midterm 2 Flashcards
(232 cards)
1
Q
a:re protists prokayrotes or eukaryotes
A
eurkaryotes
2
Q
prosists overview
A
mostly single celled but can still be very complex
3
Q
status of protist group
A
used to be a kingdom
now they are a group of convience encompassing eukaryotes that are not plants, animals, or fungi
4
Q
3 types of nutriionally diverse protsits
A
photoautothophs
heterotrophs
mixotrophs
5
Q
photoautotrophs
A
contain chloroplasts
6
Q
heterotroph
A
absorb organic molecuels or ingest large food particles
7
Q
mixotrophs
A
combine photosyntehsis and hterothropic nutrition
8
Q
reproductive diversiry in protists
A
asexual and sexual forms
some exhibit alternation of generation
9
Q
mitochondira origin in protists
A
endosymbiosis of aerobic projaryote
10
Q
endosymbiosis
A
when one organisms lives inside antoher organisms
the organsims living insde teh other is the endosymbiont
11
Q
origin of plastids in protsists
A
endosymbiosis of photosyntehtic cyanobacterium
12
Q
endosymbiotic process in prostists
A
it gave rise to teh diversiry we see today
when single celled organsism engulfed other cells, instead of them being digest they served
serial endosymbiosis likely occurred
mitochondria goes back further than plastids do
13
Q
what is the shape of mirtochondria and plastid DNA
A
genmoe made up of a circular chromosome (like bacteria)
14
Q
what indicates that mitocondria and plastids
A
they have cellular machinery including ribosmes to trasncibe and translate their dna into proetins
15
Q
what are the ribosomes or mitochondria and plastids similar to
A
more similar to bacterial ribosomes than to cytoplasmis ribosomes
16
Q
inner membrane of plastids and mitochondria
A
enzymes and transport systems homologous to those found in the plasma membrane of living bacteria
17
Q
how did endysymbiosis transafrom into an organelle
A
infloding of plasma membrane gradually turns into a nucelar envelope
engulfed aerobic bacterium - contains its cell wall, and the new cell wall of what it was enguldfed in - two cell walls seen
later thought to have engulfed photosyntehtic bacterium in which became plastids
integration of photosyntehtic metabolism
all of them had the ability to be photosyntehtic, but some lter lost this ability
18
Q
how many times is it thought primary endosymbiosis occured
A
once
19
Q
cyanobacteria
A
the first photosynthetic organsims
adoption of mitochondria
20
Q
what are red and green alage similar to
A
more similar to each other than other eukaryotes
21
Q
5 supergoups of eukaryotes
A
excavata
SAR clade
archaeplastida
unikonta
unsolved
22
Q
excavata
A
include protists with modoified mitochondria and prostists with unique flagella
the clade excavata is characterised by its cytoskeleton
some members have an “Excavated” feeding groove
this group includes diplomonands, parabasalids, and euglenozoans
23
Q
diplomonads
A
supergroup excavata
live in anerobic enviromenents
derive energy anaerobically - eg. glycolysis
have two equal sized nuclei and multiple flagella
many are parasitic (eg. giaradia intestinalis)
lack plastids
have modififed mitochondria (mitosomes)
don’t have to perfom the aerobic functions of most mitochodnria
24
Q
parabasalids
A
supergroup excavata
have reduced mitochondria called hydrogenosomes that generate some energy anaerobically
include trichomonas vaginalis, the oathgen that causes sexually transmitted infectrions in humans
25
euglenozoans
the main feature distinguishing them as a clade is a spiral or crystalline rod of unknown function inside thier flagella
clade includes kineoplastids and euglenids
26
kinetoplastids
euglenozoans, supergroup excavata
have single mitochondiron with an organised mass of DNA called a kinetoplasts
include free-living species that are consumers of prokyaroets in freshwater, marine, and moist terrestrial ecosystems
some species are parasitic, including trypanosoma
ability to change protein strucutdr eof hte face of the cell
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trypanosoma
kietoplastid, euglenozoan, supergroup excavata
causes sleeping sickness in humans
antoehr pathogenic trypanosome causes chagas' disease
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euglenids
euglenozoans, supergroup excavata
have one of two flagella that emergy from a pocket at one end of the cell
some species can be both autotrophic and htertotrophic (mixotrophs)
29
SAR clade
highly diverse group of protists defined by DNA similarities
the SAR clade is a diverse monophyletic supergoup named for the first letters of its 3 majors clades; stramenopiles, alveolates, rhizarians
30
SAR clade 3 major clades
streamenpiles, alveolates, and rhizarians
31
stramenoplies
SAR clade
includes some of hte most important photosyntehtic organsims on eath
include diatoms, oomycetes, and brown algae
most have a hariy flagellum paired with a smooth flagellum
multicellular stramenopiles - only reproductive cells have flagella
32
diatoms
stramenopile, SAR clade
unicelullar algae with a uniwure two-part glass-like wall of silicon dioxide
major compoenet of phytoplankotn - the diatoms are where htey get their nutrition
they draw caron dioxide in, and when they die they sink to the bototm of teh ocean - they are a massive part of carbon cycling
they can act like CO2 pump by trapping it as an organic molecules
the use of polar marine diatoms cna act as sea ice determinant - can look at the diatoms to understadn the age of sea ice, adn how long parts of the arctic have been frozen
