Moss Life Cycle

Alternation of generationsDefined: Plants alternate between a diploid organism

and a haploid organism

Alternation of generationsZygote created from egg & sperm

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 generationsCycle

repeats

Group 1: Seedless, Nonvascular Plants• Most primitive of

plants• Live in moist

environments– Swimming sperm

• Examples:– Liverworts– Hornworts– Mosses

Mosses• Because

nonvascular: Grow low to ground– Water transported by

simple diffusion

• Lack true leaves– only 1 cell thick

• Rhizoids anchor into soil

• Early inhabitant of new ecosystems (succession)

Moss Life Cycle• Gametophyte stage

– Dominant stage; Haploid– Looks like mat of green

shag carpet

Moss Life Cycle• Gametophyte stage

– Dominant stage; Haploid– Looks like mat of green

shag carpet• Antheridium: produces

male sperm

Male gametophyte(creates sperm)

Moss Life Cycle• Gametophyte stage

– Dominant stage; Haploid– Looks like mat of green

shag carpet• Antheridium: produces

male sperm• Archegonium: produces

female egg

Male gametophyte(creates sperm)

Female gametophyte (creates eggs)

Moss Life Cycle• Gametophyte stage

– Dominant stage; Haploid– Looks like mat of green

shag carpet• Antheridium: produces

male sperm• Archegonium: produces

female egg– Sperm swims through

water to fertilize egg

Male gametophyte(creates sperm)

Female gametophyte (creates eggs)

Moss Life Cycle• Gametophyte stage

– Dominant stage; Haploid– Looks like mat of green

shag carpet• Antheridium: produces

male sperm• Archegonium: produces

female egg– Sperm swims through

water to fertilize egg

Male gametophyte(creates sperm)

Female gametophyte (creates eggs)

zygote

Moss Life Cycle

Male gametophyte(creates sperm)

Female gametophyte (creates eggs)

zygote

stalk

• Gametophyte stage– Dominant stage; Haploid– Looks like mat of green

shag carpet• Antheridium: produces

male sperm• Archegonium: produces

female egg– Sperm swims through

water to fertilize egg

• Sporophyte stage– Stalk grows out of the

zygote

Moss Life Cycle

Male gametophyte(creates sperm)

Female gametophyte (creates eggs)

zygote

capsule

stalk

• Gametophyte stage– Dominant stage; Haploid– Looks like mat of green

shag carpet• Antheridium: produces

male sperm• Archegonium: produces

female egg– Sperm swims through

water to fertilize egg

• Sporophyte stage– Stalk grows out of the

zygote– Haploid spores created

inside capsule by meiosis

Moss Life Cycle

Male gametophyte(creates sperm)

Female gametophyte (creates eggs)

zygote

capsule

stalk

• Gametophyte stage– Dominant stage; Haploid– Looks like mat of green

shag carpet• Antheridium: produces

male sperm• Archegonium: produces

female egg– Sperm swims through

water to fertilize egg

• Sporophyte stage– Stalk grows out of the

zygote– Haploid spores created

inside capsule by meiosis– Spores released and grow

into new gametophytes

.....

Moss Life Cycle

Male gametophyte(creates sperm)

Female gametophyte (creates eggs)

zygote

capsule

stalk

Male gametophyte(creates sperm)

Female gametophyte (creates eggs)

. .

1) Spores land. Moss gametophytes grow near the ground (haploid stage)

Moss Life Cycle

Male gametophyte(creates sperm)

Female gametophyte (creates eggs)

zygote

capsule

stalk

Male gametophyte(creates sperm)

Female gametophyte (creates eggs)

Moss Life Cycle

Male gametophyte(creates sperm)

Female gametophyte (creates eggs)

zygote

capsule

stalk

Male gametophyte(creates sperm)

Female gametophyte (creates eggs)

Moss Life Cycle

Male gametophyte(creates sperm)

Female gametophyte (creates eggs)

zygote

capsule

stalk

Male gametophyte(creates sperm)

Female gametophyte (creates eggs)

2) Through water, sperm from the antheridium (male gametophyte) will swim to the archegonium (female gametophyte) to create a diploid zygote

Moss Life Cycle

Male gametophyte(creates sperm)

Female gametophyte (creates eggs)

zygote

capsule

stalk

Male gametophyte(creates sperm)

Female gametophyte (creates eggs)

zygotesporophyte

2) Through water, sperm from the antheridium (male gametophyte) will swim to the archegonium (female gametophyte) to create a diploid zygote

3) Diploid sporophyte will grow from zygote

Moss Life Cycle

Male gametophyte(creates sperm)

Female gametophyte (creates eggs)

zygote

capsule

stalk

Male gametophyte(creates sperm)

Female gametophyte (creates eggs)

sporophyte....

4) Sporophyte will create and release haploid spores and grow into new gametophytes

5) The process repeats

Moss Life Cycle

Place the steps of the moss life cycle in order.

___1___ Spores land._______ Diploid sporophyte will grow from zygote._______ Through water, sperm swim from

antheridium (male gametophyte) to archegonium (female gametophyte).

_______ Moss gametophytes grow near the ground._______ Sporophyte will create and release spores._______ Fertilization occurs.

2

3

4

5

6

Moss Life Cycle Review

Plant Life Cycle ComparisonsPlant type Sporophyte Gametophyte Dominant?

Moss Stalk with cup (capsule) at tip, which is where spores are produced.

More familiar, carpet-like plant that produces specialized gametes

GAMETOPHYTE

Fern 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 parts

SPOROPHYTE

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

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

SPOROPHYTE

Review1) Why do moss grow so low to the

ground?

2) Which stage is the main stage of moss: sporophyte or gametophyte?

3) What do moss need to reproduce?.

4) Label the parts of the diagram

5) Using the picture answer the following:

• Where are spores created?• Name the haploid stage.• Which grows from the zygote?

6) How are the antheridia and archegonia different? Similar?

7) Meiosis begins which stage of plants?

8) Fertilization begins which stage of plants?

9) How are haploid spores created?