Name: how guard cells open plant stomata
Uploaded: 2026-08-26T08:19:56.906Z
Duration: 2 min 19 s
Channel: JoVE

K12 Standards

Florida Department of Education

High School

Life Science

SC.912.L.14

SC.912.L.14.7

Regulation of Transpiration by Stomata

Planten hebben voldoende koolstofdioxide nodig uit de atmosfeer voor fotosynthese.
 De oppervlakte van bladeren bevat openingen die de gaswisseling bevorderen.
 Deze openingen heten stomata.
Door zonlicht gaan de stomata open, zodat koolstofdioxide het blad kan binnengaan waar nodig voor fotosynthese.
 Zuurstof is een bijproduct van fotosynthese en ontsnapt door de stomata naar de atmosfeer.
 Een paar sluitcellen reguleert elke stoma.
Deze gespecialiseerde cellen zwellen op als ze water opnemen van buurcellen via osmose, waardoor een opening ontstaat die gaswisseling bevordert.
 Als water de sluitcellen verlaat, krimpen deze en sluit de stoma.
 De ionenconcentratie be&#xEF;nvloedt de hoeveelheid water in de sluitcellen.
Door zonlicht nemen sluitcellen kaliumionen op.
 De toename in kaliumconcentratie trekt water de cellen in, waardoor de stoma opengaat.
 Als kalium de sluitcellen verlaat volgt water door osmose.
De sluitcellen worden slap en de stoma gaat dicht.
 Hoewel open stomata de gaswisseling bevorderen, laten ze ook water ontsnappen uit bladeren door verdamping.
 Het waterverlies door verdamping&#x2014;of transpiratie&#x2014;maakt watertransport op lange afstand mogelijk door de plant.
Transpiratie is doorgaans het grootst op warme, zonnige dagen.
 Maar als een plant onvoldoende water kan verkrijgen gaan zijn stomata snel dicht tegen het verwelken.
 Zelfs in het duister maken planten stomata open en dicht met een regelmatige cyclus van 24 uur, door een innerlijke klok.
Het openen en sluiten van stomata wordt strict gereguleerd, waardoor planten kunnen reageren op specifieke omgevingsfactoren.
 Als gatekeepers zorgen stomata voor een balans tussen gaswisseling en transpiratie.

regulatie van transpiratie door huidmondjes

Tijdens de fotosynthese verkrijgen planten de nodige koolstofdioxide en geven ze de geproduceerde zuurstof weer af aan de atmosfeer. Openingen in de epidermis van plantenbladeren zijn de plaats van deze uitwisseling van gassen. Een enkele opening wordt een stoma genoemd&#x2014;afgeleid van het Griekse woord voor &#x27;mond&#x27;. Huidmondjes gaan open en dicht als reactie op verschillende omgevingsfactoren.

Elke stoma wordt geflankeerd door twee gespecialiseerde wachtcellen die een opening cre&#xEB;ren wanneer deze cellen water opnemen. Het transport van ionen reguleert de hoeveelheid water in de wachtcellen. Wanneer ze worden geactiveerd, transporteren pompen waterstofionen uit de bewakingscel. Deze hyperpolarisatie van het membraan zorgt ervoor dat spanningsafhankelijke kaliumkanalen openen, waardoor opgeloste stoffen, zoals kaliumionen en sucrose, de wachtcellen kunnen binnendringen. De verhoogde concentratie opgeloste stoffen drijft water naar de wachtcellen, die zich ophopen in de vacuole. Als gevolg hiervan buigen de wachtcellen en vervormen ze tot een niervorm, waardoor de stoma-opening ontstaat. Wanneer opgeloste stoffen de bewakingscellen verlaten, volgt er water, wat resulteert in het krimpen van de bewakingscellen en het sluiten van de opening.

Een verscheidenheid aan omgevings- en interne signalen veroorzaakt het openen van de huidmondjes. Blauw licht activeert bijvoorbeeld lichtgevoelige receptoren op het celoppervlak die een moleculaire cascade initi&#xEB;ren die leidt tot het openen van huidmondjes. Wanneer de concentratie kooldioxide in het bladweefsel daalt, wordt bovendien de opening van de huidmondjes ge&#xEF;nduceerd, zodat cellen toegang krijgen tot deze cruciale reactant voor fotosynthese.

