S2.1.2 Chapter 2
From seed to seedling
What is inside a seed, and how does it start to grow?
Your guess
Pick one before you read on. It is fine to be wrong.
By the end you can
- Name the parts of a seed: coat, food store and tiny plant
- Test whether seeds need water to start growing, using two cups
A dry bean looks dead. It is alive. Inside is a tiny plant.
The seed coat is the skin on the outside. It protects the seed.
Inside are two halves. They are the food store. They feed the tiny plant until its leaves can make food.
Between the halves lies the tiny plant. It has a tiny root and a tiny shoot. The shoot is the part that grows up.
You can see this. Soak a dry bean in water overnight. Peel off the coat. Gently split the bean in two. Look for the tiny plant.
Draw it first
Draw the inside of a bean
1 Draw a big bean shape. Write seed coat. This is the outside.
2 Draw a line down the middle. Write food store. These are the two halves.
3 Draw a tiny root and shoot in one half. Write tiny plant.
A seed can wait a long time. It starts to grow when it gets water, air and warmth. Most seeds do not need light or soil to start.
Many seeds start in the dark, under the ground. A bean can start in a dark box too.
First the seed takes in water. It swells, and the coat splits. The root comes out first. Then the shoot grows up. A young plant like this is a seedling.
See it three ways
As a picture
In words
The seed takes in water. The root comes out first and goes down. The shoot grows up and the leaves open. Now it is a seedling.
Do seeds need water to start? Test it. Use two cups. Only one thing will be different: the water.
Try it
Do seeds need water to start?
You need: two cups, paper or a cloth, enough to fill the bottom of each cup, a few dry beans, the same kind, water, a warm place.
Be safe: Do not eat the beans. If white fuzz grows on the paper, throw it away. Then wash your hands.
- Put paper or cloth in the bottom of each cup.
- Put the same number of beans on the paper in each cup.
- Wet the paper in one cup. Keep it wet every day.
- Leave the other cup dry. Stand both cups in the same place.
- Look every day for about five days. Where do the beans change?
What you will see: Only the wet beans start to grow. They swell, the coat splits, and a root comes out first. The dry beans stay as they were. Seeds need water to start. These beans grew with no soil. It may take more days if the place is cool.
A wrong idea many people have
A seed needs soil to start growing.
Why it feels right: People plant seeds in soil. We always see seedlings come up from the ground.
The test that breaks it: Put wet paper in a cup. Lay a few beans on it. Add no soil. Keep the paper wet. After some days, roots come out of the beans. Then the shoots grow.
What is true: A seed needs water, air and warmth to start. The food store feeds the seedling at first. Soil is not needed to start.
Key words
- seed coat
- the skin on the outside of a seed. It protects the seed.
- food store
- the part of a seed that feeds the tiny plant.
- shoot
- the part of a plant that grows up from the seed.
- seedling
- a young plant that has just started to grow.
Back to your guess
The answer is B: A tiny plant and its food.
A seed holds a tiny plant and food for it. A coat covers them both.
Check yourself
Try each one before you look. A wrong answer tells you where to go next.
Which part of a bean seed protects the tiny plant?
See the answer
The seed coat
The seed coat is the skin on the outside. It covers and protects what is inside.
- If you chose A: The food store feeds the tiny plant. The coat protects it.
- If you chose B: The shoot is part of the tiny plant. The coat is the skin outside.
- If you chose C: The soil is outside the seed. The seed coat is the seed's own skin. It protects the tiny plant.
What is the food store for?
See the answer
It feeds the tiny plant until its leaves can make food.
The two halves hold food. The tiny plant uses it until its own leaves can make food.
- If you chose B: The seed coat protects the seed. The food store feeds the tiny plant.
- If you chose C: The flower comes much later, on the grown plant. The food store feeds the tiny plant.
Mei keeps one cup of beans wet and one cup dry. Only the wet beans grow. What does this show?
See the answer
Seeds need water to start growing.
The cups were the same except for water. Only the wet beans grew, so water made the difference.
- If you chose A: No soil was used. The wet beans grew on paper.
- If you chose B: Both cups stood in the same place. Only the water was different.
What comes out of a growing bean first?
See the answer
The root
The root comes out first and goes down. Then the shoot grows up.
- If you chose A: The flower comes much later, on the grown plant.
- If you chose C: The root comes out first. The shoot and leaves come after it.
From an earlier chapter
Which part of a plant takes in water from the soil?
Draw a bean seed cut open. Label the seed coat, the food store and the tiny plant.
See the answer
A bean outline labelled seed coat. A line down the middle, labelled food store. A tiny root and shoot, labelled tiny plant.
The coat protects. The food store feeds. The tiny plant is the part that will grow.
Look at the picture. Which letter shows the tiny plant?
See the answer
C
C marks the tiny root and the tiny shoot. Together they are the tiny plant, the part that grows.
- If you chose A: A is the seed coat. The coat is the skin that protects the seed.
- If you chose B: B is the food store. It feeds the tiny plant.
Ana lays wet beans on wet paper in a dark box. After five days roots come out. What does this show?
See the answer
Beans can start to grow in the dark.
The beans had water and warmth but no light. They still grew roots. Many seeds start in dark soil.
- If you chose B: The box was dark and the roots still came out. Leaves need light later, to make food.
- If you chose C: Ana used wet paper and no soil. The roots still came out.
Keep it
Copy this into your exercise book.
Seed parts: a seed coat, a food store and a tiny plant. With water, air and warmth it starts to grow. The root comes out first, then the shoot. Seeds need no soil to start.
Draw: A bean cut open. Label the seed coat, food store and tiny plant.