The oxygen molecules moves through the nostrils, pharynx, trachea, bronchus, smaller and smaller branches of the bronchial tree, and then into the alveolus.
Answer:
Cellulose
Explanation:
Cell walls made of cellulose are only found around plant cells and a few other organisms. Cellulose is a specialized sugar that is classified as a structural carbohydrate and not used for energy. ... While cell walls protect the cells, they also allow plants to grow to great heights. You have a skeleton to hold you up.
Fossil evidence because these changed occur over long time periods (millions of years).
