Presentaci

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Kingdom Plantae
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Characteristics of plants

• All Plants Eukaryotic Multicellular Autotrophic
• Used for Classification
• Pigments chlorophyll, carotenoids,
  fucoxanthins, xanthophylls
• Energy Storage starches
• Tissues vascular/non for transporting H2O
  nutrients
• Structures roots, stems, leaves
• Life Cycles/Alternation of Generations
• gametophytes n, sporophytes 2n
• Reproduction presence/absence of seed
• presence/absence of fruit

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Characteristics of plants

• Mainly terrestrial and sessile
• Display an alternation of generations.
• sporophyte and gametophyte are heteromorphic-the
  two generations look and develop differently from
  each other.
• In algae the gametophyte is dominant, in most
  plants the sporophyte is dominant.
• Sugars made via photosynthesis are used as a fuel
  source for growth and also stored as the complex
  carbohydrate starch.
• Cell walls are made of cellulose.
• The Source of the Oxygen Produced by
  Photosynthesis
• Photophosphorylation
• Tracing the Pathway of CO2

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Alternation of Generations
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• Unlike algae, plants have vascular tissue

• It transports water and nutrients throughout the
  plant body
• It provides internal support
• How is vascular tissue arranged
• differently in C3 and C4 plants?

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Making the move to dry land
Required several evolutionary breakthroughs. What
would be the key adaptations needed if you are
going from an aquatic to a terrestrial existence?

Cooksonia
Charophyte
Modern angiosperm
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Terrestrial Challenges Adaptations

• Air offers no support to fight gravity.
• Water is less available which results in
  dessication, immotility of sperm, lack of
  absorption, problems with gas exchange and a need
  for conduction
• Nutrients and water are in soil, but CO2 and
  light are above ground.

• Protective covering to prevent dehydration
• Transport system for water nutrients
• Structural system for support (woody tissue)
• Discrete organs- roots, stems, leaves
  gametangia.
• Protective covering for gametes embryos
• Mechanism to allow sperm to get to egg

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Cladogram of the major plant groups

• 4 Major Plant Groups
• Bryophytes?Nonvascular Plants
• Pteridophytes? Vascular Plants without Seeds
• Gymnosperms? Vascular Plants with Naked Seeds
• Angiosperms? Vascular Plants with Seeds, Flowers,
  and Fruits

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Avascular Plants Mosses, Hornworts Liverworts
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Life Cycle of a Moss
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Seedless Vascular Plants Ferns, Club mosses,
Horsetails and Whisk ferns

• New evolutionary adaptations
• Waxy cuticle
• Gametangia
• Features still absent in this group
• No well developed vascular system
• No support system
• Require water for sperm to swim to egg

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Cuticle waxy covering on the surface of plant
stems and leaves which prevents
desiccation Stoma (stomata) microscopic pore
surrounded by guard cells in the epidermis of
stems and leaves that allows gas exchange
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Figure 29.11  The life cycle of a fern
Fern Life Cycle1, 2
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Seedless plants formed vast coal forests

• Ferns and other seedless plants once dominated
  ancient forests
• Their remains formed coal
• Gymnosperms that produce cones, the conifers,
  largely replaced the ancient forests of seedless
  plants
• These plants remain the dominant gymnosperms
  today

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A pine tree is a sporophyte with tiny
gametophytes in its cones

• Sporangia in male cones make spores that develop
  into male gametophytes
• These are the pollen grains
• Sporangia in female cones produce female
  gametophytes

• When do most plants reproduce? Why?
• Reproduction and rearing of offspring require
  free energy beyond that used for maintenance and
  growth. Different organisms use various
  reproductive strategies in response to energy
  availability.

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Female gametophyte (n)
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Haploid spore cells inovule develop intofemale
gametophyte,which makes egg.
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Male gametophyte (pollen)grows tube to egg
andmakes and releases sperm.
Egg (n)
Sperm (n)
Male gametophyte(pollen grain)
HAPLOID
MEIOSIS
Fertilization
DIPLOID
Scale
Sporangium(2n)
Ovule
Seedcoat
Zygote(2n)
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Pollination
Embryo(2n)
Integument
HAPLOIDPollen grains(malegametophytes)(n)
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Female conebears ovules.
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Zygote developsinto embryo, andovule
becomesseed.
MEIOSIS
Seed
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Male cone producesspores by meiosisspores
develop intopollen grains
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Seed falls toground and germinates,and embryo
grows into tree.
Sporophyte
Life Cycle of a Conifer
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The flower is the centerpiece of angiosperm
reproduction

• Most plants are angiosperms
• The hallmarks of these plants are flowers
• The angiosperm plant is a sporophyte with
  gametophytes in its flowers
• The angiosperm life cycle is similar to that of
  conifers
• But it is much more rapid
• In addition, angiosperm seeds are protected and
  dispersed in fruits, which develop from ovaries

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Stigma
Egg (n)
2
Haploid spore in eachovule develops intofemale
gametophyte,which produces egg.
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Pollinationandgrowthof pollentube
Pollengrain
Pollentube
Ovule
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Haploid sporesin anthers developinto pollen
grains male gametophytes.
Sperm
Pollen (n)
HAPLOID
Meiosis
Fertilization
DIPLOID
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Zygote(2n)
Seedcoat
Food supply
Seeds
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Ovary
Seed germinates,and embryo grows into plant.

