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
Answer:
A. 2 speciation events and 5 extinctions
B. 5 speciation events and 1 extinction
Explanation:
As we can see from the diagram, there were only 2 ,aim speciation events for lineage A. The extinction events were 5 for the A lineage. Hence, as the extinction event was more rapid than the speciation event so lineage A contains only one species.
On the other hand, the diagram shows that for lineage B there were 5 speciation events and just 1 extinction event. Hence, the number of species in lineage B were more at the time zero as just one extinction had occurred.
Answer:
for testing differnt cures on animals
Explanation:
According to Twain man could not have ascended from lower animals (Darwin theory of evolution) because man makes cruel and horrible decisions, rather man descends from Higher animals. He proved his conclusions about man by using specific scientific method, he subjected every postulate itself to the crucial test of actual experiment and have adopted it or rejected it according to the results.
<span>The appendicular skeleton includes the bones of the shoulder girdle, the upper limbs, the pelvic girdle, and the lower limbs.</span>