33
oomycetes
stramenopile, SAR clade
include water moulds and their relatives
based on morphology, these organsims were previously classified as fungi
they have cell walls made of celluloses (not chitin)
they have hairy flagella typical of all stramenopiles
descendent from plastid bearing ancestors
acquire nutrients via being parasites or decomposers
34
origin of multicellulartiy
some unicellular eukaryotes developed the ability to interact with one another to give rise to a varierty of multicellular forms
occured independently multiple times - led to algae, plants, funig, and animals
adaptions allowed for the colinisation of land
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brown algae
stramenopile, sar clade
brown algae are the largest and most complex algae
all are multicellular and most are marine
include many species commonly called "seaweed"
most complex multicellular anatomy of all alage
heteromorphic generations
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heteromorphic generations
alternation of generations
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kelp
brown algae, stramenopile, sar clade
live in deep parts of the ocean
they have plant like strucutre; the root-like holdfast anchors teh algae and a stem like stipe that supports lead-like blades
the common ancestor of brown algae and land plants does not have these strucutres
analogous structures
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analogous structures
similar traits in differnet species that evolved independently to perfom the same function
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life cycle of brown alage
if meiosis occurs, zoospores are created and a haploid individual is created
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alveoltates
SAR clade
members of the alveolata clade have membrane enclosed sacs (alveoli) just under the plasma membrane
the function of alveoli in unknown, but all members of this clade have them - potentially for water regulation or stability
alveolates include dinoflagellates, apicomplexans, ciliates
41
dinoflagellates
alveolates, SAR clade
they have two flagella and each cell is reinforced by cellulose plates
1/2 of taxa are not heterotrophic
they are abundant componenets of both marine and freshwater phytoplankton
they are a diveres group of aquatic phototrophs, mixotrophs, and heterotrophs
toxic "red tides" are caused by dinoflagellate blooms
42
apicomplexans
aveolates, SAR clade
parasites of animals, and some cause serious human diseases
they spread infectious cells called sporozoites
one end (the apex) contains a compex of organelles specialsed for penetrating host cells and tissues
most have sexual and asexual stages that require two or more different host species for completion of the life cycle
one type causes malaria
43
malaria
a type of apicomplexans, alveolate, SAR clade
needs two hosts to completes its full lifecycle
44
ciliates
alveolate, SAR clade
a large, varied group of protists
use cilia to move and ffed
they have large marconuclei and small micronuclei
genetic variation results from conjugation, in which two individuals exchange haploid micronuclei
conjugation is a sexual process and is separate from reproduction, which generally occurs by binary fission
45
rhizarians
SAR clade
many species in the rhizarian clade are amoebas
amoebas are protists that move and feed by pseudopodia, extensions of teh cell surface
rhizarian amoebas differ form ameobas in other clades by having threadlike pseudopoaida
rhizarians include radiolarians, forams, and cercozoans
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radiolarians
rhizarian, SAR clade
pseudopodia of radiolarians radiate from the central body
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forams
rhizarian, SAR clade
foramiferans, or forams, are named for porous, genreally multi chambered shells, called tests
pseudopodia extend through pores in teh test
manay forams have endosymbiotic algae
foram tests in marine sediments form an extensive fossil record
the magnesium content in fossilised forams can be used to estimate chagnes in ocean temrpature over time
48
archaeplastida
the superroup that incldues red algae, red algae, and last plants
some green algae are terrestrial, and some are symbiotic with fungi, gives rise to lichen
some green alage are symbiotic with animals
sexual reproduction is common
most green algae have alternating haploid and diploid phases
lots of evidence that green algae are teh precursor to land plants
49
red and green algae
archaeplastida
considered to be the clsoest relatives of land plants
plastids arose after a heterotrohpic protist aacquired a cyanobacterial endosymbiont - primary or secondary endosymbiosis
the photosynthetic descendants of this ancient protists evloved into red algae and green alage
land plants are descended from green algae
50
secondary endosymbiosis
when a eukaryote engulds another eukaryote that has already undergone primary endosymbiosis
51
red algae
archarplastida
red algae are reddish brown in colour due to accessory pigmemts called phycoerythrin, which masks the green of chlorophyll
the colour varies from greenish red in shallow water to dark red or almost black in deep water
red algae are usually multicellular, the largest are seaweeds
52
green algae
