The correct answer is a - silicon dioxide.
Diatoms are single celled algae. They have a silica - based cell wall called a frustule, which gives each diatom a particular shape.
Diatoms exist as separate single cells although some may be found in groups or colonies. The ones found in colonies create very pretty forms: leaf shaped, oval , star and even like a period.
Outer shells of diatoms are quite valuable. They are used in industry in the manufacture of toothpaste to give it grit.
Non deciduous are evergreen trees or Shade trees are not deciduous trees. evergreen plant leaves last throughout the year.
for example a pine tree or cedar plant would be considered non deciduous because they keep leaves\ last throughout the year.
Answer:
A
Explanation:
The hypothalamus is a portion of the brain particularly concerned with homeostasis; it influences the action of the medulla oblongata, a lower part of the brain, the autonomic nervous system, and the pituitary gland.
The effect of chemical pollution on insects living in a pond i think
