A) Crossing over is the mechanism of genetic variation that results from the exchange of gene segments between non-sister chomatids.
The enzyme DNA ligase chemically bonds together two DNA strands and removes nicks in a DNA duplex.
This enzyme is catalyzer for the formation of a phosphodiester bonds. Three major processes in which DNA ligases are involved are:
• DNA replication- after the RNA primers are removed, the remained nicks are replaced by the enzyme DNA ligase
• DNA repair-usually single-strand breaks are repaired by DNA ligase and complementary strand of the double helix is used as a template
• Recombination of DNA in experiments- in gene cloning, DNA ligase joins DNA molecules together to form recombinant DNA.
Well atoms are the basic building blocks of life
A is the sun or light energy
Its common. In the last 10 million years, there have been 4 or 5 reversals per million years