Photosynthetic bacteria changed the Earth's atmosphere
Answer:
D.
Explanation:
She's trying to find the affect different shapes have on the distance the plane flies, not the affect different types of paper have on distance. If she were to use different paper for each plane she'd be testing two variables instead of one.
hope this helps :)
Answer:
Cancer is unchecked cell growth. Mutations in genes can cause cancer by accelerating cell division rates or inhibiting normal controls on the system, such as cell cycle arrest or programmed cell death. As a mass of cancerous cells grows, it can develop into a tumor.
Explanation:
We speak of irradiation by external exposure to ionizing radiation, when a person is exposed from the outside by the ionizing radiation emitted by a radioactive source located in its vicinity (like the waste of the nuclear power stations or the remains of the explosion nuclear energy such as Hiroshima and Nagasaki). In this case, exposure ceases when the source of radioactivity is moved away from the person or if a screen (shielding) is interposed between the person and the source.
While a contamination by an internal exposure to radioactive particles, that is to say when radioactive elements have penetrated inside the organism, as in the case of ingestion e radioactive product as the iodine 131 in a diagnostic or therapeutic purpose.