CLASSIFICATION

1. CLASSIFICATION

2. All female mammals produce __________ • Most mammals have ___________. • Milk • hair

3. The science of naming and classifying organisms. • taxonomy

4. Linnean taxonomy classifies organisms based on their ________ and _________ similarities. • physical • structural

5. A group of organisms in a classification system is called a _________. • taxon

6. The basic taxon in the Linnean system is the _________. • species

7. A system that gives each species a two part scientific name using Latin words. • binomial nomenclature

8. The first part of the name of a species in binomial nomenclature is called a _______. • genus

9. One or more physically similar species that are thought to be closely related. • genus

10. Genus names are always _______ and in ______ or underlined. Species names are always _______ and are also ______ or underlined. • capitalized • italics • lowercase • italics

11. The Linnean system of classification has seven levels or _______. • taxa

12. What are the taxa for the Linnean Classification system? • Kingdom, Phylum, Class, Order, Family, Genus, Species

13. What is a limitation of the Linnean classification system? • His system focused on physical similarities alone. Comparing genetic traits is more accurate.

14. The evolutionary history for a group of species is called a _________. • phylogeny

15. The most common method used to make evolutionary trees is called_________. • cladistics

16. Classification based on common ancestry. • cladistics

17. An evolutionary tree that proposes how species may be related to each other through common ancestry. • cladogram

18. A group of species that shares a common ancestor. • clade

19. Traits that can be used to figure out evolutionary relationships among a group of species that are shared by some species but are not present in others. • derived characters

20. Each place in a cladogram where a branch splits. • node

21. What is the difference between a clade and a taxon? • A taxon is a group of organisms classified together in a system such as that of Linneaus. A clade is any group of organisms that share a common ancestor, so it can contain many taxa of different levels.

22. Why does DNA often have the “last word” when scientists are constructing evolutionary relationships? • Shared or identical sequences of DNA is hard proof of common ancestry, whereas shared traits or similar characteristics can be the result of convergent evolution.

23. What was the method, proposed by Linus Pauling and Emile Zuckerkandl, of evolutionary time? (early 1960’s) • They compared the amino acid sequences of hemoglobin from a wide range of species. Their findings show that the more distantly related two species are, the more amino acid differences there are in their hemoglobin.

24. Models that use mutation rates to measure evolutionary time. • molecular clocks

25. Pauling and Zuckerkadl found that mutations tend to add up at a _________ _____ for a group of related species. • constant rate

26. How may a geologic event be related to a rate of mutation? • Geologic events may be the cause to separate or isolate a species. If the species is subjected to a different environment, different mutations may occur and the geologic event was the impetus for genetic differentiation.

27. Pauling and Zuckerkandl confirmed that the number of amino acid differences _________ with the evolutionary time between each group of species. • increases

28. Why is the comparison between amino acids in hemoglobin between species an important discovery? • The amino acid differences are greater the farther back one goes along the evolutionary history(timeline). Humans have 16 differences with mice, 18 with the horse, 35 with a bird, and 79 with a shark.

29. DNA found only in mitochondria. (mt DNA) Always inherited from the mother. (nuclear DNA is a combination of DNA from both parents) • mitochondrial DNA

30. A type of RNA useful for studying distantly related species, such as species that are in different kingdoms or phyla. • Ribosomal RNA rRNA

31. When studying the relationships among species over longer time scales, it is best to use a molecule that has a ___________ mutation rate. • lower

32. Who first used rRNA to establish that archaea diverged from the common ancestor they share with bacteria almost 4 billion years ago? • Carl Woese

33. How are molecular clocks used to measure evolutionary time? • The clocks presume that mutations occur at a constant rate for any clade or group of related taxa. Because these changes occur at a relatively constant and predictable rate, the changes can be used to measure how long ago different lineages diverged.

34. What are the benefits of mitochondrial DNA and ribosomal RNA as molecular clocks? • Mitochondrial DNA accumulates mutations relatively quickly, so it is most useful for analyzing relatedness within closely related species or change within a species. Ribosomal RNA has many conservative regions that accumulate mutations relatively slowly, so it is useful for studying taxa that are more distantly related.

35. What molecular clock might be useful to examine the evolutionary relationship between several phyla in the kingdom Plantae? • rRNA, because it accumulates mutations relatively slowly

36. Why did Woese propose classifying bacteria and archaea into separate domains, rather than just separate kingdoms? • The genetic difference between these groups of prokaryotes is greater than the genetic difference between the four eukaryotic kingdoms.

37. What are the three domains in the tree of life? • Bacteria, Archaea, Eukarya

38. Single celled prokaryotes. One of the largest groups of organisms on Earth. • Bacteria

39. Single celled prokaryotes that have the ability to live in extreme environments because of their cell walls. • Archaea

40. A domain that contains all organisms made of eukaryotic cells. They may be single celled, colonial, or multicellular. • Eukarya

41. Why do some scientists believe that bacteria and archaea have no true species? • Many of these organisms transfer genes among themselves outside of typical reproduction. They do not reproduce sexually. We define species as the ability to produce offspring by the combining of a male and female. If bacteria reproduce by binary fission, they cannot by definition be considered species.

42. Why are protists, plants, fungi, and animals classified into the same domain but into different kingdoms? • They all have eukaryotic cells, but are classified in different kingdoms based on differences in other characteristics.

43. If you come across an unusual single celled organism, what parts of the cell would you study in order to classify it into one of the three domains? • The nucleus (or lack thereof) and the cell wall

44. Explain, using the traditional definition of species, why it is difficult to classify some bacteria and archaea at the species level. • A species can be defined as an interbreeding group of organisms that produce fertile offspring. But bacteria and archaea do not breed to produce offspring; they reproduce by binary fission. In reproduction, parents pass genetic material to their offspring. However, many bacteria and archaea can take up genetic material from their environment – a transfer of genes outside of typical reproduction that does not occur in eukaryotes.

45. The Archaea lineage may include the first life on Earth, which began under much different environmental conditions from those present today. What characteristics of archaea help to support this statement? • Archaea exist in extreme environments that are similar to those of early Earth.

46. The scientific name for humans is Homo sapiens. What genus do humans belong to? • Homo

47. A particular DNA sequence accumulated three mutations over 10,000 years. After how much time would you expect this sequence to have accumulated six more mutations? Explain. • 20,000 years. Mutations occur at a fairly constant rate.

48. Are species in the same family more or less closely related than species in the same class? • Class is a more general taxon than family. Organisms in the same family are more closely related than organisms in the same class.

49. How many clades are represented in this cladogram? • A B C D • 3 • one with A, B, C and D • One with B, C and D • And one with C and D

50. What represents the derived characters that were used to construct this cladogram? • A B C D • The hash marks 1,2,3 and 4. 4 3 2 1