Answer:they won't for a pair
Explanation:Basically it all depends on process called complementary base pairing, the structure of thymine and adenine is such that it forms two hydrogen bonds and therefore pair up
2.guanine and cytosine have such structure that they form three hydrogen bonds and pair up
So Adenine complements only thymine and guanine complements cytosine and there aren't any chances of guanine pairing up with thymine.
A river that comes from rain, glaicers etc would be a good example of fresh water rivers. Cause the water is coming from something that is most likely been unthouched by man or has been filterd and cleaned from minerals in the ground.
Clear wheat her from this prediction
Answer:
Active uptake (which I think you mean active transport) is important when the concentration gradient is against that of a certain substance, so it doesn't cross the membrane through diffusion or passive transport. It is sometimes necessary if a substance needs to move across a membrane but can't do so due to electrical charge or that there is a substance on the other side of the membrane preventing diffusion.
Explanation:
