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SBI3U–DiversityofLivingThings Date:_________________________
KINGDOM PLANTAE
GeneralCharacteristics
UpdatedOctober2016
TheShifttoLand
Plantsfirstappearedonlandbetween400to500millionyearsago.Algaeare
consideredtobetheancestorsofplantsbecausebothplantsandalgaehave:
q chlorophyll
q celluloseintheircellwalls
q storefoodenergyintheformofstarch(animalsandfungistoreenergyinthe
formofglycogen)
WhataretheTerrestrialAdvantages?
q
q
q
q
GreaterCO2availability.Gasesdiffuse10,000timesfasterinairthanwater,sophotosynthesisisfasterinair.
Morelightforphotosynthesis.Lightdecreasesrapidlyinwater.
AirislessdensethanwatersothereislessMECHANICALDAMAGEfromwindthanwater(waveaction).
Initially,noPREDATORStoeattheplants.Plantsinvadedlandfirst.
WhataretheTerrestrialDisadvantages?
q
q
q
q
q
q
DESSICATION-Plantsandanimalsneedconstantaccesstowater.
AirTEMPERATUREcanfluctuatesubstantially.Watermoderatesrapidtemp.changes.
AirislessdensethanwatersoinairplantsencounterGRAVITY(nobuoyancy).
TerrestrialenvironmentmayhavetoomuchlightforSHADEplants,especiallyUVexposure.
Nowaterforspermtoswimtoegg.
InterrestrialenvironmenttheorganismisNOTbathedinwaterandminerals,somust"search"forthem.
AdaptationstoLifeonLand
q
______________-enable__________________tosurvive__________________conditions.
q
_______________"mine"thesoilfor_______________and________________totransporttotheshoot.
q
__________________(pores)inleafepidermisregulate______________________________,to
__________________CO2__________________and__________________water__________________.
q
Resistdryingoutdueto:
(1) havinga__________________(__________________layer)
See back for more
adaptations
(2) theevolutionof_____________________________________________–tohelpprotectgametes
(3) having____________________________________on__________________
q
STEMS,ROOTSandLEAVEScontain__________________TISSUESforwaterandmineraltransport.
PlantEvolutionHighlights
AlternationofGenerations
KeyTerms:
Haploid
Diploid
Sporophyte
Gametophyte Thelifecycleofplantsconsistsoftwogenerations,whichalternatebetweena__________________anda
__________________stage.Thediploidgenerationofaplantiscalledthe__________________.Through
theprocessof_______________,sporophytesproduce______________spores,whichcandevelop________
fertilization.Thehaploidsporegrowsintoaplantbodycalledthe____________________.
____________________producemaleandfemale___________,which__________atfertilizationand
developinto______________________________.Thecyclethenrepeatsitself.
Althoughallplantlifecyclesincludeasporophyteandgametophytegeneration,onestageortheother
ischaracteristicallydominantindifferentplantgroups.
In___________________________plantsthedominantstate(thefamiliargreenplant)isthe
_________________________.In__________________groupsthe__________________________isthe
more___________________generation.In_______________________plants,thegametophyteisreduced
toasmallgroupof___________entirelydependentonthesporophyte.
the seed until it sprouts. The enclosure of the seed within
the ovary is a distinction between angiosperms and
gymnosperms.
The seeds of a gymnosperm are unenclosed
and are sometimes referred to as “naked.”
HAPLOID AND DIPLOID LIFE STAGES
HAPLOID
STAGE
DIPLOID
STAGE
Q
NON-VASCULAR PLANTS
The majority of the life cycle is
spent in the haploid stage.
sporophyte dominance (2n)
mosses
sporophyte
generation
In gymnosperms, single sperm
fuses with an egg to form a zygote
Plant Life Cycles
hat advantage
in an ovule that contains
es doubleALTERNATION OF GENERATIONS
hundreds of other female cells that
are used as a source of nutrients
rtilization give
for the resulting
embryo. By
angiosperms?
1n
meiosis there are two important
contrast,
advantages that double fertilization offers angiosperms. ferns
gymnosperms
angiosperms
VASCULAR SEEDLESS PLANTS
The haploid and diploid stages are
both multicellular and physically
independent from one another.
gametophyte
generation
multicellular
1. Double fertilization
initiates formationeggof endosperm
diploid
only when an eggadults
is fertilized.sperm
Waiting to be sure that
fertilization
an egg is fertilized is a good strategy, because making 2n
endosperm is a large energy investment for a plant.
Gymnosperms invest that energy up front, and nutrients
in ovules that are mitosis
not fertilized
are wasted zygote
because those
and
development
“seeds” do not contain
an embryo. In contrast, angiosperms
do not waste energy forming endosperm in ovules that will
not contain embryos.
