Los delfines viven en grupo a
No les gusta estar porque se ponen muy tristes.

x would be the most and the least would be y because there are more fruit   and seeds than flock z has insects

in 1859, charles darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. he defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".

the three components of a nucleotide are the nitrogenous base, the phosphate group and the five-carbon sugar.

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.