Mitosis is the process whereby a cell reproduces asexually to produce two identical daughter cells. This occurs via nuclear division. Before mitosis, the number of chromosomes in the cell is doubled via chromosome replication, transforming the cell from a diploid (2n) cell to a tetraploid (4n) cell.
Meiosis is how eukaryotic cells (plants, animals, and fungi) reproduce sexually. It is a process of chromosomal reduction, which means that a diploid cell (this means a cell with two complete and identical chromosome sets) is reduced to form haploid cells (these are cells with only one chromosome set). The haploid cells produced by meiosis are germ cells, also known as gametes, sex cells or spores in plants and fungi.
Heredity is the passing on of characters from parents onto their progeny. In some organisms, like humans, a parent passes on one copy per gene to their offspring and as a result, the progeny gets two copies in total from its parents. These organisms are called diploids (2n).
Purines and pyrimidines are the two families of nitrogenous bases that make up nucleic acids – in other words, they are the building blocks of DNA and RNA. While they are similar in many respects, there are a number of key differences between them that you will be expected to know for the AP® exam. Before we get into those, however, let’s make sure you understand what purines and pyrimidines are so you can recognize questions about them even if the wording is tricky.
The word meiosis originates from the Greek language. It means to lessen; this refers to the lessening of the number of chromosomes within the cell. Meiosis is the process of chromosomal reduction in eukaryotic cells (plants, animals, and fungi), which leads to the production of germ cells (gametes/sex cells) needed for sexual reproduction.