5.5a Classification

20/05/2013 § Leave a comment

This next blog is literally about naming species and how scientists group species. Another word for it is nomenclature; the naming of species. Biologists use the binomial system in order to give all species an international name for all biologists to use. They use keys in order to identify the individual and categorize them into their group. The main characteristics of the binomial system is that there are two words in the name: the first is capitalized and is the genus, the second is lower-case and is the species name. Handwritten, the binomial name is underlined, but when printed, they use italics.

Scientists then group plants and animals into taxons, which are a group of organisms. This is the way scientists create a tree or a map which is another part of their classification, called the hierarchy of taxa. Species are grouped into a genus, genera into a family, families into an order, orders into a class, classes into a phylum, and phyla into kingdoms.

Biologists can use keys to identify species. They identify as much of what’s obvious as they can, but at some point, they need keys in order to separate certain animals into the proper species, for example, when differentiating between a dugong and a manatee, which can be quite similar. This is a dichotomy, which is a division into two, the way scientists identify in which group the individual belongs.

Finally, at the end of the reading, I learned that there are four main phyla of plants and those are (arranged by height):

  1. bryophyte – which include mosses, the shortest of the four
  2. filicinophyta – which are ferns
  3. coniferophyta – conifers (?)
  4. angiospermophyta – flowering plants, the tallest of the bunch


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

Nearly there? Sort of?



Page 206, classifying cartilaginous fish

1. State the kingdom to which all of the species in Figure 3 belong. —> Kingdom: animalia


a) Four of the fish in Figure 3 are classified in the same genus. Deduce which these fish are. —> Middle left, middle center, bottom left, bottom right.

b) Deduce with a reason whether these four fish are in:

  • i. the same or different species —> They are in different species because the species is the very last category and all four are clearly different in some way.
  • ii. the same of different families —> They are in the same family because they share multiple characteristics.

c) State two characteristics of these four fish that are not possessed by the other four fish. —> They have longer tails and wider fins.

3. The other four fish are classified into two orders. Deduce, with a reason, how the four fish are split into two orders. —> Both the top fish and the bottom center fish are one order and the middle right fish is the other order. This is because the tail and bottom fin are all common with the first order while the fish in the second order has wider fins as well as a different tail.

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