It is made of amino acids
Answer:
The kidneys take of up more Ca2+ and release vitamin D. The bones release Ca2+. The intestines increase reabsorption of Ca2+.
Answer:
Plants take in carbon-dioxide from the atmosphere during photosynthesis. The amount of carbon-dioxide absorbed by plants is roughly equal to that released by plants, animals, and decomposing/burning fossils.
Explanation:
<span>Chemical bonds hold atoms
together to form compounds. The answer is letter D. Chemical bonds may result
through the sharing of electrons as in covalent bonds or from the electrostatic
force of attraction between atoms with opposite charges as in ionic bond. There
are other bonds that exist to other compounds such as metallic bond and
hydrogen bonding. Also, the type of bonding will help us determine what will be
the phase of the compound. Just like in liquids, attractive forces are caused by
van der Waals bonds.</span>
If the receptors in muscle fibers are thought of as locks, the keys are NEUROTRANSMITTERS.
Receptors are large protein molecules which are located on the surface of neuron. They have to be opened before a neuron is activated, that is why they are considered as lock. The neurotransmitter molecules are considered as the key, because they bind to the neuron and activate neural firing.
