Parts of the plant and their functions

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Parts of the plant and their functions
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Importance of plants

• Without plants life on earth would not exist

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Plants

• Primary source of food for people and animals
• Produce oxygen
• help to keep us cool
• renew the air

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Plants

• slow wind speed
• provide a home for wildlife
• beautify surroundings
• perfume the air
• furnish building materials and fuel

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Parts of a plant

• Four basic parts
• leaves
• stems
• roots
• flowers

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Leaves

• the food factory of the plant
• produce the food used by the plant or stored for
  later use

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Shape and size of leaves

• vary among plants
• used for identification of plants

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Leaf arrangement

• alternate
• opposite
• whorled
• arranged in a circle around the stem

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External leaf structure

• petiole - leaf stalk
• leaf blade (leaf)
• has veins
• forms structural framework of the leaf

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Midrib

• large center vein from which all other leaf veins
  extend

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Margins

• edges of leaves
• assists in plant identification

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Internal leaf structure

• epidermis
• skin of the leaf
• single layer of cells
• protects leaf from loss of too much moisture

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Guard Cells

• open and close the small pore on the underside of
  the leaf

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Stomates

• allow the plant to breathe and transpire
• give off moisture

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Chloroplasts

• contain chlorophyll
• located inside the food making cells

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Photosynthesis

• process by which CO2 and H2O in the presence of
  light are converted to sugar and oxygen

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Chemical formula

• 6CO2 6H2O
• ----- in reaction with sunlight and chlorophyll
  ------
  
• C6H12O6 (glucose) 6O2

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food

• manufactured in the leaves moves downward through
  the stem to the roots
  
• used by the plant
• stored in stem or root and leaf in the form of
  sugar, starch or protein.

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Respiration

• plants respire 24 hours a day
• consume O2 and give off CO2
• plants produce more O2 through ps. Than they
  consume during respiration and growth.

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Stems

• have two main functions
• movement of water and minerals from the roots
  upward and movement of manufactured food down

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Stem functions

• support of leaves and reproductive structures

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Stems also

• used for food storage and reproduction of plants
  involving cuttings
  
• Green stems manufacture food just as leaves do

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External Stem Structure

• lenticels- breathing pores
• bud scale scars-indicate where terminal bud has
  been located previous year.

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Leaf Scars

• shows where leaf was attached
• Distance between the two represents one year of
  growth.
  

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Internal Stem Structure

• phloem- bark, carries manufactured foods down.
• Xylem- wood, carries water and minerals up.
• Cambium- separates the 2 and produces all new
  cells.
  
• Characteristic of dicots

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Internal Stem Structure

• dicot- dicotyledon, a plant with 2 seed leaves

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Monocot

• Monocotyledon - a plant with one seed leaf.
• Have vascular bundles, contain both xylem and
  phloem in each small bundle

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Monocot

• stems have no cambium
• cells enlarge to create size of mature stem

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Economic Importance

• food
• building materials

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Roots

• Usually underground
• functions
• anchor plant and hold upright
• absorb water and minerals form soil and conduct
  to stem
  
• store food, propagation

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Root Structure

• internal
• similar to stems
• older roots have xylem, phloem and cambian

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external

• root cap
• produces continuous supply of new cells
• protects roots as they push through soil

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Structure

• root hairs
• absorb moisture and minerals
• small roots

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Functions other than water and mineral absorption

• cash crops for food
• carrots
• beets
• radishes
• sweet potatoes
• propagation

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Type of root systems

• fibrous-grasses
• easier transplanting
• shorter, smaller, more compact
• lap root-carrot
• longer and fewer roots

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Flowers, Fruits, and Seeds

• pollination- color of flower attracts insects to
  fertilize flower
  
• beginning of fruit and seed formation
• fruits and seed are attractive to birds who eat
  and spread seeds.
  
• Reproduces plant
• some seeds carried on animals coats

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Parts of the Flower

• differ in size, shape, and color, some basic
  parts
  
• sepal
• green leaf-like part, covers and protects bud
  before opening

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Petals

• are actually leaves
• usually bright colors to attract pollinating
  insects.

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Parts of the Flower

• stamens
• male part of flower
• has two parts
• filament-stalk

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Anther

• anther- sac-like structure on top of filament,
  contains pollen

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Parts of the Flower

• Pistil - female part
• in the center of flower
• has three parts

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Pistil

• three parts
• stigma - top - sticky
• style - tube leading from stigma to ovary

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Ovary

• egg cells develop here
• grows to become fruit or seedcoat

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Types of Flowers

• complete
• contains 4 main parts

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Incomplete

• does not have all 4 main parts

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Perfect

• has stamens and pistils

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Imperfect

• lacks stamens or pistils

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Types of Flowers

• monoecious
• stamens and pistils are found in separate flowers
  on the same plant
  
• ex Corn

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dioecious

• male or staminate flowers found on one plant,
  female or pistilate flowers on another plant
  
• ex holly