Answer: Commensalism
Explanation: Well you can already eliminate parasitism because that is when an organism leeches off another. Mutualism is when one organism needs to depend on another compared to A where both are benefited. Then you can eliminate d because competition is when two organism compete with each other for survival not benefiting them both.
Answer:
The source of Calcium (Ca⁺⁺) for the skeletal muscle cells is the sarcoplasmic reticulum, the main store of intracellular Ca⁺⁺.
Explanation:
Calcium (Ca⁺⁺) is an ion that plays an important role in muscle contraction, a process that requires high cytoplasmic concentrations of this ion to promote myofibrillary activity.
The sarcoplasmic reticulum (SR) -equivalent to the endoplasmic smooth reticulum- is an organelle that regulates the contractile activity of skeletal muscle. The two terminal cisterns of the SR attach to the T-tube, forming a triad, which surrounds the myofibrilla.
Once the muscle cell receives the signal to contract, the Ca⁺⁺ channels are opened and allow Ca⁺⁺ to enter the cell, promoting the exit of this cation from the SR and increased its cytoplasmic levels. This stimulates muscle contraction.
The type of hormone, such as the steroid, which passes directly through the cell membrane to nuclear receptors to cause changes in gene expression within the cell, is known as hydrophobic.
Hydrophobic steroid hormones are transported in the circulation, largely bound to plasma carrier proteins. Steroids are overall hydrophobic because of they have common tetracyclic hydrocarbon core.
Hence, the steroid hormones are lipid-soluble in hydrophobic environments and they able to pass through the cell membrane of cell. Steroid hormones have the ability bind with receptors and change their structure and causing that complex to easily pass into the nucleus in order to alter or change gene expression.
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Answer:
The Agouti gene controls the distribution of black pigment. The dominant allele A restricts black pigment to the points of the horse (mane, tail, lower legs and ear rims), as seen, for example, in bays and buckskins.
