FRUITS, SEEDS & SEED DEVELOPMENT Packet #73 Chapter #30.
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Transcript of FRUITS, SEEDS & SEED DEVELOPMENT Packet #73 Chapter #30.
INTRODUCTION
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A fruit is a mature ovary
As the seed develop, the wall of the ovary thickens
The thickened wall becomes the pericarp.
As the ovary grows, the other flower parts whither away
Fruits protect the seeds and aid in dispersal.
Figure 30.8Page 599
ADAPTATIONS IN FRUIT
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Dandelions & Maple Trees Wind dispersal is
observed Fruits are described as
kites or propellers. Thistles & Grasses
Animal dispersal is observed
Fruits are described as hitchhickers or burrs.
Animal dispersal often provide resources such as fecal material that fertilize the young sporophyte plant.
Figure 30.9Page 599
CLASSIFICATION OF FRUITS
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Simple Fruits Single ovary Can be fleshy or dry
Cherry Soy bean pod
Aggregate Fruits Arise from a single
flower with several carpels
Blackberry Multiple Fruits
Arise from an inflorescence
Many flowers As the walls of the many
ovaries thicken, they fuse and become one fruit
Pineapple
STRUCTURE OF MATURE SEED
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If a common bean seed, a eudicot, is opened, several structures are observed Hypocotyl Radicle Epicotyl Plumule Seed coat endosperm
INTRODUCTION I As the seed matures, it dehydrates until only
about 5 – 15% of its weight is water Enters dormancy
Period of extremely low metabolic rate and suspended growth and development
Increases the chance that germination will occur at a favorable time
Species dependent environmental cues break dormancy Fire; light; water; temperature; digestion through
animal’s gut Sexual reproduction produces seeds with
dispersal and dormancy abilities.
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GERMINATION I
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Water HAS to be absorbed Causes the seed to swell
and rupture seed coat Triggers metabolic
changes in the embryo promoting growth
Radicle (embryonic root) emerges first from the germination seedlings
Hypocotyl pushes way up through the soil Protecting fragile shoot
apex and large cotyledons
Epicotyl spreads “true leaves” and begin photosynthesis
GERMINATION II
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Cotyledons “seed leaves” whither away.
Seedling is vulnerable to many hazards and only a small number survive.