3.2 Fruits & seeds Flashcards
State the meaning of the term, “fruit”
A structure that develops from the ovary after fertilisation
Fruit contains the seed
State the meaning of the term, “seed”
A seed develops from the ovule after fertilisation
Seed contains the plant embryo
State the function of a fruit
Distribution and protection of the seed
May impose dormancy
State the function of a seed
Distribution and protection of the embryo
May impose dormancy
Gives rise to new plants
Describe the means by which seeds are dispersed (4)
Wind (samaras (winged seeds), parachute, censer)
Water
Explosive
Animals (attachment, scatter-hoarding, frugivory)
Describe the structure of a seed
Testa
Hilum
Micropyle
Endosperm
Embryo
What does the Embryo consist of?
Plumule
Epicotyl
Cotyledons
Hypocotyl
Radicle
Funicle
What is the testa?
The outer, protective coat of a seed.
Holds seed contents together.
What is the hilum?
The attachment scar where the ovule was attached to the ovary
What is the micropyle?
Small pore next to hilum – allows water and oxygen to enter seed to trigger germination
What is the endosperm?
Starchy food reserve
What is the embryo?
A young, developing plant inside a seed.
Embryo: What is the plumule?
The embryonic shoot
Embryo: What is the epicotyl?
The stretch of stem-like tissue above cotyledons
Embryo: What is the cotyledon?
The seed leaf or leaves (dicots have two, monocots have one)
Storage of starch for the developing embryo.
Allows photosynthesis in epigeal germination.
Embryo: What is the hypocotyl?
The short stretch of stem-like tissue below cotyledons
Embryo: What is the radicle?
The embryonic root
Embryo: What is the funicle
Connects the seed to the carpel wall
What is epigeal germination?
Cotyledons appear above the ground.
The hypocotyl elongates and drags the cotyledons above the surface of the soil
These plants typically have smaller cotyledons so deploy true leaves sooner to start photosynthesis
Testa shrivels up underground
e.g. Phaseolus vulgaris (French bean)
What is hypogeal germination?
Cotyledons remain below the ground.
(The epicotyl elongates and the cotyledons remain underground)
The cotyledons are typically large food stores that allow the plant to get a head start without photosynthesis
e.g. Vicia faba (Broad bean)
Name TWO mechanisms by which seeds are dispersed by wind:
A blade or wing which spins like a “helicopter” - flutters and spins to the ground
Parachutes with feathery appendages (drift on wind currents)
