The element was poisonous to the first forms of life on earth until they evolved to take advantage of it by using cellular respiration. what is it? a. hydrogen b. nitrogen c. oxygen d. sulfur

Select the situation bellow that would produce a total displacement of zero. a. a trip to the moon and then to mars b. a horse galloping from one end of a field to another c. the criss-crossing path of a bug as it flies from flower to flower d.a round-trip ride to school and back

When is your respiration rate likely to change? a. when your intestines are digesting b. when your cells have too much glucose c. when your cells need more oxygen d. when your liver is working after a meal

Idon’t know the answer and i’ve been stuck on it for a while now skskskskks