Plant Life CyclesPlant Life CyclesPlant life cycles alternate between two cycles: Producing spores andtwo cycles: Producing spores and
producing gametes• A two‐phase life cycle is called alternation of generationsgenerations. – Diploid phase – Haploid phaseHaploid phase – Alternates betweenthe two fertilization
SPOROPHYTEPHASE
meiosisGAMETOPHYTE
PHASE
S h t h i di l id
The spore‐producing plant is the mature sporophyte.– Sporophyte phase is diploid – Begins with fertilized egg Spores produced through meiosis– Spores produced through meiosis
The gamete‐producing plant is the mature gametophyte.
fertilization
meiosis
SPOROPHYTEPHASE
GAMETOPHYTE– Gametophyte phase is haploidB i i h
GAMETOPHYTEPHASE
– Begins with spore – Gametes produced throughproduced through mitosis
Life cycle phases look different among various plant groupsplant groups
• Nonvascular plants have a dominant gametophyte phasephase. – Moss gametophytes look like green carpet – Moss sporophytes shoot up as stalk‐like structuresMoss sporophytes shoot up as stalk like structures
sporophyte (2n)
capsulespores (1n)
gametophyte (1n)
1) Moss gametophytes grow near the ground (haploid
2) Through water, sperm from the male gametophyte will swim to the female
3) Diploid sporophyte will grow from zygote
4) Sporophyte will create and release haploid spores
ground (haploid stage)
swim to the female gametophyte to create a diploid zygote
.....Sporophyte XX ‐ ArchegoniumXY ‐ Antheridium
eggegg
zygotezyg
ote
XX Archegonium
egg egg
malemale male malefemalefemalefemalefemale
zygote
zygote
Gametophyte
5) Haploid spores land and grow into new
6) The process repeats
gametophytes
groundGametophyte
Plant Life Cycle ComparisonsPlant Life Cycle ComparisonsPlant type Sporophyte Gametophyte Dominant?
Moss Stalk with cup (capsule) at tip,
More familiar, carpet‐like plant that
GAMETOPHYTE( p ) p,which is where spores are produced.
p pproduces specialized gametesXX ‐ ArchegoniumXY A h idiXY ‐ Antheridium
Fern More familiar, leafy plant with clusters of
Haploid plant body (prothallus) is size of
SPOROPHYTEplant with clusters of spore producing sacs (sori)
(prothallus) is size of a finger nail, produces both male and female parts
Conifer More familiar‐ like pine trees, produces male and female
Pollen grains are male gametophytes
SPOROPHYTE
male and female cones that produce spores
gametophytessperm, female gameotphytes are microscopic eggs
Fern Life CycleFern Life Cycle
The The sporophytesporophyte is the dominant phase for is the dominant phase for seedless vascular plantsseedless vascular plants
Fern spores form in sacs sori on underside of mature– Fern spores form in sacs, sori, on underside of mature sporophytes (fronds).
sporophyte (2n)p p y ( )
sori
A fern gametophyte, or A fern gametophyte, or prothallusprothallus, produces , produces sperm and eggssperm and eggs
gametophyte (1n))
rhizoid
A f h h ll i i h– A zygote forms on the prothallus, growing into the sporophyte.
1) Sporophyte creates and releases haploid spores
..
l
..
AdultSporophyte (diploid)
Ground
2) Haploid spores land in the soil
Ground
3) From the haploid spores, gametophyte grows in the soil
Let’s zoom in…
Ground
4) Sperm swim through water from the male parts (antheridium) to the female parts (archegonia)
Let’s zoom back out…
eggeggzygote
zygote
eggzygote
5) Diploid sporophyte grows from the zygote
sporophyte
Ground
6) Fronds uncurls into leaves.
7) Cycle repeatsHaploid spores created and released‐‐ Haploid spores created and released
...
.
Ground
1) Sporophyte creates and releases haploid spores
..
l
..
AdultSporophyte (diploid)
Ground
2) Haploid spores land in the soil
Ground
3) From the haploid spores, gametophyte grows in the soil
Let’s zoom in…
Ground
4) Sperm swim through water from the male parts (antheridium) to the female parts (archegonia)
L t’ b k tLet’s zoom back out…
eggeggzygote
zygote
eggzygote
5) Diploid sporophyte grows from the zygote
Sporophyte
Ground
6) Fronds uncurls into leaves.
7) Cycle repeats-- Haploid spores created and releasedHaploid spores created and released
...
.
ground
Plant Life Cycle ComparisonsPlant Life Cycle Comparisonsy py pPlant type Sporophyte Gametophyte Dominant?
Moss Stalk with cup at tip, More familiar, carpet‐ GAMETOPHYTEp pwhich is where sporesare produced.
