Match each statement with a layer of the atmosphere. there will be two statements for each layer. the biosphere interacts most with this layer. it is the second layer from earth's surface. it contains layers of single, unmixed gas. this layer is where most meteor showers occur. it is heated by the ozone layer beneath it. it contains the ionosphere and exosphere. winds are strong and steady in this layer. this layer can have thunderstorms or clear, sunny skies. thermosphere mesosphere troposphere stratosphere

The troposphere layer can have thunderstorms or clear, sunny skies. The biosphere interacts most with this layer. 

The stratosphere is the second layer from Earth's surface. Winds are strong and steady in this layer. 

The mesosphere is heated by the ozone layer beneath it. This layer is where most meteor showers occur. 

The thermosphere contains the ionosphere and exosphere. It contains layers of single, unmixed gas. 

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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