Plant Structure, Growth and Transport

1
Plant Structure, Growth and Transport

• Chapters 35, 36 39 (in brief)
• Biology Campbell Reece

2
Structure of Seed Plants

• 3 organs roots, stems, leaves
• Meristematic tissue only plant tissue that
  produces new cells by mitosis
• Becomes one of the 3 main tissue systems dermal,
  vascular or ground

3
3 Tissue Systems

• Dermal tissue outer covering of a plant
• Epidermis
• Cuticle waxy layer, prevents water loss and
  injury
• Ground tissue cells that lie between the dermal
  vascular tissues

4
3 Tissue Systems

• Vascular tissue transports water nutrients
  throughout the plant
• Xylem transports water made of dead cells
• Phloem transports food made of living cells
• Vascular cambium produces new xylem phloem

xylem
phloem
5
Roots Types

• Taproot primary root that grows long and thick
• Fibrous roots roots branch to such an extent
  that no single root grows larger than the rest

6
Roots Structure Function

• Structure
• Cortex, endodermis, vascular cylinder
• Root hairs tiny projections that increase
  surface area
• Root cap protects the tip of the root
• Functions
• Anchor the plant
• Absorb water and dissolved nutrients from the soil

7
Roots
8
Stems Structure

• Nodes, internodes, buds
• Monocot stems vascular bundles are scattered
  throughout the stem
• Dicot stems vascular bundles are arranged in a
  cylinder

9
Monocots vs. Dicots
10
Stems Functions

• Produce leaves, branches flowers
• Hold leaves upright in the sunlight
• Transport substances between roots and leaves

11
Leaves Structure

• Blades, petiole, veins (vascular bundles)
• Mesophyll (spongy palisade), stomata, guard
  cells

12
Leaves Functions

• Photosynthesis
• Transpiration the loss of water from a plant
  through its leaves
• Gas exchange

13
Transport in Plants

• Water Transport
• Occurs in the xylem
• Root pressure, capillary action (cohesion
  adhesion), transpiration contribute to pull
  the water up

14
Water Transport

• Water potential predicts the direction the
  water will flow
• Influenced by pressure solute concentration
• ? ?P ?S
• ?P pressure potential
• ?S solute potential
• Water has a ? of zero

15
Water Potential
16
Transport in Plants

• Nutrient Transport
• Occurs in the phloem
• Pressure-flow hypothesis sugars are moved from
  the source to the sink
• Source where sugars are produced
• Sink where sugars are stored

17
Pressure-Flow Hypothesis
18
Plant Hormones

• Auxins stimulate cell elongation
• Cytokinins stimulate cell division
• Gibberellins produce increases in size
• Ethylene stimulates fruit to ripen

19
Plant Responses

• Tropisms responses of plants to environmental
  stimuli
• Positive in the direction of the stimulus
• Negative away from the stimulus
• Gravitropism response to gravity
• Phototropism response to light
• Thigmotropism response to touch

20
Phototropism