Leaves and Light

[stricklande]

My class just completed the "Leaves and Light" experiment. We placed various colored transparencies on a houseplant, rotated it daily in our classroom, and uncovered the transparencies a week later. The leaves did not change after the week. Did we do something wrong? Was there supposed to be a change in the coloration of the leaves?

[deleted-71948]

Welcome to Science Buddies!

First, I recommend you to check off the following essential procedures for the experiment below.
- Did you use clear transparency film?
- Did you use permanent markers of various colors?
- Did you cover different parts of the plant with different sheaths (including black construction paper and transparent film painted in different marker colors) ?
- Did you place your houseplant in an area exposed to sunlight?

If you checked off everything above and the problem reoccurs, I suggest that you perform a different experiment that still explores plant pigments in relation to photosynthesis. For your reference, I linked a helpful outline of different project that is similar in concept to the "Leaves and Light" experiment.

What Color Are the Leaves Really Turning? https://www.sciencebuddies.org/science- ... p032.shtml

Hope this helps and good luck!

-Grace

[deleted-81235]

While Grace has already given you a great start, I just wanted to add a few things. The reason we see things as colored is that objects have pigments that absorb certain wavelengths. The color that we see is the combination of all of the wavelengths of light that are not absorbed, but instead reflected back to our eye. The Leaves and Light experiment includes some background information about the different pigments that plants use (chlorophyll a, chlorophyll b, and Carotenoids). Since most plants appear to be green, these pigments combined should absorb all other colors, which are then used in photosynthesis.

Light (energy) is used in plants to energize electrons to facilitate photosynthesis (to produce sugar). Contrary to popular belief, this sugar is not used only in the mitochondria to produce energy for the plant's metabolic processes (reactions which the plant carries out to survive). The sugar is also used for growth. For example, it can be used to create cellulose (another type of sugar) which is used in cell walls.

Therefore, depending on which color light was given to the houseplant, the plant should have either grown and thrived, or it should have started to die/look unhealthy.

Also, some houseplants a such as CAM (crassulaceans) and C4 plants (most grasses and grassy plants) have specific adaptations in their photosynthesis processes that allow them to survive in adverse situations. By this, I mean that they have adaptations that allow them to have a slow metabolism and growth rate if such environments were introduced to it. So, if you used either of these categories of plants, this might be why when different colored lights were given to the plant, no changes could be perceived.

I hope this helps!
Meg

[megs123]

Hi

I have to prepare my science project on the Leaves and Light Experiment but I am a little confused. Please help me figure out the science behind it.
I am essentially confused about what to expect. What are the results supposed to be like?

Black Paper - the black paper absorbs all the wavelengths of light (as it is opaque and black), so none is transmitted to the leaf and hence, it should die

Clear Film- all the wavelengths of light are transmitted (as it is clear and transparent) to the leaf and hence, it should flourish

Blue Film- Which wavelengths of light are being transmitted to the leaf in this case? How does that affect growth ?
Green Film - Which wavelengths of light are being transmitted to the leaf in this case? How does that affect growth ?
Yellow Film - Which wavelengths of light are being transmitted to the leaf in this case? How does that affect growth ?
Red Film- Which wavelengths of light are being transmitted to the leaf in this case? How does that affect growth ?

I'm not sure about what is to be expected, the colors have me confused. When something like a colored film which is translucent, reflects a color, which colors pass through? And how are they supposed to affect growth? Lastly, which colored sleeves are supposed to perform best? Which ones worse? Please help! Thanks!!!

[deleted-249560]

megs123-

I haven't done the experiment myself, so I can't tell you what you'll be seeing but I can help you with part of your question. Light bouncing off of objects or passing through filters is subtractive - that is to say, the light starts with many colors, some are absorbed and some bounce off. If you look at a blue painted wall, all the colors except for blue are absorbed and only blue is reflected. If you run white light through a blue filter, the blue is passed through and everything else is absorbed.

You asked about wavelengths of the different colors. Take a look at http://science-edu.larc.nasa.gov/EDDOCS ... olors.html and see if that helps. In general, the experiment will be exposing the leaves to different colors of light and you can expect that the leaves will like some of them and not others. Unhappy leaves turn colors and die so that's what I'd expect to happen - but as I said, i haven't done it myself.

I'd also suggest you edit your question and remove your email address. It's a rule here that we don't share personal information.

Howard