1. Why aren’t the carotenes and xanthophylls evident in most leaves until fall?
ID: 208756 • Letter: 1
Question
1. Why aren’t the carotenes and xanthophylls evident in most leaves until fall?2. White asparagus is usually more difficult to grow than green asparagus. Why?
3. The needles on Evergreen, such as the pine, are actually the leaves. Suggest some modifications in leaf structure that allows the needles to remain on an evergreen tree all winter?
4. Design an experiment that would prove that the movement of some plant structures, such as Mimosa leaves, is due to a water transport mechanisms, not reflex actions. 1. Why aren’t the carotenes and xanthophylls evident in most leaves until fall?
2. White asparagus is usually more difficult to grow than green asparagus. Why?
3. The needles on Evergreen, such as the pine, are actually the leaves. Suggest some modifications in leaf structure that allows the needles to remain on an evergreen tree all winter?
4. Design an experiment that would prove that the movement of some plant structures, such as Mimosa leaves, is due to a water transport mechanisms, not reflex actions.
2. White asparagus is usually more difficult to grow than green asparagus. Why?
3. The needles on Evergreen, such as the pine, are actually the leaves. Suggest some modifications in leaf structure that allows the needles to remain on an evergreen tree all winter?
4. Design an experiment that would prove that the movement of some plant structures, such as Mimosa leaves, is due to a water transport mechanisms, not reflex actions.
Explanation / Answer
1) There are many types of pigments in plant leaves. When leaves appear green, it is because they contain an abundance of chlorophyll. There is so much chlorophyll in an active leaf that the green masks other pigment colors. Light regulates chlorophyll production, so as autumn days grow shorter, less chlorophyll is produced. The decomposition rate of chlorophyll remains constant, so the green color starts to fade from leaves. At the same time, surging sugar concentrations cause increased production of anthocyanin pigments. Leaves containing primarily anthocyanins will appear red. Carotenoids are another class of pigments found in some leaves. Carotenoid production is not dependent on light, so levels aren't diminished by shortened days. Carotenoids can be orange, yellow, or red, but most of these pigments found in leaves are yellow. Leaves with good amounts of both anthocyanins and carotenoids will appear orange.
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