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plants and green algae. have a common ancestor (salt&freshwater) from shallow waters around shore 500 MYA. (photosynthetic eukaryotes, complex multicellular bodies) natural selection=drought resistant
How did plants evolve? What is a modern example of an early ancestor?
Adaptations occurred, leading to a organism that did not need water =470MYA (drought). A Coleochaete is similar to an early plant ancestor (disklike, multicellular colonies at the edge of lakes).
When are the oldest land plant fossils from?
When the first land plants appeared, what was the atmosphere like?
abundance of light & CO2. very little pathogens and plant eaters.
Name the struggles early plants had to conquer.
1. maintain moisture
2. support the body
3. anchor the body
4. get resources from land and air
5. reproduce without water
6. disperse offspring without water
*this changed algal structure and life cycle*
Explain an algae.
anchored by a holdfast. no rigid tissues (supported by water). absorbs CO2 and minerals from water. performs photosynthesis. flagellated sperm. offspring dispersed by water. example :Chara (elaborate charophyte)
What do land plants have to prevent moisture loss?
1. Waxy cuticle
2. Stomata: spores of waxy cuticle. allow gas exchange CO2 and O2. two surrounding cells regulate stomata opening. usually open in sunlight to exchange gas. closed at other times to prevent evaporation
Where do land plants get their resources?
1. Soil : chemicals, water, nutrients. plant roots
2. Air : chemicals, CO2, light. leaves
*discrete organs = root, leaf, stem
What region of a plant causes growth, maximizing exposure?
Distributes sugar, water, and minerals around a plant. subterranean and aerial parts connected by.
Name the 2 types of Vascular Tissue.
1. Xylem: dead cells, pipes H20 and minerals from roots to rest of body
2. Phloem: living cells, distribute sugars from leaves to rest of body
Are all plants embryophytes?
Yes, they have multicellular dependent embryo.
*Fertilized egg (zygote) develops into embryo while attached to parent
What is a pollen grain? Is moisture required?
Structure in Pines/Flowering plants containing sperm producers. carried close to egg by wind/animals. Moisture is not required
What are in the haploid phase of a plant?
Sperm/egg (gametophyte). spores.
What are in the Diploid phase of a plant?
Zygote, Sporophyte, Embryo, Sporangium (Ovule in a angiosperm)
What is a sporangium?
where meiosis occurs. haploid spores develop. seeded plants= sperm/egg cells
Define a spore.
call that can develope into a new organism without fusing without another.
How did early plants and present day mosses and ferns disperse their offspring?
tough walled spores. seedless plants use spores.
Define a seed.
plant embryo packaged with a food supply, protective covering. dispersed by wind/animals. protected from elements.
When did land plants originate?
470 MYA. BRYOPHYTES. seedless nonvascular. include mosses, liverworts, Hornworts. lack true roots/leaves/lignified cell wall. flagellated sperm only swim cm. dense mats. support each other.
When did Seedless Vascular Plants originate?
425 MYA. LYCOPHYTES (club mosses, spike mosses, quillworts) and MONILOPHYTES (ferns, horestails, whisk ferns). lignin hardened vascular tissue (support/height). Require moisture for fertilization. disperse spores by air.
When did Seeded Vascular Plants originate?
360 MYA. GYMNOSPERMS AND ANGIOSPERMS. 90% of living species now. gymnosperms earliest. Key adaptations = seeds and pollen grains. Does not require water.
"naked seeds" not produced in special chamber. Flourished with dinosaurs in Mesozoic era. Largest clade is Conifers "conebearers".
Include ornamental gingko tree, palmlike cyads, ephedra desert shrubs.
originated 140 MYA. "seed container" develope seeds with protective chamber in complex reproductive structures. Most recent. flowering plants are great majority. Include grasses, flowering shrubs, and flowering trees
Name the main lineages.
1. dependent embryo present (all plants)
2. Lignified Vascular Tissue (rise to most living plants)
3. Seeds (dominate; all living gymno/angiosperms)
4. Flowers (angiosperm)
Human Life Cycle.
only haploid stage is sex cells (gametes)
Plants, Alternation of Gen.
Haploid- gametophyte produces gametes
Diploid- sporophyte produces spores
What dominates the Moss Life Cycle (and nonvascular) ?
gametophyte= larger, more obvious
What dominates the fern life cycle (and 95% of plants) ?
Describe the Carboniferous Period.
359-299 MYA. lycophytes and monilophytes grew in forests of low lying wetlands. (now Eurasia/USA) close to equator. plants remove C02= cooling. plants die. decay, become peat. seawater/sediment covers. pressure/heat= coal
Describe fossil fuels.
oil and natural gas come from marine organisms. burning release CO2= global warming.
