Answer:
B i hope this help
Explanation:
The cell membrane consists primarily of a thin layer of phospholipids which spontaneously arrange so that the hydrophobic "tail" regions are shielded from the surrounding polar fluid, causing the more hydrophilic "head" regions to associate with the cytosolic and extracellular faces of the resulting bilayer. This forms a continuous, spherical lipid bilayer approximately 7 nm thick, barely discernible with a transmission electron microscope.
The arrangement of hydrophilic and hydrophobic heads of the lipid bilayer prevent polar solutes (e.g. amino acids, nucleic acids, carbohydrates, proteins, and ions) from diffusing across the membrane, but generally allows for the passive diffusion of hydrophobic molecules. This affords the cell the ability to control the movement of these substances via transmembrane protein complexes such as pores and gates.
The sun has little or nothing to do with any of these answers except A. The sun gives plants energy, plants give animals energy, and animals give us energy. (Unless you're vegetarian in which case you skip the animal part)
Allopatric speciation, also referred to as geographic speciation, is a method of the formation of new species due to isolation of the species from one another through geographic means.
The first step in this process is geographic isolation, which means that the original population is divided into two groups due to geographical reasons such as movement of continents or formation of water bodies.
Next, the species are subjected to different selection pressures due to their different environments. Eventually, the gene pool becomes very different for the two species due to the different selection pressures and because they are not allowed to mix.
Finally, after enough time passes, speciation occurs, which means that the two populations cannot breed to form fertile offspring.
