Title: Planning and Designing Topic: Nutrition Aim: To investigate the growth and appearance of plants in dim and bright light Hypothesis: The seedlings would be very tall and thin when grown in the dark due to etiolation. Etiolation is a process in flowering plants grown in partial or complete absence of light. Seedlings in light however, will grow upright due to the even distribution of auxins on the lateral sides of the shoot, and will also be thick/thicker than that of the seedlings in dim light. Materials and Apparatus: Soil of the same type (clay or loam or sand), Seedlings from the same location/area, 100 seedlings, a measuring cylinder, a plastic bag (2), a supply of water, a pot. Method: 1. Obtain a sample of 100 seedlings from the same area/location 2. Obtain a sample of soil of the same type and location and place in 2 separate plastic bags. 3. Label one of the plastic bags, A and the other B 4. With the use of a measuring cylinder, measure equal amounts of soil and place the amount in plastic bags A and B. 5. Divide the amount of seedlings evenly and place in a container. Label the first A and the next B. 6. Let materials A be tested in dark and materials B be tested in light. 7. For Scenario A, set up the experiment under an enclosed area, where light is minimal such as a Building or a Rooftop while for Scenario B, it is placed directly under the sun to ascertain light in every possible direction. 8. To facilitate growth of both scenarios in terms of moisture and humidity, control the time at which the seedlings are watered, preferably every 24 hours and always at the same time. 9. Repeat this process for a few days until noticeable changes in appearance of both scenarios have occurred. 10.Record the height, width and appearance of both samples and tabulate results. Variables: Manipulative/Independent Variable: The location where both experiments A and B were placed. Dependent/Responding Variable: The appearance of the seedlings, The overall growth of the seedlings
Controlled Variable: The amount of soil, The amount of water, The location/area where the seeds came from.
Expected Results: In Scenario A, there is dim light. Etiolation is a process in flowering plants grown in complete absence of light. Etiolation increases the likelihood that a plant will reach a light source, often from under the soil, leaf litter, or shade from competing plants. Seedlings grown in these conditions have long, weak stems, short leaves and are unable to photosynthesize. Chlorosis would occur as leaves would have produced insufficient chlorophyll due to the inability to receive sunlight. Chlorotic leaves are pale, yellow or yellow white. Seedlings have little or no ability to manufacture carbohydrates to sustain life and may die as a result of this. Scenario B on the other hand has the maximum potential to grow. Stems are strong and long at the same time as well as receiving equal amounts of sunlight on the lateral sides of the shoot. They usually possess long leaves which have a large surface area to ascertain maximum sunlight to increase productivity and the manufacturing of food in the plant. Treatment of Results: 1. Height of Seedlings: Tabular and Graphical Table for both the Dark and Lit Conditions: Day Number
Height (cm)
Graph: Plot a graph of Height (y-axis) against the Day Number (x-axis) 2. Appearance of Seedlings, Leaves, Stem and Root Structure: Scenario
Sources of Error:
Appearance of Leaves
Appearance of Stem
Appearance of Root
Human Error – If more than one person is measuring the heights and volumes, the measurement may vary from person to person as they have different eye levels. To correct this, measurements should be taken perpendicularly at eye level to ensure maximum accuracy.
Limitations: Temperature – The sample present in light would have a higher temperature to those in the shade and would possibly affect the rate of photosynthesis. Conclusion: Light is a factor in the overall functionality of a plant both in nutrition and health and without light, plants would be unable to sustain life.
