Leaves and the Use of Microscopes

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Leaves and the Use of Microscopes

• Unit 1 - Biology

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What is Biology?

• Biology 2 Greek words
• Bios life
• -logy study of
• So biology means.
• Study of life

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Three Major Fields of Biology

• Botany study of plants
• Human Anatomy and Physiology study of the
  structure and function of the human body
• Zoology study of animals

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Why Study Biology?

• You are living
• The food you eat is/was living
• You are surrounded by living things

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BOTANYVascular Plants
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Why Study Botany?

• All of our food comes from plants (2/3 directly
  from plants and 1/3 from animals who eat plants)
• Many drugs and antibiotics used in medicines come
  from plants
• Many plants and plant products are vital to
  industry

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Parts of a Plant

• Flowers the reproductive part of the plant.
• Not all plants have showy flowers and some plants
  dont have any flowers at all. Most plants with
  flowers will produce fruit and seeds.

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Parts of a Plant

• Flowers
• Leaves the food factory of most plants.
• Leaves go through photosynthesis to produce sugar
  for the plant.
• There are many different types of leaves.

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Parts of a Plant

• Flowers
• Leaves
• Stems
• Holds up the leaves and flowers.
• It also transports substances and can transport
  food.

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Parts of a Plant

• There are four main groups of plants based on the
  type of stem
• Tree single, tall, woody stem
• Shrub several low woody stems
• Herb non-woody plant (herbaceous stem)
• Vine woody or herbaceous grows along the
  ground or has tendrils that help it climb

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Types of Stems
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Parts of a Plant

• Flowers
• Leaves
• Stems
• Roots
• Anchors the plant into the ground.
• It absorbs water and nutrients for plant growth
• Stores food.

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Parts of a Plant

• There are two types of root systems
• Taproot system the primary root
• grows straight down and
• stays larger than secondary
• roots (ex carrot, dandelion)

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Parts of a Plant

• There are two types of root systems
• 2. Fibrous root system
• the primary root remains
• small and many
• secondary roots grow
• out in all directions
• (ex grass)

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Special Leaves

• Special leaves have a special design for a
  specific task. These are considered leaves
  because buds appear by them and they have the
  same tissue structure of leaves.
• Tendrils special leaves that
• coil around support structures

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Special Leaves

• Spines on cacti lack chlorophyll
• Leaves of Venus flytrap, sundew, pitcher plant,
  bladderwort designed to trap and digest insects

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Special Stems

• Some stems are mistaken for roots because of
  their location.
• Stolons runners that aid in asexual
  reproduction (strawberries)
• Rhizomes horizontal stems that grow underground
  (ginger, iris)
• Tubers swollen ends of rhizomes that store food
  (potatoes)
• Bulbs vertical underground shoots that store
  food (onions)

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Special Stems
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The External Structure and Function of Leaves
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Organism Hierarchy

• Molecules
• Cells
• Tissues
• Organs
• Systems
• Organism

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Plant Hierarchy

• Molecules C, H, N, O others
• Cells Plant cells with differing organelles
• Tissues Structural, vascular, meristematic
• Organs Leaf, stem, flower, root
• Systems Root and Shoot
• Organism Plant

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Plant Systems

• What is a system?
• A group of structures designed to function
  together as a unit to perform a particular job
  for the organism.

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Plant Systems

• 2 types of systems
• Root system the part of the plant ordinarily
  under ground organ involved - roots
• Shoot system the part of the plant which is
  usually found above the ground organs involved
  stem, leaves, flower

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Leaf Parts

• Blade flat, green portion of the leaf
• Petiole leaf stalk (leaves that lack a petiole
  are sessile leaves)
• Margin edge of a leaf
• Vein carry sap through a plant
• Stipule small leaf-like structure that covers a
  leaf as it is growing

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Three Basic Leaf Types

1. Broad, flat leaves roses, dandelions, maples,
   lilacs
2. Long, narrow leaves grasses, lilies, onions,
   palms
3. Needle-like or scale-like leaves pines, firs,
   cedars, spruces

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Variety in Leaf Shapes

• Broadleaf leaves can be oval, elliptical,
  heart-shaped, arrow-shaped, oblong, ovate, and
  many other types
• Needle-like leaves can be singular or in bundles.
  This is an important feature to use to identify
  them.

