True rainforests cover less than 2 percent of the earths total surface
The statement above is false. The blood levels of calcium is regulated by parathyroid hormone.When one is not getting adequate calcium in one's diet and the blood level of calcium is low, the parathyroid hormone will be released. The parathyroid hormone can increase the blood calcium in several ways:
1. by stimulating osteoclasts which break down bone and release calcium into the blood stream.
2. by increasing the amount of calcium re-absorbed by the kidney before it can be excreted in urine.
3. by triggering the formation of calcitriol which increases the absorption of dietary calcium at the intestines.
Answer:
I think it is true
Explanation:
Newton's first law, the motion of an object does not change if the net force acting on it is zero.
So if there were no friction, a moving object would keep moving, even if no other force were applied to it