Verlies van waterdamp is van cruciaal belang voor het ontstaan van transpiratiekracht: water verdampt op het oppervlak van mesofylcellen en ontsnapt via open huidmondjes in de atmosfeer. Het waterverlies zorgt voor een transpiratiekracht die extra water uit de grond naar de wortels en helemaal in de bladeren trekt.

Als er niet voldoende water beschikbaar is, zoals bij droogte, sluiten de huidmondjes zich. Het hormoon abscisinezuur (ABA) is belangrijk in dit proces, omdat het zich bindt aan receptoren op bewakingscelmembranen en de intracellulaire concentratie van opgeloste stoffen verhoogt. ABA is ook belangrijk bij de circadiane controle van de stomatale opening, waardoor meer huidmondjes bij daglicht open zijn en in het donker gesloten.

Regulatie van transpiratie door huidmondjes

During photosynthesis, plants acquire the necessary carbon dioxide and release the produced oxygen back into the atmosphere. Openings in the epidermis of ...

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Education

JoVE Core

Biology

Biologie

Plant Biology

Plantenbiologie

Plant Structure, Growth and Function

Plantstructuur, groei en voeding

KEY TERMS AND CONCEPTS

BELANGRIJKE TERMEN EN CONCEPTEN

how guard cells open plant stomata

How guard cells open and close plant stomata controls gas exchange in leaves. A stoma is a tiny opening in the leaf epidermis. The word comes from the Greek word for “mouth.” These openings let plants take in carbon dioxide for photosynthesis and release oxygen into the air.

Each stoma is surrounded by two guard cells. When these cells take up water, they create an opening. Ion transport controls how much water stays in the guard cells. A trigger causes pumps to move hydrogen ions out of the guard cell. This changes the membrane voltage and opens voltage-gated potassium channels. Potassium ions and sucrose then enter the guard cells. As solute levels rise, water moves in and collects in the vacuole. The guard cells swell, bend, and take on a kidney shape, which opens the stoma.

Stomata also close when solutes leave the guard cells. Water follows the solutes out, so the guard cells shrink and the opening closes. Blue light can start this process of opening. Light-sensitive receptors on the cell surface begin a molecular cascade. Low carbon dioxide inside the leaf can also trigger opening so cells can keep using this key photosynthesis reactant.

Water loss through open stomata helps create transpirational pull. Water evaporates from the surface of mesophyll cells and escapes into the atmosphere through the stomata. This pull draws more water from the soil, through the roots, and up into the leaves. When water is scarce, such as during drought, stomata close. The hormone abscisic acid, or ABA, helps drive this response by binding to receptors on guard cell membranes and increasing intracellular solute concentration. ABA also supports circadian control, so more stomata are open in daylight and closed in the dark.

How Guard Cells Open Plant Stomata

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basic plant anatomy: roots, stems, and leaves

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xylem and transpiration-driven transport of resources

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regulation of transpiration by stomata

How guard cells open and close plant stomata controls gas exchange in leaves. A stoma is a tiny opening in the leaf epidermis. The word comes from the Greek word for “mouth.” These openings let plants take in carbon dioxide for photosynthesis and release oxygen into the air. Each stoma is surrounded by two guard cells. When these cells take up water, they create an opening. Ion transport controls how much water stays in the guard cells. A trigger causes pumps to move hydrogen ions out of the...

adaptations that reduce water loss

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key terms and concepts

Explore how guard cells control stomata, gas exchange, and transpiration in leaves. Learn how light, CO2, and ABA affect opening and closing.

How Guard Cells Open Plant Stomata | JoVE K12

JoVE Core series brings biology to life through over 300 concise and easy-to-understand animated video lessons that explain key concepts in biology, plus more than 150 scientist-in-action videos that show actual research experiments conducted in today’s laboratories.

biology

Georgia Standards of Excellence

9-12

Botany

SBO1.

Transport

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How Guard Cells Open Plant Stomata

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