What happened during the late Carboniferous Period?
plants are removing CO2 from air= cooling. glaciers. drier climate. Forests disappear. Early Seed Plants form ( with seedless in swamps). Pollen = life on land
Seedless vs. Seeded reproduction.
1. Seedless- flagellated sperm. haploid singlecelled spores must survive as gametophyte before next generation.
2. Seeded- pollen grains, carry sperm producers through air. sporophyte launched ready to grow.
How do seeded plants reproduce?
Make all reproductive steps (spores, eggs, sperm, zygote, embryo) in one special structure (cone).
What is a cone?
modified shoot that serve as a specialized structure that manufactures reproduction.
What do the scales on a cone do?
The scales contain sporangia, which produce spores by meiosis.
What do the spores of seed plants do?
They are NOT released. They develope into gametophytes in sporophyte.
In a Male, what do haploid spores become?
Define a pollen grain.
Male gametophyte in a tough wall.
pollen grain lands on stigma (female reproductive) and undergo mitosis= produces sperm. seed plants sperm reduce to nucleus.
In a female seeded, what do haploid spores become?
haploid spores become ovules (contain egg producing gametophytes).
after pollination, pollen grain grows tube that enters ovule and releases sperm nucleus. forms diploid zygote.
What happens to a diploid zygote in a seeded plant?
undergoes mitosis, becomes sporophyte embryo. Ovule and surrounding tissues mature into seed (seed coat, embryo, food supply).
In pines, many plants have a seed coat that is winglike for dispersal.
What does an angiosperm have that makes it successful?
Define a flower.
short stem bearing modified leaves. house different male and female sporangia. site of pollination and fertilization.
How do we maintain plant diversity?
new crops/improvements (biotech or traditional breeding) ensures food supply. need forests. better existing crops. use new crops from local areas suited for domestication. some are super tolerant of conditions.
How are we destroying crop diversity?
artificial selection, habitat destruction (road division, clear cutting, logging, mining, air pollution) vast land becomes too small to sustain life.
Mitosis vs Meiosis
Mitosis- occurs in nucleus. forms 2 nuclei with with same number of chromosomes as parent.
Meiosis- cells divide to produce sex cells. single cell divides into 4 different cells with half the necessary chromosomes. creates egg and sperm cells
base of flower
encloses flower before opening
part of the stamen (male). holds another up
part of stamen (male). contain male sporangia (makes spores). releases pollen. located as sac on filament
male reproductive. produces pollen. includes anther supported by filament.
female reproductive in the center of flower. includes stigma, style, ovary.
unique angiosperm adaptation. encloses ovules (contain female gametophyte (white egg shaped)). each ovule has sporangium that produces gametophyte and becomes seed.
Define a fruit.
The matured ovary of a flower. Aids in dispersal. Must have seeds
What generation is dominant in angiosperms and gymnosperms?
Name the reasons angiosperms are so successful.
1. Flowers attract animals = more reliable than wind
2. Ability to reproduce quickly. fertile 12 hours after pollination. produce seeds in days or weeks. *typical pine takes years. allows short growing seasons
3. Fruits as seed dispersal
Describe the different fruit shapes.
1. parachutelike = wind
2. hooklike = animal ride
3. fleshy, edible = animal food
What do we use angiosperms for?
1. spices (nutmeg, cinnamon, cumin, cloves, ginger, licorice, pepper)
2. much of our food (corn, rice, wheat, grains. apples, cherries, tomatoes, squash, cucumbers)
How can flowers allocate their resources?
1. Many stamens, no petals; carpel on separate flower = lots of pollen (less certain pollination)*Red Maple
2. Large, vibrant flower = attracts pollinators. scent/color= pollinator goes to same species.
90% of angiosperms use animals for pollinators.
birds, bats, insects, bees, butterflies, moths, beetles
high energy fluid. color/smells mark food.
Describe what certain pollinators like.
birds= bright red/orange, no certain smell
beetles= fruity odors, no certain color
bees= contrasting colors to find nectar (some guides reflect UV light (electromagnet visible to bees))
nightfliers= large, light colors w/ scent. Car. flies/beetl= rot
How else do plants improve pollen transfer (Adaptations)?
1. location of nectar =max exposure
* scotch broom stamen arches over bee as it harvests nectar.
* Columbine nectar only reached with long tongues (butterflies. moths, bees. birds)
3. nat selection favors fidelity of pollinator
How does Ag work?
people domesticate tastiest, easily cultivated, increase production. Artificial Selection
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