Biology Lesson 3.4

Lesson 3.4 Seeds

Seeds are where the baby plant or embryo is found

Parts of a seed:

1.Embryo – plant itself

Parts of the Embryo:

a. Plumule (epicotyl) part of shoot that gives rise to the first true leaves

b. Radicle = root system

c. Hypocotyl = becomes the stem of the new plant

Parts of the Embryo:

a. Plumule (epicotyl) part of shoot that gives rise to the first true leavesb.Radicle = root systemc.Hypocotyl = becomes the stem of the new plant

d. Cotyledon(s) = seed leaves of the embryo; provides nutrients for embryo

A seed can have: •one cotyledon called monocots ex. corn

or•two cotyledons called

dicots ex. lima beans

Parts of a seed:1. Embryo – plant itself

2. Seed coat – protective covering some seeds have a double coat some seeds have a hilum or

scar where they attached to the ovary

Parts of a seed:1.Embryo2. Seed coat

3. Endosperm = additional stored food found in monocots that surrounds the embryo.

•Germination - sprouting of the seed

•Dormancy - period of inactivity to help seed not sprout during bad conditions

TermsTerms

•Viability ability of seeds to germinate or (how long a seed can wait and still sprouts)some seeds are viable only a few days others for thousands of years – there is great variation in viability

Indian lotus viable thousands of years

Steps to germination:1. plant absorbs water2. seed coat softens3. root and shoot push through soil4. energy used from cotyledons and

endosperm through process of cellular respiration (starch – sugar-energy)

5. Growth of stem, leaves and root. Cotyledons often grow with stem protecting leaves and providing energy.

Factors affecting germination:1. Moisture – biggie, seed goes

from 10% water to 200% water

2. Oxygen for cellular respiration

3. Temperature – best 68-86F

4. Soil – varies in quality

5. Sunlight –some need to germinate others do not

George Washington Carver

Called “the Plant Do ctor”

Taught agriculture at Tuskegee Institute

Studies chemurgi or ways to use plants to make products