Ovule
Embryo(2n)
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Seed
Sporophyte
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Fruit
Double Fertilization
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Polyploidy in plants

• common in plants, especially in 30-70
  angiosperms, are thought to be polyploid.
• i.e. Species of coffee plant with 22, 44, 66, and
  88 chromosomes suggesting ancestral condition (n)
  11 and a (2n) 22, from which evolved the
  different polyploid descendants.
• Polyploid plants are larger, leading to created
  varieties of watermelons, marigolds, and
  snapdragons

Plant Probable ancestral haploid number Chromo Ploidy level
domestic oat 7 42 6n
peanut 10 40 4n
sugar cane 10 80 8n
banana 11 22, 33 2n, 3n
white potato 12 48 4n
tobacco 12 48 4n
cotton 13 52 4n
apple 17 34, 51 2n, 3n
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Origin of Polyploidy

• Accident Doubling? Plants, (vs animals), form
  germ cells from somatic tissues. If the
  chromosome content of a precursor somatic cell
  has accidentally doubled (e.g., as a result of
  passing through S phase of the cell cycle without
  following up with mitosis and cytokinesis), then
  gametes containing 2n chromosomes are formed.
• Naturally occuring? As the endosperm (3n)
  develops in corn (maize) kernels (Zea mays), its
  cells undergo successive rounds (as many as 5) of
  endoreplication producing nuclei that range as
  high as 96n.
• When rhizobia infect the roots of their legume
  host, they induce the infected cells to undergo
  endoreplication producing cells that can become
  128n (from 6 rounds of endoreplication).

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Polyploidy and Speciation

• When a newly-arisen tetraploid (4n) plant tries
  to breed with its ancestral species (a
  backcross), triploid offspring are formed. These
  are sterile because they cannot form gametes with
  a balanced assortment of chromosomes.
• However, the tetraploid plants can breed with
  each other. So in one generation, a new species
  has been formed.

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The structure of a fruit reflects its function in
seed dispersal

• Fruits are adaptations that disperse seeds

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Types of Fruits

• Simple Fruits These fruit types are produced by
  flowers containing one pistil, the main female
  reproductive organ of a flower.
• Aggregate Fruits These fruits types are
  developed from flowers which have more than one
  pistils. They consist of mass of small drupes
  that develops from a separate ovary of a single
  flower.
• Multiple Fruits These fruit types are developed
  not from one single flower but by a cluster of
  flowers.
• Accessory Fruits These fruit types are developed
  from plant parts other than the ovary.

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Types of fleshy fruits Types of fleshy fruits Types of fleshy fruits Types of fleshy fruits Types of fleshy fruits Types of fleshy fruits
True berry have a soft epicarp and the mesocarp and endocarp is fleshly Pepo berry has an outer wall /rind that is formed from receptacle tissue that is fused to exocarp. Hesperidium have thick, leathery exocarp and mesocarp. They have a juicy, pulpy endocarp Aggregate fruit formed from the development of a number of simple carpels from a single flower. Multiple fruit individual ovaries from different flowers get clustered together forming a fruit. Accessory fruit
Tomato, Eggplant, Chili pep, Grape, Cranberry, Pumpkin, Gourd, Cucumber, Melon Orange, Lemon, Lime, Grapefruit Blackberry, Raspberry, Boysenberry Pineapple, Fig, Mulberry, Hedge apple Strawberry
There are fruits that are dry fruits and can be
differentiated as dry dehiscent and dry
indehiscent. Fruit types that contain seeds in a
seedpod that opens up and releases the seeds are
known as dehiscent fruits. Legume Sweet pea,
Beans, Peanut The indehiscent are those fruit
types that do not have a seed pot that opens.
Caryopsis Wheat, Rice , Corn, Rye Nuts The
list of fruits under this type are Walnut, Acorn
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Agriculture is based almost entirely on
angiosperms

• Gymnosperms supply most of our lumber and paper
• Angiosperms provide most of our food
• Fruits, vegetables, and grains
• Angiosperms also provide other important products
• Medications, fiber, perfumes

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Interactions with animals have profoundly
influenced angiosperm evolution

• Angiosperms are a major source of food for
  animals
• Animals also aid plants in pollination and seed
  dispersal

Figure 17.13A-C
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Connection Plant diversity is a nonrenewable
resource

• 20 of the tropical forests worldwide were
  destroyed in the last third of the 20th century
• The forests of North America have shrunk by
  almost 40 in the last 200 years

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• Some plants in these forests can be used in
  medicinal ways

• More than 25 of prescription drugs are extracted
  from plants

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Resources

• Anatomy Morphology of Plant Organs
• The Conquest of Land
• Plant Evolution Tour
• Identification of Major Fruits