Guide. A bone density test measures the density of minerals (such as calcium) in your bones using a special X-ray. This information is used to estimate the strength of your bones.
Animal cells do have vacuoles, but they are smaller, larger in number (plant cells usually have just one or a few large vacuoles) AND serve a somewhat different purpose than those of plants.
Vacuoles are vesicles which contain mostly water. 1  Plant cells have a large central vacuole in the center of the cell that is used for osmotic control and nutrient storage. 2  Contractile vacuoles are found in certain protists, especially those in Phylum Ciliophora.acuoles are vesicles which contain mostly water. 1  Plant cells have a large central vacuole in the center of the cell that is used for osmotic control and nutrient storage. 2  Contractile vacuoles are found in certain protists, especially those in Phylum Ciliophora.