named for their green grass chloroplasts
plants are descended from green algare - due to chlorophyll structure
green alage include chlorophytes and charophytes
charophtes are most closely related ot land plants
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chlorophytes/chlorophyceans
most chlorophytes life in freshwater, although many are maring
other chlorophytes live in damp soil, as sumbionts in liches or in envirnoments exposed to intense visible and ultriaviolet light
54
charophyceans
more closely realted to land plants
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routes to larger body sizes
larger size and compelxity evloved in chlrophytes by 3 mechnaisms
formation of colonies of individual cells (pond scum)
formation of true multicellular bodies by cell division and differentiation
repeated division of nuclei with no cytoplsmic division
56
unikonts
include protists that are closely related to fungi and animals
the supergroup unikonta includes animals, fungi, and some protists
includes amoebozoan clade an opisthokont clade
57
amoebozoans
they are amoebas that have love or tube shaped, rather than threadlife. psuedopodia
include slime molds, tubulinids, and entamoebas
58
slime mould
amoebozoan, supergorup unikonta
slime moulds, or mucetozoans, were once thought to be fungi
molecular systematics place slime mouls in the clade amoebozoa
slime moulds include two lineasges, plasmodial slime moulds, and cellular slime moulds
59
why is there a resemblance between slime moulds and funig
convergent evolution
60
plasmodial slime mould
slime mould, amoebozoan, unikonta
blightly coloured
multinucleate (not multi-cellular) feeding stage called plasmodium - has nothing to do with the malaria parasite plasmodium
undergoes cytoplsmic streaming to distribute nutrients an doxygen
can have intelligent characteristics and can exhibit pattern recognition
when food or habitat dries up will put out a fruiting body
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cellular slime moulds
slime mould, amoebozoan, unikonta
form multicellular aggregates in which cells are separated by their membranes
cells feed individually, but can aggregate for form a fruitng body
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tubulinids
amoebozoan, unikonta
tubulinids are a diverse group of amoebozoans with lobe or tube shaved pseudopodia
they are common in unicellular protsits in soil as well as freshwater and marine envirnoments
most tubulinids are heterotrophic and actively seek and concume bacteria and other protists
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entamoebas
amoebozoan, unikonta
parasites of vertebrates and some invertebrates
entamoeba histolytica casues ameic dysentery, third-leading cause of human death due to eukaryotic parasires (malaria is first)
64
opisthokonts
unikont clade
extremely diverse group of eukaryotes tha tinclude animals, fungi, and several groups of protsits
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ecological role of protsits
extremely improtant
they are producers, symbionts, mutlaists, and parasites
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producers
up to 1/4 of the world's photosynthesis is performed by diatoms, dinoflagellates, other algae and protists
they are vital for aquatic and marine food webs
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mutualistic symbionts
termites have a protists symbiont that enables them to digest wood
without that symbiont in their digestive system, they would not be able to feed on teh wood
photosyntehtic symbiotic dinoflagellates in coral reefs
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parasitic symbionts
plasmodium - malaria
pfiesteria - huge fish die off
giardia - beaver fever
karenia - red tides and neurotixic shellfish poisining (NSP)
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impact of a warmer world on marine protists
if sea surface temperature continues to warm due to global warming, this could have a large effect on
marine ecosystems
fishery yields
the global carbon cycle
70
which traits separate plants from algae
3 possible "plant" kingdomw - depends on who you ask
this course goes with teh definiton of embryophytes (plants with embryos)
71
derived traits of plants
major derived traits of plants (ie. lacking in charophytes)
alternation of generation
multicellular, dependent embryos
walled spores produced in sporangia
multicellular gametangia
apicla meristems
some of these traits are lsot in some lineages
some non-plant lineates also have some of these traits (convergence)
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alternation of generation
plants alternate between multiceullular stages, a reproductive cycle called alternation of generations
the gametophyte is haploid and produces haploid gametes by mitosis
fusion of gametse gives rise to teh diploid sporophyte, which produces haploid spores by meiosis
73
multicellular, dependent embryos - derived traits of land plants
as part of a life cycle with alternation of generations, zygotes are retianed within the tissues of the female parent (a gametophyte) and mitosis gives rise to a multicellular embryo
the parental tissue protects the developing enbry from harsh envirnomental conditions
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multicellular, dependent embryos
nutrients are trasnferred from parents to embryo
