- How have sea stars evolved over time and adapted to their environments?
- How does solar radiation affect the ionosphere layer?
- How did the loss of body hair influence human evolution?
- What is the role of enzymes in the breakdown of food in the stomach and small intestine?
- How does the distance of a planet from the sun affect its orbital period?
- What were the main causes of the American Civil War?
- What is the role of the water vascular system in the movement and feeding of sea stars?