Which of these statements about myelination in neurons is/are correct? Select True or False for each statement. T/F It speeds propagation by increasing the density of voltage-gated channels all along the axon. T/F Multiple sclerosis is characterized by disrupted myelination of certain neurons in the central nervous system. T/F It speeds propagation by preventing cations from leaking out across the membrane as they spread down the axon. T/F It is more commonly observed in vertebrates than in invertebrates.

Verified step by step guidance

1. Step 1: Understand the concept of myelination. Myelination is the process by which a fatty layer, called myelin, accumulates around neurons. This layer acts as an insulator to speed up the transmission of electrical signals (action potentials) along the neuron.
2. Step 2: Evaluate the first statement. Myelination does not increase the density of voltage-gated channels all along the axon. Instead, it reduces the need for these channels by insulating the axon and allowing the electrical signal to jump between gaps in the myelin sheath (nodes of Ranvier) where these channels are concentrated. So, the first statement is False.
3. Step 3: Evaluate the second statement. Multiple sclerosis is indeed a disease characterized by the disruption of myelination in neurons of the central nervous system. This leads to a slowdown or blockage of signal transmission. So, the second statement is True.
4. Step 4: Evaluate the third statement. Myelination does speed up signal propagation by preventing cations from leaking out across the membrane as they spread down the axon. This is because the myelin sheath acts as an insulator, preventing ion leakage and allowing the action potential to jump from node to node. So, the third statement is True.
5. Step 5: Evaluate the fourth statement. Myelination is indeed more commonly observed in vertebrates than in invertebrates. This is because the myelin sheath is a characteristic feature of the nervous systems of jawed vertebrates. So, the fourth statement is True.