The results of Meiosis I are two diploid cells with genetic differences on the chromosome. These differences are a result of crossing-over. Crossing-over is a process that happens after both homologous chromosomes in a pair join up to form a structure called a tetrad. Tetrads form through a process called synapsis.
A tide is the periodic rising and falling of Earth's ocean surface caused mainly by the gravitational pull of the Moon acting on the oceans. Tides cause changes in the depth of marine and estuarine (river mouth) waters. Tides also make oscillating currents known as tidal streams (~'rip tides'). This means that being able to predict the tide is important for coastal navigation.
1. (Physical Geography) the cyclic rise and fall of sea level caused by the gravitational pull of the sun and moon. There are usually two high tides and two low tides in each lunar day. See also tide-generating force, neap tide, spring tide. 2. (Physical Geography) the current, ebb, or flow of water at a specified place resulting from these changes in level: the tide is coming in.