11. c. crossing-over. Notice how one of the bottom arms of each of the gray and white chromosome overlaps with each other, then their genes switch to the other's arm. That's called crossing over, when homologous chromosomes' genes flip-flop with each other.
14. b. meiosis. Gametes are special daughter cells that are either sperm or egg for sexual reproduction. Since genes are shuffled and daughter cells are not like parent cells, this is meiosis. 1 parent --> 4 non-identical gametes.
16. a. centromeres. During late prophase and all of metaphase of mitosis, identical sister chromatids are fused together at the center of the chromosome "X" by what's called a centromere. Then, during anaphase, the sisters are pulled apart, at these centromeres, by spindles attached to centrioles toward opposite sides of the cell.
17. c. Metaphase only. Although late prophase has this appearance of chromosomes, the best answer is probably only metaphase. It's not in anaphase because that's when sister chromatids are pulled apart at their centromeres.
<u>Answer</u>: B) the mass extinction of the dinosaurs 66 millions years ago
Macroevolution is a term used to define changes of whole taxonomic groups over long periods of time. The extinction of the dinosaur is not an example of this evolutionary process. The changes occurred over a relatively short period of time and did not involve changes in a taxonomic group, but rather their extinction.
True, a function of protein is to help provide structural support and by acting as enzymes
Correct answer: Telomere
Chromosomes contain DNA packed together with histone proteins. Each chromosome has cap like structures at their ends called the telomeres. These telomeres are protective in function and they become short with each cell division. The cells eventually age as the telomere shortens after each cell division. Every time the chromosomes replicate, it would be shortened by 250 bases. Telomeres prevent the loss of important segments of the DNA as they act as a cap at the ends of the chromosomes. At the end of each division, this protective cap is lost,