5.4c Examples of Evolution

15/05/2013 § Leave a comment

Okay, let’s speed things up a little bit. What happens with evolution? A bunch of things, probably, but my puny mind can only handle so much. We can start off with Darwin’s finches, all of which he observed in the Galapagos Islands. The finches have since then been studied by Peter and Rosemary Grant, who catalogue the sizes of beaks and the size of the seeds (whether they’re large or small) every year. They discovered that with dry seasons, the collection of seeds would consist of mostly small seeds. Correlating with this condition, the next generation of finches normally have smaller beaks because natural selection had chosen those individuals in the generation with the dry season and small seeds with the smaller beak (which helped them survive). Similarly, seasons with large seeds generally produce a following generation of finches with large beaks that can crack the seeds easily. Variation in the shape and size of the beaks is therefore heritable and a result of the finches’ genes.

Alright, so, bacteria also evolve! Basically, humans use antibiotics to control bacterial diseases, right? Similarly with how the finches are picked off by natural selection, natural selection chooses the bacteria that are resistant to the antibiotics. Over time, the population of bacteria will consist more of those that are resistant to bacteria, because those reproduce while the non-resistant bacteria die off. See? Natural selection. Bacteria can evolve, too!


Essay Questions

  1. Outline what is meant by the trophic level of an organism with three examples from one named habitat. (4 max)
  2. Compare the ways in which autotrophic, heterotrophic and saprotrophic organisms obtain energy. (6 max)
  3. Draw a labelled sigmoid population growth curve. 4 marks
  4. Explain the factors that cause a population to follow the sigmoid ( S-shaped) growth curve. (8 max)
  5. Apply the concept of carrying capacity to the struggle for survival resulting from overproduction of offspring. (5 max)
  6. Outline the international system used for naming species of living organisms. (4 max)
  7. Discuss the definition of the term species. (8 max)
  8. Name the levels and the specific taxa in the hierachy of classification using humans as an example. (2 max)
  9. Describe the relationship between the rise in the concentration of atmospheric carbon dioxide and the enhanced greenhouse effect. 5 marks
  10. Outline the consequences of a global temperature rise on arctic ecosystems. 6 marks
  11. Outline the precautionary principle. 5 marks
  12. Outline the structural differences which characterize bryophytes, filicinophytes, coniferophytes and angiospermophytes. 9 marks
  13. List the structural differences between bryophytes and angiospermophytes. 5 marks
  14. Briefly explain Darwin`s theory of evolution. 4 marks
  15. Outline five types of evidence which support the theory of evolution by natural selection. 6 marks
  16. Outline one modern example of observed evolution by natural selection. 2 marks
  17. Explain the evidence from homologous anatomical structures that supports the theory of evolution. 6 marks
  18. Outline how antibiotic resistance in bacteria can arise in response to environmental change. 5 marks
  19. Antibiotic resistance in bacteria is an example of evolution in response to environmental change. Using another example, explain how an environmental change can lead to evolution. 8 marks



Page 203, evolution in rice plants

1. Why was the investigation done using hybrids rather than a single pure-bred variety? —> So that the hybrids could create new mixes of rice in their offspring. The new variety amongst the offspring gives heritability.

2. Describe the changes, shown in the chart, between the F3 and F6 generations of rice plants grown at Miyazuki. —> In Sapporo, the rice’s’ days to flowering jump up to 51 days. In Fujisaka, the days to flowering stays at around 93 to 96 days. In fact, from F4, it starts and maintain 96 but at F6, the days to flowering lowers to only about 90. In Konasu, gradually, the days to flowering change from an evenly spread set of data, to slightly differentiated (F4) to spread out, to a mean of 93 days. Basically at F3, things are more evenly spread, and at F6, there is a more clear mode value.


  • a) State the relationship between flowering time and latitude in the F6 generation. —> The higher the latitude, the earlier the flowering time.
  • b) Suggest a reason for this relationship. —> The cold weather means that spring comes earlier, which allows for the rice to flower earlier than warmer weather, which takes longer for spring to arrive.


  • a) Predict the results if the investigation had been carried on until the F10 generation. —> The same pattern continues until F10 (only four generations away). The days to flowering continue to increase slightly.
  • b) Predict the results of collating seeds from F10 plants grown at Sapporo and Miyazuki and sowing them together at Hiratsuka. —>  The seeds that don’t flourish after being sown will simply just die out or rot the fastest – or it won’t even bloom because the conditions are different for Sapporo seeds and Miyazuki seeds in Hiratsuka. They won’t even bloom in this case or if they do, it would be difficult for them to flower to a healthy extent.

Tagged: , , , ,

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

What’s this?

You are currently reading 5.4c Examples of Evolution at i am so.


%d bloggers like this: