The Plant Kingdom topic 9 pages 8387

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The Plant Kingdom topic 9pages 83-87

• The Plant Kingdom An Introduction - Learning
  Activity
• Amazing little food factories for themselves and
  most terrestrial food chains
• Retain stem cells ( meristems) for growth through
  out their life.
• Meristem cells are small and reproduce by mitosis
  and cytokinesis

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Plant ClassificationBryophytes

• Mosses have no true roots, only structures
  similar to root hairs called rhizoids.

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More on bryophytes

• Mosses have simple leaves and stems.

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Liverworts are bryophytes

• Liverworts consist of a flattened thallus.

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Bryophytes

• Maximum height is 0.5 ,meters
• Reproductive structures Spores are produced in a
  capsule. The capsule develops at the end of a
  stalk

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Life Cycle of a Moss animation

• Spores produced in capsule, found on a stalk.

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Filicinophytes

• Ferns have
• a rhizome with adventitious roots,
• Leaves
• short woody stems.
• The leaves are usually curled up in buds and are
  often pinnate ( divided up into pairs of
  leaflets).

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Filicinophytes / Ferns

• Maximum height is 15 meters
• Spores are produced in sporangia, usually on the
  underside of leaves
• All have vascular roots, leaves non-woody
  stems.

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Pinnate leaves

• There is a main nerve, called midrib, from which
  the other nerves derive. Reproductive
  strategies
• Cell Cycle Cancer Animation
• Life cycle Flifecycle2

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Coniferophytesconifers

• Conifers are shrubs or trees with roots, leaves
  and woody stems. The leaves are often narrow
  with a thick waxy cuticle

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Produce cones for reproduction
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conifers

• Maximum height is 100 meters
• Seeds are produced. The seeds develop from ovules
  on the surface of the scales of female cones.
  Male cones produce pollen

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Angiospermophytesflowering plants

• Flowering plants are very variable but usually
  have roots, leaves and stems. The stems of
  flowering plants that develop into shrubs and
  trees are woody.

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angiosperms

• Maximum height is 100 meters. Seed are produced.
  The seeds develop from ovules inside ovaries.
  The ovaries are part of flowers. Fruits develop
  from the ovaries, to disperse the seed.

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Flowers. Pistil is female part and stamen is male

• Animations
• Animations

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Photoperiodic control of flowering

• Short day plants
• Long day plants
• Studies have shown that it is not the length of
  time there is light but dark
• Go to study guide page 87
• Flower growers can manipulate light to produce
  flowering plants year round

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Phytochrome and photoperiodism
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Photoperiodism, Gravitropism, and Thigmotropism
AP Biology Unit 5
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Photoperiodism

• How a plant responds (with respect to flowering)
  to the relative amount of light (photoperiod)
• In reality, plants are responding to the relative
  amount of night.

Slide 2 of 15
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• Photoperiodism is a biological response to a
  change in relative length of daylight and
  darkness as it changes throughout the year.
• Hormones such as phytochrome, and others not yet
  identified, probably influence flowering and
  other growth processes.

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Photoperiodism Types of Plants

• 3 different types of plants
• Short Day ? flower when days are short, nights
  are long (Ex. poinsettias, chrysanthemums)
• Long Day ? flower when days are long and
  nights are short (Ex. Spinach, Radish)
• Day Neutral ? flowering does not depend on
  length of day or night (Ex. tomato)

Images taken without permission from
http//www.fernlea.com/xmas/pix/poinsettia.jpg,
and http//www.illinoiswildflowers.info/weeds/plan
ts/garden_radish.htm
Slide 3 of 15
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Question

• Poinsettias are short day plants how could
  nurseries make sure they bloom just before
  Christmas?
• Control the amount of light and dark they
  experience

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Phytochromes

• Plants absorb light via blue-light photoreceptors
  and phytochromes (Pr and Pfr).
• Pr and Pfr play a significant role in the
  flowering and germinating responses
• Experiments into the control of flowering time

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Phytochromes

• Germination and flowering occurs in response to
  red and far-red light
• effects of both lights are reversible
• Pr and Pfr are isomers (alternate forms)
• red light (660 nm) activates Pr to become Pfr
• far-red light (730 nm) activates Pfr to become Pr
  

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Flowering

• Pfr
• inhibits flowering in short day plants
• promotes flowering in long day plants
• Sunlight consists of quite a bit of red light,
  not much far red light
• During the day, which form of phytochrome is in?
• Pfr

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Flowering

• At sunset, most of the phytochrome is in the Pfr
  form
• During the night, Pfr gets converted back into Pr
  or breaks down
• Whether a plant flowers or not depends on the
  amount of Pfr left (which relates to the amount
  of night)

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Plant Hormones
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Phototropism/gravitropism

• http//bcs.whfreeman.com/thelifewire/content/chp38
  /3801s.swf

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Auxins

• Tutorial 38.2 Went's Experiment
• Plant Hormones

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Experiments

• Predict what will happen in each of these
  experiments.

