Answer:
Scientific theory definition, a coherent group of propositions formulated to explain a group of facts or phenomena in the natural world and repeatedly confirmed through experiment or observation: the scientific theory of evolution.
Explanation:
Answer:
4. The suspected causative agent must be isolated from the diseased host and grown in pure culture
Explanation:
Robert Koch (1843-1910) was one of the most important bacteriologists of all time. Famous for discovering the tuberculosis bacillus (precisely on March 24, such as today, in 1882), he also discovered the cholera bacillus and is considered the founder of bacteriology. He worked on the isolation of infectious agents and reinfections from pure cultures, experiences from which he established the "Koch Postulates".
These postulates have been taken as a reference that describes the etiology of all the causative agents of an infectious disease, although they were originally used to describe only the tuberculosis bacillus. They are the following:
1- The agent must be present in each case of the disease and absent in the healthy.
2- The agent should not appear in other diseases.
3- The agent must be isolated in a pure culture from the lesions of the disease.
4- The agent has to cause the disease in an animal that can be inoculated
Explanation:
Cancer occurs in dividing cells only because genetic materials divide into two equal portions during division. This process may be interrupted by carcinogenes or mutagenes to make mutate cells and then render them as cancer cells. In the brain, the cells are differentiated and there is no chance to start division, then how can cancer be found in the brain.
Answer:
One
Explanation:
The only star in our solar system is the Sun.
Answer:
RADON GAS
Explanation:
Radon is a naturally occurring gas, which is produced due to the radioactive decay of the Radium element. It is one of the dense gas that is mostly concentrated in the lower portion of the houses, and are trapped in the cracks and fractures of the walls of houses and buildings.
Radon gas is an invisible, colorless and odorless gas, which is a very harmful gas, and exposure to Radon gas can cause an individual to suffer from cancer.
In recent studies, it has been found that in many parts of North America, a large number of residents are exposed to Radon gas, which led to an increased risk of cancer.
