Answer:
Option A, Hormones are controlled by a feedback loop; information about a system is sent back to the controller of the system to improve its function.
Explanation:
Negative feedback loop controls the hormone production and release. This is done by eliciting the release of substances till a certain level after which the stop signal is activated thereby preventing further release. By this method, concentration of hormones in blood is maintained within the narrow range.
For example – Thyroid hormones is released when the anterior pituitary signals the thyroid. This continues till the hormones in the blood reach the threshold level. Once the threshold level is reached, hypothalamus receives a feedback and then signals anterior pituitary to inhibit further signaling to the thyroid
Hence, option A is correct
Answer:
Explanation:
The tricuspid valve separates the right atrium from the right ventricle carrying deoxygenated blood from right atrium to right ventricle
The mitral/bicuspid valve separates the left atrium from the left ventricle carrying oxygenated blood from left atrium to left ventricle
Pulmonary semilunar valves separates the right ventricle from the pulmonary artery preventing bachelor of blood.
Aortic semilunar valves separates the left ventricle from the aorta preventing backflow of blood
Answer:
A. Populations were separated through geographical isolation.
Explanation:
When talking about evolution, a good example is bacterial resistance to antibiotics.
We start with a bacteria colony, and in contact with antibiotics, most of them die.
Some of them in the colony do not die and took that antibiotic to create a mutation of its DNA to be resistance to that.
They evolved survive that antibiotic.
