Concept:

PHOTOSYNTHES

ISMula, Rockie Lou Christian L.Sanchez, Ellen Jane A.Tampil, Christine Rose G.

TITLE:

Effects of Different

Wavelengths on Photosynthesis

OBJECTIVE:

Determine what color of light is

best for photosynthesis.

Ha: There is a significant effect upon varying different colors of light as a source of energy for photosynthesis

Ho: There will be no significant effect upon varying different colors of light as a source of energy for photosynthesis

MATERIALS:

Hydrilla(5 pcs. ;12 cm. each)

Disposable glasses (5 pcs.)

Tap Water (5 bottles; 500 mL

each)

Light Bulbs (5 colors)

Ruler

Beaker

PROCEDURE:•1. The hydrilla were gathered and divided into five. Each measured 12 cm.

•2. The 5 disposable glasses were filled each with 500 mL. of tap water.

• 3. The disposable glasses were labeled with “WHITE”, “YELLOW“,“ORANGE“,“GREEN“ AND “BLUE”.

• 4. Each of the four samples were placed on different colors of light bulbs (5 watts).

YELLOW ORANGE

GREEN BLUE

• 5. Leave for two hours.

• 6. After 2 hours, samples were observed thrice within 5 minutes at 30 minute interval.

• 7. Results were gathered, compared and analyzed.

Independent Variable-color of light

Dependent Variable-Number of Bubbles

Controlled Variable-amount of tap water in each sample-length of Hydrilla in each sample-brightness of light (5watt)

RESULTS and

DISCUSSION:Which sample had the greatest number of bubbles produced?

Which sample had the least number of

bubbles produced?

Color of Light

Wavelength

Length of

Hydrilla

Type of WaterBubbles Produced

Trial 1 Trial 2 Trial 3

White 12 cm. Tap water 17 21 19

Yellow 12 cm. Tap water 29 34 30

Orange 12 cm. Tap water 46 44 52

Green 12 cm. Tap water 7 15 18

Blue 12 cm. Tap water 37 40 48

Table 1.1

Bubbles produced during three trials

Discussion:Photosynthesis is a biological process in which

light (photo) waves carry energy to plants. Plants that contain chlorophyll pigment(green plants) collects light energy, CO2 , water and other nutrients used for photosynthesis and the by-product is oxygen.

Fresh water plants and hydrilla were chosen. The reason is because it is soaked on water. When photosynthesis happens, the by-product(oxygen) will be observable and visible in the form of bubbles.

The concept of this experiment is to determine what color of visible light at the same wattage is the best for photosynthesis.

Q1: What color of light will be absorbed by the green pigment?

The answer is, all shades of blue and red except green. Green light will just be reflected by the chlorophyll. It is because a light which is the same color with the pigment will be reflected not absorbed. That is the reason why the sample observed under green light produced the least number of bubbles.

The volume of water, the intensity of light, type of plant and the length of plant was controlled, while the colors of light were varied. In this experiment the visible light (color of the rainbow) was represented by yellow, orange, green and blue. But the light sample was observe on white light. Just to compare it with the visible light, all five (5) lights were 5 watts.

Each sample were put under each color of light for 2 hours. After two hours, bubbles in each sample were counted for 5 minutes. Data tally continued for 3 trials every 30 minutes for 5 minutes counting time.

At the end, orange sample produced the most number of bubbles followed by blue, yellow, white and lastly green. Thus orange-red light is best for photosynthesis.

CONCLUSION:Therefore the orange

incandescent light source is the best

artificial source of energy for

photosynthesis.

While green incandescent light

source was merely reflected by the

chlorophyll pigment of the plant