Calcium levels in the body are maintained by hormones. If the blood calcium level rises above a set point, calcitonin is secreted by the thyroid gland and sets into motion responses to lower the blood calcium back to the set point. If the blood calcium level falls below a set point, the parathyroid gland secretes parathyroid hormone that sets into motion responses to raise the blood calcium. These homeostatic responses are examples of:
a. positive feedback
b. effectors
c. sensors
d. negative feedback
Answer:
d. negative feedback
Explanation:
Negative feedback responses are the ones that counteract the change. Any alterations in the internal body conditions such as blood calcium levels are sensed by receptors. The information is sent to the brain which in turn commands the effectors such as endocrine glands to secrete the required hormones to restore the normal conditions. Here, changes in the calcium levels are counteracted by the secretion of calcitonin and parathyroid hormones and the calcium is maintained within a narrow range. This represents negative feedback.
The cell theory was constructed by <span>Schleiden and Schwann.
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>Matthias Jakob Schleiden<span> was a German </span>botanist<span> and co-founder of the </span>cell theory, along with Theodor Schwann<span> and </span>Rudolf Virchow (not really credited towards it, he is a contributor to the said theory.
>Robert Hook---largely attributed the cell theory;started the study of cells known as the cell biology.
>Carolus Linnaeus---<span>a Swedish </span>botanist<span>, physician, and </span>zoologist<span>, who formalized the modern system of naming organisms called </span>binomial nomenclature<span>.</span>
Both of the parents would need to have ww because the trait of a straight hairline is recessive.
