Download Plant Structure, Growth and Development

Chapter 35
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Cells make up tissues and tissues make up organs.
Plants have 3 main organs:
Roots
Stems
Leaves
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Used to anchor vascular plants
Absorbs minerals and water
Stores organic nutrients
The main vertical root is the
taproot, which has branches
called lateral roots
Root tips do most absorption
Tiny root hairs increase the
surface area of the root
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Stems have nodes (where
leaves attach) and
internodes (in between
leaves)
Shoots form from axillary
buds that grow from
where leaves attach to
stems
Modified stems include:
rhizomes (ginger or
garlic), tubers (potatoes),
bulbs (onions)
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Leaves are where sunlight is
absorbed by chlorophyll for
photosynthesis
Consist of a blade and a
stalk (petiole)
Veins are the vascular tissue
(xylem and phloem)
Modified leaves include
tendrils, spines, bracts
(poinsettia), and cacti
storage leaves.
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Stomata are openings in leaves for gas exchange
Guard cells control whether stomata are open or closed
Mesophyll is the tissue where photosynthesis occurs
Xylem and phloem are in the mesophyll, and are
enclosed by bundle sheath cells
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Dermal: outer protective covering; includes
cuticle, a waxy coating that prevents water loss
Vascular: xylem and phloem
Ground: used for storage, called pith or cortex
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Meristems generate cells for new organs
Plants grow throughout their lives, but do die:
Annuals: complete their life cycles in a year or
less; grains, beans, wildflowers
Biennials: live 2 years; beets, carrots
Perennials: live many years: trees, shrubs,
grasses
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Roots and shoots grow from
the tips (apical meristems)
The root tip is covered by the
root cap (protection)
Zone of cell division: where
mitosis occurs
Zone of elongation: root cells
elongate
Zone of maturation: cells
differentiate and become
mature
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Tissues called vascular cambium and cork
cambium produces secondary xylem and phloem
which turns into wood
Rings of trees build up as trees age. The center
is called heartwood; outer layers are called
sapwood.
Bark is used for protection and has phloem in it