Which of the following best describes what happens during a cross-over event? a. tetrads change orientation as they line up along the center of the cell. b. chromatids of homologous chromosomes exchange corresponding segments. c. x and y sex chromosomes overlap and combine together during metaphase. d. spindle fibers overlap and attach to the wrong chromosomes during anaphase.

As a small change in a person's dna can cause a genetic disorder

Imagine that certain laws of physics could be ignored and you were able to travel vast distances in moments. now imagine that you traveled to an earth-like planet located light-years away that is known to support life. think about what you’ve learned in this unit and make an argument for what you think would be the dominant type of life form on this planet. consider whether a notochord is required for an organism to manipulate its environment and become a dominant creature.

What are antigens and antibodies? how are they involved in the body’s response to incompatible blood?