There are two groups of bases: Pyrimidines: Cytosine and Thymine each have a single six-member ring.
Because of their relatively simple genetic structure when compared to other organisms. Not to mention, they breed in extremely high numbers which is great for scientists looking to do many trials, as most are. Their life cycle is also very short which means we can observe their entire life span and witness the effects of testing at all stages.
Answer:
The surface fish lives near the surface of the water, but the blind fish live in caves.
Explanation: yes
