Moss Life Cycle Alternation of generations Defined Plants

Moss Life Cycle

Alternation of generations Defined: Plants alternate between a diploid organism and a haploid organism

Alternation of generations Zygote created from egg & sperm

Alternation of generations Zygote 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 Spore grows into male or female gametophyte Male gametophyte creates sperm

Alternation of generations Sperm & egg create diploid zygote (sporophyte stage restarts)

Alternation of generations Cycle 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 – Dominant stage; Haploid – Looks like mat of green shag carpet • Antheridium: produces male sperm • Archegonium: produces female egg zygote Male gametophyte (creates sperm) • Gametophyte stage – Sperm swims through water to fertilize egg 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 stalk zygote – Sperm swims through water to fertilize egg • Sporophyte stage – Stalk grows out of the zygote 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 capsule stalk zygote – Sperm swims through water to fertilize egg • Sporophyte stage Male gametophyte (creates sperm) Female gametophyte (creates eggs) – Stalk grows out of the zygote – Haploid spores created inside capsule by meiosis

Moss Life Cycle capsule stalk zygote . . • 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 Male gametophyte (creates sperm) Female gametophyte (creates eggs) – Stalk grows out of the zygote – Haploid spores created inside capsule by meiosis – Spores released and grow into new gametophytes

Moss Life Cycle 1) Spores land. Moss gametophytes grow near the ground (haploid stage) capsule stalk zygote Male gametophyte (creates sperm) Female gametophyte (creates eggs) Male gametophyte. (creates sperm) Female gametophyte. (creates eggs)

Moss Life Cycle capsule stalk zygote Male gametophyte (creates sperm) Female gametophyte (creates eggs)

Moss Life Cycle capsule stalk zygote Male gametophyte (creates sperm) Female gametophyte (creates eggs)

Moss Life Cycle 2) Through water, sperm from the antheridium (male gametophyte) will swim to the archegonium (female gametophyte) to create a diploid zygote capsule stalk zygote Male gametophyte (creates sperm) Female gametophyte (creates eggs)

Moss Life Cycle 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 capsule stalk zygote sporophyte zygote Male gametophyte (creates sperm) Female gametophyte (creates eggs)

Moss Life Cycle 4) Sporophyte will create and release haploid spores and grow into new gametophytes 5) The process repeats capsule stalk . zygote Male gametophyte (creates sperm) sporophyte Female gametophyte (creates eggs) Male gametophyte (creates sperm) Female gametophyte (creates eggs)

Moss Life Cycle

Moss Life Cycle Review Place the steps of the moss life cycle in order. ___1___ Spores land. 5 _______ Diploid sporophyte will grow from zygote. 3 _______ Through water, sperm swim from antheridium (male gametophyte) to archegonium (female gametophyte). 2 _______ Moss gametophytes grow near the ground. 6 _______ Sporophyte will create and release spores. 4 _______ Fertilization occurs.

Plant Life Cycle Comparisons Plant 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 SPOROPHYTE male gametophytes sperm, female gameotphytes are microscopic eggs

Review 1) 2) 3) 4) 5) 6) 7) 8) 9) Why do moss grow so low to the ground? Which stage is the main stage of moss: sporophyte or gametophyte? What do moss need to reproduce? . Label the parts of the diagram Using the picture answer the following: • Where are spores created? • Name the haploid stage. • Which grows from the zygote? How are the antheridia and archegonia different? Similar? Meiosis begins which stage of plants? Fertilization begins which stage of plants? How are haploid spores created?