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walled spores produced in sporangia
the sporophyte (2n) has multicellular organs called sporangia (sporeangium, singluar)
diploid cells called sporophytes undergo meiosis to generate haploid spores
the outer tissue of hte sporangium protects the developing spores until they are released into teh air
plant spores (n) grow into multi-cellular gametophytes by mitosis
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walled spores produced in sporangia
the sporophyte produces spores in organs called sproangia
although charophytes produce spores, these algae lack multicellular sporangia, and their flagellated, water-dispered spores lack sporopollenin
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sporopollenin
spore walls contain sporopollenin which makes them resistant to harsh envirnoments
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multicellular gametangia
plant spores (n) grown into multicellular gametophytes by mitosis
gametes are produced within organs called gametangia
female gametes, called archegonia, produce eggs and are the site of fertilisation
male gametangia, called antheridia, produce and release sperm
79
apical meristems
regions of rapidly growing cells at the end of a root
roots and shoots can elognate to increase exporsue to resources
growth in length is sustianed by the activity of apical meristems
plants sustain continual growth in theri apical meristems
cells from teh apical mersitems differentiate into various tissues
apical merisetms are a derived trait of land plants
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cuticle
derived trait of plants
a waxy covering of hte epidermis
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mycorrhizae
symbiotic assocations between fungi and land plants
may have helped plants withou true roots to obtain nutrients
82
highlihts of plant evolution
fossil evidence suggests that plants were onland at least 470 million years ago
fossilised spores and tissues have been extracted from 450 million year old rocks
fossils of larger strutures, such as sporangium, date 4359 million yeras ago
83
one easy way to distinguish between types of plants
whether they have an extensive vascular system or not
84
are most present day plants vascular plants
yes
85
10 phyla of extant plants
non-vascular
- liverworts
- mosses
- hornworts
vascular seedless
- lycophytes
- monilophytes
vascular seeded
- ginkgos
- cycads
- gnetophytes
- conifers
- flowering plants
86
traits of nonvascular plants
mosses and other non-vascular plants have life cycles dominated by gametophytes
bryopohytes are represented today by three phyla of smalle herbaceious (non-woody) plants
include liverworts, mosses, and hornworts
these groups are tohught to represent the earliest lineages to diverge form the common ancestor of land plants
87
liverworts phylum
hepatophyta
88
mosses phylum
bryophyta
89
hornworts phylum
anthocerophyta
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domiant generation bryophyte phyla
in all three bryophyte phyla, gametophytes are larger and longer-living that sprotophytes
sporopnytes are tyicapply repsent only part of hte time
91
bryophyta vs bryophyte
bryophyta is a phylum that includes mosses
bryophyte is a grade that incldues all non-vascular plants
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bryophyte gametophyte
a spore germinates into a gametophyte composed of protonema (protonemata) and gamete-producing gametophore
gametophyte height is constrained by lack of vascular tissues
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mature broyphyte gametophytes
mature gametophytes produce flagellated sperm in antheridia and an egg in each archegonium
sperm swim though film of water to reach and fertilise egg
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bryophyte sporophyte
gow out of archegonia, and are smallest and simplest sporophytes of all extant plant groups
a sporophyte consists for a foot, seta (stalk), and sporangium, also called a capsule, which discharges spores through a persiotme
hornwort and moss sporophytes have stomata for gas exchange, liverworts do not
95
the ecological and economic importnace of mosses
mosses are capable of inhabiting diverse and sometimes extreme einvirnoments
they are especially common ins moist forestes and wetlands
some mosses mgiht help retain nitrogen in the soil
96
sphagnum
Sphagnum, or “peat moss,” forms extensive deposits
of partially decayed organic material known as peat
Peat can be used as a source of fuel
Sphagnum is an important global reservoir of organic carbon
Overharvesting of Sphagnum and/or a drop in water
level in peatlands could release stored CO2 to the atmosphere
Low temperature, pH, and oxygen level of peatlands inhibits
decay of moss and
other organisms
97
origin of vascualr plants
bryophytes were prevalent fro the first 100 million years of plant evolution - they were the only ones at first
vascular plants originated in the silurian and underwent great diversification during the devonian and carboniferous perionds
vascular plants now dominate non-vascular plants
98
seed plants
gymnosperms
angiosperms
they share a clade
99
is something with spornagia haploid or diploid
diploid
100
seedless vascular pla.nts
the frist vascular plants were seedliss
recall that a seed consists of an embryo and its food supply surrouded by protectice coat
101
byrophytes
liverworts
