Natural selection is what caused them to change
The proteins on the two layers are not identical
The complete question is :
Which of the following best describes how ACh changes the ion permeability of the sarcolemma?
A) ACh activates acetylcholinesterase.
B) ACh entry into the axon terminal causes neurotransmitter release.
C) ACh binds to receptors in the junctional folds.
D) ACh entry into the muscle fiber causes Ca2+ to be released by the sarcoplasmic reticulum.
Answer:
C) ACh binds to receptors in the junctional folds.
Explanation:
Sarcolemma is the term used for the cell membrane of the skeleton muscle fiber cell.
At the motor end plate, there are several folds present in the sarcolemma that are known as junctional folds.
These junctional folds have several acetylcholine (Ach) receptors present on them and these are ion channels that are chemically gated.
These ion channels open upon binding of Ach and thus, the ions can diffuse into the sarcolemma.
Thus, the binding of Ach on the receptors located in the junctional folds increases the ion permeabiltity of the sarcolemma.
Answer:
actively pump water back into their cells to counter its loss due to osmosis
Explanation:
- When an organism actively regulates the osmotic pressure of the bodily fluids present in the body in order to maintain homeostasis in the body then this is termed as osmoregulation.
- Since, the Great salt lake in Utah has a lot of salt in it, the water content in the surroundings of the brine shrimp is much less and hence, the water will move out of the brine shrimp's body as osmosis causes the movement of the water from higher concentration of water to lower concentration of water.
- However, movement of water out from shrimp's body would cause it to desiccate and hence, it must have an actively pumping system that pumps the water back into their cells in order to compensate for the water lost due to osmosis.