The net primary productivity is derived from the gross primary productivity, which is a measure of the total amount of light energy that was captured and converted into chemical energy (organic compounds) during Photosynthesis. Plants allocate that biomass (energy) to power their life processes or to store energy.
Photic and aphotic I think?
Answer:
Hello!
The answer is A) Helium
Explanation:
Organic Compounds:
When organic chemistry was first introduced, all compounds that originated from living matter were classed as organic while those having a mineral or non-living origin were termed inorganic. But the modern definition states:
<em>Compounds that contain carbon atoms bonded to hydrogen are termed as organic compounds.</em>
<em> </em>Since hydrogen (H), carbon (C), oxygen (O) and nitrogen (N) are the most abundant elements in organic matter, most organic compounds are a combination of these four elements. For example, deoxyribonucleic acid or DNA, the blue-print for all life is a combination of carbon, hydrogen, oxygen, nitrogen and phosphorous; all these elements are connected through chemical bonds.
Helium would never be present in an organic molecule because it is a noble gas by nature.
Noble Gas:
Noble gases are inert chemical elements that have low chemical reactivity with other elements. Apart from higher noble gases such as Argon, Radon and Krypton, noble gases do not form compounds.
Therefore, helium would never be found in an organic compound.
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.