Answer:
When the molecules are too large.
Explanation:
Facilitated diffusion refers to the passive transport of substances down the concentration gradient via specific transport proteins present in the membrane. The large, polar, charged substances and ions cannot pass through the small spaces present between hydrophobic tails of membrane phospholipids. The transport proteins transport these substances in energy independent manner.
The gaps (approximately 1 micrometer wide) formed between myelin sheath cells long the axons are called Nodes of Ranvier. Since fat serves as a good insulator, the myelin sheaths speed the rate of transmission of an electrical impulse along the axon.
The right answer for the question that is being asked and shown above is that: "TRUE; TRUE; TRUE" (1) While the Lophophorata (this groups includes worms and mollusks) are a well-recognized group, phylogenetic (family tree) studies do not yet agree on the identity of their closest relatives. (2)The marine flatworms (polycladids) are the smallest of the free-living flatworms, sometimes reaching lengths of 15 centimeters. (<span>3)Bilateria is a classification within Animalia, and are characterized by animals which are bilaterally symmetrical (with a left and a right side to their bodies).</span>
The correct option is B: Negative
The overall charge on the cytoplasmic side of a plant cell plasma membrane is <u>negative.</u>
A plasma membrane is a kind of membrane that separates the inner material of the cell from the outer side material and is also called a cell membrane.
Only in plants and bacteria, a cell wall is present on the outer side of the cell membrane whereas in animals the cell wall is absent.
It also protects the cell material from the outer materials that are harmful in nature.
When an impulse occurs the overall charge on the cytoplasm of the membrane becomes negative.
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