Pioneer species such as lichen and moss inhabit an area after a major disturbance such as a volcanic eruption. Over time, other species are found in the disturbed area and the number of pioneer species decreases. Why does the number of pioneer species decrease? The amount of available sunlight is reduced. The pioneer species can no longer thrive. ⊝ The area has more soil to support complex plants. The competition increases between organisms. ⊝ The area is more susceptible to the wind. Seeds are captured in the pioneer plants and germinate at a higher rate. ⊝ The temperature is not as extreme as it was following the disturbance. Fewer of the pioneer species reproduce. ⊝ CLEAR ALL

Proteins are the workhorses of the cell, controlling virtually every reaction within as well as providing structure and serving as signals to other cells. proteins are long chains of  amino acids  , and the exact sequence of the amino acids determines the final structure and function of the protein. instructions for that sequence are encoded in  genes  . to make a particular protein, a messenger ribonucleic acid (mrna) copy is made from the gene (in the process called  transcription  ), and the mrna is transported to the  ribosome  . protein synthesis, also called  translation  , begins when the two ribosomal subunits link onto the mrna. this step, called initiation, is followed by elongation, in which successive amino acids are added to the growing chain, brought in by transfer rnas (trnas). in this step, the ribosome reads the  nucleotides  of mrna three by three, in units called  codons  , and matches each to three nucleotides on the trna, called the anticodon. finally, during termination, the ribosome unbinds from the mrna, and the  amino acid  chain goes on to be processed and folded to make the final, functional protein