Fern Life Cycle

Alternation of generationsDefined: Plants alternate between a diploid organism

and a haploid organism

Alternation of generationsZygote created from egg & sperm (fertilization begins sporophyte phase)

Alternation of generationsZygote divides by mitosis to create adult sporophyte

Alternation of generations

Haploid spores created by meiosis (beginning of gametophyte stage)

Alternation of generations

Haploid spores released into air

Alternation of generations

Female gametophyte creates eggs

Male gametophyte creates sperm

Spore grows into male or female gametophyte

Alternation of generations

Sperm & egg create diploid zygote (sporophyte stage restarts)

Alternation of generations

Cycle repeats

Group 2: Seedless, Vascular Plants• Evolutionary Advancement:

Vascular system – allows nutrient transport to

greater heights• Live in moist environments

– Swimming sperm• Structure:

– Rhizoids = primitive roots– Leaves = fronds

• Categories:– Club mosses– Horsetails– Ferns water

glucose

• Sporophyte phase– Dominant stage; Diploid

See appendix B in your text book

Fern Life Cycle

• Sporophyte phase– Dominant stage; Diploid– Fronds house sori (pl.)

See appendix B in your text book

Fiddlehead

Fern Life Cycle

Fiddlehead uncurlingFrond

• Sporophyte phase– Dominant stage; Diploid– Fronds house sori (pl.)

• Sorus (sing.) = Cluster of sporangia

See appendix B in your text book

Fern Life Cycle

• Sporophyte phase– Dominant stage; Diploid– Fronds house sori (pl.)

• Sorus (sing.) = Cluster of sporangia

• Sporangia make spores• Spores created by meiosis• Spores released into air

See appendix B in your text book

Fern Life Cycle

• Sporophyte phase– Dominant stage; Diploid– Fronds house sori (pl.)

• Sorus (sing.) = Cluster of sporangia

• Sporangia make spores• Spores created by meiosis• Spores released into air

See appendix B in your text book

Fern Life Cycle

Sporangia act like catapults

• Sporophyte phase– Dominant stage; Diploid– Fronds house sori (pl.)

• Sorus (sing.) = Cluster of sporangia

• Sporangia make spores• Spores created by meiosis• Spores released into air

See appendix B in your text book

Fern Life Cycle

Sporangia act like catapults

• Sporophyte phase– Dominant stage; Diploid– Fronds house sori (pl.)

• Sorus (sing.) = Cluster of sporangia

• Sporangia make spores• Spores created by meiosis• Spores released into air

• Gametophyte phase– Spore grows into prothallus

See appendix B in your text book

Fern Life Cycle

• Sporophyte phase– Dominant stage; Diploid– Fronds house sori (pl.)

• Sorus (sing.) = Cluster of sporangia

• Sporangia make spores• Spores created by meiosis• Spores released into air

• Gametophyte phase– Spore grows into prothallus– Prothallus contains:

• Archegonium: produces female egg

• Antheridium: produces male sperm

• Sperm swims to fertilize the egg

See appendix B in your text book

Fern Life Cycle

Fern Life Cycle• Sporophyte phase

– Dominant stage; Diploid– Fronds house sori (pl.)

• Sorus (sing.) = Cluster of sporangia

• Sporangia make spores• Spores created by meiosis• Spores released into air

• Gametophyte phase– Spore grows into prothallus– Prothallus contains:

• Archegonium: produces female egg

• Antheridium: produces male sperm

• Sperm swims to fertilize the egg

• Fertilization restarts sporophyte stageSee appendix B in your text book

AdultSporophyte (diploid)

.

..

.

1) Sporophyte creates haploid spores by meiosis. Spores are released from the sori on the back-side of fronds

ground

ground

2) Haploid spores land in the soil

ground

3) From the haploid spores, the prothallus (gametophyte) grows

Let’s zoom in

. .

4) Sperm swim through water from the antheridia (XY) to the archegonia (XX)

Let’s zoom back out

zygote

ground

5) Diploid sporophyte grows from the prothallus

-- prothallus eventually dies

sporophyte

6) Fiddlehead uncurls…fronds open up

ground

7) Cycle repeats…

-- Haploid spores created and released

.

.

..

Place the steps of the fern life cycle in order, from the step started for you:

__ 1 ___ Spores land on soil.

_______ Sporophyte releases spores.

_______ Through water, sperm swim from antheridium to archegonium on prothallus.

_______ Prothallus grows.

_______ Fertilization occurs.

_______ Diploid sporophyte begins to grow.

2

3

45

6

Plant Life Cycle ComparisonsPlant type Gametophyte Sporophyte Dominant Phase?

Moss More familiar, carpet-like plant that produces specialized gametesXX - ArchegoniumXY – Antheridium

Stalk with cup at tip, which is where spores are produced.

GAMETOPHYTE

Fern Haploid plant body (prothallus) is size of a finger nail, produces both male and female parts

More familiar, leafy plant with clusters of spore producing sacs (sori)

SPOROPHYTE

Conifer Pollen grains are male gametophytes sperm, female gameotphytes are microscopic eggs

More familiar- like pine trees, produces male and female cones that produce spores

SPOROPHYTE

Review1) What is the major difference between moss and

ferns?2) What are the leaves of ferns called?3) What is needed for moss and ferns to reproduce?4) Which stage is the main stage of ferns: sporophyte

or gametophyte?5) What stage is created when sperm and egg fuse:

sporophyte or gametophyte?6) Name the gametophyte of ferns.7) Which process begins the gametophyte stage?8) What structure on the fern creates spores?