Theme 2 - Plants Flashcards
(31 cards)
Plants
Multicellular eukaryotes Photoautotrophic (most) Sessile or stationary Cell walls Alternation of Generations life cycle Embryo retained inside/on female gametophyte
Primary Cell Wall
Surrounds plasma membrane and cell contents
Made up of cellulose fibres in a matrix of hemicellulose and structural protein
Rigid but flexible
Secondary Cell Wall
Cellulose fibered anchored with lignin
Added strength and rigidity
Waterproof
Hypotonic
Water leaks out (Plasmolysed)
Isotonic
No movement of water (Flaccid)
Hypertonic
Water enters (Turgid)
Gametophyte
Haploid
Multicellular
Produces gametes through mitosis
Sporophyte
Diploid
Multicellular
Produces spores through meiosis
Xylem
Secondary cell wall (lignin (hydrophobic)
Conducts H2O
Dead at maturity
Phloem
Transports sugars and solutes
Source to sink movement
Live at maturity
Vascular Bundles
Xylem, phloem, parenchyma cells and fibre cells
Fibre cells
Sclerenchyma cells provide rigidity to X and P
Bryophytes
Non-vascular Survive in water (poikilohydric drought tolerators) Flagellated sperm Mosses Dominant gametophyte generation Sporophyte on female gametophyte Protonema produces buds (gamete amplification) Moss does an ecosystem service
Seedless, vascular plants
Vascular systems w/ tracheids (no vessels)
Require water for fertilization (flagellated sperm)
Ferns (pterophytes) and Selaginella (lycophytes)
Dominant sporophyte generation
Evolved microphylls (stem outgrowth w/ 1 strand of vascular tissue (only in lycophytes)
Ferns have fronds w/ sporangia in sori on lower side
Both sexes on 1 gametophyte
Archygonia releases antheridiogen
Seed plants
Vascular systems w/ tracheids and vessels
Don’t require water for fertilization
Gymnosperms and Angiosperms
Dominant sporophyte generation (microscopic gametophyte generation)
Ovule produces female gametophyte
Archygonia
Produces eggs
Antheridia
Produces sperm
Microspores
Male gametophyte
2n produces n pollen by meiosis (multicellular); pollen divides by mitosis → non-motile sperm
Megaspores
Female gametophyte Mother cell (2n) produces many haploid (n) archygonia w/ 1 egg each, and polar bodies
Integument
Outer structure of the ovule
Changes to a seed coat after fertilization
Endosperm
3n - formed by fertilization of the polar nuclei by the second sperm cell (only in angiosperms)
Vegetative cell
Forms pollen tube
Generative cell
Produces 2 sperm
Pollen germination
Pollen grain hydrated on female tissue
Pollen tube grows through sporangium