3. why is active transport necessary for the sodium-potassium pump to work? a. the sodium would never leave a cell while potassium can move against the gradient b. the potassium would never leave a cell while sodium can move against the gradient c. it allows sodium and potassium to move against their concentration gradient d. all channel movement requires active transport to equalize the cell

Identify any four organelles that should be present in the eukaryotic organism and describe the function of each organelle

What best describes the dropping height of a ball that bounces back up to a height of 45 cm

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?