Leaf Color Change and Tree Adaptations

What natural event signals the beginning of fall and the changing of leaves?

• Longer days and warmer nights

• Shorter days and cooler nights

• Increased rainfall

• Strong winds

How are evergreen trees able to keep their leaves through winter?

• They grow new leaves every winter.

• Their leaves have a waxy coating and special chemicals to prevent freezing.

• They store extra water in their leaves.

• They move to warmer climates.

What is the main signal that tells deciduous trees to begin the process of dropping their leaves?

• A sudden drop in temperature

• The amount of sunlight decreasing as days get shorter

• The arrival of heavy rain

• An increase in wind speed

What substance is responsible for the green color of leaves?

• Carotenoids

• Anthocyanins

• Chlorophyll

• Flavonoids

Why do leaves turn yellow and orange in the fall?

• The tree creates new yellow and orange pigments.

• The green pigment breaks down, showing yellow and orange pigments that were already there.

• The leaves absorb more yellow and orange light.

• The leaves are dying and losing all their color.

How are the red pigments (anthocyanins) different from the yellow and orange pigments (carotenoids and flavonoids) in leaves?

• Red pigments are newly made by the tree in the fall, while yellow and orange pigments are always present.

• Yellow and orange pigments are newly made by the tree in the fall, while red pigments are always present.

• Red pigments are only found in certain types of trees, unlike yellow and orange pigments.

• Red pigments are always present in the leaves, but yellow and orange pigments are not.

What is the main benefit for a tree to produce red pigments (anthocyanins) in the fall?

• To make the leaves more attractive to animals.

• To help the leaves fall off the tree faster

• To protect the chlorophyll and allow the tree to collect more nutrients.

• To absorb more sunlight for photosynthesis during shorter days.