Bean seed dissection

Introduction

Knowing the parts of a seed helps us understand what is involved in germination.

Preparation:

• Three days before the dissection: Soak some broad bean seeds by following the steps below. They should swell to about twice their dry size, which makes them soft and easier to dissect.
  
  1. Choose some bean seeds.
  
  2. Wrap them in a paper towel.
  3. Keep them damp but not 'swimming' in water. Cover the container to keep the moisture in.
  

What You Will Need:

• Broad bean seeds (some dry, some pre-soaked).
• Paper towels.
• Shallow trays, e.g. clean meat or fast food trays.
• Water.
• Rulers.
• Scissors.
• Kebab sticks (or tooth picks).
• Magnifying glasses (optional).

What to do

Observations:

1. Select a dry broad bean seed and a pre-soaked one.
2. Compare and measure the sizes of the two seeds. List how the two seeds are different.
3. Use pencil to create accurate line drawings of the two seeds and look up books or the internet to help label them.

Dissect the pre-soaked seed:

1. Use the point of the kebab stick and scissors to gently slice through the outside coat of the pre-soaked seed and remove it.
2. Look closely at the inside parts.
3. Gently pull the two halves of the seed apart and look for the ‘baby plant’. Look for the tiny shoot and tiny root.
4. Draw the half of the seed that includes the baby plant. Again research to help label the parts.
5. Write brief statements about the purpose of each of the seed parts.

Using your knowledge

1. Do tests to find out if other types of seeds swell up before they germinate.
2. Find some other large seeds, for example acorns, and dissect them too. How are they different from the bean seeds?

Questions

1. Why might we need to keep seeds moist during the time they germinate?
2. Find out about how seeds (not seedlings) take up water before they germinate.

Related resources

Basic seed facts