Normal young shoot
Tip removed from shoot
Tip covered with a foil cap
Tip removed and replaced with an agar block
containing auxin
Tip removed and replaced on one side with a small
agar block containing auxin
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Applications of plant hormones
Can you explain the use of hormones in each
diagram. Click to reveal the answer.
Fresh fruits are shipped around the world. Plant
hormones are used to slow the ripening of the
fruit, so they are just ripe as they reach the
supermarket.
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Applications of plant hormones
Can you explain the use of hormones in each
diagram. Click to reveal the answer.
When a gardener takes cuttings from a plant, the
base of each cutting is first dipped into a
rooting compound to stimulate the growth of
roots. Many rooting compounds contain auxin.
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Plants adapt to where they grow

• Xerophytes - plants that are adapted to grow in
  very dry habitats.
• Spines instead of leaves, to reduce transpiration
• Thick stems containing water storage tissue
• Very thick waxy cuticle covering stem, reducing
  water loss

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• Vertical stems to absorb sunlight early and late
  in the day but not at midday when the light is
  most intense
• Very wide spreading network of shallow roots to
  absorb water after rains
• CAM physiology, which involves opening stomata
  during the cool nights instead of during intense
  day heat

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Thick leaves and cuticle
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Hydrophyteswater plants

• Air space in the leaf to provide buoyancy
• Stomata in the upper epidermis of leaf is in
  contact with the air
• Waxy cuticle on the upper surface but not on
  bottom surface
• Small amounts of xylem in stems and leaves

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Leaves

• Tissues of leaves and their function

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• Xylem brings water to replace losses due to
  transpiration

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• Phloem transports products of photosynthesis
  out of leaf. (source to sink)
• Both xylem and phloem are called the vascular
  system of plants. The vein is centrally located
  to be close to all cells.

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phloem
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Transport in phloem

• Phloem is located inside leaves. Used to
  transport sugars, amino acids, and other organic
  compounds from photosynthesis.
• Structures called sieve tubes do the
  transporting.
• This is an active process requiring ATP
• High concentration in sieve tubes of solute cause
  water to move in by osmosis

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Translocation in phloem

• Phloem tissue found throughout plants.
• Links sources and sinks.
• Sources photosynthetic tissue
• Sink roots, fruits, seeds, and leaves
• Sometimes sources turn into sinks and vice versa
  depending on plant needs.

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• This creates a high enough pressure for movement
  where ever the plant needs these products.
• The transport of any biochemical (includes
  sprayed on chemicals) in phloem is called
  translocation.
• Sucrose Transport animation
• Sugar Transport in Plants
• Tutorial 36.1 The Pressure Flow Model

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Food storage in plants

• The excess products of photosynthesis may be
  stored in storage area called tubers.

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Transpiration

• Flow of water from the roots, through the stems
  to the leaves of plants (transpiration)
• Starts with evaporation of water from the cell
  walls of spongy mesophyll.
• Water is replaced with water from the xylem

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Xylem and transport of water

• Google Image Result for http//www.phschool.com/sc
  ience/biology_place/labbench/lab9/images/xylem.gif
  
• Animations

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Structure of xylem
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Transpiration

• LabBench transpiration

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Factors which affect transpiration

• 1. Light causes stomata to open increasing the
  rate of transpiration . Close in darkness, no
  need to absorb carbon dioxide, water conservation

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• 2. Humidity water vapor in air. Because of
  evaporation of water from moist cells walls the
  humidity is usually 100 in the leaf. The lower
  the humidity outside the leaf the faster the rate
  of diffusion of water- higher rate of
  transpiration.

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• 3 Wind
• High wind increases transpiration.
• In still air or light winds rate decreased due to
  higher humidity in plant.

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• 4. temperature
• High temperatures evaporation rates rise.
  Increases rater of diffusion between the air
  spaces inside the leaf and air outside.
• Increases in temperature allow the air to hold
  more water vapor and so reduce the relative
  humidity or air outside the leaf. The
  concentration gradient therefore increases and
  water is lost more rapidly.

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Food storage in plants

• The excess products of photosynthesis may be
  stored in storage area called tubers.

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Monocot and Dicot
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True dicots vs monocots ( animation)
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• Plants Plant Organs Stems
• Primary meristems are located at the tips of
  stems and roots called apical meristems.

