There was no life on Earth for the first billion years because the atmosphere was not suitable for life. Earth's first atmosphere had lots of water vapor but had almost no oxygen. Later, frequent volcanic eruptions put several different gases into the air.
Head,Thorax,abdomen and six legs
So we can look back and see how much we have accomplished in the year with the models
Trophic levels go by,
Producer (The nuts)
Primary Consumer (Squirrels)
Secondary Consumer (Raccoons)
Tertiary Consumer (Bear)
So squirrels would be at a lower trophic level.
Hope his help :)
Because a chemical change occurred. heating, baking, cooking are can cause chemical changes. color change most frequently represents a chemical change