Excitation-contraction coupling refers to the series of events that begins with the excitation of the sarcolemma in response to stimulation by a neurotransmitter, and results in the release of calcium ions from the sarcoplasmic reticulum.
Hence, option D is the 1st process that starts the excitation-contraction coupling.
WATER
Solids will usually sink when placed in their own liquids with the exception of water
Explanation:
Ice (the solid form of water) floats on water that is cooler than 4 degrees centigrade. This is unlike any other material and this phenomenon has been referred to as the ‘water anomaly’.
Most substances will sink in their own liquid because the solid form is denser than the amount of their own liquid that they displace when immersed. This is because the particles in the solid are closely packed together hence there are more particles per volume than in the liquid form.
Water however, expands at temperatures below 4 degrees and hence ice is less dense than water at 4 degrees and below. The particles in ice are farther apart than particles of water at 4 degrees and below. There is, therefore, more particles per volume in the liquid form of water than in ice – making ice less dense.
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Wolf emigration will bring about the rabbit population increasing.
<h3>What is Emigration?</h3>
Emigration is defined as the movement of organisms away from a particular
area or habitat.
We are aware that Wolves feed on rabbits as a means of food in the
grassland ecosystem. This translates to the following below:
- The greater the wolves the lesser the rabbit
- The lesser the wolves, the higher the rabbit.
This therefore means that wolf emigration will bring about the rabbit
population increasing which makes option B the most appropriate choice.
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Answer:
cold water temperature of the lake
Explanation:
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Flu vaccines need to be revised and changed every year because the flu virus constantly mutates. Flu viruses can change in two ways: drift or shift. Antigenic drift occurs when genes of the virus slowly change during replication until the immune system no longer recognizes it. On the other hand, antigenic shift occurs when a major change in the virus happens. This usually leads to a totally different kind of virus. This is what happened during the H1N1 scare in 2009.
DNA viruses like mumps are less prone to mutation due to the presence of DNA polymerase. RNA viruses are more prone to mutation because they undergo reverse transcription to simulate the role of DNA.
