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Plants II
Chapter 30
What you need to know!
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Key adaptations to life on land unique to seed
plants.
The evolutionary significance of seeds and
pollen.
The role of flowers and fruits in angiosperm
reproduction.
The role of stamens and carpels in angiosperm
reproduction
Seeds
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Fertilized, embryo-containing female
megaspore, surrounded by nutrients and
covered by a seed coat (integument)
Seeds contain high energy nutrients like fats,
carbs, and proteins to help the new plant
embryo grow until it has leaves and can do
photosynthesis
Remain dormant until favorable conditions
Seeds and Reproduction
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Emerged 340 million years ago
Miniaturization of the gametophyte
Heterosporous
Ovum (fruit): protection of delicate, large female
megaspore (drought, UV light)
Pollen: male microspores covered by tough
membrane
Pollination: pollen grain germinates and grows a
pollen tube to let sperm reach the ovum
Pollination  fertilization  seed development
Tracheophyta – Seed Plants
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Class: Gymnosperms
– naked seeds (no
fruit), and flowerless
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Ginko and Conifers
(pines and firs)
Pollen cones (sperm)
and ovule cones
(eggs)
Wind is primary
pollinator
Seeds grow in cones
Tracheophyta – Seed Plants
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Class Angiosperm – flowering, fruit producing
plants
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Subclass: monocot (single seed leaf)
Subclass: dicots (double seedleaf)
Leaves
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flattened blade
Main photosynthetic organs
Flowers
Flowers
Specialized Cells in Plants
Parenchyma
1.
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No cell walls
Carry out most of metabolism
Few cellular divisions once mature
Collenchyma
2.
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No cell wall
Strength and support in young cells
Sclerenchyma
3.
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Thick cell walls
Carry lignin (wood forming substance)
Lose protoplast (cellular innards) when mature
Stems
Xylem
 H2O and minerals
 Thick cell walls
 Lose protoplast when mature
 Transport of water up to 15 m/h or more
 Only one way direction root  top
 Driven by water potential (vacuum)
Phloem
 Transport of sugar, AA, ions
 Sieve tubes between cells with protoplast
 Transport in any direction
 Positive pressure flow mechanism (diffusion/osmosis)
 Sugars are transported from sugar source (leaves) to sugar
sinks (starch stores)
Uptake
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Minerals enter into root cells (active transport)
Water enters into root cells (osmosis)
Transpirational pull upward to tip of plant
(water potential vacuum)
Cohesion and adhesion of water to cell walls
Photosynthesis & Transpiration
Compromise
Stomata surrounded by guard cells
 Regulate transpiration and gas exchange
Open: + transpiration / + gas exchange
 Sufficient turgor =
 Influx of potassium followed by water
 Swelling of guard cells
 Opening of stomata
Closed: - transpiration / - gas exchange
 Insufficient turgor =
 Outflux of potassium and water
 Shrinking of guard cells
 Closing of stomata
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Plant Anatomy
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Primary growth
= UP
Secondary
Growth = OUT
Monocots and Dicots (Eudicots)
Monocots
Cotyledons (seed leaves): 1
Leave veins:
parallel
Vascular tissue:
scattered
Roots:
fibrous
Photosynthesis:
C4
Flower organs:
X3
Dicots
2
netlike
ring
taproot
C3
X5
Monocots and Dicots (Eudicot)