Click image to open full size
Biology
How Seeds Sprout
Seeds Sprout
Related Tools
Related Labs
Related Worksheets
Related Cheat Sheets
A seed is a living plant embryo packaged with stored food and a protective coat. Sprouting, also called germination, begins when conditions such as water, oxygen, and suitable temperature become favorable. This process matters because nearly all crop production and many natural ecosystems depend on seeds successfully becoming seedlings. Understanding germination helps explain how plants establish roots, reach light, and begin making their own food.
Key Facts
- Germination begins when a dry seed absorbs water in a process called imbibition.
- The radicle is the first embryonic root to emerge, anchoring the seedling and absorbing water.
- Stored food in the cotyledons or endosperm supplies energy before photosynthesis begins.
- Cellular respiration during germination uses glucose and oxygen: C6H12O6 + 6O2 = 6CO2 + 6H2O + energy.
- Germination percentage = number of seeds sprouted / total seeds planted x 100%.
- After leaves unfold, photosynthesis can supply sugar: 6CO2 + 6H2O + light energy = C6H12O6 + 6O2.
Vocabulary
- Germination
- Germination is the process in which a seed resumes growth and develops into a seedling.
- Seed coat
- The seed coat is the tough outer covering that protects the embryo from drying out and damage.
- Radicle
- The radicle is the embryonic root that usually emerges first during germination.
- Cotyledon
- A cotyledon is a seed leaf that stores or absorbs food for the young plant.
- Plumule
- The plumule is the embryonic shoot that grows upward and develops into the stem and leaves.
Common Mistakes to Avoid
- Thinking seeds need sunlight to start germinating. Most seeds begin sprouting underground and mainly need water, oxygen, and the right temperature before leaves appear.
- Planting seeds too deeply. If a seed is buried too far down, the shoot may use up stored energy before reaching light.
- Overwatering seeds. Water is needed for imbibition, but soaked soil can block oxygen and slow or stop respiration.
- Assuming the seed coat becomes the first root. The seed coat splits open, but the radicle is the structure that grows out and becomes the root.
Practice Questions
- 1 A student plants 40 bean seeds, and 32 sprout after one week. What is the germination percentage?
- 2 A seedling grows from 2.0 cm tall to 8.5 cm tall in 5 days. What is its average growth rate in cm per day?
- 3 A tray of seeds is kept warm and moist, but the soil is completely waterlogged. Explain why many seeds may fail to sprout even though water is present.