Plant Tissues, Tissue Systems, and Microscope Investigation

Vocabulary flashcards covering plant cell specialization, meristematic and permanent plant tissues, plant tissue systems, and parts of the compound light microscope.

Cell Specialization

The process by which cells develop specific structures and characteristics that allow them to perform particular functions efficiently.

Cell Differentiation

The developmental process through which unspecialized cells become specialized cells with particular structures and functions, strongly associated with meristematic cells in plants.

Tissue

A group of cells that are structurally and functionally organized to perform a particular function or related functions.

Meristematic Tissues

Undifferentiated plant tissues composed of actively dividing cells that produce new cells for plant growth and development.

Apical Meristem

Meristematic tissue located at the tips of roots and shoots responsible primarily for primary growth, which increases the length of roots and shoots.

Lateral Meristem

Meristematic tissue located along the sides of stems and roots responsible primarily for secondary growth, increasing thickness or girth (e.g., vascular cambium and cork cambium).

Intercalary Meristem

Meristematic tissue found at the bases of leaves or internodes of grasses that allows rapid growth and regeneration after cutting or grazing.

Permanent Tissues

Tissues composed of mature, differentiated, and specialized cells that have lost their ability to divide and perform specific functions.

Epidermis

A single layer of cells covering young roots, stems, and leaves responsible for protection, reduction of water loss, defense against pathogens, and regulation of gas exchange.

Cutin

A waxy, waterproof substance found mainly in the epidermis of plant organs, especially leaves and young stems, to protect against water loss.

Guard Cells

Specialized epidermal cells that surround each stoma and regulate its opening and closing.

Stomata

Pores in the epidermis that allow gas exchange between the plant and the environment, permitting carbon dioxide to enter and oxygen to exit.

Root Hair

A long and thin extension found in roots that increases surface area for the efficient absorption of water and dissolved mineral nutrients from the soil.

Parenchyma

Living simple permanent tissue with relatively thin primary cell walls and large vacuoles, commonly involved in photosynthesis, storage, repair, and secretion.

Chlorenchyma

Specialized parenchyma cells in plant leaves containing chloroplasts that carry out photosynthesis.

Aerenchyma

Specialized parenchyma tissue with air spaces that provides buoyancy in aquatic plants.

Collenchyma

Living simple permanent tissue with unevenly thickened primary walls (thickened cellulose corners) that provides flexible mechanical support and elasticity to growing plant parts.

Sclerenchyma

Simple permanent tissue composed of dead cells with heavily reinforced, lignified walls that provide strong, rigid structural support and protection.

Lignin

A complex organic substance that makes plant cell walls strong, rigid, and resistant to water.

Fibers

Long and narrow sclerenchyma cells with thick lignified cell walls located in the stem and bark that provide mechanical support.

Sclereids

Sclerenchyma cells with thickened, highly lignified walls and pits running through the walls that provide toughness in seed coats and pear fruit.

Xylem

A complex permanent tissue that unidirectionally transports water and dissolved mineral nutrients from the roots to the uppermost part of the plant.

Tracheids

Elongated, dead conducting cells in the xylem with tapered ends that function in water conduction and mechanical support.

Vessel Elements

Tube-like, dead conducting cells in the xylem with lignified walls that allow efficient water transport.

Phloem

A complex permanent tissue that bidirectionally transports organic materials, particularly sugars produced through photosynthesis.

Phloem Sap

The collective name for the organic materials, sugars, and nutrients transported through the phloem.

Sieve Tube Elements

Living conducting cells in the phloem that lack nuclei at maturity, contain pores, and transport sugars and nutrients.

Companion Cells

Living nucleated phloem cells that regulate and support the function of sieve tube elements.

Dermal Tissue System

The tissue system that forms the outer protective covering of the plant (comparable to animal skin), mainly consisting of the epidermis.

Ground Tissue System

The tissue system occupying much of the internal part of roots, stems, and leaves that is neither dermal nor vascular, consisting primarily of parenchyma, collenchyma, and sclerenchyma.

Vascular Tissue System

The tissue system consisting of xylem and phloem responsible for the long-distance transport of materials connecting roots, stems, and leaves.

Eyepiece (Ocular Lens)

The optical lens through which the specimen is viewed on a microscope, commonly providing $10\times$ magnification.

Scanning Objective

The objective lens providing the lowest magnification ($4\times$) that is used to locate the specimen.

High-Power Objective

An objective lens providing $40\times$ magnification used for observing smaller details of a specimen.

Oil-Immersion Objective

An objective lens providing very high magnification ($100\times$) used with immersion oil.

Revolving Nosepiece

The mechanical part of a microscope that holds the objective lenses and allows the user to switch magnification.

Coarse Adjustment Knob

A mechanical control on a microscope that moves the objective lens or stage rapidly to bring the specimen into approximate focus.

Fine Adjustment Knob

A mechanical control on a microscope that makes small adjustments to obtain a sharp and clear image.

Condenser

An illumination part of a microscope that concentrates and directs light toward the specimen.

Iris Diaphragm

An illumination part of a microscope that controls the amount of light entering the specimen.