Plant Anatomy and Tissues Quiz

Plant Anatomy and Morphology

• Plant anatomy is the study of internal structures of specific parts or organs.
• Plant morphology is the study of external structures or forms of plant organs like leaves, stems, roots, flowers, and fruits.
• Seed plants have the same basic body, composed of three organs: leaves, stems, and roots.
• Two categories of seed plants are gymnosperms and angiosperms.
• New plant cells are produced by dividing tissues called meristems.
• Three major tissue systems (dermal, ground, and vascular) form the plant body.

Plant Tissues

• Plant tissues are made up of dead cells, providing structural strength to withstand adverse environmental conditions.
• Meristematic tissues are responsible for continuous cell division throughout the plant's life, creating new cells at sites called meristems.
• Types of meristems include:
  • Apical meristems: at the tips of roots and stems
  • Lateral meristems: in the vascular and cork cambia
  • Intercalary meristems: in nodes of monocots stem (e.g., grass).

Shoot Apical Meristem (SAM):

• Structurally more complex than root apical meristem (RAM)
• Forms lateral organs like leaves, branches, and flowers.
• Has an outer layer (tunica) and an inner layer (corpus).
• Tunica determines the characteristics of leaf edge in monocots.
• Layer two of the corpus determines the characteristics of leaf edges in dicots.
• SAM is up to 3 mm in size and has central zone (CZ), peripheral zone (PZ), and rib zone (RZ).

Root Apical Meristem (RAM)

• Root cap covers the tip of the root, protecting underlying cells from abrasion during soil penetration.
• Mucilage, a gelatinous mix, helps roots navigate soil and aids in interactions with soil microorganisms.
• Regions of cell division and elongation follow the root cap; these regions are responsible for pushing the root further through the soil.
• Root growth has zones for maturation of cells in the root.
• Three primary meristems differentiate from RAM: protoderm, procambium, and ground meristem, which generate the epidermis, and the vascular tissue system, and cortex, respectively.

Intercalary Meristem

• Found only in monocots like grass, this form of meristem is located in stem nodes and leaf blades.
• Intercalary meristem allows for rapid stem elongation and leaf regrowth.

Permanent Plant Tissues

• Unlike meristematic tissues, permanent tissues have lost their ability to divide.
• Classified into simple and complex tissues based on cell type composition.
  • Simple tissues: composed of a single cell type with similar origin, structure, and function. (e.g., parenchyma, collenchyma, sclerenchyma).
  • Complex tissues: composed of more than one cell type. (e.g., xylem and phloem).

Dermal Tissue System

• Forms the outer protective covering of the plant.
• Includes epidermis, with cuticle to prevent water loss and epidermal hairs for protection or gas exchange.
• In stems with secondary growth, the epidermis is replaced with periderm – outer bark; composed of cork (phellem) outward, and phelloderm inward.

Ground Tissue System

• Found between the dermal and vascular tissues.
• The cells of the ground tissue are derived from the apical meristem.
• Cortex (between epidermis and vascular bundles, and pith (center of the stem).

Vascular Tissue System

• Involved in transporting water, minerals, and food throughout the plant.
• Xylem: transports water and minerals, composed of tracheids and vessel elements (non-living) and parenchyma (living).
• Phloem: transports food (sugars) throughout the plant, composed of sieve tube elements, companion cells, phloem fibers, and parenchyma
• Procambium differentiates into the primary phloem and xylem tissues; vascular cambium gives rise to secondary xylem and phloem.

Root Tissues

• Root system differentiated into dermal, ground and vascular tissues.
• Dermal tissue system: covers roots, including epidermis and root hairs for primary growth (with epidermis and root hairs) but periderm forms for secondary growth covering.
• Ground tissue system: cortex (innermost layer), endodermis, pericycle.
• Vascular tissue system: vascular tissues (xylem and phloem) arranged in a radial manner in the center of the root. The procambium differentiates into primary xylem and phloem. Secondary xylem and phloem are derived from the vascular cambium.

Functions of Epidermis

• Mechanical support
• Protection (from dessication, pathogens, insects)
• Gas exchange (via stomata)
• Water loss prevention (through transpiration)
• Storage of water and minerals.

Plant Body Organization

• Roots, stems, leaves
• Ground tissues, vascular tissues, dermal tissues