Which scientist developed the idea that microorganisms can cause diseases?
paul ehrlich
anton van leeuwenhoek
louis pasteur
alexander fleming

Louis Pasteur

Louis Pasteur in 1860s, proposed germ theory. The theory was based upon the fact that diseases are caused by the microorganisms. These microorganisms are small organisms, which invade inside the body of humans, animals and other living hosts. Their growth and reproduction inside a host organism often result in diseases. Germs included were not just bacterium but wide variety of viruses, fungi, prions and others. These are called as pathogens.

any abiotic or biotic factor in an ecosystem that causes a population's size to slow or decrease is a limiting factor.

answer : haversian

[explanation: -(compact bone is organized as parallel columns, known as haversian systems, which run lengthwise down the axis of long bones. these columns are composed of lamellae, concentric rings of bone, surrounding a central channel, or haversian canal, that contains the nerves, blood vessels, and lymphatic system of the bone)]