Plant Biology

Master plant biology concepts for RRB exam preparation with comprehensive coverage of plant structure, photosynthesis, plant physiology, reproduction, and economic importance.

Introduction to Plant Biology

What are Plants?

Definition

• Plants: Multicellular organisms that produce their own food through photosynthesis
• Autotrophs: Organisms that can synthesize their own food
• Photosynthetic: Use sunlight, water, and CO₂ to produce glucose
• Eukaryotic: Cells with nucleus and membrane-bound organelles
• Stationary: Fixed in one place (except for some motile gametes)

Plant Kingdom Characteristics

• Cell Wall: Made of cellulose for structural support
• Chlorophyll: Green pigment for photosynthesis
• Vacuoles: Large central vacuoles for storage and support
• Alternation of Generations: Both haploid and diploid phases
• Multicellular: Made of many specialized cells

Importance of Plants

• Oxygen Production: Release oxygen during photosynthesis
• Food Source: Primary producers in food chains
• Habitat: Provide shelter for many organisms
• Climate Regulation: Influence weather patterns
• Soil Conservation: Prevent soil erosion

Plant Classification

Major Plant Groups

Bryophytes (Non-vascular Plants)

• Characteristics: No vascular tissue, small size, moist habitats
• Examples: Mosses, liverworts, hornworts
• Reproduction: Spores, require water for fertilization
• Habitat: Damp, shaded environments
• Economic Importance: Peat formation, soil formation

Pteridophytes (Vascular Plants without Seeds)

• Characteristics: Vascular tissue, no seeds, spore reproduction
• Examples: Ferns, horsetails, clubmosses
• Vascular Tissue: Xylem and phloem present
• Life Cycle: Dominant sporophyte generation
• Economic Importance: Ornamental plants, fossil fuels

Gymnosperms (Naked Seed Plants)

• Characteristics: Seeds not enclosed in fruit, cones
• Examples: Conifers, cycads, ginkgo, gnetophytes
• Seeds: Exposed on scales of cones
• Pollination: Wind-pollinated
• Economic Importance: Timber, paper, resins, ornamental

Angiosperms (Flowering Plants)

• Characteristics: Seeds enclosed in fruit, flowers
• Examples: Roses, wheat, rice, mango
• Flowers: Reproductive structures
• Fruits: Mature ovaries containing seeds
• Economic Importance: Food, medicine, textiles, ornamental

Detailed Classification

Based on Life Cycle

• Annuals: Complete life cycle in one year
• Biennials: Complete life cycle in two years
• Perennials: Live for more than two years

Based on Habitats

• Hydrophytes: Water plants (water lily, lotus)
• Mesophytes: Land plants with moderate water (rose, wheat)
• Xerophytes: Desert plants (cactus, succulents)
• Halophytes: Salt-tolerant plants (mangroves)

Based on Stem Characteristics

• Herbs: Soft, green stems (grass, flowers)
• Shrubs: Woody stems, multiple stems (rose, hibiscus)
• Trees: Single woody trunk (oak, mango)
• Climbers: Need support (vines, creepers)

Plant Cell Structure

Plant Cell Components

Cell Wall

• Composition: Primarily cellulose, hemicellulose, lignin
• Function: Provides structural support, protection
• Layers: Primary wall, secondary wall, middle lamella
• Plasmodesmata: Channels between cells for communication
• Growth: Flexible during growth, rigid after maturity

Cell Membrane

• Structure: Phospholipid bilayer with proteins
• Function: Regulates entry and exit of substances
• Selective Permeability: Allows certain substances to pass
• Transport: Passive and active transport mechanisms
• Receptors: Contains receptor proteins for signaling

Cytoplasm

• Location: Region between cell membrane and nucleus
• Composition: Water, dissolved substances, organelles
• Function: Site of metabolic activities
• Streaming: Cytoplasmic streaming for distribution
• Storage: Contains various dissolved substances

Nucleus

• Structure: Spherical organelle with nuclear membrane
• Contents: DNA, nucleolus, nuclear proteins
• Function: Controls cell activities, contains genetic material
• Nuclear Membrane: Double membrane with nuclear pores
• Nucleolus: Site of ribosome synthesis

Chloroplasts

• Structure: Double membrane organelle with thylakoids
• Function: Site of photosynthesis
• Chlorophyll: Green pigment that captures light energy
• Stroma: Fluid containing enzymes for Calvin cycle
• Thylakoids: Disk-like structures forming grana

