Transcript The Temple of Flora

The Temple of Flora
Exploring the Biology of Plants
An obvious plant
and another
Characteristics of living things
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Growth
Nutrition
Excretion
Sensitivity
Reproduction
Movement
Respiration
Differences between plants and
animals
Plants
• Have cell walls made of complex
polysaccharides (eg cellulose)
• Make their own food by the process of
photosynthesis, requiring carbon dioxide,
water, light energy and the green pigment
chlorophyll (in structures known as
chloroplasts)
Kingdoms of organisms
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In simpler times:
Plants
Animals
Bacteria
Viruses
Plants and Animals are eukaryotic (ie their cells
contain a nucleus); Bacteria are prokaryotic
(don’t have genetic material in a nucleus)
A historical viewpoint
• Thallophyta
– Algae
– Fungi
• Bryophyta
• Pteridophyta
• Spermatophyta
– Gymnosperms
– Angiosperms
More-recent changes
• Since then:
Fungi no longer considered to be plants
Single-celled organisms may be Protista
‘Algae’ are several groups of unrelated
simple plants (some people don’t
regard them as plants, but we’ll
ignore them)
One group of algae (blue-green) now
considered to be bacteria
Some modern plant groups
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Rhodophyta
Phaeophyta
Chlorophyta
Bacillariophyta
Bryophyta
Pteridophyta
Spermatophyta
(in other words, algae now seen as being several
different groups, and fungi have been removed)
Other ways of grouping plants
• Non-Flowering Plants (Cryptogams)/Flowering
Plants (Phanerogams)
• ‘Algae’, Bryophytes and Pteridophytes are Non-Flowering
Plants; Spermatophytes are Flowering Plants.
• Non-Vascular Plants/Vascular Plants
• ‘Algae’ and Bryophytes are Non-Vascular Plants;
• Pteridophytes and Spermatophytes are Vascular Plants.
Why are fungi not plants?
• Cell wall is not made of polysaccharide
• Do not have chloroplasts and do not
photosynthesise
Groups of fungi
• Mushrooms and toadstools
• Moulds eg Penicillium, Mucor
• Rusts
Fungi
What is missing so far?
• Lichens
• These are composed fungi with symbiotic algae
(rather like a fungus-alga-fungus sandwich)
• The fungus provides protection; the alga
photosynthesises and produces carbohydrates
which can be used by the fungus
• Classified as fungi
• Interestingly, the symbiotic alga is not known in
the free-living state
Lichens
Lichen structure
Algae
• Although once regarded as a single taxonomic
group, now realised that the different classes of
algae are a group of plants in their own right. So,
for example, Class Phaeophyceae now Division
Phaeophyta
• All simple aquatic plants reproducing by means of
spores of one sort or another
• Both marine and freshwater (including soil algae);
multicellular and unicellular; macroscopic and
microscopic
Algae
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Rhodophyta (red algae)
Phaeophyta (brown algae)
Chlorophyta (green algae)
Bacillariophyta (diatoms)
Various other groups: note, classified according to
colour (ie pigments) although their anatomy is also
significantly different
• Blue-green algae (Cyanophyceae), being prokaryotic,
now considered to be bacteria (Cyanobacteria) even
though they have cell walls and photosynthesise
Rhodophyta: Delesseria sanguinea
Rhodophyta: Phycodrys rubens
Phaeophyta: Fucus vesiculosus
Phaeophyta: Laminaria digitata
Chlorophyta: Pediastrum
Chlorophyta: Volvox
Chlorophyta: Spirogyra
Chlorophyta: Ulva lactuca
Chlorophyta: Codium fragile
Bacillariophyta: Diatoms
Oscillatoria – an example of a
Cyanobacteria
Bryophyta
• Mosses (Musci)
• Liverworts (Hepaticae)
Cell Division
• Mitosis – the type of cell division which results in identical
copies of the original cell – found where organisms are
growing or repairing tissues. Also found in simple organisms
that reproduce by ‘binary fission’
• Meiosis – cell division which results in halving the
chromosome number during the production of gametes (‘sex
cells’). As a result, a diploid cell (with two of every
chromosome: 2n) produces haploid cells (with one of each
chromosome: n). Similarly tetraploid cells (4n) produce diploid
ones (2n) and so on.
More terminology
• Gametophyte – the haploid phase in a life
cycle. i.e. a stage which produces haploid
gametes/spores by mitosis.
• Sporophyte – the diploid phase in a life cycle
i.e. a stage which produces haploid
gametes/spores by meiosis.
Life cycles
• In both Bryophytes and Pteridophytes there are two stages in
the life cycle.
• The moss/liverwort ‘plant’ is haploid (the gametophyte) and
lives in damp conditions; the spore capsule is diploid (the
sporophyte) and requires dry conditions for the spores to be
dispersed.
• The fern ‘plant’ is diploid (the sporophyte) and requires moreor-less dry conditions; there is a second stage (the prothallus:
haploid, tiny, and totally different in appearance) and his
requires damp conditions.
Mosses
• Yet more terminology if you want it:
• Acrocarpous mosses form cushions;
Pleurocarpous mosses creep across the
substratum.
Mnium hornum
Mnium hornum
Tortula ruraliformis
Ptilium crista-castrensis
Hypnum cupressiforme
Sphagnum
Marchantia
Pteridophyta
• Psilopsida (Quillworts)
• Lycopsida (Club-mosses: no relation to
‘mosses’)
• Sphenopsida (Horsetails)
• Filicopsida (Ferns)
Psilotum: Quill-wort
Psilotum: Quill-wort
Huperzia selago: Club-moss
Diphasiastrum clavatum: Club-moss
Equisetum: Horsetail
Equisetum: Horsetail
Calamites: Fossil Horsetail
Botrychium lunaria: Moonwort
Dryopteris filix-mas: Male Fern
Dicksonia: Tree Fern
Gleichenia dicarpa
Spermatophyta
• Seed plants
• Gymnosperms (Conifers, cycads etc)
• Angiosperms (Flowering plants):
– Monocotyledons (have one seed leaf eg grasses,
orchids)
– Dicotyledons (have two seed leaves – majority of
flowering plants)