Answer:
Your heart changes its rate depending on the activity, so that it can carry blood to your muscles, and therefore it needs to beat stronger if you are performing some exercise, or not so strong if you are sleeping, for example.
Explanation:
Your heart is continuously beating to keep blood circulating throughout your body.
So, here it is why your heart changes its rate: Its rate changes depending on your activity level; it is lower while you are asleep and at rest and higher while you exercise to supply your muscles with enough freshly oxygenated blood to keep the functioning at a high level.
And how: depending on your activity level, your heart has to pump enough blood to your muscles. Blood carries needed oxygen and other nutrients. Muscles need more blood sugar than any other tissue especially when working hard. To supply your muscles with oxygen your heart needs to beat faster, and this builds up your heart muscles.
Answer:
deserts
Desert biomes are the driest of all the biomes. In fact, the most important characteristic of a desert is that it receives very little rainfall. Most deserts receive less than 300 mm a year compared to rainforests, which receive over 2,000 mm.
Explanation:
All rock on the ocean floor is less than 180 million years old because <span>reverse polarity removed older rock strips magnetized in a different direction. Also,</span> the oldest parts reach the continental crust and then the ocean floor sinks beneath the continental crust, into the mantle.
