The fetus primarily gains weight during the third-trimester.
Answer:
Channel proteins and Carrier proteins
Explanation:
These are type of membrane proteins that transcend the entire length of phosphoslipid bi- layer in the plasma membrane.They facilitate the movement of ions and molecules across the walls of the plasma membranes.
Generally, substances like glucose, amino acids, are too large to pass through the phopholipid bilayers. Likewise ions of potassium, sodium calcium, because of their polarities can not pass through either. They are ferried across the phospholipid by group of protein structures called channel proteins. Some are also transported across by carrier proteins. The process by which these protein structures aided the diffusion of substances across the phospholipid bilayer is called Facilitated diffusion.
Channel proteins are pores, that are filled with water molecules with the entrance well gated. That is the entrance is controlled by part in the inner structure of the protein which can open or close the pores like a gate to control the movement of ions across it. e.g Sodium channels are gated for movement of sodium ions by voltage or ligands(chemicals) during nervous transmission to elicits action potential. Like wise Potassium channels allow diffusion of potassium ions across the phospholipid bilayers. it gates are shut when sodium channels are open; this regulate ion exchange.
Their structures are well fixed in shape , specific to the substance or ions being transported;and the rate of diffusion depends on the like hood of opening of the gate or closure.
Carrier molecules also in the membranes do not have a fixed shape, and their transport direction is determined by the direction of concentration gradients. Thus they can flip on either sides of the membranes to aid diffusion across. Their movement can be both passive and active, and the rates of diffusion depends on the number of available carrier proteins in the membrane. They are also specific to the ions they transport.And are not gated,
Therefore these two membrane integral proteins facilitate movements of substances across the phospholipild bilayers
In short, air pollution is foul air injurious to health. Air Pollution is anything that goes into the air that is harmful.Most air pollution is man-made. The largest contributor to airpollution is the burning of fossil fuels such as gas and coal. Someof the most common forms of air pollution are: Particulate matterNitrogen oxide (and other oxides of nitrogen) Sulfur oxide AcidRain VOC's (volatile organic compounds) Air pollution can also besaid as the accumulation in the atmosphere of substances that insufficient concentrations, endanger human health or produce othermeasured effects on living matter and other materials. Among themajor sources of pollution are power and heat generation, theburning of solid wastes, industrial processes, and, especially,transportation.
Answer:
I think it was Thomas Hunt Morgan
