Answer:
When the calcium level is high in the bloodstream, the thyroid gland releases calcitonin. Calcitonin slows down the activity of the osteoclasts found in bone. This decreases blood calcium levels. When calcium levels decrease, this stimulates the parathyroid gland to release parathyroid hormone.
Algae are photosynthetic, but they are also unicellular organisms (Euglena) and shares some of the common features with plants as well as animals. They move like animals and perform photosynthesis like plants. Therefore, they are classified into Protists, and not the Algae. Their most features resemble the non-photosynthetic protozoa, and not plants, and therefore, are put into the Protista.
They also lack a cell wall, which is a feature of plants.
Some scientists advocate their classification in plants because of their sexual mode of reproductiona, and formation of spores.
The genetic material, DNA, must undergo replication before a cell enters mitosis. DNA replication results in two identical copies of the DNA.
The negative impact humans could have on an ocean ecosystem is pollution, which can lead to a mass extinction on the wildlife.
