1. Seed Dispersal

2. After fertilization the petals, stamen and sepals fall off.
The ovule turns into a seed, the fertilized egg inside develops into an embryo plant.
Cotyledon:
Food store
Testa:
tough seed coat
Plumule:
Embryo shoot
Micropyle:
Hole made by pollen tube
Embryo
plant
Radicle: Embryo root

3. Water leaves the seed, it dehydrates and becomes dormant because metabolic reactions stop. The ovary develops to become a fruit.
Fleshy wall
of the ovary
(yes, you are eating an adapted ovary when you
crunch into an apple!
seed

4. Seeds can be dispersed by: Wind Water Mechanical Animals
Seeds need to be dispersed away from the parent plant in order to reduce competition for space, light, nutrients and water.
Seeds can be dispersed by:
Wind
Water
Mechanical
Animals

5. Germination

6. The seed contains the embryo plant and cotyledons (starch stores)
Testa
(tough seed coat)
Water enters the seed through the micropyle and activates enzymes.
The water also softens the testa to allow it to split.
Plumule
(embryo shoot)
Radicle
(embryo root)
Cotyledon
(storage of food for the embryo
plant)
Micropyle
(hole made by the pollen tube)

7. Enzymes are used in seed germination
Plumule
The enzymes break starch down into maltose and then glucose. The glucose is used in respiration to provide energy for growth
starch
amylase
secreted
embryo plant
absorbed
maltose
Radicle
This is the first part to grow out of the seed as it needs to absorb more water

8. Whilst germinating the plant uses food stores in the cotyledon to provide energy for growth
light
The seedling can now photosynthesise and make its own food
germination
Plant growth and development
soil

9. Changes in dry mass of the germinating seed:
Seed loses weight as it uses up starch stores in the cotyledons as the seedling cannot photosynthesise yet
Days
Dry mass/g
Weight increases as the seedling can photosynthesise and plant grows
Dry mass is the mass of solid matter with all water removed

10. Conditions required for germination
4oC A
moist
dry
Warm B C D E
Oxygen present
No oxygen
No light
Pyrogallol (absorbs oxygen)