Mitochondria

• Structure: Double membrane with cristae
• Function: Site of cellular respiration
• Energy Production: ATP synthesis
• Cristae: Inner membrane folds for increased surface area
• Matrix: Contains enzymes for Krebs cycle

Vacuoles

• Structure: Large fluid-filled sacs
• Function: Storage, waste disposal, cell support
• Turgor Pressure: Maintains cell shape
• Tonoplast: Membrane surrounding vacuole
• Contents: Water, ions, sugars, pigments

Specialized Plant Cells

Parenchyma Cells

• Characteristics: Living cells, thin walls, large vacuoles
• Functions: Photosynthesis, storage, secretion
• Locations: Leaves, stems, roots, fruits
• Examples: Mesophyll cells, cortex cells
• Specialization: Can become other cell types

Collenchyma Cells

• Characteristics: Living cells, unevenly thickened walls
• Function: Flexible support for growing parts
• Locations: Stem cortex, leaf midribs
• Flexibility: Provides support without restricting growth
• Examples: Celery strings, leaf petioles

Sclerenchyma Cells

• Characteristics: Dead cells, heavily thickened walls
• Function: Rigid support and protection
• Types: Fibers and sclereids
• Lignin: Makes walls rigid and waterproof
• Examples: Nut shells, pear grit

Xylem Cells

• Tracheids: Long, tapered cells with pits
• Vessels: Short, wide cells with perforated end walls
• Function: Water and mineral transport
• Structure: Dead cells with lignified walls
• Direction: One-way transport from roots to leaves

Phloem Cells

• Sieve Tube Elements: Living cells for food transport
• Companion Cells: Support sieve tube elements
• Function: Transport of sugars and organic compounds
• Direction: Two-way transport throughout plant
• Structure: Living cells with porous end walls

Plant Tissues

Meristematic Tissues

Apical Meristems

• Location: Tips of roots and shoots
• Function: Primary growth (length increase)
• Types: Root apical meristem, shoot apical meristem
• Cell Division: Rapidly dividing undifferentiated cells
• Importance: Essential for plant growth and development

Lateral Meristems

• Vascular Cambium: Produces secondary xylem and phloem
• Cork Cambium: Produces cork (periderm)
• Function: Secondary growth (diameter increase)
• Location: In stems and roots of woody plants
• Activity: Increases girth of stems and roots

Intercalary Meristems

• Location: Internodes of grasses and monocots
• Function: Growth from base of leaves and internodes
• Importance: Allows rapid regrowth after grazing
• Examples: Grass nodes, bamboo shoots
• Activity: Enables mowing tolerance

Permanent Tissues

Simple Tissues

• Parenchyma: Storage, photosynthesis, secretion
• Collenchyma: Flexible support
• Sclerenchyma: Rigid support
• Epidermal: Protective outer layer
• Ground Tissue: Fills spaces between tissues

Complex Tissues

• Xylem: Water and mineral transport
• Phloem: Food transport
• Periderm: Protective tissue in woody plants
• Secretory Tissues: Glands and ducts

Plant Organs

Roots

Root System Types

• Taproot System: Main root with lateral branches (dicots)
• Fibrous Root System: Many similar roots (monocots)
• Adventitious Roots: Roots from stems or leaves
• Aerial Roots: Roots above ground (orchids, mangroves)

Root Zones

• Root Cap: Protective tip covering
• Meristematic Zone: Cell division region
• Elongation Zone: Cell growth region
• Maturation Zone: Cell differentiation region
• Root Hairs: Increase surface area for absorption

Root Functions

• Anchorage: Secures plant in soil
• Absorption: Water and mineral uptake
• Storage: Food storage (carrots, radishes)
• Conduction: Transport to shoot system
• Synthesis: Production of hormones and compounds

Stems

Stem Structure

• Node: Point where leaves attach
• Internode: Region between nodes
• Buds: Potential new growth points
• Lenticels: Pores for gas exchange
• Vascular Bundles: Xylem and phloem arrangements

Stem Types

• Herbaceous: Soft, green stems
• Woody: Hard, lignified stems
• Climbing: Need support structures
• Underground: Modified for storage (tubers, rhizomes)
• Aerial: Above ground modifications

Stem Functions

• Support: Holds leaves, flowers, fruits
• Transport: Water and nutrients between roots and leaves
• Storage: Food reserves (potatoes, yams)
• Photosynthesis: Green stems can photosynthesize
• Propagation: Vegetative reproduction

