The second and third one I believe
Answer:
Internal srtucture adaption
In contrast to compact bone, spongy bones does not contain true Haversian systems( tiny tubes that form a network in bone and contain blood vessels) but consist of an irregular lattice of thin plates of bone called trabeculae.The spaces between trabeculae are filled with marrow. The cells of the red marrow are responsible for producing blood. Within trabeculae lie lacunae which contain osteocytes.<span> Blood vessels from the periosteum penetrate through to the spongy bone, and osteocytes in the trabeculae are nourished directly from the blood circulating through the marrow cavities.</span>
Answer: The food chain
Explanation: It is important to have a large number of producers and herbivores in an ecosystem because of the food chain. Without producers the herbivores would have no food. and without the herbivors the carnivores would have no food.
