Choose the best answer to complete the sentence. directional selection can be distinguished from disruptive selection by
a. the elimination of extreme variations of traits
b. selection for two extreme variations of a trait
c. the preservation of gene frequencies
d. selection for one extreme variation of a trait

Which best describes the digestive system of arthropods? a incomplete, two openings b complete, one opening c two-way, one opening d one-way, two openings

Considering the yellow and green pea color phenotypes studied by gregor mendel: a. what is the biochemical function of the protein that is specified by the gene responsible for the pea color phenotype? (1 point) b. a null allele of a gene is an allele that does not specify (or encode) any of the biochemical function that the gene normally provides (in other words, either no protein at all or only non-functional protein is produced from it). of the two alleles, y and y, which is more likely to be a null allele? (1 point) c. in terms of the underlying biochemistry, why is the y allele dominant to the y allele? (2 points) d. why are peas that are yy homozygotes green? (1 point) e. the amount of protein produced from a gene is roughly proportional to the number of functional copies of the gene carried by a cell or individual. what do the phenotypes of yy homozygotes, yy heterozygotes, and yy homozygotes tell us about the amount of sgr enzyme needed to produce a yellow color? explain your reasoning. (2 points)

Below, the levels of organization in a multicellular organism are shown from least to most complex. which level of organization can be described as several different types of tissues working together to perform a common task?