MULTICELLULAR PLANT BODY - Introduction to Biology

Plant Tissues

Different types of tissues that make up the multicellular plant body, including ground tissue, vascular tissue, and dermal tissue.

Ground Tissue System

Consists of parenchyma tissue, collenchyma tissue, and sclerenchyma tissue in plants.

Vascular Tissue System

Comprised of xylem and phloem, responsible for transporting water, minerals, and nutrients throughout the plant.

Dermal Tissue System

Includes epidermis and periderm, serving as the protective outer covering of plants.

Growth in Plants

Refers to the process of increasing in size and complexity, utilizing energy from photosynthesis and responding to the environment.

Primary Growth

Growth that occurs at the tips of roots and shoots, increasing the length of the plant.

Secondary Growth

Growth that leads to an increase in girth or circumference of the plant, involving the formation of additional wood and bark.

Root System

The underground part of the plant that anchors it, absorbs water and minerals, and stores food.

Shoot System

The aboveground part of the plant consisting of the stem, leaves, flowers, and fruits.

Herbaceous Plants

Plants that do not develop persistent woody parts above ground, in contrast to woody plants like trees and shrubs.

Woody Plants

Plants with persistent woody parts above ground, such as trees and shrubs, that can live for more than 2 years.

Annuals

Herbaceous plants that complete their life cycle in one year, reproducing and dying within that time frame.

Biennials

Herbaceous plants that take 2 years to complete their life cycles, storing extra carbohydrates in the first year for reproduction in the second year.

Perennials

Woody or herbaceous plants that live for more than 2 years, persisting through multiple growing seasons.

Dormancy

A state in which an organism reduces its metabolic activity to survive unfavorable conditions, such as winter or dry seasons.

Herbaceous Perennials

Plants that have soft, green stems and live for multiple years, with their aerial parts dying back in certain conditions.

Woody Perennials

Plants with permanent woody stems that live for hundreds or thousands of years, exhibiting dormancy in winter.

Cell

The basic structural and functional unit of plants, similar to other organisms.

Tissue

A group of cells that form a structural and functional unit in plants, with different types specialized for specific functions.

Ground Tissue System

The plant tissue system responsible for functions like photosynthesis, storage, and support.

Vascular Tissue System

The tissue system in plants that conducts materials throughout the plant body, including water, minerals, and food.

Dermal Tissue System

The tissue system that covers the plant body, including roots, stems, leaves, flower parts, and fruits.

Parenchyma

One of the three simple tissues in the ground tissue system of plants, characterized by thin cell walls.

Collenchyma

A type of ground tissue in plants with unevenly thickened cell walls for support.

Sclerenchyma

Ground tissue in plants with thick, rigid cell walls for structural support.

Parenchyma cells

Relatively unspecialized plant cells with thin primary cell walls, found throughout the plant body, performing functions like photosynthesis, storage, and secretion.

Collenchyma cells

Living plant cells with unevenly thickened primary cell walls, providing flexible support in soft, nonwoody plant organs.

Sclerenchyma cells

Plant cells with both primary and thick secondary cell walls, providing structural support to the plant body, often found as sclereids or fibers.

Xylem

Complex tissue in the vascular tissue system responsible for transporting water and minerals throughout the plant.

Phloem

Complex tissue in the vascular tissue system responsible for transporting organic nutrients like sugars throughout the plant.

Xylem

A complex vascular tissue that conducts water and dissolved minerals throughout the plant body.

Phloem

A complex vascular tissue that conducts food (carbohydrates) throughout the plant body.

Epidermis

The outermost tissue layer, usually one cell thick, that covers the primary plant body - leaves, young stems, and roots.

Tracheids

Chief water-conducting cells in gymnosperms and seedless vascular plants, long tapering cells with pits for water passage.

Vessel Elements

Efficient water-conducting cells in flowering plants, larger in diameter than tracheids, with perforations for water flow.

Parenchyma Cells

Cells in xylem that perform storage functions.

Fibers

Cells in xylem that provide structural support.

Sieve-tube Elements

Conducting cells of phloem, specialized for transporting food materials in solution.

Companion Cells

Living cells adjacent to sieve-tube elements in phloem, assisting in nutrient transport.

Periderm

Tissue several to many cell layers thick that replaces the epidermis in older woody plants, forming the outer bark.