mosses
hornworts
102
lycophytes
club mosses
spike mosses
quillworts
103
monilophytes
ferns
horsetails
whisk ferns and their relatives
104
two main groups of seedless vascular plants
lycophytes
monilophytes
105
lifecycle of seedless vascular plants
in contrast with bryophytes, sporophytes of seedless vascular plants are the larger generation, as in familiar ferns
the gametophytes are tiny plants that grow on or below the soil surface
106
sorus (sori, plural)
group of sporangium of the bottom on a fern leaf
underneath them are individual sporangia
in teh individual sporangia, misosis will occur and produce haploid cells
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haploid generation of seedless vascular plants
spors grow through mitosis and bcome the young gametophytes
will produce what root like rhizoid structure
fertilisation happens in teh archegonia
108
leaves
organs that increase the surface area of vascular plants
captures solar energy that is used for photosyntehsis
leaves are categogesi by two type - microphylls, megaphylls
109
microphylls
leaves with a singl vein
110
megaphylls
leaves with a highly breanched vascular system
111
hypothesis for micrphyll evolution
more branching occurred along the top of the stalks
as staggered branching became more common, access to light was increased
the branches would've allowed vascularisation
branched bascular strucuted would've been in each leaf - eg. fern leaves
112
sporophylls
sporophylls are modified leaves with sporangia - milestone in plant evolution
sori are lcusers of sporangia on the undersides of sporophylls
strobili are cone like structures formed from groups of sporophylls eg. lycophtes, horesetails, and gymnospersms
113
horsetails
tend to have very small leaves wiht a large stock
high levels of silica
strobilus - sporophylls in cone-like structures
a concetration of spore bearing leaves
114
homospory
most seedless vascular plants are homosporous, producing one type of spore that develops into a bisexual gametophyte
homosporous - only produces one type of spore
115
are all haploid spores the same
yes, one type of spore, one type of gametophyte
this is called homospory
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heterospory
all seed plants and some seedless vascular plants are heterospourus
heterosporous species produce megaspores, which give rise to female gametopytes, and microspores, which rise to male gametophytes
117
can you tell the difference between a megaspore and a microspore?
not without looking inside it
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megaspores
give rise to female gametophytes which will produce eggs
megaspores are not eggs - they are spores
eggs undergo fertilisaiton, spores don't
119
microspore
gives tise to male gametophytes which will produce sperm
120
where are eggs formed
archegonia
121
where are sperm formed
antheridia
122
seedless vascular plant clades
phylum lycophyta
phylum monilophyta
123
what does phylum lycophyta include
club mosses (not true mosses) spike mosses (not true mosses) and quillworts
124
what does phylum monilophyta include
ferns, horsetails, and whisk ferns and their relatives
125
phylum lycophyta
surviving species are smaller herbaceous plants
club mosses, spike mosses, and quillworts have vascular tissues and are not true mosses
many lycophytes are epiphytes
microphylls
126
spike mosses
seedless vascular, phylum lycophyta
small
horizontal growth
often have strobili
heterosporous
127
how are mega and micro phylls concentrated
in cones at the top of leaves
128
phylum monilophyta
ferns are the most diverse seedless vascular plants, with more than 12 000 species - most diverse in the tropics, but also thrive in temperature forests
horsetials were diverse during the carboniferous period, but are now restricted ot the genus equisetum
whisk ferns (psilotum) resemble ancestral vascular plants but are clseoly related to modern ferms
129
ferns
phylum monilophyta
megaphylls (unlike lycophytes)
most are homosporous
most species have stalked sporangia
130
seed plants
a seed consists of an embryo and nutrients surrounded by a protective coat
originated about 360mya
seeds enable their bearers to become dominant producesr in most terrestrial ecosystems
domestication of seed plants had begun by 8,000 years ago and allowed for permanent settlement
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largest seed
lodoicea maldivica (coco de mer)
palm in the seychelles
up to 30kg
132
smallest seed
orchid seens
10^-6g
133
are seed plants a clade
yes
134
traits of seed plants
seeds and pollen are key adaptations to life on land
in addition to seeds, it is common that they have
reduced gametophytes
heterospory
ovules (fertilisation occurs here)
pollen
135
what phase is dominant is mosses
gametophyte
136
what phase is dominant in ferns
sporophyte
137
what phase is dominant in seed plants
sporophyte - gametphyte phase is very reduced - can't be seen without a microscope
138
gymnosperm cones
microscopic gametophytes inside the ovulate cone
139
angiosperm gametophyte location
inside the flowering part of the flowers
140
reduced gametophytes
gametophytes of seed plants are typically microscopoic
remaion within teh sporangia of parental sporophyte
depend on sporophyte for nutrition
protection from uv and drying out
141
heterospory in seed plants
more seedless plants are homosporous
all seed plants are heterosporous
