Answer:
because the moon is hiding sun wen night
Answer: ensure blood flows toward your heart
Explanation:
These valves are what ensure blood flows toward your heart. Vein valves work hard, against gravity, to bring the blood that flowed down via arteries back up to your heart. When your vein valves are open and healthy, they are able to do their job properly, as the blood is easily able to flow up.
Answer: Plant growth over time
Explanation:
i would say that because its very likely that the growth of the plant will change, the rest of them seem like a independent variable. Have a good day hope i helped.
Carry out and experiment.
E.g. put a cut stalk into a beaker of colored water. The color of the water can be red, blue, yellow, etc.
Answer:
it provides energy for chemical reactions
Explanation:
enzymes are biological catalysts which speeds up a chemical reaction without changing itself.
as like catalysts providing activation energy for the reaction enzymes provides energy for a reaction
