8) is b.
im not sure if this is right though
18) is d
Answer:
False
Explanation:
In the troposphere, near the Earth's surface, human activities lead to ozone concentrations several times higher than the natural background level. Too much of this ground-level ozone is 'bad' as it is harmful to breathe and also damages vegetation.
The stratosphere or “good” ozone layer extends upward from about 6 to 30 miles and protects life on Earth from the sun's harmful ultraviolet (UV) rays.
Answer:
Cell theory
Explanation:
Cell theory is a universal theory proposed by three scientists namely: Theodor Schwann, Mathias Schleiden and Rudolf Virchow in the 1830's. The cell theory compose of three components:
- All living things are made up of one or more cells.
- Cells are the basic and fundamental unit of life
- All cells emanate from pre-existing cells.
Based on this question, these three components are what makes up the CELL THEORY.
Two populations are said to be isolated if there is no longer any Gene Flow between them.
