Oxygen was initially created in Earth's atmosphere by algaes. It is estimated that marine plants produce between 70 and 80 percent of the oxygen in the atmosphere. Nearly all marine plants are single celled, photosynthetic algae. Hope this answers the question.
The appropriate answer is D. storing sugar and providing structure. Polysaccharides are complex carbohydrates. Starch, glycogen and cellulose are polysaccharides in which the constituent molecules are made of several thousand glucose units linked in long chains. Glycogen is vital to nutrition because it is how the body stores excess glucose in muscles and in the liver.
The molecular structure of glycogen is similar to starch except that the polysaccharide chains are longer and more branched than in glycogen.
The answer is 1.) True.
Pollen tube used to transport pollen from the stigma of a flower to the ovary. Actually, it begins to grow when lands on the stigma. It grows until it reaches an ovule which is inside the ovary. This way it is secured that a nucleus of pollen will fuse with a nucleus of the ovule and that fertilization will occur.
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