Plant Physiology Vocabulary

Flashcards covering key vocabulary terms related to plant physiology, including tropism, hormones, transport, and tissue structures.

Positive Tropism

Growth towards a stimulus.

Negative Tropism

Growth away from a stimulus.

Gravitropism

Growth response to gravity; roots exhibit positive gravitropism.

Phototropism

Growth response to light; shoots exhibit positive phototropism.

Auxin

Plant hormone that controls phototropism; causes faster growth on the side of the plant furthest from light.

Phytohormone

Signaling chemicals controlling growth, development, and response to stimuli in plants.

Gibberellin

Phytohormone that causes stem elongation; promotes or inhibits cell division or elongation.

Ethylene

Phytohormone that ripens fruit; prompts or inhibits differentiation of plant tissues.

Jasmonic acid

Phytohormone that triggers the secretion of enzymes in the Venus flytrap.

Auxin efflux carriers

Transmembrane proteins that pump auxin into cells, maintaining concentration gradients of phytohormones.

Apoplast

The space outside the cell wall where auxin prompts the synthesis of a proton pump.

Expansin enzyme

Enzyme activated by acidity in the cell wall, loosening the wall's fabric.

Cytokinin

Plant hormone produced in roots and transported to shoots; interacts with auxin to regulate root and shoot growth.

Water Potential

Potential energy of water per unit volume ; freedom of movement of water.

Transpiration pull

Water is pulled up through the xylem to evaporate (transpire) out of the stomata in leaves towards a negative pressure.

Lignin

Polysaccharide that lines the outside of the xylem, preventing collapse and providing structural support.

Vascular bundle

Contains phloem and xylem for transport in stems.

Phloem

Transports sugar from leaves to other parts of the plant in stems.

Epidermis

Protective structural support and prevents water loss in plant stems.

Cortex

Structural support in stems.

Xylem

Upward transport of water out of the leaves (transpiration) in plant stems.

Cambium

Separates the phloem from the xylem; lateral meristem responsible for secondary growth.

Pith

Central core storage and functional support in plant stems.

Translocation

Process by which phloem transports sucrose and other carbon compounds from source to sink.

Phloem sap

Nutrient-rich fluid that flows through the phloem, usually containing sucrose, amino acids, hormones, and minerals.

Stomata

Pores for gas exchange in leaves; open during the day, closed at night.

Guard cells

Change shape due to turgor pressure, regulating stomatal openings.

Palisade mesophyll

Densely packed with chloroplasts; main site of photosynthesis in plant leaves.

Spongy mesophyll

Loosely packed; large air spaces facilitate gas exchange in plant leaves.

Root pressure

Positive pressure generated in xylem vessels by active transport of mineral ions.

Cohesion-tension theory

Transpiration creates tension (negative pressure); water is pulled up xylem as a continuous column due to cohesion and adhesion.

Epiphytes

Plants that grows on branches, accessing sunlight without soil, absorbing moisture and nutrients from rain, air, or organic debris.