South American Tropical Rainforest is where you would find the greatest variety of species.
Answer:
Over the ages the tendency of crop improvement efforts has been to select varieties with traits that give the highest return, largely by concentrating on genetic strains that combine the most desirable traits. The resulting homogeneity and uniformity can offer substantial advantages in both the quantity and quality of crop harvested, but this same genetic homogeneity can also reflect greater susceptibility or pathogens. Thus it appears the more that agricultural selection disturbs the natural balance in favor of variety uniformity over large areas, the more vulnerable such varieties are to losses from epidemics. The increased risks presented by genetic selection and the increased cultivation of only a few selected cultivars are easily perceived. Chapters 1 and 2 of this reports focus on crop vulnerability, because it is a broadly recognized problem. The issue of genetic vulnerability, however, is only one of several important problems affecting the management of global genetic resources.
Answer:
The macromolecules that forms pumps and channels in the cell membrane, allowing the entry and exit of molecules to the cell are protein.
Explanation:
Membrane integral proteins are a type of macromolecule attached to the structure of the membrane and have ends in contact with the cytoplasm and the extracellular medium.
These <u>protein molecules can act as channels and transporters or pumps</u>, to facilitate the passage of substances through the membrane. An example of transmembrane channels are ion channels, while a protein transporter is the sodium potassium ATP-ase pump.
Membrane proteins can also act as surface receptors and enzymes linked to the cell membrane.
The other options are not correct because
:
- <em><u>Carbohydrates</u></em><em> can be found on the membrane bound to other molecules, such as glycoproteins and glycolipids, but they do not act as pumps or channels.
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- <em><u>Lipids</u></em><em> have the function of being the main component of the cell membranes.
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- <em><u>Nucleic acids</u></em><em> are found in the nucleus, and are not part of the cell membrane.</em>
