PLANT PHYSIOLOGY & ONTOGENY

• Parts of a plant

  • Roots
  • Stem
  • Leaves
  • Flowers
  • Fruits
• Roots


  Found underground, anchor the plant, provide stability, absorb water and nutrients
• Stem


  Main structural axis, supports the plant, transports water, nutrients, and sugars, provides pathway for hormones, acts as storage organ
• Leaves


  Primary site of photosynthesis, flat and thin to maximize sunlight exposure, role in transpiration
• Flowers


  Reproductive structures, produce seeds through pollination, attract pollinators
• Fruits


  Develop from fertilized flowers, protect seeds, aid in seed dispersal
• Gibberellins


  Hormones that regulate growth and development processes in plants
• Kinds of plants


  • Herbs
  • Shrubs
  • Trees
  • Climbers
  • Creepers
  • Algae
  • Mosses
  • Ferns
  • Gymnosperms
  • Angiosperms
• Herbs


  Small, non-woody plants with soft stems, short lifespan
• Shrubs


  Medium-sized plants with multiple woody stems, shorter than trees, can be evergreen or deciduous
• Trees


  Large, woody plants with a single main stem (trunk), long lifespan, well-defined canopy
• Climbers


  Plants with specialized structures (tendrils, aerial roots) that allow them to climb and attach to surfaces
• Creepers


  Plants with trailing or prostrate stems that grow along the ground or other surfaces, often rooting at intervals
• Algae


  Diverse group of photosynthetic organisms found in various environments, ranging from single-celled to large, multicellular seaweeds
• Mosses


  Small, non-vascular plants that typically grow in damp environments, have simple leaves and reproduce by spores
• Ferns


  Vascular plants that reproduce via spores, have fronds (large divided leaves), commonly found in moist, shaded areas
• Gymnosperms


  Plants that produce seeds not enclosed in fruits, include conifers such as pine trees and spruces
• Angiosperms


  Flowering plants that produce seeds enclosed within fruits, the most diverse group of plants
• Reactions to stimuli in plant physiology

  • Phototropism
  • Gravitropism
  • Thigmotropism
  • Chemotropism
  • Nastic movements
• Phototropism


  Growth or movement of plant parts in response to light
• Gravitropism


  Growth or movement of plant parts in response to gravity
• Thigmotropism


  Growth or movement of plant parts in response to touch or mechanical stimulation
• Chemotropism


  Growth or movement of plant parts in response to chemical cues
• Nastic movements


  Non-directional, reversible movements of plant parts in response to stimuli
• Types of plant-bacteria symbiosis


  • Rhizobium-legume symbiosis
  • Plant growth-promoting rhizobacteria (PGPR) symbiosis
• Rhizobium-legume symbiosis


  Mutually beneficial relationship between leguminous plants and rhizobia bacteria, where bacteria fix nitrogen in root nodules in exchange for plant-derived nutrients
• Plant growth-promoting rhizobacteria (PGPR) symbiosis


  Mutually beneficial relationship between plants and beneficial bacteria in the rhizosphere, where bacteria promote plant growth and protect against pathogens in exchange for habitat and nutrients
• Plant responses to day length (photoperiodism)

  • Short-day plants
  • Long-day plants
  • Day-neutral plants
• Short-day plants


  Initiate flowering when the duration of darkness exceeds a specific critical period
• Long-day plants


  Require a minimum duration of darkness to initiate flowering
• Day-neutral plants


  Do not rely on day length to regulate flowering, influenced by other factors like temperature or hormonal signals
• Five kingdoms of life

  • Monera
  • Protista
  • Fungi
  • Plantae
  • Animalia
• Monera


  Kingdom of prokaryotic organisms, including bacteria and cyanobacteria
• Protista


  Kingdom of eukaryotic, mostly single-celled organisms, including algae, protozoa, and slime molds
• Fungi


  Kingdom of eukaryotic, mostly multicellular organisms, including mushrooms, molds, and yeasts
• Plantae


  Kingdom of eukaryotic, multicellular, photosynthetic organisms with cellulose cell walls, including plants
• Animalia


  Kingdom of eukaryotic, multicellular, heterotrophic organisms lacking cell walls, including invertebrates and vertebrates
• Three domains of life

  • Archaea
  • Bacteria
  • Eukarya
• Archaea


  Domain of single-celled microorganisms with distinct characteristics, often found in extreme environments
• Bacteria


  Domain of single-celled microorganisms, the most diverse and abundant group of organisms on Earth