10. disappears during prophase
A movement in response to gravity is called tropism.
Their safety is dangerous when they don't use a common measurement is because they don't know what are safe amounts of this dangerous chemical for them to use. Because they're using dangerous chemicals without a common measurement - this obviously puts them at risk.
Abiotic factors are things that aren't living that effect an environment, like pH (how acidic the soil is), the temperature, amount of light, and so on. These can effect a population by making it more difficult to survive, perhaps creating more competition over available resources and so on. So for example, if the soil is really acidic in an area, a population of plants may not be able to grow well in that environment.
