Answer:
B
Explanation:
Nerve cells can carry signals and connect all parts of the body to the brain
Answer:C). A phospholipid bilayer with proteins
Explanation: A cell membrane is a phospholipid bilayer with proteins embedded in it. The fatty acyl chains of the phospholipids are non polar and hydrophobic while the phosphate groups are polar and hydrophilic. The hydrophobic regions of the phospholipids interact with each by facing each other, forming a bilayer with a fluid interior. The polar head groups face outward interacting with the external environment of the cell. Proteins are embedded in this bilayer and they float in this sea of phospholipids. Proteins anchored to the membrane through interactions between the hydrophobic regions of the phospholipids and the amino acid side chains of the proteins. These lipids and proteins swim laterally in each face of the bilayer but movement from one face of the bilayer to another is restricted.
The DNA polymerases are enzymes that create DNA molecules by assembling nucleotides, the building blocks of DNA. These enzymes are essential to DNA replication and usually work in pairs to create two identical DNA strands from one original DNA molecule. During this process, DNA polymerase “reads” the existing DNA strands to create two new strands that match the existing ones.
Every time a cell divides, DNA polymerase is required to help duplicate the cell’s DNA, so that a copy of the original DNA molecule can be passed to each of the daughter cells. In this way, genetic information is transmitted from generation to generation.
Before replication can take place, an enzyme called helicase unwinds the DNA molecule from its tightly woven form. This opens up or “unzips” the double stranded DNA to give two single strands of DNA that can be used as templates for replication.
DNA polymerase adds new free nucleotides to the 3’ end of the newly-forming strand, elongating it in a 5’ to 3’ direction. However, DNA polymerase cannot begin the formation of this new chain on its own and can only add nucleotides to a pre-existing 3'-OH group. A primer is therefore needed, at which nucleotides can be added. Primers are usually composed of RNA and DNA bases and the first two bases are always RNA. These primers are made by another enzyme called primase.
Although the function of DNA polymerase is highly accurate, a mistake is made for about one in every billion base pairs copied. The DNA is therefore “proofread” by DNA polymerase after it has been copied so that misplaced base pairs can be corrected. This preserves the integrity of the original DNA strand that is passed onto the daughter cells.

A surface representation of human DNA polymerase β (Pol β), a central enzyme in the base excision repair (BER) pathway. Image Credit: niehs.nih.gov
Structure of DNA polymerase
The structure of DNA polymerase is highly conserved, meaning their catalytic subunits vary very little from one species to another, irrespective of how their domains are structured. This highly conserved structure usually indicates that the cellular functions they perform are crucial and irreplaceable and therefore require rigid maintenance to ensure their evolutionary advantage.
Every year the farmer was taking care of his ice field, keep it clean and clear of all the unnecessary shrubs and then reuse the debris to fertile the soil again and then grow rice again. But since he fell sick, there is no one to take care of his rice field which will leads to the growth of unnecessary plants and weeds in it.
There will grow wild plants and shrubs which will contaminate the rice field.
Organism, population, community, ecosystem, biosphere