GYMNOSPERMS
The evolution of seeds almost
completely eliminates the
prominent haploid stage seen
in mosses and ferns.
ANGIOSPERMS
mi
2. Angiosperms can produce smaller gameteshaploid
than(1n)
Haploid gametes are further
diploid (2n)
reduced in size, enabling more
gymnosperms, because the large energetic reserves will be
gametophyte
dominance
(n)
rapid seed production.
produced only afters fertilization occurs. The small size of
si
the male and female gametes
of angiosperms ensures thatFIGURE 13.29 The generational dominance varies among plant divisions.
multicellular
seeds are produced quickly.gametophyte
FIGURE 12-24 shows that as
different reproductive
in plants,
gametes
sporesstrategies have evolved
plants
developed different
reproductive
sporophyte
dominance (2n)
their gametes havePlant
becomeLife
progressively
Cyclessmaller. Rapid these haploidAscells
fromhave
two individuals
strategies,
they
have
progressed
from
having
a
production1nof seeds
allows angiosperms fertilization
to grow as annual
meiosis
fuse to create a new, diploid zygote. capsule
prominent
haploid
stage
of
life
to
simply
having
2n is, plants
plants (that
that complete
their life cycle from Through mitosis, a new diploid indiALTERNATION
OF GENERATIONS
haploid
gametes. ferns
mosses
gymnosperms
angiosperms
sprouting to seed multicelluar
production in one growing season), vidual is produced.
sporophyte
which is something gymnosperms cannot do. 1n
A plant produces haploid reproducsporophyte
generation
mi
to
is
tos
meiosiszygote
FIGURE 12-24 Overview of the haploid and diploid stages of
sporophyte
tive cells
called
plant
life spores.
cycles. Unlike animal gametes, spores do not have to fuse with
stalk
Outbreeding, the combination of
another cell. A spore will undergo cell dimulticellular
mitosis
stigma, so the stigma is not ready to receive pollen when the
haploid cells from twoeggdifferent
diploid
vision to grow into a new plant. However,
o flowers with
adults
anthers are active. And when the stigma becomes functional,
individuals,sperm
producesfertilization
offspring
this generation is haploid. These haploid
th male and
the
anthers areproduce
no longergametes,
producing pollen. Other plants
with greater genetic diversity plants
eventually
2n
male structures
use
a
molecular
recognition
system to prevent inbreeding:
(that
is,
carrying
a
greater
FIGURE 13.28 Human life cycle compared to
which fuse to produce a diploid zygote.
plant
life
cycle.
proteins
on grows
the surface
stigma will not allow pollen
diversity of alleles) than offspring
rtilize
The zygote
then
intoofa the
diploid
mitosis
and
from
the
same
individual
to
form
that
result
from
inbreeding,
zygote
sporophyte
plant.
These
generations
cana pollen tube.
emselves?
development
the combination of a male and
look quite different from one another. In
Life from
cyclesthe
vary
among
the different
plant have
female gamete
same
individual.
Angiosperms
the more primitive plants, the gametogroups
but
they
share
certain
characgametophyte
TAKE-HOME
12 · 10
a variety of ways to increase the chance that only sperm from
phyte generation
dominates, but MESSAGE
in the
teristics.will
Plants
go through
angamete.
alternaanother individual
fertilize
the female
Plants seed-producing plants the sporophyte
haploid (1n)
Angiosperms undergo a process of double fertilization,
tionand
of generations.
One generation
that have male
female reproductive
structures inisdiploid
different
generation
dominates (Figure 13.29).
(2n)
which ensures
that dominance
a plant does
haploid
(1n)
and
the
other
is
diploid
(2n).
gametophyte
(n) not invest energy in
flowers or even on different individuals, for example, increase
forming endosperm for an ovule that has not been
These are called the gametophyte and
the chance that a pollen grain
landing on a stigma comes Non-Vascular Plants
sis
fertilized.
have
also developed
methods
FIGURE
13.29Angiosperms
The generational
dominance
varies among
plant divisions.
sporophyte generations.
This is very difgametophyte
generation
Q
is
tos
ito
mi
ALTERNATION OF GENERATIONS
PhylogenyofGymnosperms
1.
2.
3.
4.
5.
6.
7.
8.
Whenwerecycadsadominantformofplant?______________________________________
Whichextinctgroupofgymnospermsisthoughttohavegivenrisetoallmodernformsofgymnosperms?
Whichdivisionofgymnospermshasthefewestspecies?______________________________________
Analyzethediagramtodeterminethenumberoflivingspeciesofgymnosperms.____________________
Whatfeatureofgymnospermssetsthemapartfromtheangiosperms?
Whatdoesthewordgymnospermmean?______________________________________
Listtheadaptationsgymnospermshavethatenablethemtoliveindryhabitats.
Listeachdivisionofgymnospermandgiveanexample.