Answer:
The lowest level, which is usually the producers.
Explanation:
This is because on every level of the trophic system, some energy is lost before the next level. So the level with the least lost energy is the lowest
Answer:
The most common nutrients causing eutrophication are nitrogen and phosphorus. The main source of nitrogen pollutants is run-off from agricultural land, whereas most phosphorus pollution comes from households and industry, including phosphorus-based detergents.
Explanation:
Answer:
Bridgham et al. (2006) showed that the interaction between a steroid hormone (aldosterone-M) and its receptor (mineralocorticoid) evolved by Darwinian gradualism. In this work, the authors demonstrated a primitive affinity between the hormone and its receptor that was initially present in chemically similar but more ancient ligands. This result has implications in understanding the association between gene duplication and the evolution of hormone signaling pathways. For example, in invertebrates, this work reinforces the importance of gene duplication in the existing interaction between paralogous glucocorticoid receptors and their receptor mineralocorticoid genes that were derived from duplication (Thornton 2001).
The publications above cited are the following:
J.T. Bridgham, S.M. Carroll, and J.W. Thornton (2006). Evolution of hormone-receptor complexity by molecular exploitation. Science, 312(5770), 97-101.
JW Thornton. Evolution of vertebrate steroid receptors from an ancestral estrogen receptor by ligand exploitation and serial genome expansions, Proc Natl Acad Sci USA (PNAS), 2001, vol. 98 10 (pg. 5671-5676).
A force of 8 N will be required.
<h3><u>Explanation:</u></h3>
Mechanical advantage is defined as the ratio of output force from a system to the input force into the system. A machine which has the mechanical advantage more than 1 means it requires less force to give more force as output. Similarly, when the mechanical advantage for the machine is less than 1,it means more force is required to give to achieve a less one.
Here in the question, the mechanical advantage of the pulley is 2.
Output force required to pull the sack of potatoes upto kitchen is 16N.
Mechanical advantage = Output force / input force.
Or, 2= 16 / input force.
So input force = 
So a force of 8 N will be required to pull the pulley.
