Meiosis
Meiosis is the division in the formation of sex cells in which a diploid (2n) cell gives 4 haploid (n) cells. It consists of two successive divisions (meiosis I and II), and DNA doubles only once before them, in interphase. In prophase I homologous chromosomes come together (conjugation) and exchange segments — crossing over; in metaphase I the pairs line up at the equator; in anaphase I whole chromosomes (not divided into chromatids) move apart to the poles, so the chromosome number halves (2n → n). Meiosis II resembles mitosis: in anaphase II the chromatids separate, giving 4 cells with n chromosomes. Thanks to meiosis the chromosome number stays constant across generations (gamete n + n = zygote 2n); independent separation of homologous pairs and crossing over increase genetic diversity, which creates combinative variation. Difference from mitosis: in mitosis there is 1 division, 2 diploid cells, genetically identical; in meiosis 2 divisions, 4 haploid cells, genetically different.
“Mitosis or meiosis?” Sort the cards (2 daughter cells, 4 gametes, crossing over, asexual reproduction, 2n → n, growth, conjugation) into two columns or both. Show homologous pairs “crossing over” with coloured thread.