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Function of stem

• Connects roots, leaves, and flowers
• Transport materials between them using xylem and
  phloem
• Support the aerial parts (especially xylem in
  woody plants)
• Pith and cortex provide cell turgor

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Terrestrial plant stems/support

• Turgid cells
• Cellulose cell walls
• Xylem tissue which has cell walls impregnated
  with lignin ( woody)

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• Plants Plant Organs - Stems

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Monocot / dicot stems

• Stem organization

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Monocot stems

• In most monocots, the vascular bundles arc
  scattered throughout thc ground tissue.

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Dicot stem

• The stems of most dicots have vascular bundles
  arranged as a ring that divides the ground tissue
  into the outer cortex and inner pith.

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Roots dicots

• In most dicots (and in most seed plants) the root
  develops from the lower end of the embryo, from a
  region known as the radicle. The radicle gives
  rise to an apical meristem which continues to
  produce root tissue for much of the plant's life.

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Monocot root

• By contrast, the radicle aborts in monocots, and
  new roots arise adventitiously from nodes in the
  stem. These roots may be called prop roots when
  they are clustered near the bottom of the stem.

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Roots
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• Roots absorb mineral ions and water from the soil
• Anchor the plant and are sometimes used for food
  storage
• Plants Transport and Nutrition - Water Movement

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Mineral uptake by roots

• Plants absorb potassium, nitrate and other
  mineral ions
• Concentration is lower than inside roots
• active transport
• Root hairs provide surface area for ion uptake

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Water uptake by roots

• High solute concentration in roots therefore
  water moves in to root from soil.
• Two paths
• Symplastic movement from cell to cell through the
  cytoplasm
• Movement by capillary action through cortex cell
  walls called apoplastic

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Nutrients Plants Transport and Nutrition
Nutrients (animation)
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Flowers

• Monocots have their flower parts in threes or
  multiples of three

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• Dicots have their flower parts in fours (or
  multiples) or fives (or multiples).

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Reproduction in flowering plants

• Egg and pollen formation and fertilization
  animation
• Life cycle of cherry (Prunus)

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• The transfer of pollen from the anther to the
  female stigma is termed pollination. This is
  accomplished by a variety of methods. Flower
  color is thought to indicate the nature of
  pollinator red petals are thought to attract
  birds, yellow for bees, and white for moths. Wind
  pollinated flowers have reduced petals, such as
  oaks and grasses.

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Double Fertilization

• The process of pollination being accomplished,
  the pollen tube grows through the stigma and
  style toward the ovules in the ovary ( you need
  to know double fertilization for AP only)
• Life cycle of a lily ( animation )
• Tutorial 39.1 Double Fertilization

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• Observe FLOWERS AND FRUITS - BIOLOGY 2402 IMAGE
  DATABASE

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Pollen tube
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• Monocot seeds will not separate into two Halves.
  Instead, the food is stored around the embryo.
• have one seed leaf which is generally long and
  thin
• Rice wheat corn

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Dicots

• has two halves.
• called cotyledons.
• food stored in the fleshy seed leaves to nourish
  the new plant until its roots and true leaves are
  ready. first two seed leaves look quite different
  from the adult leaves, which will develop later.

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Seeds
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Seeds in a Pod,
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germination

• Requirements proper
• temperature.
• water
• Water-allow vigorous metabolism to begin.
• leach away germination inhibitor
• common among desert annuals. (ABA).
• oxygen
• a preceding period of dormancy (often).

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Metabolic events of seed germination

• Water re hydration -metabolically active.
• Growth hormone gibberellins is produced in the
  cotyledons
• stimulates the production of amylase which
  converts the stored starch into maltose

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• Maltose is converted into glucose needed for
  cellular respiration
• Leaves appear above ground and photosynthesis
  begins.
• Teachers' Domain From Seed to Flower

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Germination in Dicots

• The primary root emerges through the seed coats
  while the seed is still buried in the soil.
• The hypocotyl emerges from the seed coats pushes
  up through the soil.
• bent in a hairpin shape the hypocotyl arch
• as it grows up. The two cotyledons protect the
  epicotyl structures the plumule from
  mechanical damage.

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• Once the hypocotyl arch emerges from the soil, it
  straightens out. This response is triggered by
  light.
• The cotyledons spread apart exposing the
• epicotyl, consisting of
• two primary leaves and the
• apical meristem
• Plant development ( animation)

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Germination in Monocots

• the primary root pierces the seed
• grows down
• primary leaf grows up.
• protected by the coleoptile a hollow,
  cylindrical structure.
• Once the seedling above surface, the coleoptile
  stops growing and the primary leaf pierces it.

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Go back to 3 slides and watch monocot plant
development
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Growth and development in plants

• Root organization
• http//www.wadsworthmedia.com/biology/0495119814_s
  tarr/big_picture/ch25_bp.swf

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Review of topic

• General Human Biology