The statement is true. Renin-angiotensin system will be activated when there is a loss of blood volume (or decrease of blood pressure, such as in haemorrhage or dehydration. <span>Renin is secreted by kidneys directly into the circulation when the blood flow is reduced. Renin then stimulates conversion of angiotensinogen, released by the liver, to angiotensin I which will then be converted to angiotensin II by the angiotensin-converting enzyme (ACE) found in the lungs. Angiotensin II is a vasoconstrictor(increases the blood pressure) and also stimulates the secretion of the aldosterone from the adrenal cortex. Aldosterone increases the reabsorption of sodium and water into the blood and the excretion of potassium (to maintain electrolyte balance). This also increases blood pressure and retention of water.</span>
If there wasn't a lot of organisms and energy in the productive part of the triangle, then there wouldn't be a lot of third level organisms. The energy piramid would be a lot smaller then what it is here, and maybe if the energy source was low then there might not be such a vast varity of animals in the ecosystem.
Plucking is a type of glacier erosion.Plucking occurs when the ice around the broken rocks, gets displaced with the force exerted by the retreating glacier. The glacier ice plucks the freezed rocks away along with it during glacier erosion.