Select all amino acids that match the description. the r groups of this class of amino acids are non-polar and hydrophobic, and their side chains tend to cluster together within proteins, stabilizing protein structure by means of hydrophobic interactions:
a) leucine. b) isoleucine. c) alanine.

In the diagram below, the northern hemisphere would be in what season at position a a.fall b. winter c.summer d.spring

20 point pls brianliest 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?

The big bang theory suggest that the universe is about - 300 million years old - 4.6 billion years old - 30 billion years old - 13 billion years old