We were not able to see microtubules, centrioles, rough endoplasmic reticulum, smooth endoplasmic reticulum, plasma membrane, ribosomes, golgi apparatus, vesicle, mitochondrion and chloroplast.
<span>B is the correct answer. The beginning of DNA replication occurs with the unwinding of the DNA helix by a special enzyme. The two strands that form the helix then create a replication fork. The two strands are then oriented differently, one becoming the 'leading strand' and one the 'lagging strand'. </span>
<span>DNA is made of chemical building blocks called nucleotides. These building blocks are made of three parts: a phosphate group, a sugar group and one of four types of nitrogen bases. To form a strand of DNA, nucleotides are linked into chains, with the phosphate and sugar groups alternating.</span>
The natural cause of acid rain is the <span>chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air.</span>
