Ascientist observes an enzyme polypeptide chain arrange in spiral turns that rise upaward and are held in place by hydrogen bonds. which level of structural arrangement is s/he looking for?

secondary structure (alpha helix)

poor water quality affects most estuarine organisms, including commercially important fish and shellfish. the pollutants that have the greatest impact on the health of estuaries include toxic substances like chemicals and heavy metals, nutrient pollution (or eutrophication), and pathogens such as bacteria or viruses.

the answer is d.) homologous; have mammary glands