Answer:
"As a molecule moves through the plasma membrane it passes through <em>a hydrophilic layer of phospholipid heads then a hydrophobic layer of phospholipid tails and then another hydrophilic layer of phospholipid heads".</em>
Explanation:
Biological membranes are formed by two lipidic layers, proteins, and glucans.
Lipids characterize for being amphipathic molecules, which means that they have both a hydrophilic portion and a hydrophobic portion at the same time. These molecules have a lipidic head that corresponds to a negatively charged phosphate group, which is the polar and hydrophilic portion. They also have two lipidic tails that correspond to the hydrocarbon chains -the apolar and hydrophobic portion- of the fatty acids that esterify glycerol.
Membrane lipids are arranged with their hydrophilic polar heads facing the exterior and the interior of the cells, while their hydrophobic tails are against each other, constituting the internal part of the membrane.
Through this lipidic bilayer, some molecules can move from one side of the cell to the other, which happens because of concentration differences. When this occurs, molecules must pass through the hydrophilic layer of phospholipid heads then through the hydrophobic layer of phospholipid tails and then again through another hydrophilic layer of phospholipid heads.
Answer:
A. Species that remained after the extinction were able to radiate, new adaptations arose, and these adaptations produced the diversity seen today.
Explanation:
When species went extinct they also left niches that could be occupied by "new" species; new places to live, places to be filled in the food web and different relationships to be formed. The wide availability of resources made organisms to radiate leading to a "new" diversity of shapes, sizes, and lifestyles.
B. Species that have gone extinct were able to re-evolve from the ancestors that survived the extinction. If you are extinct you are gone forever.
C. Species that remained after the extinction were unable to speciate. Therefore, the number of species on Earth today is lower than the number of species present just before either extinction. The fossil record proves that species have changed over time and the diversity has changed over the history of Earth.
D. Species that remained after the extinction represented all of the lineages that were present before the extinction event. Therefore, extinction did not change the diversity of lineages. Again, the fossil record is evidence that lineages have changed over the history of the Earth.
When the hypothalamus doesn't do it job, it can result in problems with any of these. It's also involved in processes like temperature regulation, sleep cycles, and fluid regulation in the body.
Thus, damage that prevents it from controlling the hormone system can lead to a lot of diverse problems throughout the body.