have a megaspornagium and microsporangium
142
megasporagium in seed plants
contain a megaspore that is typically single
gametophyte is female
143
microsporangium in seed plants
contain many microspores
gametphyte is male
144
gametophytic relations in seed plants
female gametophyte devekips within an ovule
male gametophyte develops within a pollen grain
fertilisation of ovule with pollen grain leads to teh development of a seed
145
ovules in seed plants
an ovule consist of a megasporangoium, megaspore, and one or more protectice integuments
integuments are diploid
146
of integuments in gymnosperms megaspores
one
147
of integuments in angiosperm megaspores
two
148
micropyle
where the pollen grain will enter the ovule
149
pollen and production of sperm
microspores develop into pollen grains, which contain male gametophytes
pollination is the transfer of pollen to part of a seed plant contianing ovules
pollen is protected by sporopollenin
flagella is not needed - less reliance on water
150
seeds developemnet
develops from the whole ovule
a seed is a sporophyte embryo, along withi its food supply, packcaged in a protective coat
151
evolution of teh seed
the frist seed plants appear in teh fossil record around 360 mya
these so-called seed ferns had fern like leaves, woody stems, and produced seed-like structures
modern trees emerged a lot earlier than we previously thought
152
secondary growth
growth outard, not just upward
153
evolution of gymnosperms
the earliest fossil evidence of extant gymnosperms are about 305 mya
mynosperms thrived as the climate dried because they had begun to acquire key terrestrial features such as seeds, pollen, and cuticles
most gymnosperms are pollinated by wind, some by smaller aminals
154
what does gymnosperm mean
naked seed
the sees are exposed on sporophylls that form cones (strobili)
155
where are angiosoperm seeds found
in ftruis, which are mature ovules
156
when did seed plants originate
late devonia
380 mya
157
progymnosperms
acquired some adaptations that characterise seed plants but not others
158
archaeopteris
progymnosperm
had charactersitics that are similar to modern day gymnosperms
had a woody stem with secondary growht
did not produce true seeds
159
angiosperms
began to replace gymnosperms near the end of hte mesozoic (251mya)
angiosperms now dominat more terrestrial ecosystems
4/10 of extant phyla of seed plans are gymnosperms
0.3% of extant specise on teh planet but a huge number of individuals
160
boreal forest
importance of numerical domiance/geographical extent of gymnospersm
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4 extant phyla of gymnosperms
cycadophyta
ginkgophyta
gnetophyta
coniferophyta
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what does cycadophyta incldue
cycads
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what does ginkgophyta include
ginkgo biloba - only living species of ginkgophyta
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what does gnetophyta include
3 genera
gnetum
ephedra
welsitschia
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what does coniferophyta incldue
conifers, such as pine, fir, and redwood
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phylum cycadophyta
large cones and palm like leaves
thrived during the mesozoic, but relatively few species exist today
unlike most seed plants, cycads have flagellated sperm
individuals have large cones and palm like leaves
south african cycads are facing extinction - lots of species cycads but they are not thiriving
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phylum ginkgophyta
consists of a single living species - ginkgo balboa
like cyacads it has flagellated sperm
it has a high tolerance to air pollution and is a population ornamental tree
they were used as a decorative tree because they are pretty, but the femal drops fruit that smells really bad so now they sell males
taken as a memory enhacer - ground leaves
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phylum gnetophyta
comprises of 3 genera - gnetum, epherda, and welwitschia
species vary in appearance and some are tropical while others live in deserts
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genus welwitschia
only one species
desert plant
SW africa
leaves among the largest of all extant land plants
ovulate cones
diocecious - different male and female plants
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genus gnetum
~35 species
tropics
cones look like fruit but they're cones
trees, shrubs, vines
look similar to flowering plants - ie. seeds resemble fruits
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genus ephedra
~40 species
arid regions
global
ephedrine
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ephedrine
an extract form ephradra, is a stimulant
stimulates brain, increases heart reate and blood pressure, expand bronchila tubes
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phylum coniferphyta
by far the largest of the gymnosperm phyla
~3/4 of gymnosperms
most conifers are evergreens and carry out photosyntehsis year round
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3 key eatures of the pine life cycle
domincance of the sporophyte generation
development of seeds form fertilised ovules
the transfer of spoerm to ovulens by pollen
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pine life cycle
