Plant Biology Notes

Plant-Like Protist Diversity

• 4 Supergroups of Protists: Includes diverse eukaryotic organisms such as

  • Excavata: Diplomonads, Parabasalids, Euglenozoans
  • SAR Clade: Stramenopiles (Diatoms, Brown algae), Alveolates (Dinoflagellates, Apicomplexans), Rhizarians
  • Archaeplastida: Red algae, Green algae, Land plants
  • Unikonta: Amoebozoans and Opisthokonts (Fungi, Animals)

• Characteristics of Protists:

  • Mostly unicellular; some multicellular
  • Eukaryotic cells with organelles
  • Play a role in ecosystems as primary producers, decomposers, and symbionts

Stramenopiles

• Diatoms:
  • Unicellular with silica walls
  • Major component of phytoplankton; found in aquatic environments
• Brown Algae:
  • Multicellular, complex structures (kelps)

Alveolates

• Dinoflagellates:
  • Cellulose body, important phytoplankton
  • Associated with 'red tide' due to toxin production

Archaeplastida

• Red Algae:
  • Multicellular, cellulose walls, supports ecosystems in marine environments
• Green Algae:
  • Unicellular (e.g., Chlamydomonas) and multicellular (e.g., Volvox)

Bryophytes (Non-Vascular Plants)

• Dominant gametophyte phase (haploid), no vascular tissues
• Moss Life Cycle:
  • Begins with wind-dispersed spores, developing into male/female gametophytes
  • Water is necessary for fertilization

Seed Plants - Gymnosperms and Angiosperms

• Gymnosperms:
  • Naked seeds (includes conifers), adapted for dry environments
• Angiosperms:
  • Enclosed seeds (flowers and fruits), most diverse and widespread group

Plant Structure and Growth

• Plants have definite tissues: Dermal, Vascular, Ground
• Meristems:
  • Primary (apical) growth for length
  • Secondary growth (cambium) for thickness

Plant Transport

• Water movement through xylem and nutrients through phloem
• Mechanisms: Capillary action, transpiration, root pressure

Plant Nutrition

• Essential elements: Macronutrients (N, P, K) & Micronutrients (Fe, Mn)
• Cation exchange in soil facilitates nutrient uptake

Fungi and Lichens

• Fungi: Decomposers and symbionts, diverse structures (hyphae, mycelium)
• Lichens: Mutualistic associations between fungi and photosynthetic organisms, important for soil formation.