Plants and Fungi

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Plants and Fungi
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By the end of this class you should understand

• The differences between algae, plants and fungi,
  and between groups of plants
• The role of vascular structures in organisms
• The reproductive cycles of different plants and
  fungi
• The functions of major structures and materials
  unique to each group

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Algae, Plants, and Fungi

• Algae, plants, and fungi are all different groups
  of living things
• Easy to lump together because they are all
  immobile
• Commonality Cell walls!
• Major differences exist between the three groups

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Structure and Lifestyle

• Algae Photosynthetic and have cell walls but
  their cells are not organized into tissues and
  organs
• Also cant live on land
• Fungi Have cell walls but are not photosynthetic
• Fungi must grow on their food
• Plants are photosynthetic and have tissues/organs

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Apparent Tangent

• If you want to build a building with bathrooms on
  every floor but you dont have good pipes, how
  tall can you make the building?
• If you have good pipes, how tall can you make the
  building?

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Plant Structures

• A major development that separates most plants
  from algae is being vascular
• A vascular plant has xylem and phloem
• Vascular structures help bring water from roots
  up to the leaves, and sugar from leaves to the
  roots
• Xylem brings water up
• Phloem brings sugar down

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Algae, Mosses and Ferns

• There are clearly more advanced structures in
  each of these groups
• Algae are completely nonvascular and live in
  water
• Bryophytes (including mosses) are plants that can
  live on land but are restricted in height because
  they are not vascular
• Ferns are vascular plants
• Date back to before the dinosaurs

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Moss Fern Life Cycle

• Mosses and ferns are clearly related because they
  have similar life cycles
• Rather than produce gametes that immediately
  fertilize to make new plants, their gametes
  undergo mitosis and grow into a gametophyte
• Gametophytes produce gametes through mitosis that
  fertilize to make a sporophyte

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Behold the Multistage Life Cycle!
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Additional Note on Plant Sex

• Some plants are divided into male plants and
  female plants
• One plant produces male gametes or pollen,
  another plant produces female gametes
• Other plants are hermaphrodites, and each plant
  can make both male and female gametes
• Some of these hermaphrodites can self-pollinate,
  others are restricted from doing so

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Plant-Only Structures

• Plants grow their sturdy structures (including
  xylem and phloem) using carbohydrates
• Made from photosynthesis!
• Sugars linked into a mesh called lignin are
  super-durable
• Wood is made with lignin
• Cell walls are usually made of another
  carbohydrate compound called cellulose

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Additional Plant Structures

• Unlike algae, plants can grow on land
• Use lignin to stand up straight
• Use vascular structures to bring water into plant
• Plants have different organs to adapt to living
  on land
• Roots
• Stems
• Leaves

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Plant Groups

• Bryophytes
• Mosses
• Seedless vascular plants
• Ferns
• Seed plants
• Gymnosperms
• Plants with pinecones (pine, redwood, etc)
• Angiosperms
• Flowering and fruiting plants

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Bryophytes

• Mosses and similar small plants such as
  liverworts
• The large part of the plant is usually the
  gametophyte (haploid)
• Produces small sporophytes that produce new
  spores through meiosis
• No xylem/phloem, allow nutrients and water to
  diffuse across its surface
• Thus limited in size

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Seedless Vascular Plants

• Ferns are the most common example of seedless
  vascular plants
• Seedless sporophyte/gametophyte stages
• Vascular have xylem/phloem so can get tall
• The sporophyte is the main plant
• Gametophytes are produced by the small structures
  on the underside of the leaves
• Produce spores that grow into new ferns

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Seed Plants

• Seeds are a more recent invention of plants
• First gymnosperms appeared around 300 million
  years ago
• Seeds are useful because they are durable and can
  wait for the right moment to start growing
• As opposed to new sporophytes which dont have a
  protective covering at any point
• Divided into gymnosperms and angiosperms

