moss life cycle alternation of generations defined: plants alternate between a diploid organism and...
TRANSCRIPT
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?