Answer No 1:
A concentration gradient can be described as a phenomenon by which molecules travels from an area which is highly concentrated to an area which has low concentrations of that molecule.
Answer No 2:
A molecule is said to be diffusing down a concentration gradient when molecule acquire the phenomenon of concentration gradient i.e move from higher concentration to lower concentration. This mechanism is also termed as passive transport. Active transport is the opposite of passive transport. In active transport, molecules move against the concentration gradient i.e from an area of lower concentration to an area of higher concentration.
Answer: c
Explanation: all cell membranes need to maintain function
Biogeographical studies use information for various fields, such as evolutionary biology, geography, geology, and climate science to determine how organisms evolved through time and how the moving of tectonic plates resulting in forming continents, mountain ranges and islands has affected their distribution.
Studies in this field explain how organisms that now live on different continents are very closely related and how the flora and fauna of islands are connected to one of the closest continents etc.
I think B is the answer The Clean Air Act That prevented air pollution and protected the ozone layer as well as promote public health. This act gave Enviromen. Protection Agency the power to take effective action fighting environmental air pollution