The answer to this question would be: vitamin
Some bacteria can produce vitamin K2 in the intestine. Other bacteria also able to change vitamin K1 into vitamin K2. But the amount produced is not much, so human still need to fulfill it from the diet. Vitamin K has a role in calcium regulation and in blood clotting pathway.
The elodea is getting the carbon dioxide from its environment like when underwater animals breathe out carbon dioxide the plants will use that carbon dioxide. The plants can also get the carbon dioxide from the atmosphere which can "dissolve" in water.
Answer:
I'm not too sure specifically for 9th grade. Though I am in 12th grade right now and currently using the Edrolo biology textbook which is solely based on the key dot points/skills for the entire subject. They also include past exam questions or similar exam style questions both multiple choice and short answer for each topic and chapter within the book.
Explanation: