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All land plants share a single common ancestor....
A type of green algae charophyte that is still a mystery
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What are the two types of green algae and how do they differ?
- Chlorophyta- aquatic
- Charophyta - sister to all land plants
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Name the four traits that charophytes share with land plants
- 1. Rings of cellulose-synthesising proteins
- 2. peroxisome enzymes (break down peroxide)
- 3. structure of flagellated sperm is very similar
- 4. formation of a pharagmoplast
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What are the four key traits of land plants?
- 1. Alternation of generations and protected embryos
- 2. walled spores produced in sporangia3. multicellular gametangia (archaegonia=female; antheridia=male)
- 4. apical meristems
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Archaegonia
female gametangia of land plants
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Antheridia
male gametangia of land plants
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Apical Meristems:
localized regions of cell division at the tips of roots and shoots
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How do land plants deal with having limited water availability?
- They have waxy cuticle on exposed surfaces to help prevent water loss
- Exchange gases via stomata
- Tracheids are specialized for water and mineral transport
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True or False: Land plants have both diploid and haploid generations
True
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The diploid generation of land plants is known as:
sporophyte
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The haploid generation of land plants is known as:
gametophyte
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What does Haplodiplontic mean?
- A cycle that produces an alternation of generations in land plants
- Sporophyte (diploid)
- Gametophyte (haploid)
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Which generation (gametophyte/sporophyte) is more prominent in mosses, liverworts and ferns?
the Gametophyte generation
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Which generation (gametophyte/sporophyte) is more prominent in gymnosperms and angiosperms?
Sporophyte generation
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What is the dominant gametophyte generation?
Bryophytes
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Bryophytes
- Dominant gametophyte generatioin
- NON-VASCULAR PLANTS
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What are 5 traits of bryophytes?
- closest living descendants of the first land plants
- include liverworts, mosses, hornworts
- non-tracheophytes; they have no tracheids
- have other conducting cells for moving water and nutrients
- Many bryophytes have mycorrhizal associations-symbiotic relationship between fungi and plants
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Which group contains the closest living descendants of the first land plants?
A. Bryophytes
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Bryophytes include which species?
- Liverworts
- Mosses
- Hornworts
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Are bryophytes vascular or non-vascular?
NON-VASCULAR
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Which of the following type(s) of bryophytes are non-photosynthetic?
a. liverworts
b. mosses
c. hornworts
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What do liverworts and mosses have in common?
- Both are non-photosynthetic
- Sporophyte that depends on the gametophyte for nutrients
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Characteristics of liverworts?
- ancient phylum
- flattened gametophytes with flattened lobes that look like liver
- produce upright structures that contain gametangia
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Characteristics of mosses?
- Alternation of generations
- can withstand droughts
- stomata close in hot, dry conditions thereby minimizing water loss
- have rhizoids (root like structures)
- most mosses highly sensitive to air pollution
- peat moss can absorb up to 25 times their weight
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Which of the bryophytes has rhizoids?
Mosses
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Define stomata:
structures found on some plants (like moss) that close in dry conditions to minimize water loss
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True or false: Moss have xylum
FALSE. They have water conducting tissues, but NOT xylum
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Peat moss can absorb up to ____ times its weight in water
25 times!
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Characteristics of Hornworts:
- Stomata in sporophyte open and close to regulate gas exchange
- photosynthetic
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Which type of bryophyte has stomata in the sporophyte that close to regulate gas exchange?
Hornworts
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Which of the bryophytes is photosynthetic?
Hornworts
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Why is moss so important?
- Help retain nitrogen in the soil
- mosses can live in very cold or dry areas because they can lose most of their body water then rehydrate when moisture is available.
- Sphagnum or peat moss does not readily decay
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What are 4 significant features of Sphagnum (peat moss)?
- Does not readily decay
- Used as a fuel source in Ireland and Canada
- Used as a soil conditioner
- Peatlands contain roughly 30%of the world's soil carbon
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_____ does not readily decay. Low temperatures, lower pH, and oxygen level of ___ lands have preserved corpses for thousands of years!
- Sphagnum (peat moss)
- peat-lands
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Tracheophyte Plants have what three characteristics?
Roots, stems, and leaves
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_____ is the first known vascular land plant. To which clad does it belong?
Cooksonia
Lycophytes
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What type of tissue allows for distribution of nutrients in most plants?
Vascular tissue
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Vasular land plants contain two types of vascular tissues:
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Xylem
conducts water and minerals from roots (only one direction-up)
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Phloem
conducts sucrose and hormones (multi-directional)
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In which region of the plant does vascular tissue develop?
Vacular tissue develops in the sporophyte
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Vascular plants have a reduced (sporophyte/gametophyte)
Gametophyte
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What are the three clades of vascular plants? (LSP)
- Lycophytes
- Pterophytes
- Seed plants (gymnosperm/angiosperm)
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What came first: the stem or the root?
The Stem!
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What purpose do the roots serve?
Structural support and transport capability
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Leaves evolved (only/more than) once.
More than once
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Why is it believed that plants evolved more than once?
- Lycophytes have no vascularization in their leaves
- But ferns and seed plants have true leaves
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Which clade in vascular plants conatin plants with no vascularization in their leaves?
Lycophytes
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_____ are another innovation of some phyla.
Seeds
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What is the purpose of seeds?
- Protect embryo from drying out
- Protection from predators
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What is the dominant sporophyte generation of the vascular clades?
Lycophytes
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_____ were the first plants to have a dominant sporophyte generation
Lycophytes
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Name plants that are classified as Pterophytes
- Ferns
- horsetails
- whisk ferns
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What is the big distinction between pterophytes and lycophytes?
Pterophytes require water for fertlization and are seedless
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From the pterophyte group, ____lose their roots and leaves secondarily
Whisk ferns. (whisk! whisk!)
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_______ have jointed stems with brush-like leaves. The stems have silica deposits in epidermal cells of their ribs.
Horsetails
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____ from the group Pterophyte have fronds and bear sori.
Ferns
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What are sori?
Sporangia located on the underside of fern fronds
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In ferns, the gametophyte is ______ shaped and can do what?
Heart shaped; can live independently
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(Phloem/Xylum) conducts sucrose and hormones, in what direction?
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Which vascular body conducts water? And in which direction(s)?
Xylem
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