Answer:
In general, negative selection eliminates from the population very harmful changes to proteins that kill or stop reproduction. ... The authors also found a correlation between genes predicted to be under negative selection and genes implicated in certain hereditary diseases
Explanation:
Lobe-finned fishes are characterized by lobes in their fins in addition to the basic characteristics of fishes.
<h3>What are lobe-finned fishes?</h3>
Lobe-finned fishes are a group of fish known as Sarcopterygii. They possess the basic characteristics of fishes such as swim bladder, lateral lines, etc.
They are a sister group of ray-finned fishes. In addition, lobe-finned fishes possess the following characteristics:
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Cations are positive so they have less electrons than protons, while anions are negative so they have more electrons.
Answer:
The correct statement concerning the cell membrane lipid molecules is that "energy is not expended during diffusion" (Option d)
Explanation:
Biological membranes are formed by two lipidic layers arranged with their hydrophilic polar heads facing the exterior and the interior of the cells, and their hydrophobic tails against each other. Membranes are fluid, which means that molecules that form it have the capability to move through it.
Lipids can easily change places with other neighbor lipids by <u>lateral diffusion</u> in the same layer. This is passive diffusion, which means that it does not need energy to happen.
Lipids can also diffuse transversally to the other layer, but this kind of movement is not as easy as lateral diffusion.
There are also other lipidic movements as rotational diffusion that imply the rotation of the molecule.
Through this lipidic bilayer, there is also a passive transport of some particles from one side of the cell to the other which happens because of concentration differences.