The Stages In Seedling Growth Flashcards
Give an example of germination in which the cotyledons remain below the soil
Broad beans
What is special about the germination of a broad bean?
The cotyledon remains below the soil
What is the first step in the germination of a broad bean
3
The seed absorbs water
Enzymes become active
The radicle begins to grow
What is the second step in the germination of a broad bean?
The radicle bursts out through the testa (seed coat) and grows down due to geotropism
What causes the radicle to grow downwards?
Geotropism
What does the radicle burst out through?
The testa (seed coat)
What is the third step in the germination of a broad bean?
The plumule emerges
When does the plumule emerge?
After the radicle has grown downwards
What is the fourth step in the germination of a broad bean?
The plumule grows up through the soil and its delicate leaves are protected by the plumule being hooked over
What direction does the plumule grow?
The plumule grows up though the soil
How does the plumule protect its delicate leaves?
By being hooked over
Why does the plumule grow upwards while remaining hooked over?
To protect its delicate leaves
What is the fifth step in the germination of a broad bean?
2
The cotyledons (and endosperm, if present) shrivel as food is transferred from them
The radicle develops into the primary root (or tap) root, which forms many side roots
Why do the cotyledons (and endosperm, if present) shrivel?
As food is transferred from them
What does the radicle develop into?
The primary root (tap root)
What is the primary root also called?
The tap root
What does the primary root do?
It forms many side roots
What is the sixth step in the germination of a broad bean?
2
Once above the ground, the plumule straightens up and produces the first true leaves
These soon become green and start to photosynthesise
What happens to the plumule once above ground?
It straightens up and produces the first true leaves
What will soon happen to the first true leaves?
They will become green and start to photosynthesise
List the stages in the growth of a broad bean.
6
- seed absorbs water - enzymes - active - radicle - grows
- Radicle bursts through testa - grows down- geotropism
- plumule emerges
- plumule grows up - hooked - protect - delicate leaves
- cotyledons (and endosperm if present) shrivel - food transferred from them - radicle - primary root (tap root) - forms many side roots
- Once above ground - plumule straightens up - produced first true leaves - become green - photosynthesise
Give an example of germination in which cotyledons move above the soil
Sunflower seeds - fruits with the fruit wall (pericarp) and the seed wall (testa) being fused
What is different about a sunflower seed compared to other seeds?
(2)
Sunflower seeds are fruits
Their fruit wall (pericarp) and their seed wall (testa) are fused together
What is different about the germination of a sunflower seed?
The cotyledons move above the soil
List the steps in the germination of a sunflower seed
4
The cotyledons are forced above the soil
Once above the soil the fruit wall (pericarp) falls to the ground
The cotyledons open out, become green and photosynthesise
The plumule emerges from between the cotyledons and forms the first true leaves
What is the fruit wall called?
The pericarp
What happens to the pericarp when the cotyledons are forced above the soil?
They fall to the ground
What first happens when the cotyledons are above the ground?
The pericarp falls to the ground
What happens after the pericarp falls to the ground?
They become green and photosynthesise
What emerges from between the cotyledons?
The plumule
What does the plumule form during the germination of the sunflower seed?
The first true leaves