Leaves

Leaf Structure

• Blade (Lamina): Flat, expanded part
• Petiole: Stalk connecting blade to stem
• Midrib: Central vein of blade
• Veins: Vascular tissue distribution
• Stomata: Pores for gas exchange

Leaf Types

• Simple: Single blade (oak, maple)
• Compound: Multiple leaflets (rose, neem)
• Pinnate: Leaflets arranged on both sides
• Palmate: Leaflets radiating from one point
• Needle-like: Reduced leaves (pine, cypress)

Leaf Arrangement

• Alternate: One leaf per node
• Opposite: Two leaves per node, opposite each other
• Whorled: Three or more leaves per node
• Rosette: Cluster of leaves at base
• Basal: Leaves from base of plant

Leaf Functions

• Photosynthesis: Primary site of food production
• Transpiration: Water loss through stomata
• Gas Exchange: CO₂ intake, O₂ release
• Storage: Food reserves (succulents)
• Protection: Spines, waxy coatings

Flowers

Flower Structure

• Calyx: Outer whorl of sepals
• Corolla: Second whorl of petals
• Androecium: Male reproductive organs (stamens)
• Gynoecium: Female reproductive organs (carpels)
• Receptacle: Base where flower parts attach

Flower Parts

• Sepals: Protect developing flower
• Petals: Attract pollinators
• Stamens: Male organs (anther + filament)
• Pistil: Female organ (stigma + style + ovary)
• Ovules: Female gametes inside ovary

Flower Types

• Complete: All four whorls present
• Incomplete: Missing one or more whorls
• Perfect: Both male and female organs
• Imperfect: Either male or female organs
• Monoecious: Male and female flowers on same plant
• Dioecious: Male and female flowers on separate plants

Fruits

Fruit Structure

• Pericarp: Fruit wall (exocarp, mesocarp, endocarp)
• Seeds: Developed from ovules
• Placenta: Tissue bearing ovules/seeds
• Funicle: Stalk connecting seed to placenta
• Hilum: Point where seed attaches to funicle

Fruit Types

• Simple Fruits: From single flower with one ovary
• Aggregate Fruits: From single flower with multiple ovaries
• Multiple Fruits: From multiple flowers
• Dry Fruits: Hard pericarp when mature
• Fleshy Fruits: Soft pericarp when mature

Fruit Functions

• Seed Protection: Protects developing seeds
• Seed Dispersal: Aids in seed distribution
• Food Storage: Nutrients for seed germination
• Animal Attraction: Colors, flavors, textures

Photosynthesis

Photosynthesis Overview

Definition

• Photosynthesis: Process of converting light energy to chemical energy
• Equation: 6CO₂ + 6H₂O + Light Energy → C₆H₁₂O₆ + 6O₂
• Location: Chloroplasts in plant cells
• Importance: Primary energy source for most life on Earth

Requirements

• Light Energy: From sunlight
• Carbon Dioxide: From atmosphere
• Water: From soil through roots
• Chlorophyll: Green pigment in chloroplasts
• Enzymes: Catalysts for biochemical reactions

Products

• Glucose: Sugar for plant energy and growth
• Oxygen: Released to atmosphere
• Water: Some water produced
• ATP: Energy currency molecule
• NADPH: Energy carrier molecule

Light Reactions

Location: Thylakoid membranes of chloroplasts

Steps:

1. Light Absorption: Chlorophyll absorbs light energy
2. Water Splitting: H₂O → O₂ + H⁺ + electrons
3. Electron Transport: Energy transfer through photosystems
4. ATP Formation: Through chemiosmosis
5. NADPH Formation: Electron carrier molecule

Key Components:

• Photosystem II: First photosystem in light reactions
• Photosystem I: Second photosystem
• Electron Transport Chain: Series of protein complexes
• ATP Synthase: Enzyme that produces ATP
• Oxygen: Byproduct released to atmosphere

Calvin Cycle (Dark Reactions)

Location: Stroma of chloroplasts

Phases:

1. Carbon Fixation: CO₂ combines with RuBP
2. Reduction: ATP and NADPH used to reduce 3-PGA
3. Regeneration: RuBP regenerated for cycle continuation

Key Molecules:

• RuBP: Five-carbon molecule that accepts CO₂
• 3-PGA: Three-carbon intermediate
• G3P: Three-carbon sugar produced
• Rubisco: Enzyme that fixes CO₂
• Glucose: Final product after multiple cycles

