I think that this would be carbohydrates, I'm not completely sure though.
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Explanation:
Biome and the ecosystem are the words that are sometimes applied interchangeably to explain a particular kind of environment.
The biome represents the geographical region that has the same kind of ecological atmosphere, climate and mostly consistent collection of the species and it is made of a large number of ecosystems.
An ecosystem represents a particular element of the biome and a species that nearly interact in it.
Thus the biome is the collection of various types of ecosystems.
D is the answer. A gene is a part of a chromosome.
Cancerous cell just continue to divide giving rise to mases of cells called tumor.
