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
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Enzymes are considered catalysts, they help reactants and can be used over and over
To test the effectiveness...
A. This variable should be controlled (the same in both groups).
B. The new chemical is what is being added to the experimental group.
C. This is the control group to which the treated couch should be compared.
D. This is the experimental group to which data should be taken.
Final answer: D
Answer:
Differential reproduction leads to a change in allele frequencies over time. This occurs because of natural selection favoring "successful" individuals that produce more viable offspring.
The sickle-cell allele is maintained in populations exposed to malaria through balancing selection, since heterozygous individuals have protection against the disease.
