Lesson 5 ·Class 9 · Seeds — Structure and Germination · Flow Lab
What Triggers Germination
Water, air and the right warmth.
A dry seed is alive but dormant. Give it the right conditions and watch it wake.
→ → → →
😴 Step 1 of 5 · Dormant seed
The seed is dry and inactive — its water content is very low and respiration is barely ticking over.
water + oxygen + suitable temperature → germination
25°C
Rate of germination 71%
Free play — step through the process at your own pace, and move the slider to see what changes. Switch to when you're ready to test yourself.
Three conditions are essential: water, oxygen and a suitable temperature. Light is not required by most seeds.
What this lesson covers
Challenges to clear
- Advance to the part that emerges first.
- Step through the whole germination.
- Drop the temperature to 5 °C or below and read what happens.
The task
A dry seed is alive but dormant. Give it the right conditions and watch it wake.
What this lesson covers
- Dormant seed — The seed is dry and inactive — its water content is very low and respiration is barely ticking over.
- Water is absorbed — Water enters through the micropyle. The seed swells and the testa splits.
- Enzymes switch on — Water activates enzymes that digest the stored food into soluble form the embryo can use.
- Radicle emerges — The radicle comes out first and grows downward to anchor the seedling and absorb water.
- Plumule emerges — The plumule grows upward into the shoot. Once leaves open, the seedling feeds itself.
- water + oxygen + suitable temperature → germination
- Too cold — enzymes work far too slowly for the seed to germinate.
- Too hot — the enzymes are denatured and germination fails.
Hint
Three conditions are essential: water, oxygen and a suitable temperature. Light is not required by most seeds.