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Intracellular Route

A pathway nutrients take in roots to get to xylem. Intracellular is the route going inside of cells and through the plasmodesmata.

Extracellular Route

Route taken by nutrients to xylem. Traveling inside the hydrophilic walls and extracellular space and never in the cytoplasm of a cell.

Casparian Strip

A waxy barrier that denies nutrients and water traveling in cell membranes to pass into xylem. Forces them to enter cytoplasm and finish in the intracellular way.

Xylem Sap

A solution of water and inorganic nutrients. Flows up from roots to the leaves.

Root Pressure

A build up of inorganic ions in the xylem causing water to enter by osmosis and push the xylem sap up the tree.

Transpiration

The loss of water through leaves. A long string of H2O molecules in cohesion are pulled out by the drier air bringing water up through the tree.

Transpiration-cohesion-adhesion-tension Mechanism

Transpiration exerts a pull that is relayed downward along a string of molecules held together by cohesion and held up by adhesion.

Phloem Sap

A sugary solution containing inorganic ions, amino acids, and hormones and most importantly sucrose. Phloem sap moves throughout the plant in various directions as opposed to xylem sap's upwards movement.

Sugar Source

A plant organ that is a net producer of sugar by photosynthesis or by breakdown of starch. Leaves being the primary sugar source in plants.

Sugar Sink

An organ that is a net consumer or storer of sugar. Fruits growing roots, stems, and buds are all examples.

Pressure Flow Mechanism

Also known as translocation. A widely accepted hypothesis for angiosperms. At sugar sources sugar gets loaded onto phloem tube bringing in water which raises the pressure inside the tube. At sugar sinks sugar exits the phloem and water follows creating hydrostatic pressure.

Essential Element

A chemical element that is essential to a plant completing its life cycle.

Macronutrients

Nine of the essential elements. Called macronutrients because plants require large amounts of them. 98% of a plants dry weight is made up of carbon oxygen, hydrogen, nitrogen, sulfur, and phosphorous.

Micronutrients

Nutrients plants need very small amounts of such as chlorine, iron, boron, zinc, or copper. Function mainly as cofactors in plants.

Fertilizers

Compounds that promote the growth of a plant.

Compost

A soil-like mixture of decomposed organic material, acts as a fertilizer used by gardeners.

Topsoil

The top of ground subject to extensive weathering. Made up of rock particles of various sizes, living organisms, and humus.

Humus

The remains of partially decayed material.

Cation exchange

A method by which root hairs pick up positively charged ions. Root hairs release hydrogen ions to detach ions from their particles.

Nitrogen Fixation

process in which bacteria convert nitrogen gas into nitrogen compounds plants can use to make proteins

Phototropism

The growth of a shoot in response to light. An adaptive response, directing growing seedlings and the shoots of mature plants toward the sunlight driving photosynthesis. Cells elongate faster in darkness.

Auxins

Made in meristems of apical buds, young leaves, and embryos within seeds. Stimulates stem elongation, affects root growth, differentiation branching, development of fruit, apical dominance, phototropism and gravitropism.

Cytokinins

Made in roots. Affect root growth and differentiation. Stimulate cell division, growth and germination, delays aging.

Gibberellins

Made in meristems of apical buds and roots, young leaves and embryos. Promotes seed germination, bud development, stem elongation, leaf growth, flowering, fruit development, root growth, and differentiation.

Abscisic Acid

plant hormone that inhibits cell division in buds and vascular cambium. Made in leaves steams and roots.

Ethylene

plant hormone that speeds the ripening of fruits. Found in fruits and leaves and stems.

Tropisms

Directed growth responses that cause parts of plants to grow toward or away from a stimulus.

Gravitropism

A plants response to gravity. Gravity pulls organelles containing dense starch to low points of cell. Signals auxin to be released. Cells on upper side elongate and root grows straight down.

Thigmotropism

A directional growth of a plant in response to touch.

Circadian Rythm

rythmic pattern of a behavior (in an animal) or biological cycle (in a plant) that follows an approximately 24-hour natural cycle

Biological Clocks

Internal timing systems that continue without external clues, and control (to some extent) the timing of activities of plants and animals.

Photoperiod

relative lengths of night and day

Short-Day Plants

Generally flower in late summer, fall, or winter when there is less light.

Long-Day Plants

plants that bloom only when the period of day is longer than a specific period of darkness

Phytochromes

A class of light receptors in plants. Mostly absorbing red light, these photoreceptors regulate many plant responses, including seed germination and shade avoidance.

Systemic Acquired Resistance

A defensive response in plants infected with a pathogenic microbe; helps protect healthy tissue from the microbe.

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