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Plant Life Cycles Meiosis Review • Cell starts diploid – Ex: Human = 46 chromosomes • Cell divides twice to create 4 cells • End result: Haploid cells – Ex: Human = 23 chromosomes • Cells created: Sperm, egg, pollen Alternation of generations (In general) • Diploid zygote created • Diploid zygote grows into a diploid sporophyte • Haploid spores created by meiosis • Haploid spores grow into haploid gametophytes – Male gametophyte creates haploid sperm – Female gametophyte creates haploid egg • Sperm and egg fuse to make a diploid zygote • Cycle restarts SPOROPHYTE PHASE fertilization meiosis GAMETOPHYTE PHASE Moss Life Cycle 1)Moss gametophytes grow near the ground (haploid stage) 2) Through water, sperm from the male gametophyte will swim to the female gametophyte to create a diploid zygote 3) Diploid sporophyte will grow from zygote 4) Sporophyte will create and release haploid spores ... sporophyte zyg egg ote zyg egg ote zyg egg ote male male female zyg egg ote female female gametophyte male female male 5) Haploid spores land and grow into new gametophytes 6) The process repeats gametophyte ground ... sporophyte zyg egg ote zyg egg ote zyg egg ote male male female zyg egg ote female female gametophyte male female male 5) Haploid spores land and grow into new gametophytes 6) The process repeats gametophyte ground Fern Life Cycle 1) Sporophyte creates and releases haploid spores . . . . Adult Sporophyte (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 zyg egg ote zyg egg ote zyg egg ote 5) Diploid sporophyte grows from the zygote sporophyte ground 6) Fronds uncurls into leaves. 7) Cycle repeats -- Haploid spores created and released . . . ground . 1) Sporophyte creates and releases haploid spores . . . . Adult Sporophyte (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 zyg egg ote zyg egg ote zyg egg ote 5) Diploid sporophyte grows from the zygote sporophyte ground 6) Fronds uncurls into leaves. 7) Cycle repeats -- Haploid spores created and released . . . ground . Plant Life Cycle Comparisons Plant 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 Fern More familiar, leafy plant with clusters of spore producing sacs (sori) Haploid plant body 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 Conifer Life Cycle 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 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) 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 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) 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 Comparisons Plant type Sporophyte Gametophyte Dominant? Moss Stalk with cup at tip, which is where spores are produced. More familiar, carpetlike plant that produces specialized gametes GAMETOPHYTE Fern More familiar, leafy plant with clusters of spore producing sacs (sori) Haploid plant body is size of a finger nail, produces both male and female parts SPOROPHYTE Conifer (Gymnosperm) More familiar- like pine trees, produces male and female cones that produce spores Male gametophytes are pollen grains sperm Female gametophytes are microscopic eggs SPOROPHYTE Angiosperm Life Cycle Flowers contain reproductive organs protected by specialized leaves • Sepals and petals are modified leaves. • Sepals are outermost layer that protects developing flower • Petals can help to attract animal pollinators • A stamen is the male structure of the flower • anther produces pollen grains carpel • filament supports the anther stamen filament anther stigma style ovary • The innermost layer of a flower is the female carpel. • stigma is sticky tip • style is tube leading from stigma to ovary petal • ovary produces female gametophyte sepal Flowering plants can be pollinated by wind 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 – pollination occurs as animal feeds from flower to flower – animal pollination more efficient than wind pollination Fertilization takes place within the flower Male gametophytes, or pollen grains, are produced in the anthers. – male spores produced in anthers by meiosis – each spore divides by mitosis to form two haploid cells – two cells form a Pollen grain single pollen grain Stamen Anther Filament One female gametophyte can form in each ovule of a flower’s ovary • Many cells can be made in the ovule • 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 ovule .. Let’s zoom in… 3. Flowering plants go through the process of double fertilization. female gametophyte egg Double Fertilization sperm polar nuclei ovule 1 sperm fuse with the polar nuclei = triploid (3n) endosperm 1 sperm fuse with the egg = zygote 4. Each ovule becomes a seed. endosperm seed coat Endosperm provides food supply for embryo The surrounding ovary grows into a fruit. embryo 5. Seeds get dispersed 6. Seed germinates, and the cycle starts over ground Plant Life Cycle Comparisons Plant 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 Fern More familiar, leafy plant with clusters of spore producing sacs (sori) Haploid plant body is size of SPOROPHYTE a finger nail, produces both male and female parts Conifer (Gymnosperm) More familiar - like pine trees, produces male and female cones that produce spores Male gametophytes are pollen grains sperm Female gametophytes are microscopic eggs SPOROPHYTE Flowers (Angiosperm) More familiar - apple tree, peach tree, zucchini, berries, etc. Contain flowers that produce male and female spores Pollen grains are male gametophytes 2 haploid cells = pollen tube + sperm SPOROPHYTE Female gametophyte in ovule egg + 2 polar nuclei
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