The heart valves actually touch the flowing blood, therefore they are

Surrounded by microtubules, located near the nucleus. (don't try to google it) (give answer only if u know)

Which of the following are false concerning microbes? a. microbes generate oxygen through photosynthesis.b. the primary role of microbes on the planet involves causing disease in animals and humans.c. microbes produce vitamins in the intestines.d. microbes play a role in breaking down waste and decomposing dead organisms.

What substance is the most acidic. lemon juice. tomato juice. sodium hydroxide. water