Factors Affecting Photosynthesis

Light Intensity

• Low Light: Limited photosynthesis
• Optimal Light: Maximum photosynthesis rate
• Excess Light: Photoinhibition, damage to chlorophyll

Carbon Dioxide Concentration

• Low CO₂: Limited photosynthesis
• Optimal CO₂: Maximum photosynthesis
• High CO₂: No further increase, may be wasteful

Temperature

• Low Temperature: Reduced enzyme activity
• Optimal Temperature: Maximum photosynthesis
• High Temperature: Enzyme denaturation, reduced rate

Water Availability

• Low Water: Stomatal closure reduces CO₂ intake
• Optimal Water: Normal photosynthesis
• Excess Water: Root damage, reduced uptake

Plant Physiology

Water Relations

Water Absorption

• Root Hair Zone: Main absorption area
• Osmosis: Water movement across membranes
• Root Pressure: Force pushing water upward
• Capillary Action: Water movement in small tubes
• Cohesion-Tension: Water column in xylem

Water Transport

• Xylem Vessels: Water transport tubes
• Cohesion: Water molecules sticking together
• Adhesion: Water molecules sticking to vessel walls
• Transpiration Pull: Water evaporation creates tension
• Root Pressure: Positive pressure from roots

Transpiration

• Definition: Water loss through stomata
• Functions: Cools plant, draws water upward
• Regulation: Stomatal opening/closing
• Factors Affecting: Light, temperature, humidity, wind
• Rate Control: Guard cells control stomatal aperture

Mineral Nutrition

Essential Elements

• Macronutrients: Required in large amounts
  • Nitrogen (N), Phosphorus (P), Potassium (K)
  • Calcium (Ca), Magnesium (Mg), Sulfur (S)
• Micronutrients: Required in small amounts
  • Iron (Fe), Manganese (Mn), Zinc (Zn)
  • Copper (Cu), Boron (B), Molybdenum (Mo)

Nutrient Functions

• Nitrogen: Protein synthesis, chlorophyll formation
• Phosphorus: Energy transfer, nucleic acids
• Potassium: Enzyme activation, water regulation
• Calcium: Cell wall formation, signaling
• Magnesium: Chlorophyll molecule
• Iron: Chlorophyll synthesis, respiration

Nutrient Deficiencies

• Nitrogen: Yellowing of older leaves
• Phosphorus: Dark green leaves, stunted growth
• Potassium: Yellowing at leaf edges
• Calcium: Growing tip death
• Magnesium: Yellowing between veins
• Iron: Yellowing of young leaves

Plant Hormones

Auxins

• Function: Cell elongation, apical dominance
• Location: Produced in apical meristems
• Applications: Rooting hormones, weed control
• Transport: Polar transport downward
• Effects: Phototropism, gravitropism

Gibberellins

• Function: Stem elongation, seed germination
• Location: Produced in young leaves, roots, embryos
• Applications: Breaking dormancy, fruit development
• Effects: Increases cell division, elongation

Cytokinins

• Function: Cell division, delay aging
• Location: Produced in root tips
• Applications: Tissue culture, shelf-life extension
• Effects: Promotes shoot formation

Abscisic Acid (ABA)

• Function: Stress response, dormancy
• Location: Produced in mature leaves
• Effects: Stomatal closure, seed dormancy
• Applications: Stress tolerance enhancement

Ethylene

• Function: Fruit ripening, senescence
• Location: Produced in ripening fruits, aging tissues
• Applications: Controlled ripening, flower induction
• Effects: Leaf and flower fall, fruit ripening

Plant Reproduction

Asexual Reproduction

Vegetative Propagation

• Stem Cuttings: Rose, sugarcane
• Leaf Cuttings: Begonia, African violet
• Root Cuttings: Sweet potato, dahlia
• Layering: Jasmine, bougainvillea
• Grafting: Mango, apple

Natural Methods

• Runners: Strawberry
• Suckers: Chrysanthemum, banana
• Tubers: Potato
• Rhizomes: Ginger, turmeric
• Bulbs: Onion, garlic

Advantages

• Genetic Uniformity: Offspring identical to parent
• Rapid Multiplication: Quick population increase
• Quality Maintenance: Preserves desirable traits
• Adaptation: Well-adapted to local conditions

Sexual Reproduction

Alternation of Generations

• Sporophyte: Diploid (2n) generation, produces spores
• Gametophyte: Haploid (n) generation, produces gametes
• Spores: Produced by meiosis in sporophyte
• Gametes: Produced by mitosis in gametophyte
• Fertilization: Fusion of gametes to form zygote

