I think its a hope that helped :)
Answer:
A
Explanation:
An isolated system can NOT exchange energy or matter with it's surroundings. This is why it is isolated.
Answer:
multicellular; single celled organisms are often too tiny to be seen without a microscope
By studying a particular species .
The muscles that contract (during cold or fright), the slanted hair follicle is pulled upright, dimpling the skin surface with goosebumps are called arrector pili muscle.
The arrector pili muscle are tiny muscle that attaches to the base of the hair follicle at one end and to the dermal tissue on the other end. When the body feels cold or fright the body generate heat and the arrector pili muscle contract all at once, that causes goosebumps on the skin.
The arrector pili muscle acts as the thermoregulator. Straight stand hair increases air trapping, so that the heat loss from the body decreases. The arrector pili muscle are mediated by the sympathetic nervous system.
To learn more about sympathetic nervous system here
brainly.com/question/12958051
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