Transcript Inquiry into Life, Eleventh Edition

Honors Biology
Chapter 9
Plant Anatomy
John Regan
Wendy Vermillion
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Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
9.1 Plant organs
• Plant organs
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Roots
Stems
Leaves
Flowers
• Roots
1. Anchor plant to soil and give support
2. Absorb water and minerals
3. Increased surface area for absorption from root hairs
• Epidermal extensions
4. Produce growth hormones
5. Food storage in perrenials-live year after year
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Organization of plant body
• Fig 9.1
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Vegetative organs of a tomato plant
• Fig 9.2
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Plant organs cont’d.
• Stems
1. Provide structural support for leaves
2.
Transport substances through plant body
• Water and minerals from roots to leaves
• Products of photosynthesis from leaves to other organs for storage
3.
4.
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Photosynthetic in some varieties
Store water in succulents
Node- point of attachment of leaf to stem
Internode- regions between nodes
Apical meristem- region of growth in length
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Plant organs cont’d.
• Leaves
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Major synthetic organs in most varieties
Blade- wide portion of leaf
Petiole- stalk that attaches leaf to stem
Deciduous leaves- lost in cold weather
• Separates from stem at abscission layer
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Plant organs cont’d.
• Monocots versus eudicot plants
– Eudicots are the larger group which includes many of the most
familiar flowering plants
– Monocots include grasses, palms, and many important food
plants such as rice, wheat, and corn
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Flowering plants are either monocots or
dicots
• Fig 9.3
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Plant tissues cont’d.
• Vascular tissue
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Specialized for transport of substances through plant body
Two types of vascular tissue- xylem and phloem
Xylem- transports water and minerals
Phloem-transports food
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9.3 Organization of leaves
• Leaf Structure
– Cuticle – outer waxy covering, prevents water loss
– Upper epidermis- protection
– Mesophyll- cells have many chloroplasts
• Palisade mesophyll- elongated cells
• Spongy mesophyll- irregular cells with many air spaces which
increase surface area for gas exchange
- Lower epidermis- protection, contains stomata(holes)
surrounded by guard cells-regulate opening and closing of
stomata
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Leaf structure
• Fig 9.8
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Classification of leaves
• Fig 9.9
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Shot tip and primary meristems
• Fig 9.11
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Organization of stems cont’d.
• Herbaceous stems-mature nonwoody stems
– Exhibit only primary growth
– Epidermis covered by waxy cuticle
– Distinctive vascular bundles-xylem oriented to inside, phloem to
outside
– Eudicots-vascular bundles in ring, central pith stores water and
carbohydrates, cortex wide and photosynthetic
– Monocot-vascular bundles scattered, narrow cortex, large
amount of pith
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Herbaceous eudicot stem
• Fig 9.12
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Monocot stem
• Fig 9.13
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Organization of stems cont’d.
• Woody stems- have both primary and secondary tissues
– Primary- formed from primary meristems behind shoot apical
meristem
– Secondary-develop from lateral meristems: vascular cambium
and cork cambium
– Primary growth is growth in length
– Secondary growth increases girth and occurs only in conifers
and woody dicots
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Diagrams of secondary growth of stems
• Fig 9.14
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Tree trunk
• Fig 9.15
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Organization of stems cont’d.
• Stem diversity
– Stolons- above ground horizontal stems, also called runners;
vegetative reproduction
– Rhizomes- underground horizontal stems; vegetative
reproduction
– Corms-bulbous underground stems
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Stem diversity
• Fig 9.16
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9.5 Organization of roots
• Root tip
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Apical meristem protected by root cap
Root is divided into zones
Zone of primary cell division-primary meristems
Zone of elongation-cells lengthen as they differentiate
Zone of maturation- fully differentiated cells; root hairs present
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Eudicot root tip
• Fig 9.17
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Organization of roots cont’d.
• Tissues of an eudicot root
– Epidermis-single layer of cells; root hairs present
– Cortex-parenchymal cells containing starch granules
– Endodermis-controls entrance of water and nutrients; boundary
between cortex and inner vascular cylinder
– Vascular tissue-pericycle is the first layer of vascular
cylinder;can divide and give rise to lateral roots
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Organization of roots cont’d.
• Organization of monocot roots
– Same growth zones as eudicot roots
– Do not undergo secondary growth like many eudicot roots
– Pith is surrounded by a vascular ring of alternating xylem and
phloem bundles
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Monocot root
• Fig 9.19
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Root diversity
• Fig 9.20
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Uptake and transport of nutrients
cont’d.
• Stomata and water transport
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Stomata must be open for water and mineral transport to occur
Each stoma is surrounded by a pair of guard cells
Guard cells regulate the opening and closing of the stomata
Blue light activates a flavin protein, which initiates activity of a H+
pump
– K+ is actively transported into the guard cells
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Opening and closing of stomata
• Fig 9.23
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