Lead is toxic, but do you know why?
a. lead is toxic mainly because it preferentially replaces other metals in biochemical reactions.
b. in so doing it interferes with the proteins that regulate blood pressure, heme production (which can lead to anemia) and sperm production.
c. lead also displaces calcium in the reactions that transmit electrical impulses in the brain, which diminishes the ability to think and recall information.

80 points pls brainliest 1. what does a red shift mean? blue shift? 2. describe the big bang theory. according to this theory, how old is the universe? 3. scientists believe the universe is expanding. what is the evidence that supports this? 4. describe a nebula. 5. describe the 3 types of galaxies. what is a barred spiral galaxy? 6. what is a light year? how far is alpha centauri from earth? 7. describe the universal law of gravitation. be sure to include gravitational force between two objects. 8. describe the planets’ orbits around the sun. 9. what is the asteroid belt? where is it located? 10. describe rotation and revolution of earth. what determines an earth day and year? 11. how do galaxies exist? 12. compare and contrast the inner and outer planets. 13. what causes the seasons?