Which statement about viruses is correct? viruses cannot change which species they infect. viruses can mutate to infect new species. bird viruses can never infect mammal species. plant viruses only infect plant species that have rna.

The second statement is correct.  Viruses can infect all cellular life forms, but each cellular species can be infected by own limited specific range of viruses. Most viruses that harm animals can not harm humans. But, some viruses can infect different species of mammals, for example both bats and humans can be infected be rabies.

hope it mark me as brainlieast.

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!