Suggest and explain what happen to the movement of sugar in winter when a tree has no leaves?
Because the plant has no existing leaves, its only source of sugar for growth is the sugar stored in roots, tubers, or bulbs from the last growing season. These storage sites now serve as sources, while actively developing leaves are sinks.
During winter, when a tree has no leaves, the movement of sugar within the tree undergoes certain changes. To understand this, we need to explain the process of sugar movement in trees.
Trees produce sugar through photosynthesis, a process that occurs in their leaves. During photosynthesis, trees use sunlight, carbon dioxide, and water to produce glucose (a type of sugar) as a source of energy. This glucose is then transported throughout the tree for various purposes such as growth, storage, and energy utilization.
The movement of sugar within a tree occurs primarily through a tissue called phloem. Phloem is composed of specialized cells called sieve tubes that act as conduits for transporting sugar and other nutrients. These sieve tubes form a network that extends from the leaves down to the roots and other parts of the tree.
When a tree enters the winter season and loses its leaves, the photosynthetic activity decreases significantly since there are no leaves to absorb sunlight. As a result, the production of sugar decreases. However, the tree still requires energy for various essential functions, such as maintaining cellular processes and surviving the winter. Therefore, it relies on the stored sugars that were produced during the previous growing season and are stored in various parts of the tree, including roots, stems, and branches.
During winter, the movement of sugars is primarily regulated by temperature and the dynamics of water within the tree. When temperatures drop, the water within the tree can freeze, which can disrupt the flow of sugars. However, trees have mechanisms to prevent or minimize damage caused by freezing.
First, trees increase the concentration of sugars in their cells, which lowers the freezing point of the sap. This enables them to maintain a relatively fluid state even in cold temperatures. They also produce specialized proteins called antifreeze proteins or cryoprotectants that help prevent ice crystals from forming within the cells.
Second, trees can adjust their osmotic pressure within the phloem cells. Osmotic pressure refers to the concentration of dissolved substances, including sugars, which affects the movement of water. By adjusting osmotic pressure, the tree can regulate water movement and prevent damage caused by freezing.
Overall, during winter when a tree has no leaves, the movement of sugar within the tree slows down as photosynthesis is minimal or absent. However, the stored sugars from the previous season are utilized, and the tree employs various mechanisms to maintain the fluidity and prevent damage caused by freezing temperatures.