hvorfor blir bladene på trær gule?

[tameg]

Hei. kan noen forklare HELT enkelt om hvorfor bladene på trær skifter fra grønn til gulaktig farge om høsten?

[Zeph]

Klorofyll er et grønt pigment i bladene. Når bladet slutter å danne klorofyll, blir det grønne pigmentet borte. Men det finnes atskillig flere pigmenter i trærnes blader, bl.a. karotenoider og antocyaniner. Om høsten får bladene farger som avhenger av hvilke pigmenter de har, hvilke de har mye og lite av, og hvordan produksjonen av de ulike pigmentene i bladet endrer seg.

Plants make their own food. They take water from the ground through their roots. They take a gas called carbon dioxide from the air. They turn water and carbon dioxide into food and oxygen. Oxygen is a gas in the air that we need to breathe.

 

Plants make their food using sunlight and something called chlorophyll. Chlorophyll gives leaves their green color.

 

Winter days are short and dry. Many plants stop making food in the fall. The chlorophyll goes away. Then we can see orange and yellow colors. These colors were in the leaves all summer, but the green covered them up.

 

Some leaves turn red. This color is made in the fall, from food trapped in the leaves. Brown colors are also made in the fall. They come from wastes left in the leaves.