Question

biology

(5) Your research team has discovered that plants seem to grow hardier when exposed to white

light (full spectrum) but fail to grow under green light. Design a complete experimental set-up (see Criteria section above) that would support this premise.

.. what would the hypothesis and the independent variable/dependent variable and control variable will be? ..

Answer 1

Hypothesis : Plants grow better under blue , red, yellow lights than they will under white and green lights.

Background : The relationship between light and plant growth can be demonstrated by exposing leaves to various colors ot light.Light is an inevitable factor for photosynthesis.But the spectrum of light most utilized by a leaf is limited to three distinct colors,red ,blue and yellow.For example, leaves appear green because most leaves reflect green colour rather than absorb and use.

Independent variable : Color of light.

Dependent variable : Plant height.

Controlled variables : Soyabean plants of same size, fertilizer, soil,water,potting soil,coloured filters,10 gallon aquarium tank.

Procedure : Plant four soyabean plants of same size in an aquarium containing 5" of well moistened potting soil.Apply the recommended dosage of fertilizer.Place a colored filter tent over each plant.One filter should be clear.Use blue,yellow and red film for the other filters.Place the aquarium in direct sunlight.Keep in the same location during the experiment and water daily.Measure each plant every day and record your findings in a notebook.Be sure to measure from the bottom of the aquarium and not the surface of the potting soil.

Materials : All the materials for this project are available locally.You can obtain a 10 gallon aquarium from a pet shop.Office stores sell colored transparency sheets.Most garden supply shops sell soyabean seeds,potting soil and plant fertilizer.Be sure to germinate your soyabean plants to a height of 4" before beginning your experiment.

SUMMARY : Color of light has a measurable impact on the amount of energy a plant absorbs because the colors in light have different wavelengths and those wavelengths provide different levels of energy.Green light is the least effective for plants because they are themselves green due to the pigment chlorophyll and therefore least absorbed by plants.