A substance that enters Earth's cycles and does harm to living things is

A. oxygen.

B. freshwater.

C. a pollutant.

D. hydrogen

How is a spider web like a food chain?

Farmers in Nick's village are using excessive chemical fertilizers for increasing the productivity of their crops. Nick and his team of other community activists are concerned that prolonged use of chemical fertilizers will impact the environment.

What is the most common type of lab accident?

Which part of the human body is most similar to stomata in plants?

Kayla says that turning on a radio involves an energy transformation, but Joey says that energy cannot be transformed.

If you had purple flowers and white flowers the bees go visit the purple flowers more, why?

The word hyponatremia derives from the words hypo ("under" or "less") and natrium ("sodium"). The word natrium is the basis for the abbreviation Na for sodium.

Prokaryotes whose cell walls do not contain peptidogly can

Which is true regarding tolerable upper intake levels (uls) ?

Which cells quickly respond to produce antibodies on second exposure to the same antigen?