Designer Seeds

Pre-Lab:

Seeds ensure that plants will continue to live on this Earth. It may take years before a seed will germinate, but this is a survival strategy. Plants have developed different methods to make sure their seeds find a suitable location to grow. Since plants themselves are not mobile they must have a mechanism to disperse, otherwise, all plants would grow in one area.

There are four basic methods of seed dispersal including by wind, by attachment to fur or feathers, by passing through an animal's gut, or by animals moving the seeds. Wind dispersal allows seeds to travel with the wind. Sometimes the distance that seeds travel can be long. For instance, if a seed gets into the upper atmosphere it can travel along the jet stream and travel hundreds, if not thousands of kilometers. Attachment to the fur of mammals or the feathers of birds helps seeds to "walk" or "fly" to a new location. The seeds may drop and fall into a suitable location to grow. When an animal eats a seed, sometimes its stomach cannot digest the outer portion of the seed and the seed is passed through the animal’s digestive system intact. Some animals move seeds purposely for storage and later consumption. Animals can drop seeds by mistake resulting in germination at that spot.

Purpose: To investigate how seeds are dispersed

Materials: Various types of seeds, magnifying glass, paper, tape

Procedure:

Part A: Seed Stations

At each lab station observe each seed/fruit:

  1. Describe its features (what it looks like)
  2. Sketch a diagram of the seed and label any significant parts or features you can identify
  3. Speculate on how the seed is transported and explain what observations were used to make this conclusion.

Part B: Designer Seed Challenge

With your lab partner to design a wind dispersed container that will carry your seed the farthest.

Rules:

  1. you may not use more than one piece of paper, but you do not have to use the whole piece
  2. you may tape, cut, tear, or do anything you choose as long as your seed is fixed to the container and will not fall out.
  3. You will have 20 minutes to assemble your seed structure and test it no more than three times.
  4. All seeds/structures will be dropped in front of a wind source.

Discussion

1)What seed designs worked the best? Why? /2

2)What features of the seed designs mimicked seeds found in nature? Did those seed travel farthest? Why or why not? /3

3)Why would the seed benefit from travelling the farthest? /1

4)How was this experiment similar to what might happen in nature? How was it different? /2

5)What other variables in the natural environment would affect how far a seed might travel? /2