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Seed Structure

• Seeds are formed from the fertilization of a
  microspore (pollen) and megaspore (ovule)
• This occurs at the flower
• A seed always has a protective coating around the
  new embryo, stored food for the embryo, and
  usually a delivery system for getting it away
  from the parent plant
• In angiosperms this delivery system is called a
  fruit (not always delicious)

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Gymnosperm

• Gymnos refers to nudity
• The gymnasium is so called because the Greeks
  always exercised naked
• Gymnosperms have naked seeds with no fruit
• Does have a protective armor around the seeds
• These are what we think of as pinecones
• Pines, redwoods, conifers

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Angiosperm

• Angiosperms have flowers for improved
  fertilization
• All other plants must depend on wind
  fertilization only, and some angiosperms do as
  well
• Angiosperms all produce fruits for their seeds
• The fruit serves as a delivery system for
  separating the offspring from parents (seed
  dispersal)
• Reduces competition

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Examples of Seeds and Fruits
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Flower Anatomy

• Flowers vary wildly in structure (of course) but
  all have certain features in common
• Petals (often to attract pollinators)
• Stamen (produce pollen)
• Carpel (holds ovule and allows fertilization)
• Flowers often have some method of attracting
  animals to bring the pollen from one flower to
  another
• Edible pollen
• Nectar
• Structures that resemble female insects

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Generic Flower
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Fungi

• Fungi diverged from protists around the time of
  the Cambrian Explosion (500 mya)
• Fungi are actually more closely related to
  animals than to plants
• Their cell walls are made of chitin, the same
  material in an insect exoskeleton
• Mushrooms, molds, and yeasts are all fungi

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Fungal Anatomy

• All fungi live as tiny interconnected threads
  that grow inside their environment such as the
  soil
• Each thread is called a hypha (plural hyphae)
• A cluster of hyphae is called a mycelium
• The large cap that grows out of the ground is the
  reproductive fruiting body of the fungus which
  remains buried underneath

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Fungus Food

• Fungi grow on their food and digest it externally
• No internal digestive system
• By secreting enzymes on their food, they break it
  down, then absorb the nutrients through their
  cell walls
• Nutrients can diffuse from one cell to the next,
  but they have no vascular system and so are
  limited in height

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Giant Fungi?

• Since fungi have no vascular system they cannot
  grow very tall
• They can, however, grow sideways a very large
  distance
• The largest known organism on earth is a fungus
  that covers at least 4 square miles (over 2000
  acres) in Oregon
• WTF

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Hyphae in Action

• Many fungi do not produce any fruiting body and
  are entirely made of hyphae
• These are called molds or yeasts
• The hyphae are actually haploid and only
  fertilize to make a zygote during mating season
• The zygote immediately undergoes meiosis to make
  more hyphae

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Mushroom Anatomy

• In mushroom species, the stalk and cap are formed
  by the hyphae after they have undergone
  cytoplasmic fusion
• This means that two haploid cells have fused
  their cytoplasm but not their nuclei
• This is written as the cells being nn instead of
  2n
• In the mushroom cap, the nuclei fuse, a zygote is
  formed, and then it undergoes meiosis to make
  more new spores for hyphae

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Fungus Environments

• Fungi grow on their food since they cant chase
  after it
• Fungal spores are spread by the wind and land on
  all sorts of things that are edible
• Many fungi grow in soil eating dead things
• Some fungi grow on our food (bread molds)
• Some fungi grow on our flesh!

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Fungal Infections

• Fungi that grow on a living thing are using a
  parasitic feeding strategy
• In humans and other animals, fungal infections
  can be a source of disease (athletes foot, yeast
  infections, ringworm)
• Many fungi can grow on specific plants and kill
  them for food (often called rusts)
• The famous potato blight in Ireland was a protist
  similar in structure to a fungus

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Fungi as Partners

• Some fungi live in a symbiotic relationship
  (mutually beneficial) with other organisms
• Lichen are a composite organism with algae or
  cyanobacteria living inside the cell walls of
  fungi
• How does each side benefit?
• Some fungi grow on roots of plants, call
  mycorrhizae (singular mycorrhiza)
• How does each side benefit?

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See you in lab!