Plant Tissues/Functions/Structures Flashcards
Plant Cells are morphologically diverse and classified into three main types?
○ Parenchyma
○ Collenchyma
○ Sclerenchyma
Plant cells are unique relative to other eukaryotes because of their?
○ central vacuoles,
○ Plastids
○ cell walls
plant “organs” are made of ?
○ meristematic,
○ dermal,
○ ground
○ vascular tissues
where does primary plant growth occur?
Primary plant growth occurs at apical meristems in the shoot and root
plasmodesmata ?
Plasmodesmata are microscopic channels that traverse the cell walls of plant cells, facilitating communication and transport of molecules between adjacent cells.
what do plastids do?
store energy as starch
what are cell walls made of?
composed of cellulose
thylakoid membrane
site of light-dependent photosyth rxns.
All plastids have an outer and inner membrane, but in chloroplasts the inner membrane is extensive and highly folded.
Parenchyma Cell
🔹 Key Fact: Most common cell type (flesh of plants)
🔹 Features:
Non-specialized but can perform many functions
Thin primary cell wall (flexible)
Includes specialized types:
1. Aerenchyma → found in wetland plants (e.g., wild rice)
2. Chlorenchyma → photosynthetic cells
Collenchyma Cells
🔹 Key Fact: Provides flexible support
🔹 Features:
Found near the outside of non-woody stems
Unevenly thickened primary cell wall
Works with turgid parenchyma (internal pressure)
Sclerenchyma Cells
🔹 Key Fact: Rigid, thick-walled cells (for strength & support)
🔹 Features:
Inelastic secondary cell walls
Usually dead at maturity
Two main types:
- Sclereids (can be alive) → Found in nut shells, hard fruit pits
- Fibers = Long & thin for structural support
Vegetative (non-reproductive) organs
○ Stem
○ Leaf
○ Root
Reproductive organs
○ Sepals
○ Petals
○ Stamens
○ Carpels
Vegetative tissue types:
○ Dermal tissue (plant skin/ protection)
○ Vascular tissue (water an nutrient transport)
○ Ground tissue (photosyth and storage)
Stems act as the ?
Plant Transport system
non-woody vs. woody stems?
monocot = non-woody
Dicot = both
Conifer = woody
Trichomes
- Epidermal cells that grow outward to form microscopic, hairlike projections
- Protection (pests and UV)
- Communications
- Shapes and functions vary
- Trap or attract insects
Xylem Transport
Transpiration → Water loss from leaves
Root Absorption → Water uptake from soil
Cohesion → H-bonding between water molecules
Tracheids:
○ Long and narrow
○ Tapered ends with pits
○ Present in all vascular plants
Sieve Cells
Long, narrow, tapered ends (all vascular plants)
Metabolic control by albuminous cells
Leaf Structures
Function: Photosynthesis & gas exchange
Layers:
Upper Epidermis → Protects leaf, contains stomata & guard cells
Palisade Mesophyll → Dense chloroplasts (main photosynthesis site)
Spongy Mesophyll → Air spaces for gas exchange
Lower Epidermis → Stomata & guard cells regulate gas/water loss
Veins (Vascular Tissue) → Xylem & Phloem, surrounded by bundle sheaths (fibers for support)
Typical Root Structure
Function: Anchor, store nutrients, absorb water
Regions:
Root Cap → Protects apical meristem (growth zone)
Region of Elongation → Cells expand
Root Hairs → Maximize surface area for absorption
Root layers
Epidermis → Outer protective layer
Cortex → Stores nutrients
Endodermis → Surrounds vascular tissue
Casparian Strip → Waterproof band filters nutrients & blocks harmful substances
Vascular Tissues → Xylem & Phloem
Pericycle → Lateral root initiation site (growth hub, adapts to soil)
Adaptations - Survival Strategies:
Epiphytic Orchids → No roots, absorb water from air
Thick Cuticles → Prevent water loss (orchids, cacti)
Cactus Spines → Modified leaves (reduce water loss, protect plant)