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Variety in Leaf Margins

• Three main types of leaf margins are
• Entire smooth and unbroken
• Toothed small or large teeth
• Lobed extensions that stick out

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Where the Petiole Joins the Branch

• Three structures that may be found on a branch
• Stipule
• Bud contains developing leaf
• Bud scale scar markings that show where a bud
  used to be

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Simple vs. Compound Leaves

• Simple leaves have one blade on every petiole
• Compound leaves have more than one blade on every
  petiole
• Compound leaves can have a variety of arrangements

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Leaf Arrangements

• Leaves are arranged so that all leaves on a stem
  will have maximum exposure to sunlight
• Leaves have many different arrangements.
• (Vocab a node is the point where a leaf grows
  from the stem)

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Opposite

• Opposite when 2 leaves grow from the same node
• Attach at right angles to the leaves directly
  above and below them
• Ex maple, mint, coleus

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Alternate

• Alternate only 1 leaf grows from each node
• The leaves alternate sides as they go up the
  branch.
• Ex apple, oak, birch

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Whorled

• Whorled three or more leaves grow from each
  node
• Ex loosestrife, Easter lily

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Rosette (Basal)

• Rosette cluster of leaves grow around the base
  of the plant
• Usually a plant with a rosette arrangement
  doesnt have a stem
• Ex dandelion

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Leaf Venation

• Venation pattern of veins in a leaf
• Parallel veins are parallel to each other
• Pinnate one major vein with smaller veins
  extending
• Palmate 2 or more major veins extending outward
  from one point

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Leaf Venation
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Evergreen vs. Deciduous

• Evergreen foliage remains green year-round
• Deciduous sheds leaves annually
• Coniferous bears cones usually evergreen
• Some examples of deciduous conifers bald
  cypress, European larch, ginkgo
• Evergreen broadleaf trees also exist, normally
  in the tropics.

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Phototropism

• Tropism a plants response to external stimuli
• Individual leaves will orient themselves so that
  each blade is at approximately a 90o angle to the
  light. The petiole twists because there is more
  growth on the side that doesnt have the light.

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Phototropism

• This movement is an example of phototropism the
  growth response of a plant stimulated by light
• Phototropism

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Other Tropisms

• Some other common plant tropisms
• Hydrotropism response to water (roots grow
  toward water)
• Thigmotropism response to touch (ex vines
  wrap around a pole, sensitive plant)

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Other Tropisms

• Geotropism response to gravity can be positive
  or negative (positive roots grow down negative
  stem grows up)
• Heliotropism sun-tracking (ex sunflowers)

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Leaf Anatomy(WKST)
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Cell Structure

• Most cells have three basic parts.
• Cell membrane Separates the inside of a cell
  from the outside
• Nucleus Controls activities in the cell
• Cytoplasm A mixture of fluid and organelles
  between the nucleus and the cell membrane

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Cell Structure

• Plant cells have some components that are not
  found in animal cells.
• Cell wall A rigid layer outside the cell
  membrane that gives structure to a plant cell
  made of cellulose
• Chloroplasts Contain the pigment chlorophyll
  absorb energy from the sun for photosynthesis
• Vacuole A storage area inside of the cell
  (found in some animal cells)

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PHOTOSYNTHESISandCELLULAR RESPIRATIONVideo
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Photosynthesis

• Purpose Make food for the plant
• Occurs in the chloroplasts
• Photosynthesis putting together with light
• All plants that go through photosynthesis have
  chloroplasts regardless of their color.
  Photosynthesis takes place in the chloroplasts.
• Its estimated that plants produce 300 billion
  tons of food each year.

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Formula for Photosynthesis

• light
• carbon dioxide water glucose oxygen
• 54 photons light
• CO2 H20 C6H12O6 O2
• 54 photons light
• 6CO2 6H20 C6H12O6 6O2

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Leaf Practice
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Two Phases of Photosynthesis

• Light Phase Requires light
• Dark Phase Doesnt require light, but can
  happen in the light

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Light Phase

• Solar energy is converted into the chemical
  energy of ATP and NADPH.
• Chlorophyll absorbs the solar energy. Water,
  ADP, and NADP are ingredients for the reaction.
• ATP, NADPH, and oxygen are the products.