Pollination

• Self-Pollination: Pollen transferred to same flower
• Cross-Pollination: Pollen transferred to different flower
• Agents: Wind, insects, birds, water, bats
• Mechanisms: Nectar, color, scent, shape
• Compatibility: Genetic barriers prevent selfing

Fertilization Process

1. Pollen Germination: Pollen tube grows down style
2. Tube Growth: Through style to ovary
3. Sperm Transport: Two sperm cells travel down tube
4. Double Fertilization: One sperm fertilizes egg, other fuses with polar nuclei
5. Seed Development: Zygote develops into embryo

Seed Development and Germination

Seed Structure

• Seed Coat: Protective outer covering
• Embryo: Young plant (radicle, plumule, cotyledons)
• Endosperm: Food reserve tissue
• Cotyledons: Seed leaves containing food
• Hilum: Point of attachment to funicle

Seed Dormancy

• Definition: Period of suspended growth
• Types: Physical, physiological, morphological
• Breaking Methods: Scarification, stratification, light
• Advantages: Survival through unfavorable conditions
• Regulation: Hormones (ABA vs. gibberellins)

Germination Process

1. Imbibition: Water uptake by seed
2. Enzyme Activation: Metabolic processes begin
3. Growth Resumption: Embryo starts growing
4. Radicle Emergence: Root emerges first
5. Plumule Emergence: Shoot emerges above ground

Factors Affecting Germination

• Water: Essential for metabolic processes
• Temperature: Optimal range varies by species
• Oxygen: Required for respiration
• Light: Some seeds need light, others darkness
• Hormones: Balance of growth regulators

Economic Importance of Plants

Food Plants

Cereals

• Rice (Oryza sativa): Staple food for half world population
• Wheat (Triticum aestivum): Bread, pasta, flour
• Maize (Zea mays): Food, animal feed, industrial uses
• Millet (Pennisetum glaucum): Drought-resistant grain
• Barley (Hordeum vulgare): Beer, malt, animal feed

Pulses

• Pea (Pisum sativum): Protein-rich legume
• Lentil (Lens culinaris): High protein content
• Chickpea (Cicer arietinum): Important protein source
• Bean (Phaseolus vulgaris): Various types and uses
• Soybean (Glycine max): Oil and protein

Vegetables

• Potato (Solanum tuberosum): Staple tuber crop
• Tomato (Solanum lycopersicum): Fruit vegetable
• Onion (Allium cepa): Flavoring vegetable
• Cabbage (Brassica oleracea): Leafy vegetable
• Carrot (Daucus carota): Root vegetable

Medicinal Plants

Important Medicinal Plants

• Tulsi (Ocimum sanctum): Immunity booster, anti-inflammatory
• Neem (Azadirachta indica): Antibacterial, antifungal
• Amla (Emblica officinalis): Rich in Vitamin C
• Ashwagandha (Withania somnifera): Stress relief
• Turmeric (Curcuma longa): Anti-inflammatory

Traditional Medicine

• Ayurveda: Ancient Indian medicinal system
• Unani: Traditional medicine system
• Siddha: Tamil traditional medicine
• Homeopathy: Plant-based remedies
• Modern Medicine: Plant-derived pharmaceuticals

Industrial Plants

Fiber Plants

• Cotton (Gossypium spp.): Textile industry
• Jute (Corchorus capsularis): Sacking, twine
• Flax (Linum usitatissimum): Linen production
• Hemp (Cannabis sativa): Rope, textiles
• Silk Cotton (Bombax ceiba): Fiber, kapok

Timber Plants

• Teak (Tectona grandis): High-quality timber
• Sal (Shorea robusta): Construction timber
• Deodar (Cedrus deodara): Aromatic timber
• Sandalwood (Santalum album): Aromatic wood
• Bamboo (Bambusa spp.): Construction, furniture

Oil Plants

• Mustard (Brassica juncea): Cooking oil
• Groundnut (Arachis hypogaea): Edible oil
• Sunflower (Helianthus annuus): Oil production
• Coconut (Cocos nucifera): Oil, copra
• Sesame (Sesamum indicum): Oil seeds

