1. Notes: Seeds

2. What is a seed?
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food.
The formation of the seed completes the process of reproduction in seed plants.

3. Why are seeds advantageous for plants?
maintain dormancy until better environmental conditions arise
afford protection to young plant at vulnerable developmental stage
contain adequate food supply until photosynthesis is possible
dispersal of plants

4. Skill: draw internal structure of seeds

5. SEED STRUCTURE External Embryo Seed coat (testa) Hilum Cotyledon
Epicotyl / Hypocotyl
Pumule
Radical

6. Seed Coat AKA testa The seed coat protects the embryo
Can be of varying thicknesses, depending on the seed type.

7. Hilum
Scar from the seed being attached to the parent plant

8. Embryo
The embryo is what forms the new plant once the opportune conditions are present.

9. Cotyledon The cotyledon is the first leaf that germinates.
It is filled with stored food that the plant uses before it begins photosynthesis.
Some plants have 1 cotyledon (monocot) and some have 2 cotyledons (dicot).

10. Epicotyl /Hypocotyl The basis for the plant’s stem.
It is known as the epicotyl above the cotyledon and a hypocotyl below the cotyledon.
These grow upward in response to light.

11. Plumule
The shoot tip with a pair of miniature leaves.

12. The Radicle
The part of the seed where the root develops.

13. SEED STRUCTURE Seed coat (testa) Embryo Cotyledon Epicotyl / Hypocotyl
Pumule
Radical

14. SEED DISSECTION MATERIALS Soaked pinto seed Dissecting microscope
Tweezers
Ruler

15. SEED DISSECTION EXTERNAL INTERNAL Draw the external pinto bean
Label structures from notes
INTERNAL
Carefully remove the seed coat.
Gently pull apart the two halves of the seed.
Examine each half with the dissecting microscope
Draw what you see inside the bean
Label structures from notes
REVIEW THE RULES FOR LAB DRAWING IN YOUR STUDENT GUIDE
BE SURE YOU MEASURE AND RECORD THE LENGTH OF YOUR SEED

16. Plumule
Embryo
Cotyledon
Epicotyl
Hypocotyl
Radicle

17. Germination
After seed is formed, dehydration occurs until water is only about 10-15% of its weight
Seed becomes dormant
When conditions become right, the seed will begin to develop into a functional plant

18. Initial process in seed germination
The absorption of water
Release of a plant growth homorne – gibberellin (gibberellic acid)
Gibberellin causes production of amylase, which hydrolyses starch into maltose
Maltose is further hydrolysed into glucose, which can be used in cellelar respiration
The early glucose may also be converted into cellulose to make new cell walls