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Light Phase

• Energy from the sun splits the water molecule
  into hydrogen and oxygen.
• Hydrogen connects with NADP to form NADPH.
• Oxygen will later be released.
• ATP and NADPH store energy.

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Dark Phase

• Happens in the light, but does not require light
  energy
• The dark phase is known as the Calvin cycle

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Dark Phase

• 2 3-carbon molecules combine to make glucose. C
  and O come from the carbon dioxide. H comes from
  the NADPH.
• The energy to do this comes from ATP breaking
  down into ADP.

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What Affects Photosynthesis?

• Shortage of water
• Temperature extremes (ph. occurs best at 32-95o
  F)
• Poor light intensity
• Shortage of carbon dioxide

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Stages of Sugar

• Glucose form of sugar as it is made in a plant
• Sucrose form of sugar as it is transported
  formed by glucose and fructose molecules
  attached this is why sap tastes sweet
• Starch form of sugar as it is stored complex
  carbohydrate many sugar molecules are joined
  together
• Fructose same chemical formula as glucose,
  but arranged differently

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Cellular Respiration

• Cellular respiration is the process by which food
  energy is released in the presence of oxygen
• This occurs in the mitochondria
• In plants, requires glucose and oxygen
• Gives off carbon, water, and energy
• Three parts glycolysis, Krebs cycle, electron
  transport chain

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Glycolysis

• One molecule of glucose is broken into two
  3-carbon molecules of pyruvic acid
• 2 molecules of ATP provide the energy
• 4 molecules of ATP end up being produced

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Krebs Cycle

• In a series of reactions, pyruvic acid is broken
  down into carbon dioxide
• NADH, FADH2, and ATP are formed
• High energy electrons are also produced

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Electron Transport

• The electrons are used to convert ADP into ATP

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Totals

• One glucose molecule can produce 36 ATP molecules
  after it goes through cellular respiration
• Without oxygen, glucose can only produce 2 ATP
  molecules during glycolysis and none during the
  Krebs cycle and electron transport (without
  oxygen, cells complete either alcoholic
  fermentation or lactic acid fermentation)

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FALL COLORATION ANDWILTING
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Why Do Leaves Turn Colors?

• The changes in the fall are triggered by the
  change in daylight.
• The abscission layer forms between the base of
  the petiole and the stem.
• This prevents materials from being able to go in
  and out of the leaf.
• This causes the chlorophyll to begin to
  deteriorate.

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Plant Pigments

• When the chlorophyll deteriorates, other pigments
  that were hidden by the chlorophyll are now able
  to be seen.
• Chlorophyll green colors
• Xanthophyll yellowish colors
• Carotene yellowish-orange colors
• Anthocyanin bright red, blue, and purple colors

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Falling Leaves

• The enzyme cellulase weakens the cell wall of the
  abscission layer.
• The leaf will break off under its own weight or
  with the help of wind
• A protective layer of cork cells forms at the
  base of the petiole producing the leaf scar on
  the branch

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Water and Wilting

• Not all water taken in by the plant is used.
• Much of it escapes through transpiration
• Factors that affect the rate of transpiration
• Humidity
• Temperature
• Intensity of sunlight
• Wind speed
• Amount of CO2 in the air
• Amount of soil water available

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Water and Wilting

• The guard cells are important in controlling the
  rate of transpiration
• When there is a lot of water in the plant, the
  guard cells become turgid and the stoma opens
• When water is moving out of the guard cells
  faster than it can be replaced, the guard cells
  close the stoma

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Wilting

• Transpriation
• Wilting occurs when more transpiration is
  occurring than water getting into the plant.
• Temporary wilting may occur on a hot day when a
  plant is in the sun. The sun causes more water
  to be lost than the plant can get from its roots.
  When the plant is in the shade, it is able to
  catch up and the cells become turgid again.

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Wilting

• In permanent wilting, there is usually a drought
  or poor retention of soil water so the plant
  cannot replace any of the water lost through
  transpiration.