Jane is researching air quality levels in large cities. which element should represent about 80% in each of her samples?

Write a paragraph at least 5 sentences “why all vaccinations should be mandatory”

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.

The most famous fossil called archaeopteryx is which of the following? a dinosaur a fern a fish a bird