Are viruses alive? the scientific debate continues. viruses exhibit some characteristics of life, but others are missing. the most obvious reason why scientists still refer to viruses as non-living is that they a) do not change over time. b) do not contain any genetic material. c) are much smaller than anything alive. d) are not composed of one or more cells.

Drag each tile to the correct box. the body monitors the levels of oxygen in the blood to regulate breathing. isabel is running in a marathon and is near the finish line. she feels out of breath. how will her nervous system work to generate a reaction? arrange the tiles in chronological order. isabel's breathing rate increases. sensory receptors in the arteries detect low oxygen levels. the brain sends signals through motor neurons. sensory neurons generate an impulse. the central nervous system relays an impulse to certain brain regions.

What two factors does carrying capacity compare? population size and resource use population growth and resource availability resource use and time population size and time

Which of the following would involve looking at different structures of organisms and comparing how similar they are? a. vestigial structuresb. radiometric datingc. homologous structures