Bast fibers

Fibers obtained from the stems of eudicot plants such as flax (linen), hemp, jute, and ramie, which are generally considered soft fibers.

Leaf fibers

Fibers consisting of xylem cells, phloem cells, and fibers clustered together in the leaves or stems of monocot plants, known as hard fibers.

Surface fibers

Fibers found on the surface of seeds and fruits, with cotton being the most significant example, not true fibers but trichomes attached to seeds.

Cotton

A crucial surface fiber associated with seeds, cultivated in warmer regions for thousands of years, with each pound containing about 90 million seed hairs.

Flax

A plant whose slender stems provide fibers for linen cloth, known for its strength, durability, and beauty, historically grown since prehistoric times.

Primary cell wall

The first layer of cell wall deposited during cell division, composed mainly of cellulose and other polysaccharides.

Middle lamella

A pectin-rich layer that cements adjacent plant cells together.

Secondary cell wall

A layer added between the plasma membrane and the primary cell wall, often containing lignin for strength.

Simple pit

A pit pair with an interruption in the secondary cell wall, allowing water movement.

Bordered pit

A pit pair with a small opening in the secondary cell wall that functions like a valve.

Torus

A thickening in the primary cell walls that blocks the opening of bordered pits under pressure.

Water

Chemical formula H2O, essential for plant growth and various physiological processes.

Permeable primary cell wall

Allows water to pass through, found in simple pit pairs.

Tracheid

A type of water-conducting cell in xylem, characterized by tapering ends and pits.

Stomata

Small pores in the epidermis of leaves and stems that regulate gas exchange and water loss.

Cuticle

A waxy layer secreted by epidermal cells that reduces water loss from plant surfaces.

Trichomes

Outgrowths on the epidermis with various functions, such as reducing water loss or deterring herbivores.

Root hairs

Unbranched trichomes that increase the surface area of roots for better water and mineral absorption.

Periderm

The outer bark of woody plants, replacing the epidermis during secondary growth.

Phelloderm

A type of plant tissue that functions primarily in storage.

Cell division

The process in which a cell divides, resulting in an increase in the number of cells.

Cell elongation

The lengthening of a cell as the cytoplasm grows and the vacuole fills with water, exerting pressure on the cell wall causing it to expand.

Cell differentiation

The process in which cells specialize into various cell types to compose the mature plant body and perform specific functions.

Meristems

Areas in plants where cell division occurs, composed of cells that form new cells and do not differentiate.

Primary growth

Increase in the length of a plant, occurring at the tips of stems and roots due to the activity of apical meristems.

Secondary growth

Increase in the girth of a plant due to the activity of lateral meristems like the vascular cambium and cork cambium.

Apical meristem

Area of cell division at the tip of a stem or root in a plant, producing primary tissues.

Protoderm

Young, undifferentiated tissue that eventually develops into the epidermis of a root or stem.

Procambium

Meristematic tissue that eventually develops into xylem and phloem.

Ground meristem

Meristematic tissue that gives rise to cortex, pith, and ground tissue in plants.

Shoot Apical Meristem

The region of plant tissue at the tip of a shoot where cell division occurs, leading to growth in length.

Leaf Primordia

Small embryonic leaves that protect the shoot apical meristem and eventually develop into mature leaves.

Secondary Growth

The increase in girth of stems and roots in woody plants due to cell divisions in lateral meristems like the vascular cambium and cork cambium.

Vascular Cambium

A layer of meristematic cells that produces secondary xylem and phloem, contributing to the growth in thickness of stems and roots.

Cork Cambium

A layer of meristematic cells that forms cork cells and cork parenchyma, leading to the development of the periderm in woody plants.

Bud

A dormant embryonic shoot that can develop into an apical meristem.

Lateral Meristem

An area of cell division on the side of a vascular plant responsible for secondary growth, including the vascular cambium and cork cambium.

Ground Tissue System

Consists of parenchyma tissue, collenchyma tissue, and sclerenchyma tissue, providing various functions like support and storage in plants.

Vascular Tissue System

Composed of xylem and phloem, responsible for conducting water, minerals, and food materials throughout the plant body.

Dermal Tissue System

Includes the epidermis and periderm, serving as the outer protective covering of plants with functions like gas exchange and water loss regulation.