Answer: A.
Explanation:
Cells generally have a relatively short lifestyle in that they grow, divide and then die off. This is not the case with cancerous cells as those ones mutate and then multiply such that they eventually form a tumor.
Looking at the graph, most of the cells are remaining at a lower or manageable number because they are dying off. Cell A on the other hand is simply increasing in number which means that it is a cancerous cell as it is increasing its number by mutating instead of dying off like other cells would.
Well, when chromosomes cross over during prophase 1 of meiosis, the homologous pair of chromosomes exchange segments of DNA which happen to be the genes. So the significance of crossing-over during prophase 1 is that it adds genetic variation to sexually reproducing organisms.
Epiglottis is the flap of cartilage that covers the opening of the larynx
The enzyme responsible for that is DNA helicase.
