Genetic recombination refers to the process by which two DNA  molecules exchange genetic information. The three types of genetic  recombination are crossing over, conservati â¦ ve site-specific  recombination and transpositional recombination.
This produces a crystal lattice, which is commonly known as 'ice'. Ice floats because it is about 9% less dense than liquid water. In other words, ice takes up about 9% more space than water, so a liter of ice weighs less than a liter water. The heavier water displaces the lighter ice, so ice floats to the top. One consequence of this is that lakes and rivers freeze from top to bottom, allowing fish to survive even when the surface of a lake has frozen over.
Balloons filled with helium only float in our atmosphere because the average density of the gas and the balloon itself is less than that of the atmosphere around it. An easy way to show this is to try and put a blown up balloon underwater-the density of the water forces the balloon to rise to the surface. balloon expands to a certain level until the gas inside it is at an equal level of pressure with the gas outside, E.G: There are the same number of atoms bouncing off the inside of the balloon as there are bouncing off the outside, forming a balance of forces.