The ozone layer protects life on earth by absorbing harmful ultraviolet radiation. The ozone layer is located between seventeen kilometers and thirty-five kilometers above the earth's surface in the stratosphere (2). The ozone layer is also known as the earth's shield. This layer contains high concentrations of ozone. It is interesting to note that Ozone is made up of three oxygen molecules; water consists of one hydrogen molecule and two oxygen molecules. It absorbs about ninety-seven percent of the sun's ultraviolet rays.
The thickness and depth of the atmosphere on earth varies from one geographic location to the other. This thickness not only vary with location but also with time of year.
Equator is warmer than any other part of the world and hence the air mass over the equator is, on average, warmer there than anywhere else on Earth. Cold air is denser than warm air . However the gravitational force is exerted in equal amount across the world , therefore , the same amount of air molecules over the equator go upward while the air molecules in the coldest regions on Earth i.e the poles hovers near the surface of earth . Thus, the atmosphere is thickest and deepest at the equator.
Answer: a. Haploid spores are released to form zygotes, which grow into gametophytes.
A fern has two different stages of the life cycle; the sporophyte and gametophyte. In the sporophyte, spores are released. After this life cycle comes the gametophyte or the sexual phase, <span>haploid spores are released to form zygotes, which grow into gametophytes. </span>
