Crossing over happens in Meiosis 1 only. In Prophase 1 a cells chromatin (chromatin = chromosomes that have not condensed yet) condense and pair up forming homologous chromosomes (paired = XX (2 chromosomes together)). When this happens segments/ alleles of the chromosomes pairing up swap over. This creates genetic diversity as each chromosome is different, it has parts from its pair. This leaves every chromosome unique and individual.
I hope this helps, sorry some of the vocab is rather technical. By the way I would suggest watching the
'Crash Course: Meiosis' on YouTube, this really helped me when I was learning this topic. :D
The reason why the animal that has been struck by the arrow
goes limp and quickly suffocates because the acetylcholine receptor sites are
blocked and this was made possible because of the drug curare they use in
poisoning the top of the arrows.
The correct answer of the question above is the first statement. In anaphase I, homologous pairs are separated but sister chromatids stay joined together. It is <span>best statement that describes the major difference between anaphase of mitosis and anaphase I of meiosis.</span>
B - They both use protein channels (I think so at least) they differ because active transports use a pump to leave the cell and it uses atp (cell energy).