Hi, I don’t see the following questions
Light excites the electrons in chlorophyll a molecules of photosystem 1. As these electrons move to another primary electron receptor, electrons from photosystem 2 replace them.
Therefore the answer is FROM PHOTOSYSTEM 2.
<span>To prove his Theory of Evolution. After studying the different species of finches he found the Galapagos Islands, Darwin focused on breeding pigeons by selecting specific traits of different individuals (this is mainly a method through which different kinds of dog breeds came about). On the basis of these studies Darwin concluded that natural selection and artificial selection acted roughly in the same way. Darwin's decision to enforce a certain trait represented, in a sense, the selective pressure which is present in a natural environment (the law of the fittest).<span>
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Heat is considered as a water pollutant because it decreases the capacity of water to dissolve oxygen, and it increases the rate of metabolism fish. Valuable species of game fish cannot survive in water with very low levels of dissolved oxygen.
Answer:
Water erosion refers to the removal of the top most or surface layer of soil by the flow of water. The long term effect of water erosion can be because of drastic rain fall and may be because of flood. These two reasons can adversely effect the human life. The water erosion is responsible for the removal of fertile layer of soil, therefore, the region will not be appropriate to grow vegetation. The long term effect may result in stagnation of water, therefore, long time is required so that the region gets dried. The long term accumulation of water over an agricultural field can spoil the crop production.
Prevention that can be taken to reduce long term effect of water erosion:
1. Plantation of long root bearing trees over flood prone regions and around the agricultural field: This will allow the trees to tightly hold up soil and prevent it's erosion.
2. Add rocks over the soil: In an agricultural field or flood prone area, the rocks will act as barrier for the movement of run off water, hence, will prevent water erosion. It will increase the absorption of water by soil.
3. Building of walls: This will also act as a barrier in a flood prone region and will prevent the water being added up to the agricultural land.
4.Remove soil compaction: If the soil compaction of the effected region is removed, the water retention property of the soil can be improved. Machines, animals and humans can be used for this purpose to remove the compaction of upper layer of soil.
Explanation: hope this helps.
