Chap 2.1 Biology(Abeka)

System

A group of structures that work together to perform a specific job for an organism.

Root System

The underground portion of a plant responsible for absorbing water and nutrients.

Shoot System

The above‑ground portion of a plant including leaves, stems, and flowers.

Organ

A structure within a system that has a definite form and performs one or more specific functions.

Blade

The flat portion of a leaf.

Leaf Margin

The edge of the leaf blade.

Vein

Pipelines that carry food and water throughout the leaf blade.

Midrib

The large central vein running down the middle of the leaf.

Petiole

The stalk that attaches the leaf blade to the stem and contains vascular tissue.

Sessile Leaf

A leaf that lacks a petiole and attaches directly to the stem.

Stipules

Small leaf‑like or scale‑like structures that protect the leaf while it develops.

Bud

A structure containing developing leaf or stem tissue.

Bud Scale

Protective outer covering of a dormant bud.

Bud‑Scale Scar

Marks left on a stem after bud scales fall off.

Simple Leaf

A leaf with one blade per petiole.

Compound Leaf

A leaf with more than one blade per petiole.

Node

A growth point on a stem where leaves or buds form.

Opposite Leaf Arrangement

Two leaves grow from each node.

Alternate Leaf Arrangement

One leaf grows from each node in an alternating pattern.

Whorled Leaf Arrangement

Three or more leaves grow from each node.

Rosette

A cluster of leaves growing around the base of a plant.

Tissue

Living material arranged to perform a specific task for an organ.

Structural Tissue

Makes up most of the plant body; includes epidermal, cork, parenchyma, and strengthening tissue.

Epidermal Tissue

Protects and covers leaves, roots, stems, and other exposed areas; prevents water loss and injury.

Cuticle

A waxy layer on the epidermis that seals in water.

Root Hairs

Tiny extensions of root epidermal cells that absorb water and nutrients.

Cork Tissue

Forms the outer bark of stems and roots; protects and waterproofs.

Parenchyma

Tissue found in roots, stems, leaves, and fruits; makes and stores food.

Support and Strengthening Tissue

Fibers that strengthen roots, stems, and large veins.

Vascular Tissue

Transports liquids (sap) throughout the plant.

Xylem

Carries water and minerals upward from the roots.

Phloem

Carries food (sap) downward from the leaves.

Sap

Sweet liquid found in vascular tissue containing water, sugars, and nutrients.

Meristematic Tissue

Tissue responsible for plant growth and repair.

Cambium

A type of meristematic tissue that produces new vascular tissue.

Epidermis

Outer protective layer covering both upper and lower leaf surfaces.

Stomata

Small openings in the leaf surface that allow gas exchange.

Transpiration

Loss of water vapor from a leaf through the stomata.

Mesophyll

Middle portion of the leaf where most photosynthesis occurs.

Palisade Mesophyll

Upper mesophyll layer with tightly packed cells for photosynthesis.

Spongy Mesophyll

Lower mesophyll layer with air spaces for gas exchange.

Leaf Veins

Structures running through mesophyll containing vascular tissue.

Cell

The basic structural unit of all living things.

Cell Wall Function

Provides support and protection for plant cells; made of cellulose.

Cellulose

A complex carbohydrate made up of long chains of glucose molecules

Lignin Function

Adds stiffness to woody plant cell walls; strengthens trees and shrubs.

Herbaceous Plant Support

Relies on internal water pressure (turgor pressure) rather than lignin; wilts when water is low.

Chloroplast Function

Tiny chemical “factories” Uses light energy to manufacture food; contains chlorophyll.

Chlorophyll

Green pigment that captures light energy for photosynthesis.

Vacuole Function

Stores food materials, fluids, and minerals; large in plant cells, smaller and more numerous in animal cells.

Organelles

"Little organs" inside the cytoplasm that perform specific functions for the cell.

Cell membrane

Separates it from its environment and regulates what enters and leaves the cell

Nucleus

Controls the cells’s activities