Answer: Diffusion, Osmosis and Active Transport
Explanation:
The processes of transport between the cell and the external environment can be grouped into groups: Passive Processes - occur through the plasma membrane, without energy expenditure to the cell, to equalize cell concentration with the external medium. Examples of such processes are diffusion, facilitated diffusion and osmosis. Active processes - occur through the plasma membrane, with energy expenditure, maintaining the concentration difference between the cell and the external environment. For example, sodium-potassium pump. Diffusion In diffusion, particles move from the highest concentration medium to the lowest concentration medium, so that it can be distributed throughout the medium. Therefore diffusion is a process called passive transport. Facilitated Diffusion is the passive transport of substances across the plasma membrane, without wasting cell metabolic energy, allowing the passage of substrates (molecules or ions) from a more concentrated to a less concentrated medium through specific mediation of carrier proteins, enzymes carriers or permeases along the plasma membrane. This process is mainly used to transport carbohydrates, amino acids, vitamins and some ions: sodium, potassium, calcium. Osmosis is the name given to the movement of water between media with different concentrations of solutes separated by a semipermeable membrane. It is an important physicochemical process in cell survival.
The sodium-potassium pump is an example of active transport. Sodium concentration is higher in the extracellular environment while potassium is higher in the intracellular environment. Importantly, the energy required for this change comes from the breakdown of the ATP (adenosine triphosphate) molecule into ADP (adenosine diphosphate) and phosphate. The sodium (Na +) ion in the cytoplasm is pumped out of the cell. In the extracellular medium, the potassium ion (K +) is pumped into the internal medium. If there was no efficient active transport, the concentration of these ions would equal. Thus, the sodium and potassium pump is important as it establishes the difference in electrical charge between the two sides of the membrane that is critical for muscle and nerve cells and facilitates the penetration of amino acids and sugars.
Answer:
variation
Explanation:
Genetic variation is what makes us all unique as a result of subtle changes in our DNA. The Theory of Evolution is a process in which organisms change over time as a result of adapting to their environment. Charles Darwin came up with the term Survival of the fittest, in any environment plants and animals from the same species show natural variation in their physical characteristics, like neck lengths in giraffes. Darwin suggested that the plants and animals best suited to the environment will survive and pass on their characteristics to their offspring. Over time, the characteristics of the surviving members of the species will become predominant.
Example: Peppered moth
In London in the 1800's, 98% of peppered moths had light colored bodies and only 2% were dark. The light moths were the same color as the trees so they could easily hide from hungry birds and not get eaten. The dark moths however were easy to see and were eaten. Then came the factories and smoke of the industrial evolution and many trees turned black with soot and suddenly the dark moths were able to survive better as they now looked like the trees and the light colored moths were easier to spot and eat. By 1895 the dark peppered moths made up 95% of the population and the light colored moths only 5%. This is an example of natural selection, because of the gene that makes the moths dark, it allowed them to flourish when the environment changed, they adapted, reproduced and survived.
