Answer:
13. C
14. C
15. B
16. B
17. B
Explanation:
13. Having a long neck is a selective advantage for giraffes. Their long necks make them better suited to reaching food supply at the top of trees, improving their fitness and chances of reaching reproductive age and passing on traits to the next generation. This is how natural selection acts on these traits meaning that over time, giraffes evolve a long neck.
14. The variation in the mice tail length has shifted over time, which suggests that the frequency of the alleles that control tail length has changed. This is clear when you look at the peak of the graph, which has shifted towards longer tail lengths. This suggests alleles coding for longer tail lengths are becoming more common, with the loss of shorter tail lengths
15. If a mutation spontaneously appears in the rabbit genome that makes them resistant to the virus, then they are much more likely to survive than other members of their population. This selective advantage means they are more likely to reach sexual maturity and reproduce, passing the mutation on to the next generation, where they also will benefit. Rabbits breed a lot and quickly, so natural can happen reasonably quickly in these populations, meaning the numbers of resistant rabbits will rise.
16. A vestigial structure is one that is now redundant. That means that the organism no longer uses it. These remain because there are no real selective pressures acting on them that would cause their disappearance to accelerate. Instead, they remain. These bones indicate that at one point, whale populations used to have additional limbs, suggesting they evolved from four legged animals.
17. Changes in the genetic code of an organism can sometimes produce effects such as changes to protein structure, composition, and amount. These can have changes on a much larger scale such as in the structure of forelimbs. Beneficial changes will be positively acted on by natural selection. For example, a bat could develop a stronger wing structure for rapid flying, where as the whale forelimbs are very large to make them powerful in the water. Natural selection can only act on these changes if they are heritable, meaning they have to have changed in the DNA. Any physical changes not present in the DNA will not be passed on to the next generation or undergo evolution.
