Plant Biology Study Flashcards

This set of vocabulary flashcards covers plant tissues, vascular structures, specialized cell types, and plant growth responses based on Units C3.1 - C3.5.

Dermal Tissue (Epidermis)

The outermost layer of cells that covers the entire body of non-woody (herbaceous) plants, usually only one cell thick, acting as a protective "skin" and regulating water uptake or loss.

Ground Tissue

The tissue layer beneath the epidermis making up the majority of the plant body, responsible for food and water storage in roots, photosynthesis in leaves, and structural support in stems.

Palisade Tissue (Palisade Mesophyll)

A layer of long, rigid, rectangular cells packed with chloroplasts found directly below the upper epidermis, responsible for the majority of a plant's photosynthesis.

Spongy Mesophyll Tissue

A layer of loosely packed, irregularly shaped cells between the palisade tissue and lower epidermis that facilitates the diffusion of oxygen and $CO_2$ throughout the leaf.

Vascular Tissue

A complex system of vessels or tubes consisting of xylem and phloem that transports water, minerals, and dissolved sugars throughout the plant.

Phloem

Vascular tissue composed of living cells (sieve tube and companion cells) that transports dissolved sugars and organic nutrients from leaves to areas of growth or storage.

Sieve Tube Cells

Long, cylindrical phloem cells with perforated end walls (sieve plates) that lack a nucleus at maturity and form a pipeline for sugar-rich sap.

Companion Cells

Small, specialized cells adjacent to sieve tube cells that direct their activities and provide metabolic energy for the active transport of sugars.

Xylem

Vascular tissue made of thick-walled, hollow cells that are dead at maturity, used for moving water and minerals upward and providing structural support.

Meristems

Specific regions where cells constantly undergo mitosis to produce new growth, allowing the plant to grow in length and width through undifferentiated cells.

Vascular Bundle

A strand in a plant stem or leaf containing both xylem and phloem tissue bundled together, serving as a transport highway and structural reinforcement.

Root Hairs

Tiny, hair-like projections from root epidermal cells that increase surface area to maximize the absorption of water and dissolved minerals.

Guard Cells

Specialized, kidney-shaped epidermal cells surrounding each stoma that control its opening and closing to regulate gas exchange and minimize water loss.

Cuticle

A waxy, non-cellular substance secreted by epidermal cells that forms a waterproof barrier to prevent water loss and protect against microorganisms.

Gravitropism

A plant's growth response to gravity, resulting in roots growing downward (positive) and stems growing upward (negative).

Phototropism

A directional growth response where a plant grows toward or away from a light source to maximize light absorption for photosynthesis.

Nastic Response

A plant movement occurring in response to a stimulus like touch or temperature that is independent of the direction of the stimulus.