plant bend from side to side. Auxin make the cells on the darker side grow faster than the lighted side. Sunlight slows or kills the auxin when light falls on them. As long as one side of the plant gets enough sunlight, it can make food for the whole plant to survive.

How do plants know which way is up? Curving of the roots result from asymmetric growth as the plant elongates. Elongation of plant cells is affected by the same plant growth hormone called auxin. If roots and shoots were affected in the same way plants would grow in circles. Fortunately auxin stimulates cell elongation in different ways in roots and shoots. Phototropism is apparently mediated by the shoot tip and unequal auxin distribution, with auxin transported toward the darker side of the shoot.

The light on plant growth is called phototropism, while the gravity on the direction of plant growth is called gravitropism. Together both forces, light and gravity, are responsible for enabling plants to make a vertical growth axis that places shoots and roots in their right places. While light makes shoots grow toward it, gravity has the opposite effect. Light can be used to change the direction of a plant’s growth. But in the absence of light, shoots and roots use the force of gravity alone to orient themselves in an up and down direction.

Hypothesis

If I place a plant close to the window, it will grow taller than a plant in the dark.

Materials

- 3 foam cups- Cotton balls

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- 12 Beans- Water

Procedures

1. Place the cotton balls in the cups2. Place 4 beans in each cup3. Water the beans4. Place one cup close to the window, one cup away from the window but receiving light, and one

cup in the dark closet5. Take pictures at the beginning, middle and end of your experiment6. Water the beans every 2 days7. Watch them grow for 2 weeks and write down the observations in a data table

Variables

- Light

Control

- Beans- Water- Temperature

Data

Experiment 1

Size of stem (in) Size of Leaves (in)Close to window 12.5 2.5Away from window 15 1.5In the dark 20 0.5

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Experiment 2

Size of stem (in) Size of Leaves (in)Close to window 10.25 3.5Away from window 16.5 1.5In the dark 19 0.75

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Experiment 3

Size of stem (in) Size of Leaves (in)Close to window 13 4Away from window 14 2In the dark 17.75 0.75

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Results

The 3 trials showed the same results. The plants in the dark grew the tallest, but had the smallest and most light colored leaves. The plants close to the window grew smallest, but had the biggest and greenest leaves. Also, the plants close to the window bent towards the light.

Results (Average)

Size of stem (in) Size of Leaves (in)Close to window 11.9 3.3Away from window 15.2 1.7In the dark 18.9 0.7

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Conclusions

My hypothesis was wrong, it said that the plant close to the window would grow the tallest, but actually the one in the dark was tallest. The project was very interesting, I found out that plants in the dark grow tall but have small leaves. Plants in the light grow small but have big and greener leaves. They also bend towards the light.

Applications

If you want to plant a plant to have seeds and fruit it is best to plant it close to sunlight, because plants that are close to sunlight grow stronger and healthier. Plants in the dark grow weaker and taller because they are looking for light. If they don’t find light they will end up dying.

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