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DNA is made up of subunits called nucleotides. Each nucleotide is comprised of one nitrogenous base (either adenine, cytosine, guanine, or thymine), one phosphate, and one deoxyribose sugar. The nucleotid...

human chorionic gonadotropin (hCG) is a hormone which is closely associated with the early stages of pregnancy. It is produced by the blastocyst once it has implanted int...

First, the blood enters through the right and left atria. The atrioventricular valves are closed, so the blood pools up inside them. Then, the sinoatrial node (SAN) sends a pulse for the atria to contract...

The nerve impulse will reach the end of the presynaptic neuron, where voltage-gated calcium channels are opened due to depolarisation. Calcium ions then diffuse into the presynaptic neuron, resulting in v...

At prophase I of meiosis, after the homologous pair of chromosomes pair up in the process called synapsis, the non-sister chromatids overlap, forming an X-shape. They then exchange their alleles at the po...