Explain how the use of biomass energy can both improve and decrease water quality.

Biomass energy comes from crops that are grown expressly for that purpose. The growth of these crops helps decrease the rate of soil erosion and therefore sedimentation buildup in waterways and also decreases the runoff of fertilizers and pesticides into those waterways. The combustion of biomass, on the other hand, can decrease water quality involves the use of water to create steam. When this water is returned to the environment, it can contaminate waterways.

fertilization, pictured in figure 24.23a is the process in which gametes (an egg and sperm) fuse to form a zygote. the egg and sperm each contain one set of chromosomes. to ensure that the offspring has only one complete diploid set of chromosomes, only one sperm must fuse with one egg. in mammals, the egg is protected by a layer of extracellular matrix consisting mainly of glycoproteins called the zona pellucida. when a sperm binds to the zona pellucida, a series of biochemical events, called the acrosomal reactions, take place. in placental mammals, the acrosome contains digestive enzymes that initiate the degradation of the glycoprotein matrix protecting the egg and allowing the sperm plasma membrane to fuse with the egg plasma membrane, as illustrated in figure 24.23b. the fusion of these two membranes creates an opening through which the sperm nucleus is transferred into the ovum. the nuclear membranes of the egg and sperm break down and the two haploid genomes condense to form a diploid genome.

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