the pine tree is the sporophyte and produces sporangia in male adn female cones
small cones produce microspores called pollen grains, each of which contain a male gametophyte
the familiar larger cones contain ovules, which produce megaspores that develop into female gametophytes - they are very reduced
it takes well over two years from cone production to mature seed
microspores mature into pollen grains = microgamteophytes (4 celled)
megagametophyets reianted within megapsoragium
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phylum anthrophyta
all angiospersm are in this phylum
antho = flower
phyta = plant
angio = contained
sperm = seed
all angiospersm are considred flowering plants even if we don't see the flower
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flowers
a unique angiosperm structure specialised for sexual reproduction
a flower is a specialised shoot that can have up to 4 rings/types of specialised leaves (sporophylss called floral organs
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ttypes of floral organs
sepals
petals
stamen (anther and filament)
carpels (stigma, style, and ovary with one or more ovules)
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outer whorl
sepals
type of modified leaf
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2nd whorl
petals
modified leaves
main function - attract pollinators
if plants don't need to attract pollinators they have reduced or lack petals
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3 whorl
anthers and stamen
anther and filament make up teh stamen
anther is where the microspores are located
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intermost whorl
carpel
female part has 3 areas
stigma - where pollen lands
style - when pollen down down (the stem part)
ovary - inside there are ovules that will become th seeds for hte next generation
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complete flowers
have
stamen (male part)
carpel (female part)
petals
sepals
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what happens if a flower has both stamen and carpel
it is complete/perfect/bisexual
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incomplete flowers
missing one of the 4 (stamen, carpel, petals, sepals)
eg. grasses don't have petals
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role of fruits
as seeds develop from ovules after fertilisation, the ovary wall thickens, and the ovary matures into a fruit
fruit protects seeds and aids in their dispersal
mature fruits can be fleshy or dry
various adaptations of fruits and seeds help to disperse seeds
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dry fruits
nuts and grains, milkweed
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fleshy fruits
grapes, tomato, plum
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angiosoerm life cycle
sporophyte flowers are composed of both male and female structures
male geametophytes are contained within pollen grains produced by the microsporangia of anthers
female gametophytes, or embryo sacs, develop within an ovule contained within an ovary at the base of a stigma
most flowers have mechanisms to ensure cross pollination between flowers form different plants of the same sperice
angiosperms do not have an archegonia to house the egg
they have an embry sac instead - reduced female gametophyte stages
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double fertilisation
happens in angiosperms - the only time in the plant kingdom this occurs
one sperm cell fuses with the egg to produce a sygote, the other fuses with the two nuclei in teh centre for form endosperm
when the zygote is formed, we are at teh diploid stage agian
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why does double fertilisation occur
may help synchronise the development of the embry and its food supply
ensures that the plant is not wasting nutrients on ovules developing that did not get fertilised
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angiosperm evolution
originated at least 140mya
during the late mesozoic, major breanches of the clade diverged from common ancestor
we do not fully understand how angiosoerms origniated from other seed plants
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archaefructus sinensis
chienes fossil
125mya
had floats - potentially to keep it near the surface in an aqueous envirnoment
seems to be a relaive of the angiosperm, may belong to teh earliest diveging group of antiosperms
eg. it has anterhs and seeds iwthin closer carpels but lacks petals and sepals
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angiospoerm phylogeny
the ancerstor of angiosperms and gymnosperms diverged about 305mya
until the 1990s, most systematists divided flowering plants into two groups based on the number of seed leaves (colyledons) in the enbry
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monocot
one cotyledon
196
dicot
two cotyledon
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cotyledon
number of seed leaves within the embryo of a plant seed
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monocot characteristics
one cotyledon in teh embryo
leaf venetaion - usually parallel
stems have vascular bundles distributed thorughtput the stem
roots tend to be fibrous - no main root
pollen grain with one opening
floral organs usually in multiples of 3
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eudicot characterisitics