Ornamental Plants

Flowering Plants

• Rose (Rosa spp.): Ornamental, perfume
• Marigold (Tagetes spp.): Religious, ornamental
• Jasmine (Jasminum spp.): Fragrance, garlands
• Hibiscus (Hibiscus spp.): Ornamental flowers
• Chrysanthemum (Chrysanthemum spp.): Cut flowers

Foliage Plants

• Ferns: Indoor decoration
• Philodendron: House plants
• Money Plant: Indoor air purifier
• Snake Plant: Low maintenance indoor plant
• Peace Lily: Beautiful foliage, flowers

Plant Ecology

Plant Communities

Types of Plant Communities

• Forest Communities: Trees, shrubs, herbs
• Grassland Communities: Grasses, herbs
• Desert Communities: Xerophytic plants
• Aquatic Communities: Water plants
• Alpine Communities: High-altitude plants

Plant Succession

• Primary Succession: colonization of bare areas
• Secondary Succession: Recolonization after disturbance
• Climax Community: Stable, mature community
• Pioneer Species: First colonizers
• Climax Species: Dominant in stable communities

Environmental Adaptations

Xerophytic Adaptations

• Thick Cuticle: Reduces water loss
• Reduced Leaves: Minimizes transpiration
• Deep Roots: Access to deep water
• CAM Photosynthesis: Night-time CO₂ uptake
• Succulence: Water storage tissues

Hydrophytic Adaptations

• Aerenchyma: Air-filled tissues for buoyancy
• Reduced Roots: Limited root systems
• Floating Leaves: Air chambers underneath
• Submerged Leaves: Thin, flexible leaves
• Air Sacs: Floatation devices

Epiphytic Adaptations

• Aerial Roots: Absorb moisture from air
• Scales: Absorb water and nutrients
• CAM Photosynthesis: Water conservation
• Lightweight Structure: Reduce host burden
• Rapid Growth: Quick colonization

Practice Questions

Question 1

What is the difference between xylem and phloem?

Question 2

Explain the process of photosynthesis with its equation.

Question 3

What are the essential macronutrients required for plant growth?

Question 4

Differentiate between taproot and fibrous root systems.

Question 5

What is the role of stomata in plant physiology?

Question 6

Explain alternation of generations in plants.

Question 7

What are the main plant hormones and their functions?

Question 8

Describe the process of double fertilization in flowering plants.

Question 9

What are the economic importance of plants?

Question 10

Explain the adaptations of xerophytic plants.

Quick Reference

Plant Kingdom Classification

• Bryophytes: Non-vascular (mosses, liverworts)
• Pteridophytes: Vascular, no seeds (ferns, horsetails)
• Gymnosperms: Naked seeds (conifers, cycads)
• Angiosperms: Enclosed seeds (flowering plants)

Plant Cell Components

• Cell Wall: Cellulose, structural support
• Chloroplasts: Photosynthesis, chlorophyll
• Vacuoles: Storage, turgor pressure
• Mitochondria: Respiration, ATP production
• Nucleus: Genetic material, cell control

Photosynthesis Equation

• 6CO₂ + 6H₂O + Light Energy → C₆H₁₂O₆ + 6O₂
• Location: Chloroplasts
• Light Reactions: Thylakoid membranes
• Dark Reactions: Calvin cycle in stroma

Plant Hormones

• Auxins: Cell elongation, apical dominance
• Gibberellins: Stem growth, seed germination
• Cytokinins: Cell division, anti-aging
• Abscisic Acid: Stress response, dormancy
• Ethylene: Fruit ripening, senescence

Important Indian Plants

• Food: Rice, wheat, maize, pulses
• Medicinal: Tulsi, neem, amla, turmeric
• Industrial: Cotton, jute, teak, bamboo
• Ornamental: Rose, marigold, jasmine

Memory Tips

Plant Parts Functions

• Roots: Anchorage, absorption, storage
• Stem: Support, transport, storage
• Leaves: Photosynthesis, transpiration, gas exchange
• Flowers: Reproduction, pollination
• Fruits: Seed protection, dispersal

Photosynthesis Steps

• Light Reactions: Light → ATP + NADPH + O₂
• Calvin Cycle: CO₂ + ATP + NADPH → Glucose
• Factors: Light, CO₂, temperature, water

Plant Hormones Mnemonic

• ATCE: Auxins (growth), Turgor (water), Cytokinins (division), Ethylene (ripening)

Plant Tissues

• Meristematic: Growth (apical, lateral, intercalary)
• Permanent: Function (parenchyma, collenchyma, sclerenchyma)
• Complex: Transport (xylem, phloem)

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