During the cardiac cycle, the bicuspid valve closes: a. while the ventricle is in diastole b. when the ventricle is in systole c. while the atrium is contracting

Which must be kept in mind when determining if an explanation is correct? check all that apply. which must be kept in mind when determining if an explanation is correct? check all that apply.

Me 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?

Number and variety of living organism; includes genetic, species, and ecological types