two cotyledons
veins tend to be net like - branch pattern - eg. maple leaf
vascular tissue tends to be formed in a vascular ring, allows for secondary growth
taproot - very main root and smaller roots that branch off form it
pollen grains have 3 openings
flower parts usually in multipels of 4 or 5
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angiosperm diversity
the vast majority of species once categorised as dicots form a large clade now known as eudicots
the rest of the former dicots are grouped into 4 small lineages
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basal angiosperms
former dicot
include amborella, water lilies, and star anise
202
magnoliids
former dicot
evolved later
203
products from seed plants
Most food comes from angiosperms
Six crops (wheat, maize, potatoes, cassava, and sweet potatoes) yield 80% of the calories consumed by humans
Modern crop products of relatively recent genetic change form artificial selection
Many seed plants provide wood
Secondary compounds of seed plants are used in medicines
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threats to plant diversity
Destruction of habitat is causing extinction of many plant species
Loss of forests reduces the absorption of atmospheric CO2 that occurs during photosynthesis
Loss of plant habitat is often accompanied by loss of the animal species that plants support
Unprotected ecosystems may contain undiscovered medicinal compounds
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plants hierarchical organisaiton
consits of cells, tissues, and organs
206
what generates primary and secondary growth
different meristems
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what does primary growth do
lengthens roots and shoots
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what does secondary growth do
increases the diameter of stems, and roots in woody plants
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what produces the plant body
growth, morphonegisns, and cell differentiation
210
plant tissue
a tissue is a group of cells consisting of one or more cell types that together perfomr a specailsied function
an organ consists of several types of tissues that together carry out particular functions
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root and shoot system
roots - below ground
shoots - above ground
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what do roots rely on
sugar produced by photosyntehsis in the shoot system
213
what do shoots rely on
water and minerals absorbed by the root system
214
what is the function of a plant stem
they need to get taller to get more sunlight - competition
larger roots - more access to water food and nutrients
structural support
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indeterminate growth
the ability for a plant to grow throughout its life
216
determinante growth
in some plants, when their organs reach a certain size they cease to grow
usually when it starts producing seeds/fuits and then it dies
217
meristems
perpetually embryonic tissue and allow for indeterminante growth
two main types - apical and lateral
218
apical meristems
located at the tips of roots and shotos and at teh axillary buds of shoots
elongat shoots and roots in a rpocess called primary growth
219
lateral meristems
add thickness to woody plants in a process caled secondary growth
220
secondary grwoth
increases the diameter of stems and roots in woody plants
many land plants display seconday growth, the growth in thickness produced by lateral mertsitsm
is a characteristic of gymnosperms and many eudicots, but not monocots
as the platn grows, rings form
221
tilia stem
gwoth rings are xylem
xylem has lignified cell walls - they are sturdy and long living
222
what do elengated intials produce
tracheids
vessel elements
fibers of xylem
sieve-tube elements
companion cells
axially oriented parehchyma
fibres of the pholeme
223
2 types of water conducting cells in teh xylem
tracheids and vessel elements
224
tracheids
dead at maturity
found in the xylem of all vascular plants
no perforating plates
eater goes side to side as it zigzags up
225
vessel elements
dead at maturity
water conducting cell of the xylem
common to most angiosperms and a few gynosperms
align end to end to form long micropipes called vessels
have perforating plate that can stop water is the plant is cut
water mostly goes vertically in them
226
sugar conducting cells of hte phloem
sieve tube elements are alaive at functinal maturity thought they lack organelles
sieve plats are the porous end walls that allow fluid to flow between cells along the sieve tube
each sieve tube element has a companion cell whose nucleus and ribosomes serve both cells
sieve tube plate is similar to the perforating plates in xylem
they have companion cells
the function of these cells is conduction - long and narrow
227
what forms tree rings
where early and late wood meet
228
the study of trees
dendrochronology
analysis of tree ring growth patters
can be used to study past climate change
229
heartwood
where waste products go
less active - eg. not transporting water anymore
vascular rays can be seen spreading out
230
sapwood
the more active part of the stree
231
vascular cambium
produce new cells for xylum and ploem to produce from
232
bark
composed of secondary phloem and layers of periderm
the junction of these is the cork cambium
