Answer – 3. A weakened form of a virus
When getting a vaccination, the substance which is injected into the body is a weakened form of a virus. This weakened from of the virus has the ability to arouse the body’s defense mechanism without causing an infection.
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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.
<span>characteristics of skeletal muscle:</span><span>
contains nerve endings; is a voluntary muscle; striped/striated, multi-nucleated (has many nuclei); attached to the bones of the skeleton</span>
The air diffuses into the capillaries surrounding the alveoli.
2. The pulmonary veins carry oxygenated blood to the heart.
3. Air enters the bronchioles in the lungs and reaches the alveoli.
4. The capillaries join together to reach the arteries, transferring the oxygen.
5. The oxygen-rich blood moves from the aorta and reaches the kidneys through a series of blood vessels.
6. The left atrium fills with oxygen-rich blood and contracts to fill the left ventricle.
Answer:
The answer is (A. A cladogram.)
