Autumn Leaf Color Changes and Functions

Deciduous trees change leaf color in autumn as chlorophyll breaks down, revealing yellow and orange pigments. This process allows trees to recycle nutrients like nitrogen and phosphorus before shedding leaves for winter. Some trees produce red pigments to protect against chlorophyll-induced damage. This nutrient recovery is crucial for new growth in spring, making trees efficient recyclers.

What is the primary reason leaves of deciduous trees change color in autumn?

• They gain new pigments.

• They produce more chlorophyll.

• They lose chlorophyll, revealing other pigments.

• They absorb more sunlight.

Why do deciduous trees drop their leaves each year?

• To attract pollinators.

• To avoid the cost of winterizing them.

• To grow new leaves immediately.

• To increase photosynthesis.

What do trees recover from their leaves before dropping them?

• Chlorophyll and glucose.

• Carbon dioxide and oxygen.

• Nitrogen and phosphorus.

• Water and sunlight.

What happens to chlorophyll molecules during the disassembly process?

• They are stored in the roots.

• They are used to produce oxygen.

• They become more reactive.

• They are converted into glucose.

How do reactive oxygen molecules affect leaves?

• They enhance photosynthesis.

• They cause damage to leaf cells.

• They help in nutrient recovery.

• They protect the tree from pests.

What is the role of yellow and orange pigments in leaves?

• They attract insects for pollination.

• They are new pigments produced in autumn.

• They help with photosynthesis and are revealed when chlorophyll breaks down.

• They are responsible for leaf drop.

What special pigments do some trees produce to protect against chlorophyll damage?

• Black and white pigments.

• Red and purple pigments.

• Green and blue pigments.

• Yellow and orange pigments.

Why do some trees have red leaves in the fall?

• To attract more sunlight.

• Because they stop photosynthesis.

• Due to the production of new red pigments.

• To conserve water.

What percentage of nitrogen and phosphorus can trees recover from their old leaves?

• 75%

• 50%

• 25%

• 10%

What is the ultimate benefit of the autumnal color change for trees?

• To prepare for winter.

• To recycle nutrients efficiently.

• To attract animals.

• To increase leaf size.