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STOMATA ON LEAVES
CELL WALL
GUARD CELL
STOMA (PORE)
EPIDERMAL CELLS
STOMATA – STRUCTURE
• Found on the lower (and sometimes upper)
epidermis (surface) of leaves
• Holes/pores in leaf
• Singular – stoma, plural – stomata
• Hole is surrounded by two guard cells
• These can open by becoming turgid and close by
becoming flaccid
• Guard cells contain chloroplasts
• Usually open during the day and closed at night
STOMATA – ROLES, FUNCTIONS
• To control the entry and exit of gases into and
out of the leaf
• Guard cells open and close to control this
• Stomata respond to outside conditions
• When conditions are right for photosynthesis,
stomata open wide for gas exchange
• When it is too dry or dark, stomata close up.
• Closed stomata prevent water loss in plant
TRANSPORT OF WATER AND FOOD
• Vascular bundles/tissues
• Contain xylem for
transporting water UP
from roots to leaves
• Contain phloem for
carrying food/nutrients
like sugars and amino
acids down from leaves
to plant
Vascular Bundle
Xylem
Phloem
A vascular bundle in a stem
Your turn to find some!
• Use the celery stems to cut a VERY fine slice
• View under microscope
• Find a vascular bundle on low then med
power
• Xylem will be redish? Maybe?
WHAT YOU SHOULD TRY TO SEE
XYLEM
PHLOEM
DIDYMO ORGANISMS
Didymo algae cell
Unicellular organisms
• They will be
moving!
Paramecium