Answer:
the answer is two for this question
Bacteria to amphibians. amphibians started to turn to fish and some started walking to land. They started laying eggs and turning into reptiles. those reptiles started growing hair turning them into four legged mammals. the mammals then turned to primates which evolved into us.
The conduction of nerve impulses relies upon the movement of positively-charged ions across the nerve cell membrane. The entry of sodium into the cell produces a wave of positive charge that travels down the length of an axon. Then chemicals called neurotransmitters are secreted out of the end of the axon onto the next nerve in the series (the postsynpatic nerve). This narrow space in between neurons is called the synapse. These neurotransmiiters released by the presynaptic nerve bind to receptors on the postsynaptic nerve. The binding of these receptors opens up channels in this second nerve's membrane that allow sodium ions to enter the nerve cell and initiate another wave of positive charge, and so on... The nerve signal can only move as fast as these ions and neurotransmitters can diffuse to generate this process.
<span>As a professional athlete repeats a given activity many times over, the nerve cells "upregulate" their receptors, meaning that they produce additional receptors to put in the membrane. This is just a natural reaction to the nerve being repeatedly stimulated in the same way over and over. When neurotransmitter is secreted from the presynaptic neuron, there are more receptors on the postsynaptic neuron for it to bind, more channels open up, more ions enter in a shorter time and build up positive charge to create the impulse faster, and so the overall effect is faster. </span>
<span>Additionally, there are sheaths of fatty tissue (called myelin) that insulate the charge in the neuron and allow it to be conducted faster. As people age, these sheaths can start to degrade, making the nerve cell more "leaky" and causing the impulse to be conducted more slowly. </span>
Answer;
-Inactivation; limited
Differentiation requires inactivation of particular genes to produce populations with limited capabilities that form tissues.
Explanation;
-Cell differentiation is how generic embryonic cells become specialized cells. This occurs through a process called gene expression.
-Gene expression is the specific combination of genes that are turned on or off (expressed or repressed), and this is what dictates how a cell functions.
-Gene expression plays a critical role in the morphological changes that take place in a developing embryo and fetus and in the differentiation of stem cells to form specialized cells.
Small, highly concentrated cell organelles that produce proteins are called <span>ribosomes. Ribosomes can be free-floating or attached to endoplasmic reticulum.</span>
