How is the nitrogen cycle important to humans? O It produces free nitrogen that humans can breathe.
O It converts nítrogen into a form that humans can obtain by eating other organisms.
O it produces nitrogen compounds that humans can breathe.
OIt converts nitrogen into a form that humans can obtain by absorbing it through their skin.

Compare and contrast the adaptations of free-living flatworms and parasitic flatworms

You have a solution that contains phospholipid vesicles in a test tube. these vesicles have phospholipid bilayers, but do not contain any membrane transporters. you add a number of different molecules to the solution, and wait a period of time for them to equilibrate. if you could measure the concentration of each molecule, for which of the following would you expect to measure equal concentrations inside and outside of the vesicles? assume for this question that the overall osmolarity inside and outside the vesicles is the same (that is, there is no appreciable diffusion of water across the membrane). (select two answers) an amino acid with a hydrophobic side-chain a small non-polar molecule a negatively charged ion a small polar molecule a small lipid hormone

Read the following scenario to answer the following question. over the past 60 years, many amphibian species have experienced significant population declines, and some species have become extinct. scientists suspected that local human activities such as the destruction of wetlands, regional pollution, and deforestation were the main reasons for these losses. however, research over the past 20 years reveals significant amphibian population declines in protected areas of the world, such as nature preserves and parks. these global declines suggest widespread problems including increased ultraviolet radiation, acid rain, and disease. in switzerland, for example, 14 of the 20 native amphibian species are threatened with extinction. when most populations of a wide-ranging amphibian species are lost and the few remaining populations are widely separated, we expect to see that a. the founder effect becomes increasingly important b. microevolution no longer occurs c. gene flow between populations is reduced d. artificial selection becomes a greater factor in microevolution