Muscle cramps are caused when the muscle takes longer than normal to relax after a contraction. During contraction, the myosin heads attach on their binding sites on the actin filament and pulls on the filament hence shortening the sarcomeres. For the myosin head to release its binding site on the actin filament, ATP attaches to an active site on the myosin and is hydrolyzed to ADP and Pi. This causes relaxation after a contraction cycle. Cramps, therefore, may be due to depletion of ATP molecule in the muscles cells.
Another reason for cramps may be a high amount of calcium in the muscles that bind to troponin on the actin filaments. This exposes the myosin binding sites longer hence promotes the formation of cross-bridge even when the contraction of the muscle is not intended anymore.
The type of natural selection demonstrate is B. stabilizing selection.
There are different types of natural selections, each affecting the population density of a specific allele in a different way. In stabilizing selection, the non-extreme trait is maximized. This is seen in the curve as there is less population observed at the extreme ends of the spectrum but a greater population lying in the average, less extreme zone.
The correct answer for the question is B. Fossil.
Fossils are remnants, traces of animals or plants, from the past ages that have been preserved. Fossils may be classified as cast and mold fossil, insect preserved in amber, petrified wood, compression fossil of a fern and pyritized ammonite.
It is often useful for scientists to study a population of cells that are all at the same stage of the cell cycle.
<h3>Why the discovery of cyclins and cdks was enabled?</h3>
The discovery of cyclins and cdks was enabled by studying frog eggs that divided synchronously after fertilization; extracts from the embryos were thus representative of the cell-cycle stage at which the extract was made.
Researchers have devised means to synchronize asynchronous populations of cultured cells. for example, serum starvation deprives cells of mitogens and blocks cells in the g0/g1 phase of the cell cycle.
Therefore, It is often useful for scientists to study a population of cells that are all at the same stage of the cell cycle.
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Answer:
Savanna
Explanation:
Lack of rainfall over a period of time may convert a temperate deciduous forest into a Savanna.
Grasslands are characterized by a domination of grasses rather than large shrubs or trees. Savanna is a grassland with a few scattered individual trees. Savannas are always found in areas that are quite hot. The annual rainfall in a typical savanna may range from about 76.2-101.6 cm. Some savanna regions may receive as low as 15.24 cm -25.4 cm of rain in a year, followed by a long period of drought when fires can occur.