All of the following prevent pathogens from entering the human body except
a. red blood cells
b. tears
c. mucus
d. skin

Which of the following is not a benefit of green revolution? a) new crop varieties b) increased crop yields c) cost effective d) new crops may require larger amonts of water than the previous ones.

Photosynthesis converts light energy to chemical energy. which molecules are the end product of this transformation of energy in this reaction?

When a person is exercising the body needs to deliver increased amounts of oxygen to the muscles which component of blood ensures that the muscles will receive it