Answer: because they cannot be produced in the body and must be consumed from outside sources
Answer:
Disease can be density-dependent because organisms have to live close enough to one another for the disease to spread.
Answer:
Microtubules have an inner diameter of 25 nm and an outer diameter of 30 nm.
Explanation:
Microtubules is a microscopic tubular structure that is present in the cytoplasm of cells; they are polymer structures that form part of the cytoskeleton that gives shape to cytoplasm of eukaryotic cells and some prokaryotic cells. A microtubules can be as long as 50 nm in diameter. The average inner diameter of microtubules is 25 nm while that of the outer diameter is 30 nm.
