This question would be better placed under the Chemestry section
1 the atmosphere because gas is everywhere.
In comparison they both show feeding relationship in an ecosystem.
In contrast, a food chain is a simple linear feeding relationship while a food web is a complex feeding relationship.
2) The arrows is to show the direction of the feeding relationship
Three
different ways the relatedness of species could be assessed is through:
<span>1.
</span>Their genotype. Similarity in DNA between the species is a good
indication of their relatedness.
<span>2.
</span>Their phenotype. If the two species have similar body form and function,
then there is a good possibility that they are related.
<span>The presence of intermediates, either living
or in the fossil record, can show relatedness between two species.</span>
Might be Cell Differentiation...