AS

Plant Anatomy: Vocabulary Flashcards

The Plant Cell

  • Cell wall: made of cellulose; gives strength and rigidity; functions include protecting the protoplast and providing structure.
  • Plasma membrane: selectively permeable; regulates entry/exit of substances; mechanisms include passive diffusion for gases (CO₂, O₂) and active transport for sugars, salts; organizes cellulose production for cell walls; supports cell growth and differentiation.
  • Protoplast: the living component of the cell (cytoplasm plus organelles).
  • Cytoplasm: contains plant organelles.
  • Organelles mentioned: rough endoplasmic reticulum (RER), smooth endoplasmic reticulum (SER), ribosomes, Golgi apparatus, mitochondria, chloroplasts, vacuoles, plastids.
  • Nucleus: two main roles — cellular activities and determining when/which proteins are produced; repository for genetic information (DNA, RNA); passes on genetic code to daughter cells during cell division.
  • Endoplasmic reticulum and ribosomes: rough ER with ribosomes synthesizes proteins; smooth ER involved in other lipid/enzymatic processes.
  • Golgi apparatus: modifies, sorts, and packages proteins and lipids.
  • Chloroplasts and plastids: plastids store food or pigments; chloroplasts are the site of photosynthesis and contain chlorophyll.
  • Chloroplasts: site of photosynthesis; contain chlorophyll; thylakoids are disc-shaped structures inside chloroplasts and host the light-dependent reactions.
  • Thylakoids: location of light-dependent reactions of photosynthesis; photons drive electron transport.
  • Chlorophyll: green pigment that absorbs light; located in thylakoid membranes (stacks of thylakoids).
  • Chromoplasts: pigmented plastids containing carotenoids; responsible for yellow, orange, red colors in flowers, aging leaves, fruits, and some roots (e.g., carrots).
  • Mitochondria: provide energy in the form of ATP; sites of respiration; essential for cellular energy.
  • Vacuole: stores up to 90\% of the cell volume in mature plant cells; tonoplast surrounds the vacuole and regulates movement of substances; vacuolar sap contains water, inorganic salts, sugars, dissolved proteins, organic acids, toxins (defense); stores water-soluble pigments (anthocyanins) contributing to blue, violet, purple, dark red, or scarlet colors; maintains turgor pressure for rigidity and support.
  • Summary: The plant cell contains a coordinated set of organelles and membranes that enable growth, energy production, storage, and metabolism.

Plant Tissues

  • Tissue: a group of organized cells of similar structure that perform a collective function.
  • Meristematic Tissue: actively dividing, undifferentiated cells that will differentiate into other tissues; found in areas of active growth.
  • Permanent Tissues: fully differentiated cells; divided into Simple and Complex tissues.

Meristematic Tissues

  • Meristem types: Shoot apical meristems (in buds); Root apical meristems; Lateral meristems (e.g., vascular cambium, cork cambium).
  • Shoot meristems: at the ends of shoots; produce new buds and leaves.
  • Root meristems: at tips of roots behind the root cap; produce permanent tissues.
  • Lateral meristems: involved in secondary growth (e.g., vascular cambium produces xylem and phloem; cork cambium contributes to bark).
  • Meristem patterns:
    • Opposite: meristems occur across from each other.
    • Alternate: meristems alternate along the stem.
    • Whorled: meristems are close together forming a spiral.

Permanent Tissues

  • Simple permanent tissues: uniform, composed of one type of cell.
    • Parenchyma: found in herbaceous plants, fruit flesh, swollen roots, and succulents; thin-walled with large vacuoles; may contain chloroplasts and can become meristematic for wound healing.
    • Collenchyma: cell walls thickened by cellulose; provides structural support and flexibility; common in young stems and leaf veins.
    • Sclerenchyma: thick-walled, lignified; protoplast dies; nonliving; common in stems and bark.
  • Complex permanent tissues: composed of two or more cell types.
    • Epidermis: outermost cell layer; may include cuticle, trichomes, stomata.
    • Secretory tissues: various secretory cells and structures.
    • Vascular tissue: xylem and phloem; responsible for transport.

Stomata

  • Stomata are leaf pores that regulate water loss and gas exchange; stomata may open or close to control transpiration and photosynthesis.

Vascular System

  • Two primary vascular tissues: Xylem and Phloem.
  • Vascular plant: any species that has vascular tissue (xylem and phloem).

Xylem and Phloem

  • Xylem: conducts water and dissolved minerals from roots to all parts of the plant.
  • Phloem: conducts food and metabolites from the leaves (source) to stems, flowers, fruits, roots, and storage organs (sink).

Plant Organs

  • Stems, Buds, Leaves, Roots, Flowers, Fruit, Seed.

Learning Objectives (concept recap)

  • Describe the cell structure and function of major organelles.
  • List and describe the primary tissues of higher plants and their functions: Meristematic vs Permanent; Simple vs Complex.
  • Understand the role of xylem and phloem tissues and their components.
  • Recommended Reading: Chapter 3.0-3.2