<span>a. They have homologous structures because they have a common ancestor.
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Answer: A.) The nitrogen cycle recycles nitrogen through an ecosystem, making it available to all organisms.
Explanation: Nitrogen is an essential nutrient for plants and a significant component of proteins, which all animals need to grow, reproduce and survive. The nitrogen cycle converts nitrogen into compounds that plants and animals can use.
<span>Thy hyaline cartilage covers and protects the ends of bones at freely movable joints. The hyaline cartilage contains elements that are found commonly in areas such as the ear. It is made this way because it is very elastic allowing the joints it is covering to have more flexibility.</span>
Plants leafs increasing carbon dioxide. it's remove dust air pollution
