What are the characteristics and composition of the 5 layers of the atmosphere – troposphere, stratosphere, mesosphere, thermosphere, exosphere?

1) The troposphere is the first layer above the surface and contains half of the Earth's atmosphere. Weather occurs in this layer. 

2) Many jet aircrafts fly in the stratosphere because it is very stable. Also, the ozone layer absorbs harmful rays from the Sun.

3) Meteors or rock fragments burn up in the mesosphere.

4) The thermosphere is a layer with auroras. It is also where the space shuttle orbits. 

5) The atmosphere merges into space in the extremely thin exosphere. This is the upper limit of our atmosphere.

The answer would be abrasion.

The answer is a: the eggs have half as many chromosomes as the body cells