plike plant that produces specialized gametesXX ArchegoniumXX ‐ ArchegoniumXY – Antheridium
Fern More familiar leafy Haploid plant body SPOROPHYTEFern More familiar, leafy plant with clusters of spore producing sacs (sori)
Haploid plant body (prothallus) is size of a finger nail, produces both male and female
SPOROPHYTE
parts
Conifer More familiar‐ like pine trees, produces
l d f l
Pollen grains are male gametophytes
f l
SPOROPHYTE
male and female cones that produce spores
sperm, female gameotphytes are microscopic eggs
Conifer Life CycleConifer Life Cycle
The The sporophytesporophyte is the dominant phase is the dominant phase for seed plantsfor seed plantsfor seed plantsfor seed plants
1) Male and female seed cones grow in adult sporophytes
2) Pollen grains released from the male seed cones‐‐ Pollen is the male gametophyte
Let’s zoom into the female seed cone…
3) Pollen grain sticks to the female ovule
5) Two nuclei transfer into female spore
4) Pollen tube grows from the male spore
5) Two nuclei transfer into female spore‐ one fertilizes the egg
6) Diploid embryo develops (sporophyte stage restarts)6) Diploid embryo develops (sporophyte stage restarts)
7) After seeds harden, the cone reopens and the seeds are released
8) Seed will land
Ground
9) Seedling grows into (sporophyte)…the cycle repeats
Ground
1) Male and female seed cones grow in adult sporophytes
2) Pollen grains released from the male seed cones‐‐ Pollen is the male gametophyte
Let’s zoom into the female seed cone…
3) Pollen grain sticks to the female ovule
5) Two nuclei transfer into female spore
4) Pollen tube grows from the male spore
5) Two nuclei transfer into female spore‐ one fertilizes the egg
6) Diploid embryo develops (sporophyte stage restarts)6) Diploid embryo develops (sporophyte stage restarts)
7) After seeds harden, the cone reopens and the seeds are released
8) Seed will land
Ground
9) Seedling grows into (sporophyte)…the cycle repeats
Ground
Plant Life Cycle ComparisonsPlant Life Cycle ComparisonsPlant Life Cycle ComparisonsPlant Life Cycle ComparisonsPlant type Sporophyte Gametophyte Dominant?
Moss Stalk with cup at tip, which is where spores are produced.
More familiar, carpet‐like plant that produces specialized gametes
GAMETOPHYTE
gametesXX ‐ ArchegoniumXY ‐ Antheridium
Fern More familiar, leafy plant Haploid plant body SPOROPHYTEFern More familiar, leafy plant with clusters of spore producing sacs (sori)
Haploid plant body (prothallus) is size of a finger nail, produces both male and female
t
SPOROPHYTE
parts
Conifer(Gymnosperm)
More familiar‐ like pine trees, produces male and female cones that
Male gametophytes are pollen grainssperm
SPOROPHYTE
female cones that produce spores
spermFemale gametophytes are microscopiceggs
Angiosperm Life CycleAngiosperm Life Cycleg p yg p yFlowers contain reproductive organs protected by
specialized leaves
stamen
filament anther
• Sepals and petals are modified leaves.
• Sepals are outermost layer that protectsd l i fl filament antherdeveloping flower
• Petals can help to attract animal pollinators
carpel style
stigma• A stamen is the male structure of the flower
• anther produces pollen grains
• filament supports the antherovary
filament supports the anther
• The innermost layer of a flower is the female carpel.
ti i ti k ti
petalsepal
• stigma is sticky tip
• style is tube leading from stigma to ovary
• ovary produces female gametophyte
Flowering plants can be pollinated by wind or animalswind or animals
• Wind pollinated flowers have small flowers and large amounts of pollen.
• Animal pollinated flowers have larger flowers and less pollen.
many flowering plants pollinated by animal pollinators y g p p y p
– pollination occurs as animal feeds from flower to flower
– animal pollination more efficient than wind pollination
Fertilization takes place within the flowerMale gametophytes, or pollen grains, are produced in the anthers.
l d d i– male spores produced inanthers by meiosis
– each spore divides byeach spore divides bymitosis to form twohaploid cells p– two cells form asingle pollen grain
Pollen grain
StamenAnther
Stamen
Filament
One female gametophyte can form in each ovule of a flower’s ovary
• Many cells can be made in the ovule
of a flower s ovary
y• One cell becomes the egg• One cell becomes 2 polar nuclei• The rest die
Polar nuclei (2n)
1. Pollen stick to animal or released into wind.
2. Animal finds a new flower to feed on and pollen grains land on the stigma (pollination)
3 Pollen tube grows and 2 nuclei transfer into the ovule3. Pollen tube grows and 2 nuclei transfer into the ovule
..
Let’s zoom in…
3. Flowering plants go through the process of double fertilizationfertilization.
femalegametophyte
egg
sperm
Double Fertilization
ovule
polar nuclei
1 sperm fuse with the polar nuclei = triploid (3n) endosperm1 sperm fuse with the egg = zygote1 sperm fuse with the egg = zygote
d
4. Each ovule becomes a seed.endosperm
seed coat
Endosperm provides food supply for embryo
embryoTh di i t f itThe surrounding ovary grows into a fruit.
5. Seeds get dispersed
6 Seed germinates and the cycle starts over6. Seed germinates, and the cycle starts over
Ground
Plant Life Cycle ComparisonsPlant Life Cycle ComparisonsPlant type Sporophyte Gametophyte Dominant?Moss Stalk with cup at tip,
which is where sporesare produced.
More familiar, carpet‐like plant that produces specialized gametes XX Archegonium
GAMETOPHYTE
XX ‐ ArchegoniumXY ‐ Antheridium
Fern More familiar, leafy plant with clusters of spore
Haploid plant body is size of a finger nail produces
SPOROPHYTEwith clusters of spore producing sacs (sori)
of a finger nail, produces both male and female parts
Conifer More familiar ‐ like pine Male gametophytes are SPOROPHYTEConifer(Gymnosperm)
More familiar ‐ like pine trees, produces male and female cones that produce spores
Male gametophytes are pollen grains spermFemale gametophytes are microscopic eggs
SPOROPHYTE
Flowers(Angiosperm)
More familiar ‐ apple tree, peach tree,
Pollen grains are male gametophytes 2
SPOROPHYTE
zucchini, berries, etc. Contain flowers that produce male and f l
g p yhaploid cells = pollen tube + sperm
Female gametophyte in