Speciation forms new species.
Directional selection favors one extreme of a phenotype, which leads to evolution and adaptive change of a species.
Disruptive selection selects against the average and leads to evolution and genetic variation of a species.
Stabilizing selection favors the average individual in a population, which does not lead to adaptive change or evolution, and reduces variation.
Explanation:
under what circumstance does a negative cell presents An antigen to another negative cell
Answer: adenine (A), uracil (U), guanine (G), and cytosine (C). When this base-pairing happens, RNA uses uracil (yellow) instead of thymine to pair with adenine (green) in the DNA template below.Bases. ... The four bases that make up this code are adenine (A), thymine (T), guanine (G) and cytosine (C). Bases pair off together in a double helix structure, these pairs being A and T, and C and G. RNA doesn't contain thymine bases, replacing them with uracil bases (U), which pair to adenine1.
Explanation: